Selective Release of MicroRNA Species from Normal and Malignant Mammary Epithelial Cells
Figure 3
Extracellular miR-16 Levels Correlate with Nanovesicle Abundance.
A Plot of extracellular to intracellular levels of miRNAs quantitated by qRT-PCR using stem-loop primers of cells lines BT-20, MCF 10A, MCF7, MDA-MB-231 and SK-BR-3. MiRNA levels were calculated using standard curves, and corrected for recovery by normalization to a spiked synthetic RNA (INT-RNA) introduced at the time of RNA-extraction (Materials and Methods and Table S4). Error bars indicate the measure of one standard deviation of 3 independent experiments. B Relative levels of miR-16 and absolute levels of CD81 were measured in P70 fractions of seven independent experiments and plotted. The line indicates a best-fit power curve (r2 = 0.95). C The P70 was collected daily from media conditioned by MCF7 cells (solid symbols), or from MCF 10A cells (open symbol) cultures and miRNAs were quantified in triplicate. The release rates were linear; r2 = 0.79 for miR-1246 (inset), r2 = 0.98 for miR-16, r2 = 0.85 for miR-451; and r2 = 0.87 for miR-720 of MCF7 cells.