| BackgroundRenal cell carcinoma(RCC)is one of the most common malignant tumors of the urinary system,affecting more than 400,000 patients every year,and its incidence is still increasing year by year.The main pathological type of RCC is clear cell renal cell carcinoma(ccRCC),accounting for about 80%～90%of all cases.Unfolded protein response(UPR)under endoplasmic reticulum stress(ER stress)is an important cellular adaptive regulatory mechanism.When a cell enters an irreversible state of ER stress under external stimuli,terminal unfolded protein response(TUPR)will initiate and induce cell apoptosis.Current studies have shown that TUPR in tumor cells can induce apoptosis,which plays an indispensable role in the development of tumors.However,the current research on TUPR-related genes in ccRCC is still blank.Therefore,understanding the specific role of TUPR in ccRCC cells is of great significance for the treatment of tumor patients.MethodsIn this study,the transcriptome sequencing data and corresponding clinical information of 526 ccRCC patients were obtained from The Cancer Genome Atlas(TCGA).According to 9 terminal TUPR-related genes had been reported,the TUPR gene expression matrix was extracted and R software was used for unsupervised cluster analysis.The patients were divided into different subgroups and differences in gene expression,clinical information,pathway enrichment,and immune infiltration among subgroups were analyzed.The prognostic model related to TUPR was constructed by Least absolute shrinkage and selection operator(LASSO)regression and Cox proportional-hazards model,and we tested its efficacy.Then we treated ccRCC cells with tunicamycin(Tm)to induce TUPR and detect cell proliferation and apoptosis.The TUPR-related gene STT3B was screened out by RT-qPCR under terminal ER stress in ccRCC cells and its expression was detected in normal kidney tissue and ccRCC tissue.Then we constructed a STT3B-silencing ccRCC cell line and detected its proliferation,apoptosis and related gene expression under terminal ER stress to study the related functions of STT3B in ccRCC cells.ResultsBy unsupervised clustering,we divided the ccRCC patients in the TCGA database into two subgroups,in which patients with high expression of TUPR-related genes had better prognosis,earlier T stage or clinical stage,as well as a higher degree of immune infiltration and lower expression of immune checkpoint genes,whose gene expression was characterized by strongly ER stress and apoptosis.Our prognostic model showed that TUPR-related genes also had a good predictive effect on the prognosis of ccRCC patients.The experimental results showed that Tm treatment for more than 12 hours can induce the occurrence of TUPR in ccRCC cells,resulting in weakened proliferation and an early apoptosis state of ccRCC cells.Through RT-qPCR,we found that the expressions of 9 TUPR-related genes were all increased,among which STT3B was most related to TUPR in ccRCC.STT3B was significantly positively correlated with the expression of the currently known ER stress-related genes.Compared with normal renal tubular epithelial cell line or adjacent normal tissues,STT3B was lower expressed in ccRCC cells and tissues.After silencing STT3B we found that the expression of ER stress-related genes in ccRCC cells was upregulated,but it did not affect the cell proliferation and apoptosis,Following by Tm treatment of STT3B-silencing ccRCC cell line,we found that STT3B silencing upregulated ER stress-related gene expression under terminal ER stress,as well as reduced the proliferation ability of ccRCC cells and promote cell apoptosis.ConclusionsIn summary,in this study we confirmed the relationship between TUPR-related genes and survival prognosis,clinical information,and immune infiltration in ccRCC patients by unsupervised clustering and Cox regression model of the expression profiles of ccRCC patients in the TCGA database.Through cellular functional experiments,we confirmed that the occurrence of TUPR can inhibit the proliferation of ccRCC cells and induce cell apoptosis.As a marker gene,STT3B was closely related to the occurrence of TUPR in ccRCC cells,and the lack of its expression improves the sensitivity of ccRCC cells to Tm-induced TUPR.TUPR-related genes were expected to serve as novel molecular markers and potential therapeutic targets for ccRCC. |
