Study On the Molecular Mechanism of LncRNA SOX2-OT Affecting Breast Cancer Cell Proliferation and Radiosensitivity by Regulating miR-519e-5p
CHEN Hui1, SHEN Zhongfei1, SONG Binbin2, PENG Rong1, YU Muxin1, XU Yufen2, SUN Yanbao3, LU Guoming1*
This article explored the effect and possible mechanism of lncRNA SOX2-OT on the proliferation and radiosensitivity of breast cancer cells. The expression of lncRNA SOX2-OT and miR-519e-5p in normal breast epithelial cells MCF-10A and breast cancer cell lines (MCF-7, T47D and Bcap-37) were detected by qRTPCR. The localization of lncRNA SOX2-OT in T47D cells was analyzed by nucleocytoplasmic isolation and RNA fluorescence in situ hybridization. The expression of lncRNA SOX2-OT and miR-519e-5p in breast cancer T47D cells was significantly different from that in MCF-10A cells (P<0.05). Breast cancer T47D cells were selected as the research object.The T47D cells were transfected with lncRNA SOX2-OT siRNA, miR-519e-5p mimic, overexpressed RNA SOX2-OT, co-transfected with lncRNA SOX2-OT siRNA and miR-519e-5p inhibitor, co-transfected overexpression RNA SOX2-OT and miR-519e-5p mimics were transfected to obtain si-lncRNA SOX2-OT group, si-NC group, miR-519e-5p group, miR-NC group, si-lncRNA SOX2-OT+anti-miR-519e-5p group, si-lncRNA SOX2-OT+anti-miR-NC group, RNA SOX2-OT+miR-519e-5p mimics group, si-lncRNA SOX2-OT+miR-NC group. Cell proliferation activity was observed by CCK-8 method, cell survival fraction was calculated by colony formation assay, and cell sensitization ratio was calculated by single-click multi-target mathematical model. CyclinD1 and γ-H2AX protein expressions in cells were detected by western blotting. The dual-luciferase reporter gene experiment verified the regulatory relationship between lncRNA SOX2-OT and miR-519e-5p. The results showed that the lncRNA SOX2-OT was mainly localized in the cytoplasm of T47D. The knockdown of lncRNA SOX2-OT or up-regulation of miR-519e-5p, the proliferation activity and survival fraction of T47D cells were both decreased (P<0.05), and the sensitization ratios were 1.195 and 1.343, respectively. CyclinD1 protein expression in cells decreased (P<0.05), and the expression of γ-H2AX protein increased (P<0.05). The lncRNA SOX2-OT targeted and negatively regulated miR-519e-5p in T47D cells. Down-regulation or up-regulation of miR-519e-5p reversed the effects of knock-down or up-regulation of lncRNA SOX2-OT on T47D cell proliferation and radiosensitivity, respectively. In conclusion, the lncRNA SOX2-OT may promote breast cancer cell proliferation and reduce cell radiosensitivity through targeting and negatively regulating miR-519e-5p.
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