富含亮氨酸重复序列免疫球蛋白样蛋白2调控血小板源性生长因子受体β信号通路促进胶质母细胞瘤细胞周期进展

Leucine-rich repeats and immunoglobulin-like domains 2 promoted the cell cycle progression of glioblastoma cells through modulating the platelet-derived growth factor receptor β signaling pathways

目的探讨富含亮氨酸重复序列免疫球蛋白样蛋白2(LRIG2)调控血小板源性生长因子受体β(PDGFRβ)信号通路促进胶质母细胞瘤(GBM)细胞周期进展的机制。方法免疫组织化学法检测肿瘤组织中蛋白表达;流式细胞术检测细胞周期进展;裸鼠皮下移植瘤模型检测细胞在体成瘤能力;免疫荧光共聚焦及免疫共沉淀检测蛋白结合;Western blot检测信号通路蛋白表达。结果人GBM组织中LRIG2与PDGFRβ蛋白表达呈正相关(χ^2=6.411,P<0.05)。PDGF-BB刺激下,LRIG2过表达组S期及G2/M期细胞百分比均明显高于对照组[(22.74±1.23)%比(11.60±0.82)%,t=13.052,P<0.05;(19.06±1.04)%比(9.36±0.65)%,t=13.699,P<0.05]。裸鼠皮下移植瘤LRIG2过表达组肿瘤体积明显高于对照组[(1 372.56±167.88) mm3比(413.34±76.79) mm3,t=11.619,P<0.05]。GBM细胞中LRIG2蛋白与PDGFRβ蛋白存在共表达,且存在物理性结合。PDGF-BB刺激下,LRIG2过表达组U87细胞中PDGFRβ、磷酸化PDGFRβ(p-PDGFRβ)、磷酸化蛋白激酶B(p-Akt)、磷酸化信号转导与转录激活因子-3(p-STAT3),细胞周期蛋白(Cyclin) B1和Cyclin D1表达水平均明显高于对照组。结论LRIG2通过调控PDGFRβ信号通路促进GBM细胞周期进展。

Objective To investigate the effects of leucine-rich repeats and immunoglobulin-like domains 2 (LRIG2) protein on the cell cycle progression of glioblastoma cells and the underlying mechanisms. Methods Tumors tissues were subjected to immunohistochemical staining to detect the protein expression levels.Flow cytometric analysis was used to detect the in vitro cell cycle progression, respectively. Subcutaneous tumor formation in nude mice was performed to investigate the tumor growth in vivo. Immunofluorescence and co-immunoprecipitation (Co-IP) were used to detect the protein interaction, and western blotting was used to examine the signaling pathway proteins. Results Protein expression level of LRIG2 positively correlated with the level of platelet-derived growth factor receptor β(PDGFRβ) in human glioblastoma (χ^2=6.411, P<0.05). The percentage of cells in S or G2/M phase dramatically increased in the platelet derived growth factor-BB (PDGF-BB)-induced LRIG2-overexpressing U87 cells, compared with the control cells [(22.74±1.23)% vs.(11.60±0.82)%, t=13.052, P<0.05;(19.06±1.04)% vs.(9.36±0.65)%, t=13.699, P<0.05]. The volume of tumor xenografts at the terminal experiments were significantly increased in the mice injected with LRIG2-overexpressing U87 cells [(1 372.56±167.88) mm3 vs.(413.34±76.79) mm3,t=11.619, P<0.05]. LRIG2 and PDGFRβ were co-expressed and physically interacted in glioblastoma cells. The levels of PDGF-BB-induced phosphorylated PDGFRβ(p-PDGFRβ), phosphorylated protein kinase B (p-Akt), phosphorylated signal transducer and activators of transcription 3 (p-STAT3), Cyclin B1 and Cyclin D1 were markedly increased in LRIG2-overexpressing cells. Conclusion LRIG2 promoted the cell cycle progression of glioblastoma cells, which validated LRIG2 as a promising potential therapeutic target for treatment of glioblastoma.