RESUMO
Objective: To detect the expression of lncRNA RAB11B-AS1 in osteosarcoma and investigate its role in osteosarcoma cells proliferation and the responsible mechanisms. Methods: Osteosarcoma and corresponding adjacent normal tissues were collected from 24 patients subjected to operations from October 2015 to October 2017 in the Third Affiliated Hospital of Southern Medical University.RAB11B-AS1 expression was detected in osteosarcoma specimens by quantitative real-time polymerase chain reaction (qRT-PCR). Lentiviral vectors that stably over-expressing RAB11B-AS1 were constructed and transfected into U2OS osteosarcoma cell line.The effect of RAB11B-AS1 on osteosarcoma cell proliferation and apoptosis was investigated by cell counting kit (CCK-8) assay and flow cytometry.U2OS osteosarcoma xenograft model of nude mice was established to observe the effect of RAB11B-AS1 on xenograft growth in mice, and the role of RAB11B-AS1 in proliferation and apoptosis of osteosarcoma cells was investigated by immunohistochemistry and TUNEL staining of osteosarcoma slices.The relationship between RAB11B-AS1 and RAB11B was explored using luciferase reporter assay.The data were compared with t test between the two groups. Results: Expression of RAB11B-AS1 was significantly down-regulated in osteosarcoma (0.010±0.015) versus their paired non-neoplastic tissues (0.022±0.030) (t=2.117, P=0.045). Up-regulation of RAB11B-AS1 resulted in decreased proliferative rate of U2OS cells (F=15.659, P<0.001). The ratios of cells in G0-G1 phase, S phase, G2-M phase were 62.6%±6.3%, 21.4%±2.2%, 16.3%±1.6% respectively in RAB11B-AS1 up-regulated group versus 59.4%±5.9%, 25.9%±2.6%, 15.5%±1.1% respectively in control group, and cell ratio in G0-G1 and S phase were increased significantly by RAB11B-AS1 up-regulation (t=17.124, 17.321, both P<0.05). Apoptosis rate was significantly elevated in RAB11B-AS1 over-expressed cells (12.7%±1.3%) when compared with that in control (10.3%±1.0%)(t=17.321, P=0.003). Mice transplanted with osteosarcoma cells that overexpressed RAB11B-AS1 exhibited lower growth rate of tumor (F=8.798, P=0.009). Mechanistically, RAB11B-AS1 expression correlated negatively with RAB11B expression (r=-0.356, P=0.044). Conclusions: lncRNA RAB11B-AS1 expression is down-regulated significantly in osteosarcoma tissues.RAB11B-AS1 may suppress the progression of osteosarcoma via down-regulating RAB11B.