Figure 3. miR-221 knockdown induces apoptosis, inhibits cell proliferation and supresses tumor growth in mice.

MDA-MB-231, BT-20, and MDA-MB-468 cells stably expressing miR-221-ZIP or scramble-ZIP were used to perform apoptosis, cell proliferation, and in-vivo tumor growth assays. (A) Cleaved caspase 3 and phosphorylation of BAD were measured as apoptosis markers. All cell lines were seeded at similar density as the parental cell lines and cultured for 72 hours until the parental cell lines reached 80–95% confluencey, before cell lysates were prepared and subject to cleaved caspase 3 assays. (B) Cell proliferation measurements were normalized to the readings in parental cells at day 1. (C) Nude mice were implanted subcutaneously with MDA-MB-231 parental cells, and MDA-MB-231 cells stably expressing miR-221-ZIP or scramble-ZIP. Tumor measurements were recorded and tumor growth inhibition was calculated as described in Materials and Methods. T-test was performed in (A) and (B) and one way ANOVA was performed in (C) to compare the differences between parental cells versus miR-221-ZIP cells. *denotes p-value ≤0.05. ***denotes p-value ≤0.005.