Tumor and Stem Cell Biology miRNA Signatures Associate with Pathogenesis and Progression of Osteosarcoma

Osteosarcoma remains a leading cause of cancer death in adolescents. Treatment paradigms and survival rates have not improved in twodecades. Driving the lack of therapeutic inroads, themolecular etiology of osteosarcoma remains elusive. MicroRNAs (miRNAs) have demonstrated far-reaching effects on the cellular biology of development and cancer. Their role in osteosarcomagenesis remains largely unexplored. Here we identify for the first time anmiRNA signature reflecting the pathogenesis of osteosarcoma from surgically procured samples from human patients. The signature includes high expression of miR-181a, miR-181b, and miR-181c as well as reduced expression ofmiR-16,miR-29b, andmiR-142-5p. We also demonstrate thatmiR-181b andmiR-29b exhibit restricted expression to distinct cell populations in the tumor tissue. Further, higher expression of miR-27a and miR-181c in pre-treatment biopsy samples characterized patients who developed clinical metastatic disease. In addition, higher expression ofmiR-451 andmiR-15b in pre-treatment samples correlatedwith subsequent positive response to chemotherapy. In vitro and in vivo functional validation in osteosarcoma cell lines confirmed the tumor suppressive role ofmiR-16 and the pro-metastatic role ofmiR-27a. Furthermore, predicted target genes for miR-16 and miR-27a were confirmed as down-regulated by real-time PCR. Affymetrix array profiling of cDNAs from the osteosarcoma specimens and controls were interrogated according to predicted targets of miR-16, miR142-5p, miR-29b, miR-181a/b, and miR-27a. This analysis revealed positive and negative correlations highlighting pathways of known importance to osteosarcoma, as well as novel genes. Thus, our findings establish a miRNA signature associated with pathogenesis of osteosarcoma as well as critical pre-treatment biomarkers of metastasis and responsiveness to therapy. Cancer Res; 72(7); 1865–77. 2012 AACR.