The Effect Of TNFSF13B And PPARGC1A On The Tumor Microenvironment And Prognosis In Clear Cell Renal Cell Carcinoma And The Underlying Mechanism

Part I Identification of Tumor Microenvironment-Related Prognostic Genes in Clear Cell Renal Cell CarcinomaObjective Increasing evidence suggests that the tumor microenvironment(TME)plays crucial roles in carcinogenesis,cancer progression,prognosis and immunotherapeutic efficacy in clear cell renal cell carcinoma(ccRCC).In this study,we comprehensively analyzed ccRCC RNA-sequencing data from The Cancer Genome Atlas(TCGA)database to identify candidate prognostic TME-related genes involved in ccRCC,and to further explore their clinical significance.Methods The transcriptome and clinical data of ccRCC were extracted from the TCGA database,and the immune and matrix components of each sample were estimated by the ESTIMATE algorithm.The "Limma" R package was used to screen the differentially expressed genes(DEGs)between immune and matrix components,and the obtained DEGs were subjected to functional and pathway enrichment analysis by Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG).The key genes associated with ccRCC prognosis were screened by protein interaction network and univariate Cox regression analysis.We further investigated the differential expression of key genes in tumor and normal tissues and their expression levels in relation to the survival and clinicopathological characteristics of ccRCC patients.Results The content of immune components in TME was correlated with the overall survival of ccRCC patients(P<0.05).A total of five TME-related pivotal genes(IGLL5,MZB1,HSD11B1,TNFSF13B,and PPARGC1A)were identified.Compared to the normal tissues,the expression level of TNFSF13B in ccRCC tumor tissues was significantly higher,while the expression level of PPARGC1A was significantly lower(both P<0.001).Meanwhile,the expression level of TNFSF13B was positively correlated with tumor progression and poor survival prognosis in ccRCC patients,and the expression level of PPARGC1A was negatively correlated with tumor progression and poor survival prognosis in ccRCC patients(both P<0.05).Conclusion The expression levels of TNFSF13B and PPARGC1A are closely related to the prognosis of ccRCC patients,and have the potential to be the prognostic markers and therapeutic targets for ccRCC.Part Ⅱ The Effect of the Expression of TNFSF13B and PPARGC1A on the Clear Cell Renal Cell Carcinoma MicroenvironmentObjective To investigate the differential expression levels and prognostic roles of TNFSF13B and PPARGC1A,key genes related to the tumor microenvironment(TME),in clear cell renal cell carcinoma(ccRCC),and to further explore the effects of the two genes on the ccRCC microenvironment and the underlying mechanisms.Methods 1.Transcriptomic and clinical data of the ccRCC datasets were obtained from the gene expression omnibus(GEO)database.Retrospectively collected pathological paraffin tissue sections and fresh tissue samples from 35 ccRCC patients from our hospital between October 2019 and July 2021 for immunohistochemistry,real-time quantitative PCR,and western blotting studies.To verify the true expression levels of TNFSF13B and PPARGC1A in clinical ccRCC tissues and the impact of their expression on the prognosis of ccRCC patients.2.The transcriptomic data of ccRCC was obtained from the cancer genome atlas(TCGA)database.Gene set enrichment analysis(GSEA)was conducted among the samples of TNFSF13B and PPARGC1A high and low expression groups to investigate potential pathways and functions.3.The CIBERSORT algorithm was applied to estimate the abundance of 22 tumor-infiltrating immune cells(TICs)in ccRCC tumor samples from the TCGA database.Correlations between TNFSF13B and PPARGC1A expression and TICs were evaluated using differential analysis and correlation analysis.4.Associations between TNFSF13B and PPARGC1A expression and tumor mutational burden,immune checkpoints expression levels,and response to immunotherapy involved in ccRCC were further explored.Results 1.The results further validated that the expression levels of TNFSF13B in ccRCC tumor tissues were significantly higher and that PPARGC1A were significantly lower than in normal tissues,and patients with high TNFSF13B expression and low PPARGC1A expression probably exhibited worse prognosis.2.GSEA revealed that genes in the groups with high TNFSF13B and PPARGC1A were enriched mainly in immune-related activities.3.By combining difference and correlation analyses,the expression of both TNFSF13B and PPARGC1A were found to be significantly associated with multiple types of TICs.For example,the proportion of CD8 T cells and regulatory T cells were positively correlated with TNFSF13B expression and negatively correlated with PPARGC1A expression.4.TNFSF13B and PPARGC1A expression were significantly correlated with the tumor mutational burden,several immune checkpoints expression,and drug sensitivity involved in ccRCC.Conclusion The expression levels of TNFSF13B and PPARGC1A are closely related to the survival prognosis of ccRCC patients.They may play significant roles in the remodeling of the ccRCC microenvironment,and are expected to be potential therapeutic targets and predictive markers of the immunotherapeutic response in ccRCC.