MiR-16-1*and miR-16-2*possess strong tumor suppressive and anti-metastatic properties in osteosarcoma
AbstractOsteosarcoma (OS) is an aggressive malignancy affecting mostly children and adolescents. MicroRNAs (miRNAs) play important roles in OS development and progression. Here we found that miR-16-1* and miR-16-2* “passenger” strands as well as the “lead” miR-16 strand possess strong tumor suppressive functions in human OS. We report different although strongly overlapping functions for miR-16-1* and miR-16-2* in OS cells. Ectopic expression of these miRNAs affected primary tumor growth, metastasis seeding, and chemoresistance and invasiveness of human OS cells. Loss-of-function experiments verified tumor suppressive functions of these miRNAs at endogenous levels of expression. Using RNA immunoprecipitation (RIP) assays, we identify direct targets of miR-16-1* and miR-16-2* in OS cells. Furthermore, validation experiments identifiedFGFR2as a direct target for miR-16-1* and miR-16-2*. Overall, our findings underscore the importance of passenger strand miRNAs in osteosarcomagenesis.Novelty and ImpactOsteosarcoma (OS) can be a fatal disease. MicroRNAs (miRNAs) play crucial roles in osteosarcomagenesis. In this study, we identify miR-16-1* and miR-16-2* as strong tumor suppressors and anti-metastatic genes in OS. This is the first report demonstrating tumor suppressive functions of passenger strands of these miRNAs in OS. Given thatMIR-16-1is located in 13q14 region that is commonly deleted in several human malignancies, our findings shed light on oncogenic mechanisms triggered by 13q14 deletion.