MicroRNA-26a acts as a tumor suppressor inhibiting gallbladder cancer cell proliferation by directly targeting HMGA2.

MicroRNAs (miRNAs) are a class of small, single-stranded, non-coding RNA molecules which can act as oncogenes or tumor suppressor genes in human cancer. However, the possible functions and mechanisms of miRNA action in gallbladder cancer (GBC) have not been elucidated. In the present study, it was found that miR-26a was often downregulated in GBC and the expression of miR-26a was associated with neoplasm histological grade. miR-26a significantly inhibited the proliferation of GBC cells based on the gain-of-function assays. Furthermore, we demonstrated that high mobility group AT-hook 2 (HMGA2) was a direct target of miR-26a. The results showed that HMGA2 mRNA levels and miR-26a levels were negatively correlated. In addition, we confirmed that reintroduction of HMGA2 antagonized the inhibition of miR-26a to GBC cell proliferation and all these effects were achieved through the cell cycle. Together, all these results suggest that miR-26a expression contributes to GBC proliferation by targeting HMGA2. miR-26a shows promise as a prognosis factor and therapeutic target of GBC patients.