Osteosarcoma (OS) is the most common primary tumour of bone. Patient survival rates have stagnated and for patients with metastatic disease the 5-year survival rate remains at 20%. Deregulated miRNA expression patterns are well documented in many cancers. In this study we have utilized two mouse models of OS1,2 and human OS cells to identify miRNAs that contribute to the pathogenesis of OS.
The expression levels of 583 miRNAs were profiled in low passage cell cultures derived from primary and metastatic tumours from mouse models of osteoblastic and fibroblastic OS1,2. By comparison to in vitro differentiated preosteoblast and osteoblast cells derived from a mouse bone marrow stromal cell line3, 76 miRNAs were identified to be deregulated in OS cells (>2-fold expression p<0.05). Of 30 candidates selected for further validation in independent mouse OS cell cultures and whole tumours compared to primary preosteoblast and osteoblast cells isolated from WT C57BL6 mice, 70% validated by QPCR. miR-155-5p (>5-fold upregulated in OS), and miR-148a-3p and miR-335-5p (>10-fold downregulated in OS) were selected for examination in human OS. QPCR analyses confirmed the aberrant expression patterns seen in mouse OS cells in established human OS cell lines and low passage cell cultures derived from primary human OS xenograft material compared to normal osteoblast cells derived from healthy human bone.
Using a bioinformatic approach, genes linked with differentiation, proliferation and oncogenesis were identified as predicted targets of the miRNAs. QPCR profiling of the mRNA targets confirmed OS cells exhibit deregulated mRNA expression patterns consistent with regulation by the miRNAs. Current experiments are investigating the biological impact of restoring these miRNAs on OS biology.