MicroRNA-140-5p is Downregulated in Osteosarcoma and Overexpression of MicroRNA-140-5p Inhibits Cancer Cell Proliferation by Downregulating GLUT-1

MicroRNA-140-5p plays pivotal role in different types of human malignancies, while its involvement in osteosarcoma is unknown. Our study aimed to investigate the functionality of microRNA-140-5p in osteosarcoma. Plasma levels of microRNA-140-5p and glucose transporter 1 (GLUT-1) in both osteosarcoma and healthy controls were measured by qRT-PCR and ELISA, respectively. Correlation between plasma levels of microRNA-140-5p and GLUT-1 was analyzed by Pearson correlation coefficient. Correlation between plasma levels of microRNA-140-5p and clinical data of patients with osteosarcoma was analyzed by Chi-square test. MicroRNA-140-5p mimic and GLUT-1 expression vector were transfected into cells of human osteosarcoma cell lines, and the effects on microRNA-140-5p expression, GLUT-1 expression and cell proliferation were analyzed by qRT-PCR, Western-blot and CCK-8 assay, respectively. Plasma levels of microRNA-140-5p were significantly lower and plasma levels of GLUT-1 were significantly higher in osteosarcoma patients than that in healthy controls. Levels of plasma microRNA-140-5p and GLUT-1 were reversely correlated in osteosarcoma patients. Plasma levels of microRNA-140-5p were correlated with tumor size but not with other clinical data of patients. MicroRNA-140-5p mimic significantly inhibited cancer cell proliferation, while GLUT-1 overexpression significantly promoted cancer cell proliferation. MicroRNA-140-5p mimic significantly downregulated GLUT-1 expression. GLUT-1 overexpression showed no significant effect on microRNA-140-5p expression but attenuated the inhibitory effects of microRNA-140-5p mimic on cell proliferation. We therefore conclude that microRNA-140-5p is downregulated in osteosarcoma and overexpression of microRNA-140-5p may inhibit cancer cell proliferation by downregulating GLUT-1.