Abstract: Objective To detect the expression of miR-140 in osteosarcoma tissues and investigate the effect of miR-140 on the proliferation, apoptosis and invasion of human osteosarcoma cell line U2. Methods The real-time polymerase chain reaction(qRT-PCR) was used to detect the expression levels of miR-140 in osteosarcoma tissues and corresponding paratumorous tissues from 40 patients. The expression levels of miR-140 in osteosarcoma cell line U2 after transfected with miR-140 mimic were measured by qRT-PCR. The proliferation and apoptosis of U2 cells were assessed by cell counting kit (CCK-8 method) and flow cytometry, respectively. And the in vitro invasion ability of U2 cells was detected with Transwell chamber assay, The protein changes of histone deacetylase 4 (HDAC4) of U2 cells after transfection were detected by Western blotting. Results The 72.5% (29/40) of miR-140 was low expressed in osteosarcoma tissues compared with the adjacent normal tissues (P<0.05).The miR-140 expression of U2 cells after transfection was significantly up-regulated (P<0.05), The apoptosis rate of U2 cells was significantly increased (P<0.05), The proliferation and invasion abilities were inhibited significantly (P<0.05). The relative protein expressions of HDAC4 in miR-140 mimic transfection group were significantly lower than those in negative control group (P<0.05). Conclusion MiR-140 is low expressed in human osteosarcoma tissue. MicroRNA-140 inhibits the proliferation and invasion activities of osteosarcoma cell line U2 and promotes cells’ apoptosis in vitro. These biological effects may partially attribute to miR-140 characters of targeting and inhibiting the HDAC4 expression.

Key words: osteosarcoma, microRNA-140, histone deacetylase 4, apoptosis