MicroRNA-29a regulates liver tumor-initiating cells expansion via Bcl-2 pathway

Abstract

MicroRNAs (miRNAs) participate in tumorigenesis, progression, recurrence and drug resistance of hepatocellular carcinoma (HCC). However, few miRNAs have been identified and entered clinical practice. Herein, we report that miR-29a is downregulated in tumor-initiating cells (T-ICs) and has an important function in liver T-ICs. Functional studies revealed that miR-29a knockdown promotes liver T-ICs self-renewal and tumorigenesis. Conversely, a forced miR-29a expression inhibits liver T-ICs self-renewal and tumorigenesis. Mechanistically, we find that miR-29a downregulates Bcl-2 via binding its mRNA 3′UTR in liver T-ICs. The correlation between miR-29a and Bcl-2 is validated in human HCC tissues. Furthermore, the miR-29a expression determines the responses of hepatoma cells to sorafenib treatment. Analysis of patient-derived xenografts (PDXs) further demonstrated that the miR-29a high patients are more sensitive to sorafenib treatment. In conclusion, our findings revealed the crucial role of the miR-29a in liver T-ICs expansion and sorafenib response, rendering miR-29a as an optimal target for the prevention and intervention of HCC.