microRNAs (miRNA) are regulators of cellular pathways and alterations of normal miRNA expression levels have been shown to increase tumorigenesis. miR-24 has been demonstrated as having both tumor suppressive and oncogenic properties depending on cell context. Here, we demonstrate a possible role for pre-miR-24-2 as a tumor suppressor in the MCF-7 breast cancer cell line through the preferential processing of mature miR-24-2* over miR-24. Specifically, we show that the ectopic expression of miR-24-2* in MCF-7 breast cancer cells results in a suppression of cellular survival both in vivo and in vitro. Notably, the overexpression of miR-24-2* results in a dampening of cell survival through the targeted suppression of PKCα. In addition, a similar biological change is observed in vivo where MCF-7 cells overexpressing pre-miR-24-2 have decreased tumorigenicity and tumor incidence. Taken together our data demonstrate that when overexpressed biogenesis of the pre-miR-24-2 favors miR-24-2* in the MCF-7 breast cancer cell line and suggests a tumor suppressive role for miR-24-2* observed through the inhibition of PKCα-mediated cellular survival.
Keywords: PKCα cellular survival; breast cancer; miR-24-2*; miRNA maturation; strand preference.
© 2013 Wiley Periodicals, Inc.