Effect of RNaseH-1 on inhibition of telomerase-negative osteosarcoma and enhancement of radiosensitivity
Yu Xiaoyan, Wang Qingqing, Wang Yuan, Zhou Yunfeng
Department of Radiation & Medical Oncology, Zhongnan Hospital of Wuhan University, Clinical Cancer Study Center, Key Laboratory of Tumor Biological Behavior of Hubei Province, Wuhan 430071, China
Abstract：Objective To investigate the effect and mechanism of RNaseH-1 on the radiosensitivity of the osteosarcoma cells via the alternative lengthening of telomeres (ALT) mechanism to maintain the telomere length. Methods ALT osteosarcoma cell U2OS and telomerase-positive osteosarcoma cell 143B over-expressing RNaseH-1 were constructed by lentiviral transfection. After cell transfection, cell proliferation and cell cycle were determined using CCK-8 assay and flow cytometry. The effect of RNaseH-1 on the radiosensitivity of osteosarcoma cells was examined by colony formation assay. DNA injury (γ-H2AX foci) was assessed by immunofluorescent assay. The expression levels of related proteins were detected by Western blot. Results The proliferation abilities of U2OS cells were significantly declined following the over-expression of RNaseH-1, and G1 cell cycle arrest was noted (all P<0.05). Over-expression of RNaseH-1 in U2OS cells increased the phosphorylated levels of ATM and Chk2, down-regulated the expression of homologous recombination (HR)-related proteins RAD51 and BRCA1significantly aggravated DNA damage and remarkably enhanced the radiosensitivity (all P<0.05). Over-expression of RNaseH-1 exerted no inhibitory effect upon the telomerase-positive 143B cells (P>0.05). Conclusion RNaseH-1 over-expression suppresses telomerase-negative osteosarcoma cells and enhances the radiosensitivity probably via the role of RNaseH-1 in inhibiting the homologous recombination repair and activating the ATM signaling pathway.
Yu Xiaoyan,Wang Qingqing,Wang Yuan et al. Effect of RNaseH-1 on inhibition of telomerase-negative osteosarcoma and enhancement of radiosensitivity[J]. Chinese Journal of Radiation Oncology, 2021, 30(6): 625-630.
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