GPR87 promotes invasion and migration through the RHO/ROCK pathway in non-small cell lung cancer

Objective·To explore the role and molecular mechanism of GPR87 in regulating the invasion and migration of non-small cell lung cancer (NSCLC).Methods·Bioinformatics methods, including GEO, UALCAN, KM Plotter and other public database analysis platforms, were used to screen candidate genes related to NSCLC invasion and predict their clinical relevance to NSCLC. Eighty NSCLC clinical patient samples and corresponding clinical pathological data were collected from Yichang Central People's Hospital from January 2018 to August 2020. Immunohistochemistry was used to analyze the expression of GPR87 in tumor tissues and the clinical relevance of GPR87 was analyzed. siRNA-GPR87 and pCMV-GPR87-his were transfected into the human lung adenocarcinoma cell line A549 and the human lung squamous cell carcinoma cell line SK-MES-1, to construct cell lines with low and high expression of GPR87. Transwell assay was used to investigate the effect of GPR87 expression on the migration and invasion ability of NSCLC cells. ELISA was used to detect the secretion of MMP7 in the culture supernatant. RT-qPCR was used to detect the mRNA expression levels of GPR87, MMP2, MMP7, MMP9, E-cadherin, N-cadherin, vimentin, snail, twist, RHOA, RHOC, and ROCK1. ELISA was used to detect the secreted protein MMP7. Western blotting was used to detect the protein expression levels of GPR87, MMP9, E-cadherin, vimentin, RHOA, and ROCK1.Results·Bioinformatics analysis of clinical sample data showed that GPR87 was highly expressed in NSCLC. Patients with higher expression of GPR87 had worse clinical stage and were more prone to lymph node metastasis, suggesting that GPR87 might be a key gene for the high invasiveness of NSCLC. Downregulation of GPR87 expression significantly reduced the invasion and migration ability of A549 and SK-MES-1 cells, while overexpression of GPR87 enhanced the invasion and migration ability of A549 and SK-MES-1 cells. Further detection revealed that downregulation of GPR87 led to decreased mRNA expression levels of MMP2, MMP7, MMP9, RHOA, RHOC, and ROCK1, as well as a reduction in the secretion of MMP7 and the protein expression levels of MMP9, RHOA, and ROCK1 in A549 and SK-MES-1 cells. Overexpression of GPR87 increased the mRNA expression levels of MMP2, MMP7, MMP9, RHOA, RHOC, and ROCK1, as well as the secretion of MMP7 and the protein expression levels of MMP9, RHOA, and ROCK1. Regardless of GPR87 knockdown or overexpression, the expression of genes and proteins related to epithelial-mesenchymal transition (EMT) in the cells did not change significantly.Conclusion·High expression of GPR87 is closely related to the high invasiveness of NSCLC. In SK-MES-1 and A549 cells, GPR87 can activate the RHOA/ROCK1 signaling pathway, promote the expression of MMPs, and ultimately promote the invasion and migration of NSCLC.