Dysregulation of microRNA-106a-5p-RUNX1 axis associates with clinical progression and prognosis of osteosarcoma patients.

MicroRNA-106a-5p (miR-106a-5p) functions as a tumor suppressor in osteosarcoma cells. Here, we aimed to identify novel target genes of miR-106a-5p in osteosarcoma, as well as to investigate their prognostic value and the biological functions. At first, the mammalian runt-related factor 1 (RUNX1) was identified as one of the target genes of miR-106a-5p in osteosarcoma cells by luciferase reporter gene assay, real-time quantitative RT-PCR and Western blot analysis. Then, the expression levels of miR-106a-5p and RUNX1 in osteosarcoma tissues were detected, and their associations with clinicopathological features and patients' prognosis were statistically analyzed. Compared with adjacent non-cancerous tissues, miR-106a-5p and RUNX1 mRNA/protein expression in osteosarcoma tissues were significantly decreased and increased, respectively (all P < 0.01). Low miR-106a-5p, high RUNX1 and miR-106a-5p-low/RUNX1-high expression in osteosarcoma tissues were all significantly associated with advanced Enneking stage, positive metastasis and shorter overall survival (all P < 0.05). Moreover, miR-106a-5p and RUNX1 expression, alone or in combination, were identified as independent prognostic factors for osteosarcoma patients' overall survival. Functionally, the enforced expression of miR-106a-5p significantly suppressed proliferation and invasion of osteosarcoma cells, while the overexpression of RUNX1 effectively reversed its suppressive roles. In conclusion, our findings show the dysregulation of miR-106a-5p-RUNX1 axis in human osteosarcoma tissues and suggest its crucial roles in cancer progression and patients' prognosis. More interestingly, miR-106a-5p may function as a tumor suppressor in osteosarcoma cells via regulating its target gene RUNX1.