Nothing Special   »   [go: up one dir, main page]
Previous Article in Journal
Medicinal Herbal Extracts: Therapeutic Potential in Acute Lung Injury
You seem to have javascript disabled. Please note that many of the page functionalities won't work as expected without javascript enabled.
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Future Pharmacology
Volume 4
Issue 4
10.3390/futurepharmacol4040038
futurepharmacol-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

HPV Proteins as Therapeutic Targets for Phytopharmaceuticals Related to Redox State in HPV-Related Cancers

by
Alfredo Cruz-Gregorio
1,*,
Ana Karina Aranda-Rivera
2 and
José Pedraza-Chaverri
2
1
Departamento de Fisiología, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano 1, Belisario Domínguez Sección 16, Tlalpan, Mexico City 14080, Mexico
2
Laboratorio F-315, Departamento de Biología, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
*
Author to whom correspondence should be addressed.
Future Pharmacol. 2024, 4(4), 716-730; https://doi.org/10.3390/futurepharmacol4040038
Submission received: 20 August 2024 / Revised: 14 September 2024 / Accepted: 30 September 2024 / Published: 4 October 2024
Browse Figures
Figure 1
<p>Phytopharmaceutical molecules with anticancer effects, inducing cell death via apoptosis. Cyanidrical derivative of 11-keto-β-boswellic acid, known as 2-cyano-3,11-dioxide-1,12-dien-24-oate butyl (BCDD); human papillomavirus (HPV); p53-upregulated modulator of apoptosis (PUMA); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); kinase B (AKT); estrogen receptor (ER); Epigallocatechin-3-gallate (EGCG); lipid from Pinellia pedatisecta Schott (PE).</p> "> Figure 2
<p>Phytopharmaceutical molecules with anticancer effects, targeting HPV E6/E7 oncoproteins. Staurosporine (ST); mouse double minute 2 homolog (MDM2); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); activator protein 1 (AP-1); inducible nitric oxide synthase (iNOS); cyclooxygenase-2 (COX-2); interleukin (IL); peroxisome proliferator-activated receptor γ (PPARγ); B-cell lymphoma 2 (BCL-2).</p> "> Figure 3
<p>Quercetin and DHA decrease HPV E6/E7 oncoproteins by activating proteasome and p53. Staurosporine (ST); Docosahexaenoic acid (DHA); ubiquitination-proteasome system (UPS); reactive oxygen species (ROS); growth phase 2 (G2).</p> ">
Versions Notes

Abstract

:
The high-risk Human Papillomavirus (HR-HPV) is the causal agent of different human cancers such as cervical, vulvar, and oropharynx cancer. This is because persistent HR-HPV infection alters several cellular processes involved in cell proliferation, apoptosis, immune evasion, genomic instability, and cellular transformation. The above is mainly due to the expression of early expression proteins of HR-HPV, which interact and alter these processes. HR-HPV proteins have even been shown to regulate redox state and mitochondrial metabolism, which has been suggested as a risk factor for cancer development. Redox state refers to a balance between reactive oxygen species (ROS) and antioxidants. Although ROS regulates cell signaling, high levels of ROS generate oxidative stress (OS). OS promotes damage to DNA, proteins, carbohydrates, and lipids, which causes mutation accumulation and genome instability associated with cancer development. Thus, OS has been associated with the establishment and development of different types of cancer and has recently been proposed as a cofactor in HR-HPV-associated cancers. However, OS also induces cell death, which can be used as a target for different molecules, such as phytochemicals. Furthermore, phytochemicals target HPV oncoproteins E6 and E7, causing their degradation. Because phytochemicals could induce OS and target HPV oncoproteins, we hypothesize that these compounds induce cell death in HPV-associated cancers. Since the redox state is crucial in developing, establishing, and clearing HR-HPV-associated cancer, this review focuses on evidence for using phytochemicals as therapeutic agents that target HPV proteins and the redox state to induce the elimination of HPV-related cancers.

1. Introduction

Human Papillomavirus (HPV) is the most common sexually transmitted infection worldwide, which usually spreads from person to person during skin-to-skin contact, infecting any part of the genital area, including the vulva, the inside of the vagina, or the penis [1]. It can even infect the anus and some areas of the head and neck, throat, tongue, and tonsils [2]. Although most HPV infections resolve within less than 2 years, some viral types, particularly HPV 16 and HPV 18, can persist for decades and cause different types of cancer, with cervical cancer being the most common. In 2022, cervical cancer was one of the most important causes of mortality in women, occupying the fourth most common cancer among women, ranking only after breast, lung, and colorectal cancer [3].
HPVs are a large and diverse group of viruses with more than 200 fully characterized types [4]. The HPV types identified so far are classified as low-risk HPV (LR-HPV) or high-risk HPV (HR-HPV), depending on their carcinogenic potential, where LR-HPV is associated with benign lesions or warts in the anogenital region and on the skin, as well as infections of the respiratory system. In contrast, HR-HPV is associated with the development of cancer [5].
Cancer development is related to HR-HPV protein expression since these proteins interact and alter several cellular processes involved in cell proliferation, apoptosis, immune evasion, genomic instability, and cellular transformation [6]. Moreover, HR-HPV proteins have even been shown to regulate the redox state, which has been suggested as a risk factor for cancer development [7]. Redox state refers to the balance among reactive oxygen species (ROS) and antioxidants that reduce them. An imbalance of this redox state can be caused by a significant increase in the generation of ROS or by low detoxification by the cellular antioxidant system that neutralizes and eliminates them, causing oxidative stress (OS) and tissue damage [8]. ROS are highly reactive compounds formed by oxygen-containing free radicals, such as the superoxide anion radical (O2•−) and hydroxyl radical (HO•), and non-radical oxidant molecules, such as hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) [8]. The production of ROS can be generated by various cellular processes or chemical reactions associated with metabolism and oxidative bursts. However, its cell production mainly occurs in the mitochondria during the production of adenosine triphosphate (ATP) in the electron transport chain due to the partial reduction in molecular oxygen (O2), forming O2•−, which, in turn, is reduced to H2O2 by superoxide dismutase (SOD). Subsequently, the H2O2 is reduced to H2O by another enzyme, such as catalase (CAT), glutathione peroxidase (GPx), and other peroxidases [8]. ROS regulates cell signaling and many processes that induce cell proliferation and differentiation. However, high levels of ROS generate OS, which promotes damage to DNA, mutation accumulation, and genome instability associated with cancer development [9]. OS-induced genomic instability is associated with DNA breakage and cross-linking, where the DNA damage repair (DDR) machinery hybridizes the HPV genome with the host cell genome, resulting in the viral genome integration into the cellular genome [10,11]. During this process, there is a loss of the open reading frame for the expression of E2, which is an antagonist of the expression of the E6 and E7 oncoproteins, so at this time, these oncoproteins are overexpressed, inducing the cancerous phenotype associated with HPV [12]. Thus, OS has been associated with the establishment and development of HR-HPV-associated cancers.
Interestingly, OS also induces cell death, which can be used as a target for different molecules, such as phytochemicals, which induce cell death via redox state regulation [13]. This is because phytochemicals may be pro-oxidant components that, upon interacting with HPV-associated cancer cells with an oxidative condition, may synergize with the pro-oxidant activity of phytochemicals, inducing cell death.
Since HPV proteins are crucial for developing, establishing, and even eliminating HR-HPV-associated cancers, these proteins may be targeted by different phytochemicals that can also induce OS. Thus, HPV protein degradation and OS induction may be a potential target of phytochemicals in synergizing cell death of HPV-related cancers. This review focuses on the evidence for the association of the redox state with HPV proteins, pointing out the use of phytochemicals that target HR-HPV proteins and the redox state to eliminate these cancers.

2. HR-HPV and Function of Its Proteins during the Viral Life Cycle

HPV types are divided into five genera or genotypes (alpha, beta, gamma, mu, and nu) based on DNA sequence analysis. Genotypes classified as alpha include mucosal HR-HPV associated with the development of cervical cancer [14]. Beta genotypes encompass HR and LR-HPV associated with asymptomatic infections in people with immunocompetent immune systems. However, in immunocompromised people, a persistent infection may increase the risk of developing skin cancer [15]. Genotypes classified as gamma, mu, and nu are only present in benign skin lesions, so they will not be addressed in this review [16].
HR-HPV genomes typically consist of 8000 DNA base pairs divided into three regions of interest: (1) the long control region (LCR), which contains the elements necessary for HPV genome replication and the transcription of HPV genes; (2) the early (E) region, which codes for six proteins (E1, E2, E4, E5, E6, and E7) involved in virus replication and regulation of the HR-HPV life cycle (E1 and E2) and is even part of the oncogenic capacity of HPV; and (3) late (L) region genes that encode the L1 and L2 proteins, which build the capsid and allow the assembly of the viral particles (Table 1) [16].
As mentioned below, HR-HPV proteins are necessary for the HR-HPV life cycle and the induction of tumorigenesis. For instance, HR-HPV reaches its target cells through microlesions in the epithelium. It has been proposed that healing, where active cell division occurs, is necessary for the virus genome to enter the nucleus, so lesion formation is required for infection of a mitotically active cell [17]. HR-HPV infection occurs after HPV contacts its target cell, where experimental models suggest that the virus enters via endocytosis mediated by vesicles coated with clathrin and/or caveolin, depending on the type of HR-HPV [17,18]. Infection caused by HPV requires the binding of L1 with the heparan sulfate proteoglycan (HSPG) receptors and possibly also laminin, which initiates the infection and entry of the viral particles to the basal lamina [19]. These interactions produce structural changes in the virion capsid, allowing L2 to interact with the host membrane, favoring transfer to secondary receptors such as alpha 6 integrin and growth factor receptors in the basal keratinocyte, which is necessary for virus internalization [20]. Once the viral particle has been endocytosed, it begins its journey to the nucleus through an early and late endosome, causing the disassembly of the capsid during its transport to the Golgi network and the subsequent transfer of the viral genome to the nucleus. During this process, the L2 protein is released with the viral DNA from the late endosomes and enters the nucleus after the nuclear envelope breakdown during mitosis [21]. This is how L2, forming the L2-DNA complex, ensures the correct entry of the viral genomes into the nucleus. As soon as HR-HPV DNA reaches the nucleus of the basal cells, transcription of the HPV viral proteins and amplification of the genome begins. The viral genome can remain in episomal form with a low copy number or abandon this latency and take advantage of the cellular differentiation of the epithelium [22]. In this way and in parallel with the maturation of the epithelium, HPVs express their genes sequentially. First, the early genes are expressed in the basal layers, and then, in the superficial layers of the more differentiated epithelium, their late proteins [23]. Briefly, in infected basal keratinocytes, the viral protein E2 participates in the initiation of viral DNA replication by loading the E1 helicase at the origin of replication, and although E1 is the main replication protein, E2 enhances and supports the functions of E1. These viral proteins recruit the cell’s DNA replication machinery to initiate viral DNA replication and ensure proper viral genome segregation between daughter cells [24,25]. Likewise, oncoproteins E6 and E7 interact with human telomerase reverse transcriptase (hTERT), p53, and pRB, causing cell immortalization, preventing cell death, and promoting the cell cycle [6]. In the upper layer, E4 induces the rupture of cellular keratin, which releases virions when the epithelium is detached [26]. L1 and L2 are expressed in these layers, allowing the viral capsid to form and envelop the HR-HPV genome [27,28]. This process continues under certain physiological conditions of “immunological permissiveness” induced by E5, and after a generally long period of persistence of the infection, the HPV genome integrates into the cellular genome. During this integration, E2, causing the overexpression of E6 and E7 oncoproteins mentioned above. The latter induces significant cell cycle deregulation, apoptosis, and cell proliferation, leading to cancer development [12].

3. Redox State and HR-HPV Proteins

There is a broad relationship between the redox state, infection, and development of cancer associated with HR-HPV. The latter is because infections caused by this virus generate chronic inflammation as a response of the immune system, producing migration of leukocytes to the site of infection that releases chemokines, favoring the eradication of the viral infection. This chronic inflammatory process increases ROS levels; however, the chronic inflammatory process is not the only producer of ROS [29]. The presence of HPV proteins is also associated with the reduction and production of these species [7]. Thus, HR-HPV proteins related to the redox state have emerged as a crucial target in the prevention and treatment of HPV-related cancer since by targeting these proteins, the development of these types of cancer can be considerably reduced.
For example, cells derived from HPV-negative C33A cervical cancer were examined to determine how the ectopically expressed E1, E2, E6, and E7 viral proteins of types 16 and 18 comprehensively regulated redox status. E6 was found to reduce the amount of the main intracellular antioxidant glutathione (GSH) and CAT protein levels, along with their enzymatic activity, which increased ROS production and DNA damage. In contrast, E7 oncoproteins increased GSH levels and CAT protein levels and activity, associated with decreased ROS levels, without affecting DNA integrity. In turn, the coexpression of the E6 and E7 oncoproteins counteracted the effects observed individually for each of the viral proteins [30]. Interestingly, the combined expression of E5, E6, and E7 increases the levels of ROS and DNA damage measured by phosphohistone 2AX (γH2AX) and the comet assay in HaCaT epithelial cells. It was also found that during hypoxia, these oncoproteins further increased ROS and DNA damage [31]. It has been shown that HR-HPVs produce multiple full-length E6 mRNA transcripts through alternative splicing [32]. Thus, the HR-HPV E6 oncoprotein can be expressed as full-length and spliced isoforms, which lack the C-terminal end of full-length E6, corresponding to smaller isoforms called E6*. E6*s allow the virus to expand its proteome from a reduced genome size, which promotes the genetic diversity and resistance of the virus against host immunity, increasing its chances of survival [32]. Because the functions of the splice variants related to the redox state were still unclear, different studies were carried out using HPV+ (SiHa) and HPV- (C33A) cervical carcinoma cells to demonstrate the influence of HR-HPV 16 E6* [33]. Thus, it was discovered that E6* produces changes in mitochondrial function, sustained depolarization, and reduces the level of GSH due to the cellular OS produced. There is evidence that a reduced level of GSH can also be an early marker of cell death via apoptosis; therefore, when the level of GSH decreases, the release of cytochrome c occurs, which is an indicator of a more permeable mitochondrial membrane and an increase in the activity of caspase-9 and 3, inducing mitochondrial apoptosis [34]. The TP53-induced glycolysis and apoptosis regulator (TIGAR) is a 2,6-bis-fructose-phosphatase that localizes to the outer membranes of mitochondria under conditions of hypoxia or glucose deprivation and contributes to mitochondrial quality control, preventing mitophagy and ROS accumulation by increasing intracellular levels of nicotinamide adenine dinucleotide phosphate (NADPH) and reduced GSH [35]. E6 has recently been shown to activate TIGAR, providing protection to cells against oncogene-induced oxidative genotoxicity. In this context, it has been shown that E6 oncoprotein triggers a metabolic stress response similar to the Warburg effect and activates the PI3K/PI5PI4K/AKT signaling pathway, which phosphorylates TIGAR on serine residues and targets it to the mitochondria independently of hypoxia in HPV-transformed cells [35]. In HPV-positive primary cervical cancer tissues, elevated levels of TIGAR, p53, and c-Myc are observed. Furthermore, their xenograft studies have shown that suppressing TIGAR expression by lentivirus-siRNA inhibits HR-HPV-induced tumor formation in vivo. So, these findings suggest that the modulation of p53 survival signals and the antioxidant functions of TIGAR could play additional crucial roles during HPV-induced carcinogenesis [35].
On the other hand, Marullo et al. [36] found that the expression of E6 and E7 induces ROS production in an isogenic human cell model of HPV-positive head and neck cancer (HNSC). They demonstrated that OS generated by E6/E7 is mediated by nicotinamide adenine dinucleotide phosphate oxidases (NOX), leading to DNA damage and chromosomal aberrations. This mechanism of genomic instability differentiates HPV-positive tumors from HPV-negative tumors, as NOX-induced oxidative stress was only observed in HPV-positive cells. They also identified NOX2 as the primary source of HPV-induced oxidative stress since NOX2 inhibition significantly reduced ROS generation, DNA damage, and chromosomal aberrations in HPV-positive cells. Due to their chronic OS, HPV-positive cells are more susceptible to ROS-induced DNA damage and ionizing radiation (IR). Indeed, exposure to IR results in the formation of complex lesions in HPV-positive cells, as indicated by the higher amounts of chromosome breaks observed in this cell group [36]. Regarding E6, it showed that E6 influences the phenotype of HNSCC cells by altering mitochondrial metabolism partly because the E6 oncoproteins of HPV-16 and HPV-18 generate ROS production and OS. The increase in ROS is due to the E6 oncoproteins of HPV-16 and HPV-18 improving cellular respiration and promoting mitochondrial oxygen consumption, which produces an increase in the levels of mitochondrial proteins, a process associated with a decrease in phosphorylation of protein kinase B (AKT) at serine 473 (p-AKT) and therefore an increase in mitochondrial mass that could be related to the increase in FoxO3a in the presence of E6 since it is an essential molecule in inducing mitochondrial production. On the other hand, ATP-linked respiration (or oxidative phosphorylation [OXPHOS]-linked respiration) was not significantly affected due to the presence of the E6 protein; however, there was an increase in mitochondrial respiration associated with the uncoupling of mitochondria that promotes the production of ROS, producing OS as observed by the drop in the glutathione/glutathione disulfide (GSH/GSSG) ratio. These increases in OS produce DNA damage evaluated by measuring γH2AX levels, demonstrating that E6 also causes DNA damage in HNSCC cells [37].
Shim J. and his research team [38] worked on the HPV16 E7 oncogene and its effect on receptor-mediated apoptosis, cell death through the mitochondrial pathway, and the modulation of apoptosis-related factors. This study demonstrated that the expression of E7 modulates the expression of Bcl-xL, IL-18, Fas, Bad, and cytochrome C, which provides the cell with resistance to cell death caused by OS. The protection against OS is through the positive regulation of CAT in HaCaT cells that overexpress E7. This antioxidant enzyme is part of the antioxidants that eliminate H2O2 and are part of various transduction pathways of physiological and oxidative stimulus signals, which is why they are important in carcinogenesis and tumor progression since their overexpression prevents the production of ROS [38]. This same group of researchers had already provided evidence that this defense is partly attributed to the elevated expression of CAT [39]. Note that the anatomical site where HPV proteins are expressed influences the redox state differentially. Thus, it has been shown that in epithelia related to the head and neck, the expression of E6 and E7 induces ROS and OS, and in other anatomical sites, such as the cervix model, this coexpression does not induce ROS or OS. However, adding E5 expression increases ROS and OS in an epithelial model [31], demonstrating high complexity in how HPV proteins interact with the cellular environment and can even synergize processes such as OS.
Regarding HR-HPV E2, it has been shown that E2 from high-risk HPV-18 is located in the mitochondrial membranes, where it modifies the cristae morphology due to the interaction of E2 with the OXPHOS proteins of complex III. This interaction induces the production of mitochondrial ROS. Although this release of ROS does not induce apoptosis, it is correlated with the stabilization of HIF-1α and the increase in glycolysis activity. Furthermore, it was shown that this interaction between E2 and mitochondria is not shared by the E2 protein of non-oncogenic HPV-6, suggesting that the alteration of cellular metabolism induced by HR-HPV E2 proteins could play a role in the development of cancer by promoting ROS and the Warburg effect [40]. The immune system is key in the development of high-grade squamous intraepithelial lesions since normally, after HPV infection, the immune system eliminates them in most cases. However, some infections evolve to the cancerous phenotype, which could be related to overcoming the immune system. Although the mechanisms of this latter immune overcoming are unclear, different evidence shows that the redox state and HPV proteins may be related. For example, a group of researchers worked with gC1qR, a multifunctional cellular protein of the immune system that interacts with complement components, in C33a and SiHa cells, providing evidence for the roles of gC1qR in HPV-16 E2-induced apoptosis [41]. The gC1qR protein, in addition to being the receptor for the globular heads of C1q, has various functions as it is part of the mitochondrial matrix, such as controlling cell growth, differentiation, and apoptosis, as well as inducing ROS production and increasing the uptake of Ca2+ by reducing the electron flow of complex I. This group of researchers indicated that gC1qR is a physiological inhibitor of HPV 16-induced cervical squamous carcinoma cell survival that interacts with E2, and due to this interaction, it induces mitochondrial dysfunction and, therefore, increases ROS production, OS, and cell death via apoptosis [41]. Thus, E2 could induce immune receptors, provoking mitochondrial dysfunction, ROS generation, and cell death. So far, we have not found any work relating E1 to the redox state. However, considering the combined expression of E1 and E2 proteins, it has been shown that the co-expression of E1 and E2 decreases GSH and MnSOD levels and SOD activity, increasing ROS levels, followed by an increase in γH2AX. Thus, the latter works show that combining HPV proteins can enhance the effect on the redox state, provoking OS and oxidative damage. Note that the combination of different HPV proteins is related to their expression in infection or in a cancer context; that is, in the infection process, E1 and E2 are overexpressed, but in cancer, the expression of these proteins is decreased. In contrast, E5, E6, and E7 expression is overexpressed in cancer but decreased in infection. Note that the E2 protein downregulates E6 expression, so the context in which all proteins are overexpressed simultaneously is not functional for infection or cancer. However, it is advisable to know the possible effects of the expression of HPV proteins on the redox state. De Marco F. et al. [42] showed that HK-168 cells that had been transformed in vitro with the complete HPV-16 genome had a lower apoptotic effect and, therefore, an increase in detoxification mechanisms after ultraviolet (UV)B radiation exposure compared to HaCaT cells, which did not express any HPV protein. Likewise, HK-168 cells showed an increase in the activity of SOD and quinone oxidoreductase 1 (NQO1), which is an antioxidant enzyme that catalyzes the reduction in quinones from proteins and lipids to their corresponding hydroquinones [42]. Likewise, De Marco F. and his research team demonstrated that tissues infected by HPV-16 from patients with invasive squamous cervical carcinoma or with dysplastic lesions of HR-HPV showed high levels of glutathione-S-transferase (GST) compared to the tissue control [43]. Adding to the above, a team of researchers measured the proteins from the host cell that interact with the E7 protein of HPV-16. They found that the E7 protein of HPV-16 interacts and stabilizes the GSTP1 protein under UV radiation and exposure to H2O2 compared to control cells, which have neutralizing activities against cell damage [44]. Although HPV proteins normally have effects on modulating the redox state, during the HR-HPV viral cycle, the L1 and L2 proteins require OS conditions to properly complete the assembly of the capsomer. This is because, in an oxidative environment, disulfide interactions between the L1 proteins are promoted, accelerating the formation of disulfide bridges in L1 proteins [45]. Moreover, the HR-HPV E7 protein has a high cysteine content that remains in its basal reduced state under conditions like a normal cell. However, a stable disulfide bridge forms between cysteines 59 and 68 under OS. Cysteine 59 protects other cysteines, and its mutation increases the overall susceptibility of E7 to oxidation, including the central cysteine 24, which binds to the pRb protein. Interestingly, the glutathionylation of Cys 24 also inhibits pRb binding, which is deglutathionylated upon reduction, with this protection suggesting the crucial role of this Cys 24 in the HPV E7 protein. Remarkably, it has been shown that Cys 59 and 68, located 18.6 Å apart, induce a significant structural reorganization, maintaining a strong zinc association. Note that these changes are reversible upon the restoration of a reducing environment, and this restoration by E7-induced enzymes such as CAT may be a possible explanation for the activation of enzymes that decrease ROS and, therefore, function as a redox on–off switch in E7-binding proteins such as pRb. Thus, conserving these non-canonical cysteines in the HPV E7 proteins suggests a redox function that, together with its previously known chaperone function, supports the idea of a multifunctional pathological role of this viral oncoprotein [46]. Therefore, HPV proteins regulate the redox state, but at the same time, HPV proteins depend on the redox state.

4. HPV Proteins as Redox Targets for Phytopharmaceuticals

4.1. HPV Oncoproteins as the Target of PE and BCDD Phytopharmaceuticals

Phytopharmaceutical molecules are polyphenols with preventive and anticancer effects that may have the ability to specifically target viral oncogenes [47]. Phytopharmaceuticals are of great interest as pharmaceutical agents against HPV-related cancers, where HPV proteins have emerged as a crucial target in the prevention and treatment of cervical cancer. That is why a group of researchers studied the rhizome of Pinellia pedatisecta Schott, known as Pedate Pinellia Rhizome in traditional Chinese medicine, which has long been used to treat various conditions, such as poisonous snake bites, swelling, and toxins. Thus, Li et al. [48] conducted a study to evaluate a new lipid-soluble extract obtained from the rhizomes of Pinellia pedatisecta Schott (PE) on cervical cancer cells (Table 2, Figure 1). They examined its effects on cell growth in HR-HPV-positive cervical cancer cell lines, the expression of HPV E6, and the corresponding possible mechanisms of action, where they demonstrated that PE significantly inhibits the growth of CaSki and HeLa cervical cancer cells in in vitro cultures but does not affect the growth of normal HBL-100 cells [48]. These results suggest that PE exerts a specific effect on cervical cancer cells that are positive for HR-HPV types 16 and 18. Likewise, they also found that PE can negatively regulate the expression of the E6 gene at the mRNA and protein levels in CaSki and HeLa cells. Therefore, the E6 gene could be a key target of PE action since it could reverse the oncogenic activities associated with said gene, including immortalization and avoiding apoptosis. This group also provided evidence that PE can activate p53 and induce apoptosis in cervical cancer cells since after treatment with PE, nuclear condensation and the formation of apoptotic bodies were clearly observed in the CaSki and HeLa cell lines [48]. Moreover, the results obtained by RT-PCR and Western blotting revealed that PE suppressed the expression of Bcl-2 while it stimulated the expression of Bax, caspase-8, and caspase-3 in CaSki cells, suggesting that PE could activate caspase-8 through the mitochondria-dependent pathway, which subsequently triggers caspase-3 activation. The latter, in turn, participates in the fragmentation of cytoskeletal and nuclear proteins, which ultimately induces apoptosis [48]. On the other hand, boswellic acids, a series of pentacyclic terpenoid molecules produced by the plants of the genus Boswellia, and similar compounds have been reported to show remarkable anticancer activity against various tumors [49]. Khan S et al. [50] studied and provided evidence that treatment with a new cyanidrical derivative of 11-keto-β-boswellic acid, known as 2-cyano-3,11-dioxide-1,12-dien-24-oate butyl (BCDD), produced a reduction in the expression of the viral E6 mRNA and promoted the accumulation of transcriptionally active p53 in the nucleus of HeLa cells. Also, BCDD significantly regulated the temporal expression of p53/PUMA/p21, inhibiting the activation of p-AKT and nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) cell survival pathways. Furthermore, BCDD accelerated the activation of PUMA through the p53 pathway, resulting in the translocation of p53 and p21 to the cell nucleus. In addition, BCDD suppressed the antiapoptotic activity of Bcl-2, increased the expression of Drp-1, and altered mitochondrial functions, thus promoting the activation of proapoptotic proteins and caspases. It also inhibited telomerase expression, likely leading to a marked reduction in the tumorigenic potential of high-grade cervical cancers. As a result, BCDD induced apoptosis in cervical cancer cells, as evidenced by DNA fragmentation and poly (ADP-ribose) polymerase (PARP) cleavage [50].

4.2. HPV Oncoproteins as the Target of EGCG and Jaceosidin Phytopharmaceuticals

Catechins are dietary polyphenols found in green tea and are associated with diverse beneficial health effects. Epigallocatechin-3-gallate (EGCG), the most abundant and active tea catechin, is known for its biological and pharmacological properties, including antioxidative and antitumor activity. EGCG has shown antitumor effects on different cancers such as breast, ovarian, skin, lung, colon, liver, stomach, and prostate both in vitro and in vivo. In HPV-related cancer, EGCG decreases the cell viability of HeLa and Caski cells, arresting the cell cycle and inducing apoptosis. These effects are associated with reducing HPV E6/E7 expression in these HPV-positive cervical cancer cells. Moreover, EGCG inhibits the expression of estrogen receptor (ER)α and aromatase, key molecules in estrogen synthesis in cervical cancer [51]. Interestingly, EGCG, folic acid, vitamin B12, and hyaluronic acid have been shown to clear HPV infection in low-grade squamous intraepithelial lesions (LSIL) of cervical lesions. This was demonstrated by results from a Papanicolaou (PAP) smear, an HPV DNA test, and biopsies, suggesting an eradication of viral infection on cervical lesions in patients. Thus, the authors suggest their results support the potential of conducting randomized placebo-controlled studies, bringing it closer to treatment in regulating redox status and eliminating cancer cells. This example of phytochemical treatment goes beyond in vivo and in vitro studies, bringing it closer to a treatment for patients infected with HPV [62]. Jaceosidin (4,5,7-trihydroxy-3,6-dimethoxyflavone), a compound isolated from Artemisia argyi, is a molecule that inhibits the binding between the E6 oncoprotein and the p53 tumor suppressor protein. Jaceosidin also inhibited the binding between the E7 and the Rb tumor suppressor protein in HPV+ SiHa and CaSki cells [52]. Thus, it has been shown that jaceosidin inhibited the functions of the E6 and E7 oncoproteins. In this regard, Cherry et al. found that luteolin can interact directly with HPV-16 E6 and E6AP, which avoids p53 degradation via proteasome. This group of researchers used a Docking analysis to investigate the binding of lutein and E6, finding that luteolin binds to E6 in a hydrophobic pocket, interfering with the binding between E6 and E6AP [53].

4.3. HPV Oncoproteins as the Target of Wogonin, Curcumin, Tanshinone IIA, Berberine, and Withaferin a Phytopharmaceuticals

Wogonin, another phytotherapeutic compound derived from Scutellaria baicalensis, suppresses E6 and E7 oncoproteins expression, increasing p53 and pRb tumor suppressors in SiHa and CasKi HPV+ cells (Figure 2) [54]. Curcumin, a hydrophobic polyphenol derived from the rhizome of curcuma, also downregulates HPV E6 and E7 oncogenes, promoting apoptosis in CaSki cells. With this downregulation, curcuma decreases the NF-kB and activator protein 1 (AP-1) transcription factors and COX-2, inducible nitric oxide synthase (iNOS), and cyclin D1 proteins [55,63]. Tanshinone IIA, a diterpenoid from Salvia species, also downregulates E6 and E7, inhibiting the growth of HeLa, SiHa, and CasKi, triggering apoptosis [56]. Berberine, an alkaloid from Berberis species, decreases E6 and E7, inhibiting cervical cancer cell growth [57]. Withaferin A (steroid Lactone) from Withania somnifera represses E6 and E7 oncoproteins, inducing apoptosis in CasKi cells [58]. The latter works suggest that these compounds might be a potential drug for treating cervical cancers targeting HPV oncoproteins. Note that although the latter works do not measure the redox state, it is possible that ROS production is induced because E6 induces mitochondria dysfunction, which induces ROS levels increases and OS, resulting in mitochondrial apoptosis.

4.4. HPV Oncoproteins as the Target of Amentoflavone and Staurosporine

Flavonoids are a group of secondary plant compounds that show a wide range of biological activities, including antibacterial, antiviral, antioxidant, and anticancer properties. Numerous flavonoids have been shown to have antitumor effects in several human cancer cell lines. Amentoflavone, a biflavonoid present in Selaginella Tamariscina, has all the latter benefits; however, the mechanism underlying the anticancer effects of amentoflavone in human cervical cancer cells is unknown. Lee S, et al., [59] demonstrated that amentoflavone induces apoptosis in cervical cancer SiHa and CaSki cells by suppressing the expression of the HPV E7 protein. They observed that amentoflavone modulates cyclins and tumor suppressors in these cells, where cyclins and hyperphosphorylated retinoblastoma (p-pRb) are downregulated, while inhibitors of cyclin-dependent kinases and p53 are enhanced. Amentoflavone also increases the expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and phosphatase and tensin homolog deleted on chromosome ten (PTEN) 10, while inhibiting the expressions of cyclooxygenase-2 (COX-2) and E7-mediated interleukin-32 (IL-32), along with decreased AKT phosphorylation, suggesting that amentoflavone could act as a PPARγ activator. Furthermore, a decrease in the expression of the anti-apoptotic factor B-cell lymphoma 2 (BCL-2) and an increase in the expression of the apoptotic factor Bax was observed, resulting in the release of cytochrome c into the cytosol of cervical cancer cells treated with amentoflavone. Likewise, amentoflavone treatment leads to the activation of caspases-3 and -9 and the proteolytic cleavage of PARP [59]. Thus, these findings indicate that amentoflavone activates PPARγ/PTEN expressions, inducing apoptosis by suppressing E7 expression, cell cycle arrest in the sub-G1 phase, and mitochondria-derived intrinsic pathways in cells of human cervical cancer SiHa and CaSki, so these results suggest that amentoflavone has a potential for development as a therapeutic agent for the human cervical cancer-targeting HPV E7 oncoprotein [59]. Another group of researchers carried out studies using staurosporine (ST). ST is a natural product originally isolated from the bacterium Streptomyces staurosporeus in CaSki and HeLa cells. The ways in which ST activates the apoptotic cascade were not completely understood; therefore, years later, this group of researchers conducted studies to determine whether ST-induced apoptosis is associated with the expression of ST. Likewise, they examined the ability of ST to regulate the expression of the viral oncogenes E6 and E7, the cellular oncogene MDM2, and certain cell cycle regulators, as well as studying the biochemical changes that affect subcellular compartments [60]. This group of researchers provided evidence that ST inhibited the expression of the viral oncogenes E6 and E7, as well as the expression of MDM2, resulting in an increase in the levels of p53, which was transiently localized to the mitochondria. Furthermore, a simultaneous increase in p53-regulated proteins p21(WAF1) and Bax was observed, while the expression of Bcl-2 and Bcl-X(L) decreased. After ST treatment, the release of cytochrome c to the cytosol and the activation of caspases-9 and -3 were observed, leading to the cleavage of poly (ADP-ribose) polymerase (PARP). Furthermore, characteristic morphological changes were observed that confirmed the execution of apoptosis [60]. These findings suggest that ST can reactivate apoptosis in HPV-positive human carcinoma cells targeting E6 and E7 oncoproteins, highlighting its potential as an effective chemotherapeutic agent to increase the sensitivity of tumor cells to apoptosis.

4.5. HPV Oncoproteins as the Target of DHA

It has been proven that docosahexaenoic acid (DHA), the most unsaturated omega-3 fatty acid, exhibits proapoptotic activity against tumor cells (Figure 3). Similarly, this compound induces apoptosis in SiHa cancer cells that express HPV-16, and this effect can be partially reversed by ubiquitin-proteasome proteasome system (UPS) proteasome inhibition, suggesting the involvement of the UPS in DHA-induced death in HPV-infected oncogenic cells [61]. In this work, Jing K et al. [61] provided evidence that the activation of UPS by DHA leads to proteasomal degradation of viral E6/E7 proteins and induction of apoptosis in HPV-infected cancer cells. Moreover, the increase in UPS activity and degradation of E6/E7 oncoproteins were linked to DHA-induced excessive mitochondrial ROS generation. Both exogenous OS and pharmacological induction of mitochondrial ROS showed DHA-like effects, and inhibition of ROS production suppressed UPS activation and stabilization of viral E6/E7 proteins, avoiding apoptosis. These findings identify a novel role for DHA in regulating UPS and E6/E7 HPV viral proteins and support using DHA as an anticancer agent with a unique mechanism for the chemoprevention and treatment of HPV-associated tumors [61]. Quercetin, a polyphenolic flavonoid with anticancer capacity, caused cell cycle arrest in the G2 phase and triggered apoptosis in both HeLa and SiHa cervical cancer cells. Likewise, it was observed that quercetin stimulated the activation of p53, increasing both the total amount of the p53 protein and its localization in the cell nucleus, which was associated with an increase in the expression of its transcriptional targets, such as Bax and p21, because quercetin at high concentrations can function as a pro-oxidant molecule that causes DNA damage, inducing cell cycle arrest and/or mitochondrial apoptosis, either independently or dependent on p53. Also, quercetin increased the activity of caspases 3/7 and generated cellular morphological changes characteristic of apoptosis in HeLa and SiHa cervical cancer cells. These findings are consistent with previous research showing how quercetin induced mitochondrial apoptosis. Based on molecular docking results, it was predicted that quercetin could interfere with the interaction between E6 and E6AP by binding to the E6 site, which could prevent the formation of the binding complex between E6 and p53 and, thus, the degradation of p53. Therefore, these results suggest that quercetin promotes the nuclear localization of p53 by interfering with forming the E6/E6AP complex in cervical cancer cells [64].

5. Conclusions

Research on HPV and its relationship with cancer has revealed the crucial importance of understanding redox status and mitochondrial metabolism in this context. This literature review has highlighted how the redox state plays a fundamental role in developing HPV-associated cancer, influencing key aspects such as cellular metabolism, survival, and apoptosis. High-risk HPV proteins have been observed to interfere with mitochondrial functions, driving cellular transformation towards cancer. However, these same proteins can also be sensitized to certain treatments that induce mitochondrial apoptosis. Therefore, it is suggested that developing therapies specifically targeting redox state, mitochondria, and HPV proteins in related cancers could offer better treatment options and improve patient survival. This approach could represent a significant advance in the fight against HPV-linked cancers, taking advantage of both the vulnerabilities and therapeutic opportunities identified concerning redox status and mitochondrial metabolism.

Author Contributions

Conceptualization and writing, A.C.-G.; review and editing, A.C.-G., A.K.A.-R. and J.P.-C.; figure preparation, A.K.A.-R. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Wolf, J.; Kist, L.F.; Pereira, S.B.; Quessada, M.A.; Petek, H.; Pille, A.; Maccari, J.G.; Mutlaq, M.P.; Nasi, L.A. Human Papillomavirus Infection: Epidemiology, Biology, Host Interactions, Cancer Development, Prevention, and Therapeutics. Rev. Med. Virol. 2024, 34, e2537. [Google Scholar] [CrossRef] [PubMed]
  2. Roman, B.R.; Aragones, A. Epidemiology and Incidence of HPV-Related Cancers of the Head and Neck. J. Surg. Oncol. 2021, 124, 920–922. [Google Scholar] [CrossRef] [PubMed]
  3. Bray, F.; Laversanne, M.; Sung, H.; Ferlay, J.; Siegel, R.L.; Soerjomataram, I.; Jemal, A. Global Cancer Statistics 2022: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J. Clin. 2024, 74, 229–263. [Google Scholar] [CrossRef]
  4. Chan, C.K.; Aimagambetova, G.; Ukybassova, T.; Kongrtay, K.; Azizan, A. Human Papillomavirus Infection and Cervical Cancer: Epidemiology, Screening, and Vaccination-Review of Current Perspectives. J. Oncol. 2019, 2019, 3257939. [Google Scholar] [CrossRef]
  5. Burd, E.M. Human Papillomavirus and Cervical Cancer. Clin. Microbiol. Rev. 2003, 16, 1–17. [Google Scholar] [CrossRef] [PubMed]
  6. Scarth, J.A.; Patterson, M.R.; Morgan, E.L.; Macdonald, A. The Human Papillomavirus Oncoproteins: A Review of the Host Pathways Targeted on the Road to Transformation. J. Gen. Virol. 2021, 102, 001540. [Google Scholar] [CrossRef]
  7. Cruz-Gregorio, A.; Manzo-Merino, J.; Lizano, M. Cellular Redox, Cancer and Human Papillomavirus. Virus Res. 2018, 246, 35–45. [Google Scholar] [CrossRef]
  8. Aranda-Rivera, A.K.; Cruz-Gregorio, A.; Arancibia-Hernández, Y.L.; Hernández-Cruz, E.Y.; Pedraza-Chaverri, J. RONS and Oxidative Stress: An Overview of Basic Concepts. Oxygen 2022, 2, 437–478. [Google Scholar] [CrossRef]
  9. Cruz-Gregorio, A.; Aranda-Rivera, A.K. Redox-Sensitive Signalling Pathways Regulated by Human Papillomavirus in HPV-Related Cancers. Rev. Med. Virol. 2021, 31, e2230. [Google Scholar] [CrossRef]
  10. Chen Wongworawat, Y.; Filippova, M.; Williams, V.M.; Filippov, V.; Duerksen-Hughes, P.J. Chronic Oxidative Stress Increases the Integration Frequency of Foreign DNA and Human Papillomavirus 16 in Human Keratinocytes. Am. J. Cancer Res. 2016, 6, 764–780. [Google Scholar]
  11. Molina, M.A.; Steenbergen, R.D.M.; Pumpe, A.; Kenyon, A.N.; Melchers, W.J.G. HPV Integration and Cervical Cancer: A Failed Evolutionary Viral Trait. Trends Mol. Med. 2024, 30, 890–902. [Google Scholar] [CrossRef] [PubMed]
  12. McBride, A.A.; Warburton, A. The Role of Integration in Oncogenic Progression of HPV-Associated Cancers. PLoS Pathog. 2017, 13, e1006211. [Google Scholar] [CrossRef] [PubMed]
  13. Gaikwad, S.; Srivastava, S.K. Role of Phytochemicals in Perturbation of Redox Homeostasis in Cancer. Antioxidants 2021, 10, 83. [Google Scholar] [CrossRef]
  14. Gheit, T. Mucosal and Cutaneous Human Papillomavirus Infections and Cancer Biology. Front. Oncol. 2019, 9, 355. [Google Scholar] [CrossRef]
  15. Oyouni, A.A.A. Human Papillomavirus in Cancer: Infection, Disease Transmission, and Progress in Vaccines. J. Infect. Public Health 2023, 16, 626–631. [Google Scholar] [CrossRef]
  16. Doorbar, J.; Egawa, N.; Griffin, H.; Kranjec, C.; Murakami, I. Human Papillomavirus Molecular Biology and Disease Association. Rev. Med. Virol. 2015, 25 (Suppl. S1), 2–23. [Google Scholar] [CrossRef] [PubMed]
  17. Cruz-Gregorio, A.; Aranda-Rivera, A.K. Human Papilloma Virus-Infected Cells. Subcell. Biochem. 2023, 106, 213–226. [Google Scholar] [CrossRef]
  18. Spoden, G.; Freitag, K.; Husmann, M.; Boller, K.; Sapp, M.; Lambert, C.; Florin, L. Clathrin- and Caveolin-Independent Entry of Human Papillomavirus Type 16--Involvement of Tetraspanin-Enriched Microdomains (TEMs). PLoS ONE 2008, 3, e3313. [Google Scholar] [CrossRef]
  19. Cruz-Gregorio, A.; Aranda-Rivera, A.K.; Ortega-Lozano, A.J.; Pedraza-Chaverri, J.; Mendoza-Hoffmann, F. Lipid Metabolism and Oxidative Stress in HPV-Related Cancers. Free Radic. Biol. Med. 2021, 172, 226–236. [Google Scholar] [CrossRef]
  20. Mikuličić, S.; Strunk, J.; Florin, L. HPV16 Entry into Epithelial Cells: Running a Gauntlet. Viruses 2021, 13, 2460. [Google Scholar] [CrossRef]
  21. DiGiuseppe, S.; Bienkowska-Haba, M.; Guion, L.G.M.; Keiffer, T.R.; Sapp, M. Human Papillomavirus Major Capsid Protein L1 Remains Associated with the Incoming Viral Genome throughout the Entry Process. J. Virol. 2017, 91, e00537-17. [Google Scholar] [CrossRef] [PubMed]
  22. Kajitani, N.; Satsuka, A.; Kawate, A.; Sakai, H. Productive Lifecycle of Human Papillomaviruses That Depends Upon Squamous Epithelial Differentiation. Front. Microbiol. 2012, 3, 152. [Google Scholar] [CrossRef] [PubMed]
  23. Kirk, A.; Graham, S.V. The Human Papillomavirus Late Life Cycle and Links to Keratinocyte Differentiation. J. Med. Virol. 2024, 96, e29461. [Google Scholar] [CrossRef]
  24. Bergvall, M.; Melendy, T.; Archambault, J. The E1 Proteins. Virology 2013, 445, 35–56. [Google Scholar] [CrossRef]
  25. Evande, R.; Rana, A.; Biswas-Fiss, E.E.; Biswas, S.B. Protein–DNA Interactions Regulate Human Papillomavirus DNA Replication, Transcription, and Oncogenesis. Int. J. Mol. Sci. 2023, 24, 8493. [Google Scholar] [CrossRef]
  26. Doorbar, J. The E4 Protein; Structure, Function and Patterns of Expression. Virology 2013, 445, 80–98. [Google Scholar] [CrossRef]
  27. Wang, J.W.; Roden, R.B.S. L2, the Minor Capsid Protein of Papillomavirus. Virology 2013, 445, 175–186. [Google Scholar] [CrossRef] [PubMed]
  28. Buck, C.B.; Day, P.M.; Trus, B.L. The Papillomavirus Major Capsid Protein L1. Virology 2013, 445, 169–174. [Google Scholar] [CrossRef]
  29. Checa, J.; Aran, J.M. Reactive Oxygen Species: Drivers of Physiological and Pathological Processes. J. Inflamm. Res. 2020, 13, 1057–1073. [Google Scholar] [CrossRef]
  30. Cruz-Gregorio, A.; Manzo-Merino, J.; Gonzaléz-García, M.C.; Pedraza-Chaverri, J.; Medina-Campos, O.N.; Valverde, M.; Rojas, E.; Rodríguez-Sastre, M.A.; García-Cuellar, C.M.; Lizano, M. Human Papillomavirus Types 16 and 18 Early-Expressed Proteins Differentially Modulate the Cellular Redox State and DNA Damage. Int. J. Biol. Sci. 2018, 14, 21–35. [Google Scholar] [CrossRef]
  31. Hochmann, J.; Millán, M.; Hernández, P.; Lafon-Hughes, L.; Aiuto, N.D.; Silva, A.; Llaguno, J.; Alonso, J.; Fernández, A.; Pereira-Prado, V.; et al. Contributions of Viral Oncogenes of HPV-18 and Hypoxia to Oxidative Stress and Genetic Damage in Human Keratinocytes. Sci. Rep. 2023, 13, 17734. [Google Scholar] [CrossRef] [PubMed]
  32. Zheng, Y.; Li, X.; Jiao, Y.; Wu, C. High-Risk Human Papillomavirus Oncogenic E6/E7 mRNAs Splicing Regulation. Front. Cell. Infect. Microbiol. 2022, 12, 929666. [Google Scholar] [CrossRef] [PubMed]
  33. Evans, W.; Filippova, M.; Filippov, V.; Bashkirova, S.; Zhang, G.; Reeves, M.E.; Duerksen-Hughes, P. Overexpression of HPV16 E6* Alters β-Integrin and Mitochondrial Dysfunction Pathways in Cervical Cancer Cells. Cancer Genom. Proteom. 2016, 13, 259–273. [Google Scholar]
  34. Circu, M.L.; Aw, T.Y. Glutathione and apoptosis. Free Radic. Res. 2008, 42, 689–706. [Google Scholar] [CrossRef] [PubMed]
  35. Yapindi, L.; Bowley, T.; Kurtaneck, N.; Bergeson, R.L.; James, K.; Wilbourne, J.; Harrod, C.K.; Hernandez, B.Y.; Emerling, B.M.; Yates, C.; et al. Activation of P53-Regulated pro-Survival Signals and Hypoxia-Independent Mitochondrial Targeting of TIGAR by Human Papillomavirus E6 Oncoproteins. Virology 2023, 585, 1–20. [Google Scholar] [CrossRef]
  36. Marullo, R.; Werner, E.; Zhang, H.; Chen, G.Z.; Shin, D.M.; Doetsch, P.W. HPV16 E6 and E7 Proteins Induce a Chronic Oxidative Stress Response via NOX2 That Causes Genomic Instability and Increased Susceptibility to DNA Damage in Head and Neck Cancer Cells. Carcinogenesis 2015, 36, 1397–1406. [Google Scholar] [CrossRef]
  37. Cruz-Gregorio, A.; Aranda-Rivera, A.K.; Aparicio-Trejo, O.E.; Coronado-Martínez, I.; Pedraza-Chaverri, J.; Lizano, M. E6 Oncoproteins from High-Risk Human Papillomavirus Induce Mitochondrial Metabolism in a Head and Neck Squamous Cell Carcinoma Model. Biomolecules 2019, 9, 351. [Google Scholar] [CrossRef]
  38. Shim, J.-H.; Kim, K.-H.; Cho, Y.-S.; Choi, H.-S.; Song, E.Y.; Myung, P.-K.; Kang, J.S.; Suh, S.-K.; Park, S.N.; Yoon, D.-Y. Protective Effect of Oxidative Stress in HaCaT Keratinocytes Expressing E7 Oncogene. Amino Acids 2008, 34, 135–141. [Google Scholar] [CrossRef]
  39. Shim, J.-H.; Cho, K.-J.; Lee, K.-A.; Kim, S.-H.; Myung, P.-K.; Choe, Y.-K.; Yoon, D.-Y. E7-Expressing HaCaT Keratinocyte Cells Are Resistant to Oxidative Stress-Induced Cell Death via the Induction of Catalase. Proteomics 2005, 5, 2112–2122. [Google Scholar] [CrossRef]
  40. Lai, D.; Tan, C.L.; Gunaratne, J.; Quek, L.S.; Nei, W.; Thierry, F.; Bellanger, S. Localization of HPV-18 E2 at Mitochondrial Membranes Induces ROS Release and Modulates Host Cell Metabolism. PLoS ONE 2013, 8, e75625. [Google Scholar] [CrossRef]
  41. Gao, L.-J.; Gu, P.-Q.; Fan, W.-M.; Liu, Z.; Qiu, F.; Peng, Y.-Z.; Guo, X.-R. The Role of gC1qR in Regulating Survival of Human Papillomavirus 16 Oncogene-Transfected Cervical Cancer Cells. Int. J. Oncol. 2011, 39, 1265–1272. [Google Scholar] [CrossRef] [PubMed]
  42. De Marco, F.; Perluigi, M.; Foppoli, C.; Blarzino, C.; Cini, C.; Coccia, R.; Venuti, A. UVB Irradiation Down-Regulates HPV-16 RNA Expression: Implications for Malignant Progression of Transformed Cells. Virus Res. 2007, 130, 249–259. [Google Scholar] [CrossRef] [PubMed]
  43. De Marco, F.; Bucaj, E.; Foppoli, C.; Fiorini, A.; Blarzino, C.; Filipi, K.; Giorgi, A.; Schininà, M.E.; Di Domenico, F.; Coccia, R.; et al. Oxidative Stress in HPV-Driven Viral Carcinogenesis: Redox Proteomics Analysis of HPV-16 Dysplastic and Neoplastic Tissues. PLoS ONE 2012, 7, e34366. [Google Scholar] [CrossRef] [PubMed]
  44. Mileo, A.M.; Abbruzzese, C.; Mattarocci, S.; Bellacchio, E.; Pisano, P.; Federico, A.; Maresca, V.; Picardo, M.; Giorgi, A.; Maras, B.; et al. Human Papillomavirus-16 E7 Interacts with Glutathione S-Transferase P1 and Enhances Its Role in Cell Survival. PLoS ONE 2009, 4, e7254. [Google Scholar] [CrossRef]
  45. Conway, M.J.; Alam, S.; Ryndock, E.J.; Cruz, L.; Christensen, N.D.; Roden, R.B.S.; Meyers, C. Tissue-Spanning Redox Gradient-Dependent Assembly of Native Human Papillomavirus Type 16 Virions. J. Virol. 2009, 83, 10515–10526. [Google Scholar] [CrossRef]
  46. Chemes, L.B.; Camporeale, G.; Sánchez, I.E.; de Prat-Gay, G.; Alonso, L.G. Cysteine-Rich Positions Outside the Structural Zinc Motif of Human Papillomavirus E7 Provide Conformational Modulation and Suggest Functional Redox Roles. Biochemistry 2014, 53, 1680–1696. [Google Scholar] [CrossRef]
  47. Cháirez-Ramírez, M.H.; de la Cruz-López, K.G.; García-Carrancá, A. Polyphenols as Antitumor Agents Targeting Key Players in Cancer-Driving Signaling Pathways. Front. Pharmacol. 2021, 12, 710304. [Google Scholar] [CrossRef]
  48. Li, G.-L.; Jiang, W.; Xia, Q.; Chen, S.-H.; Ge, X.-R.; Gui, S.-Q.; Xu, C.-J. HPV E6 Down-Regulation and Apoptosis Induction of Human Cervical Cancer Cells by a Novel Lipid-Soluble Extract (PE) from Pinellia Pedatisecta Schott in Vitro. J. Ethnopharmacol. 2010, 132, 56–64. [Google Scholar] [CrossRef] [PubMed]
  49. Shah, B.A.; Qazi, G.N.; Taneja, S.C. Boswellic Acids: A Group of Medicinally Important Compounds. Nat. Prod. Rep. 2009, 26, 72–89. [Google Scholar] [CrossRef]
  50. Khan, S.; Chib, R.; Shah, B.A.; Wani, Z.A.; Dhar, N.; Mondhe, D.M.; Lattoo, S.; Jain, S.K.; Taneja, S.C.; Singh, J. A Cyano Analogue of Boswellic Acid Induces Crosstalk between P53/PUMA/Bax and Telomerase That Stages the Human Papillomavirus Type 18 Positive HeLa Cells to Apoptotic Death. Eur. J. Pharmacol. 2011, 660, 241–248. [Google Scholar] [CrossRef]
  51. Qiao, Y.; Cao, J.; Xie, L.; Shi, X. Cell Growth Inhibition and Gene Expression Regulation by (-)-Epigallocatechin-3-Gallate in Human Cervical Cancer Cells. Arch. Pharm. Res. 2009, 32, 1309–1315. [Google Scholar] [CrossRef] [PubMed]
  52. Lee, H.-G.; Yu, K.-A.; Oh, W.-K.; Baeg, T.-W.; Oh, H.-C.; Ahn, J.-S.; Jang, W.-C.; Kim, J.-W.; Lim, J.-S.; Choe, Y.-K.; et al. Inhibitory Effect of Jaceosidin Isolated from Artemisiaargyi on the Function of E6 and E7 Oncoproteins of HPV 16. J. Ethnopharmacol. 2005, 98, 339–343. [Google Scholar] [CrossRef] [PubMed]
  53. Cherry, J.J.; Rietz, A.; Malinkevich, A.; Liu, Y.; Xie, M.; Bartolowits, M.; Davisson, V.J.; Baleja, J.D.; Androphy, E.J. Structure Based Identification and Characterization of Flavonoids That Disrupt Human Papillomavirus-16 E6 Function. PLoS ONE 2013, 8, e84506. [Google Scholar] [CrossRef]
  54. Kim, M.S.; Bak, Y.; Park, Y.S.; Lee, D.H.; Kim, J.H.; Kang, J.W.; Song, H.-H.; Oh, S.-R.; Yoon, D.Y. Wogonin Induces Apoptosis by Suppressing E6 and E7 Expressions and Activating Intrinsic Signaling Pathways in HPV-16 Cervical Cancer Cells. Cell Biol. Toxicol. 2013, 29, 259–272. [Google Scholar] [CrossRef] [PubMed]
  55. Maher, D.M.; Bell, M.C.; O’Donnell, E.A.; Gupta, B.K.; Jaggi, M.; Chauhan, S.C. Curcumin Suppresses Human Papillomavirus Oncoproteins, Restores P53, Rb, and PTPN13 Proteins and Inhibits Benzo[a]Pyrene-Induced Upregulation of HPV E7. Mol. Carcinog. 2011, 50, 47–57. [Google Scholar] [CrossRef]
  56. Munagala, R.; Aqil, F.; Jeyabalan, J.; Gupta, R.C. Tanshinone IIA Inhibits Viral Oncogene Expression Leading to Apoptosis and Inhibition of Cervical Cancer. Cancer Lett. 2015, 356, 536–546. [Google Scholar] [CrossRef]
  57. Saha, S.K.; Khuda-Bukhsh, A.R. Berberine Alters Epigenetic Modifications, Disrupts Microtubule Network, and Modulates HPV-18 E6-E7 Oncoproteins by Targeting P53 in Cervical Cancer Cell HeLa: A Mechanistic Study Including Molecular Docking. Eur. J. Pharmacol. 2014, 744, 132–146. [Google Scholar] [CrossRef] [PubMed]
  58. Munagala, R.; Kausar, H.; Munjal, C.; Gupta, R.C. Withaferin A Induces P53-Dependent Apoptosis by Repression of HPV Oncogenes and Upregulation of Tumor Suppressor Proteins in Human Cervical Cancer Cells. Carcinogenesis 2011, 32, 1697–1705. [Google Scholar] [CrossRef]
  59. Lee, S.; Kim, H.; Kang, J.-W.; Kim, J.-H.; Lee, D.H.; Kim, M.-S.; Yang, Y.; Woo, E.-R.; Kim, Y.M.; Hong, J.; et al. The Biflavonoid Amentoflavone Induces Apoptosis via Suppressing E7 Expression, Cell Cycle Arrest at Sub-G1 Phase, and Mitochondria-Emanated Intrinsic Pathways in Human Cervical Cancer Cells. J. Med. Food 2011, 14, 808–816. [Google Scholar] [CrossRef]
  60. Bernard, B.; Fest, T.; Prétet, J.L.; Mougin, C. Staurosporine-Induced Apoptosis of HPV Positive and Negative Human Cervical Cancer Cells from Different Points in the Cell Cycle. Cell Death Differ. 2001, 8, 234–244. [Google Scholar] [CrossRef]
  61. Jing, K.; Shin, S.; Jeong, S.; Kim, S.; Song, K.-S.; Park, J.-H.; Heo, J.-Y.; Seo, K.-S.; Park, S.-K.; Kweon, G.-R.; et al. Docosahexaenoic Acid Induces the Degradation of HPV E6/E7 Oncoproteins by Activating the Ubiquitin–Proteasome System. Cell Death Dis. 2014, 5, e1524. [Google Scholar] [CrossRef] [PubMed]
  62. Aragona, C.; Bezerra Espinola, M.S.; Bilotta, G.; Porcaro, G.; Calcagno, M. Evaluating the Efficacy of Pervistop®, a New Combination Based on EGCG, Folic Acid, Vitamin B12 and Hyaluronic Acid on Patients with Human Papilloma Virus (HPV) Persistent Infections and Cervical Lesions: A Pilot Study. J. Clin. Med. 2023, 12, 2171. [Google Scholar] [CrossRef] [PubMed]
  63. Divya, C.S.; Pillai, M.R. Antitumor Action of Curcumin in Human Papillomavirus Associated Cells Involves Downregulation of Viral Oncogenes, Prevention of NFkB and AP-1 Translocation, and Modulation of Apoptosis. Mol. Carcinog. 2006, 45, 320–332. [Google Scholar] [CrossRef] [PubMed]
  64. Clemente-Soto, A.F.; Salas-Vidal, E.; Milan-Pacheco, C.; Sánchez-Carranza, J.N.; Peralta-Zaragoza, O.; González-Maya, L. Quercetin Induces G2 Phase Arrest and Apoptosis with the Activation of P53 in an E6 Expression-Independent Manner in HPV-Positive Human Cervical Cancer-Derived Cells. Mol. Med. Rep. 2019, 19, 2097–2106. [Google Scholar] [CrossRef]
Futurepharmacol 04 00038 g001
Figure 1. Phytopharmaceutical molecules with anticancer effects, inducing cell death via apoptosis. Cyanidrical derivative of 11-keto-β-boswellic acid, known as 2-cyano-3,11-dioxide-1,12-dien-24-oate butyl (BCDD); human papillomavirus (HPV); p53-upregulated modulator of apoptosis (PUMA); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); kinase B (AKT); estrogen receptor (ER); Epigallocatechin-3-gallate (EGCG); lipid from Pinellia pedatisecta Schott (PE).
Figure 1. Phytopharmaceutical molecules with anticancer effects, inducing cell death via apoptosis. Cyanidrical derivative of 11-keto-β-boswellic acid, known as 2-cyano-3,11-dioxide-1,12-dien-24-oate butyl (BCDD); human papillomavirus (HPV); p53-upregulated modulator of apoptosis (PUMA); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); kinase B (AKT); estrogen receptor (ER); Epigallocatechin-3-gallate (EGCG); lipid from Pinellia pedatisecta Schott (PE).
Futurepharmacol 04 00038 g001
Futurepharmacol 04 00038 g002
Figure 2. Phytopharmaceutical molecules with anticancer effects, targeting HPV E6/E7 oncoproteins. Staurosporine (ST); mouse double minute 2 homolog (MDM2); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); activator protein 1 (AP-1); inducible nitric oxide synthase (iNOS); cyclooxygenase-2 (COX-2); interleukin (IL); peroxisome proliferator-activated receptor γ (PPARγ); B-cell lymphoma 2 (BCL-2).
Figure 2. Phytopharmaceutical molecules with anticancer effects, targeting HPV E6/E7 oncoproteins. Staurosporine (ST); mouse double minute 2 homolog (MDM2); nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB); activator protein 1 (AP-1); inducible nitric oxide synthase (iNOS); cyclooxygenase-2 (COX-2); interleukin (IL); peroxisome proliferator-activated receptor γ (PPARγ); B-cell lymphoma 2 (BCL-2).
Futurepharmacol 04 00038 g002
Futurepharmacol 04 00038 g003
Figure 3. Quercetin and DHA decrease HPV E6/E7 oncoproteins by activating proteasome and p53. Staurosporine (ST); Docosahexaenoic acid (DHA); ubiquitination-proteasome system (UPS); reactive oxygen species (ROS); growth phase 2 (G2).
Figure 3. Quercetin and DHA decrease HPV E6/E7 oncoproteins by activating proteasome and p53. Staurosporine (ST); Docosahexaenoic acid (DHA); ubiquitination-proteasome system (UPS); reactive oxygen species (ROS); growth phase 2 (G2).
Futurepharmacol 04 00038 g003
Table 1. HPV proteins and their main functions.
Table 1. HPV proteins and their main functions.
ProteinNameAssociated Functions
Non-structuralE1DNA binding and helicase activity. It is part of replication and transcription.
E2It is part of replication, transcription, genomic segregation and encapsidation. Anti-proliferative function by acting as a transcriptional repressor of the expression of the E6 and E7 oncogenes.
E4Regulation of late genes, viral maturation and encapsidation. It facilitates the release of the virion since it causes the collapse of the keratin filaments and induces the arrest of the cell cycle in the Gap/Mitosis (G/M) phase.
E5It contributes to the evasion of the immune response by decreasing the expression of the major histocompatibility complex (MHC) class II.
E6It induces the proteasomal degradation of p53 and cooperates with E7 to induce cell proliferation and transformation.
E7It binds to retinoblastoma protein and activates the E2F transcription factor, deregulates the G1/synthesis (S) checkpoint, and cooperates with E6 to induce cell proliferation and transformation.
StructuralL1Main structural protein, involved in virus internalization, comprises 80% of the capsid.
L2Capsid protein involved in virus internalization and DNA transport into the host cell nucleus.
Table 2. Effects of phytopharmaceutical compounds on HPV oncoproteins.
Table 2. Effects of phytopharmaceutical compounds on HPV oncoproteins.
PhytopharmaceuticalEffects on HPV Oncoproteins and Apoptotic MechanismsReference
Lipid from Pinellia pedatisecta Schott (PE)Negatively regulates E6 gene expression, activating p53.
Suppresses Bcl-2 expression, activates Bax, caspase-8, and caspase-3		[48]
BCDDReduces E6 mRNA expression.
Increases p53/PUMA/p21
Decreases Bcl-2		[50]
EGCGDecreases HPV E6/E7 expression[51]
JaceosidinInhibits the binding between E6 and p53, increasing p53[52]
LuteolinInteracts with HPV-16 E6 and E6AP, avoiding p53 degradation[53]
WogoninSuppresses E6 and E7 oncoproteins expression, increasing p53 and pRb[54]
CurcuminDownregulates HPV E6 and E7 oncogenes, promoting apoptosis
Decreases NF-kB and AP-1		[55]
Tanshinone IIADownregulates E6 and E7 oncoproteins[56]
BerberineDecreases E6, E7[57]
Withaferin ARepresses E6 and E7 oncoproteins[58]
AmentoflavoneSuppresses E7, deactivating cyclins and activating pRB
Decreases Bcl-2 and increases Bax along with caspase-3 and caspase-9
Increases PPARγ and PTEN, inhibiting COX-2 and IL-32		[59]
Staurosporine (ST)Inhibits E6, E7 and MDM2, increasing p53.[60]
Docosahexaenoic acid (DHA)Activates proteosome-inducing HPV E6/E7 oncoproteins degradation.[61]
B-cell lymphoma 2 (BCL-2); p53 upregulated modulator of apoptosis (PUMA); human papillomavirus (HPV); E6-associated protein (E6-AP); nuclear factor kappa-light-chain enhancer of activated B cells (NF-kB); activator protein 1 (AP-1); peroxisome proliferator-activated receptor γ (PPARγ); phosphatase and tensin homolog deleted on chromosome ten (PTEN); cyclooxygenase-2 (COX-2); interleukin (IL); mouse double minute 2 homolog (MDM2); cyclooxygenase-2 (COX-2); 2-cyano-3,11-dioxide-1,12-dien-24-oate butyl (BCDD); epigallocatechin-3-gallate (EGCG).
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Cruz-Gregorio, A.; Aranda-Rivera, A.K.; Pedraza-Chaverri, J. HPV Proteins as Therapeutic Targets for Phytopharmaceuticals Related to Redox State in HPV-Related Cancers. Future Pharmacol. 2024, 4, 716-730. https://doi.org/10.3390/futurepharmacol4040038

AMA Style

Cruz-Gregorio A, Aranda-Rivera AK, Pedraza-Chaverri J. HPV Proteins as Therapeutic Targets for Phytopharmaceuticals Related to Redox State in HPV-Related Cancers. Future Pharmacology. 2024; 4(4):716-730. https://doi.org/10.3390/futurepharmacol4040038

Chicago/Turabian Style

Cruz-Gregorio, Alfredo, Ana Karina Aranda-Rivera, and José Pedraza-Chaverri. 2024. "HPV Proteins as Therapeutic Targets for Phytopharmaceuticals Related to Redox State in HPV-Related Cancers" Future Pharmacology 4, no. 4: 716-730. https://doi.org/10.3390/futurepharmacol4040038

Article Metrics

Article metric data becomes available approximately 24 hours after publication online.
Back to TopTop