Objectives: This study aims to investigate the effect of the regulator of G-protein signaling 2 (RGS2) on the proliferation and invasion of oral squamous cell carcinoma (OSCC) cells and its potential molecular mechanism. Metho⁃ds The expression status and clinical significance of RGS2 in head and neck squamous cell carcinomas and matched adjacent normal tissues were evaluated using TCGA database. Three OSCC cell lines (i.e., SCC-9, Cal27, and Fadu) were overexpressed with RGS2, and the effect of RGS2 on cell proliferation and invasion was determined using the Transwell, clone formation, and cell counting kit (CCK)-8 assays. Moreover, the yeast two-hybrid scree-ning and co-immunoprecipitation (Co-IP) assays were conducted to detect the correlation of RGS2, four and a half LIM domains protein 1 (FHL1), and damage DNA-binding protein 1 (DDB1).
Results: The expression level of RGS2 in OSCC was significantly lower than that in matched adjacent normal tissues (P=0.023). The high RGS2 expression level was negatively correlated with lymphovascular invasion (P<0.001). After transfection with lentiv-RGS2, the expression of RGS2 was increased, and the invasion and proliferation abilities of OSCC cell lines were evidently inhibited. FHL1 could competitively bind with RGS2, which decreased the integration of DDB1 and RGS2, inhibited the ubiquitination process of RGS2, and maintained the stability of the RGS2 protein.
Conclusions: RGS2 plays an important role in the inhibition of OSCC proliferation and invasion. The structure stability of RGS2 is competitively regulated by FHL1 and DDB1.
目的: 探讨G蛋白信号调节因子2（RGS2）对口腔鳞状细胞癌细胞增殖、侵袭的影响及调控机制。方法: 基于TCGA数据库，评估RGS2在头颈鳞状细胞癌及配对癌旁组织中表达情况，并分析其临床病理相关性；口腔鳞状细胞癌细胞系（SCC-9、Cal-27、Fadu）分别稳定过表达RGS2和空载对照基因，通过Transwell侵袭实验、平板克隆实验、细胞计数试剂盒（CCK）-8生长曲线实验，比较过RGS2表达组、对照组细胞的侵袭、增殖能力；通过酵母双杂交技术、免疫共沉淀技术检测RGS2与四个半LIM结构域蛋白1（FHL1）、DNA损伤结合蛋白（DDB1）的相关性。结果: RGS2 在头颈鳞状细胞癌组织中表达显著低于癌旁组织（P=0.023），且高表达患者肿瘤淋巴血管侵犯显著减少（P<0.001）；过表达RGS2能显著抑制口腔鳞状细胞癌细胞的增殖、侵袭能力；抑癌基因FHL1可竞争性与RGS2结合，降低泛素化相关蛋白DDB1与RGS2的结合，抑制RGS2的泛素化过程，从而维持RGS2稳定。结论: RGS2可抑制口腔鳞状细胞癌细胞的侵袭、增殖能力，RGS2蛋白在细胞中稳定的受FHL1和DDB1竞争性调控。.
Keywords: four and a half LIM domains protein 1; invasion; oral squamous cell carcinoma; proliferation; regulator of G-protein signaling 2; ubiquitination.