Identification of GNB1 as a downstream effector of the circRNA-0133711/miR-145-5p axis involved in breast cancer proliferation and metastasis

Abstract Objectives Despite the involvement of the G protein beta-1 (GNB1) protein in various cancer types, its relationship to breast tumours is presently uncertain. This research focused on the expression of GNB1 in breast cancer and its possible biological ramifications in an effort to explain this confusion. Methods The expression levels of GNB1 in adjacent normal tissues and breast cancer were compared. We next constructed GNB1-overexpressed or -knockdown MDA-MB-231 cell lines in order to clarify GNB1’s function in breast cancer. We used colony-formation assays, CCK-8 assays, xenograft models, and transwell migration/invasion assays to evaluate the effect of GNB1 on tumorigenicity, migration, and invasion. Moreover, we used western blot analysis to investigate the significance of FAK/mTOR signalling in GNB1-regulated tumour stimulatory effects in breast cancer. Finally, we investigated the upstream regulatory signaling of GNB1 using luciferase reporter and functional repair assays. Results When comparing human breast cancer specimens to specimens of normal tissue, we discovered that GNB1 was noticeably overexpressed. This phenotype was also found to be substantially associated with unfavourable clinical outcomes. Functional research findings indicate that elevated expression of GNB1 stimulated the proliferation and metastasis of breast cancer cells. Additionally, we discovered that GNB1 activated the FAK/mTOR signalling cascade by directly inducing the phosphorylation of the FAK protein through specific contacts. According to the results of the RNA pull-down assays and dual-luciferase reporter, we concluded that circRNA-0133711 functions as a competitive endogenous RNA (ceRNA) that sequesters miR-145-5p and thereby relieves its repressive effect on GNB1 expression. Conclusions Collectively, our research findings elucidate the hitherto unexplored important role of the circRNA-0133711/miR-145-5p/GNB1 axis in the formation of breast cancer, and provide a new biomarker for clinical diagnosis and treatment of breast cancer.