Background Clear cell renal cell carcinoma (ccRCC) is one of the most lethal malignancies in the urinary system and the existing immunotherapy has not achieved satisfactory outcomes. Therefore, this study aims at establishing a novel gene signature for immune infiltration and clinical outcome (overall survival and immunotherapy responsiveness) in ccRCC patients. Methods Based on RNA sequencing data and clinical information in The Cancer Genome Atlas (TCGA) database, we calculated proportions of immune cells in 611 samples using an online tool CIBERSORTx. Multivariate survival analysis was conducted to determine crucial survival-associated immune cells and immune-infiltration-related genes (IIRGs). Next, the clinical specimens and common renal cancer cell lines were applied to confirm IIRGs expression at protein and RNA levels. Finally, functional enrichment analyses and siRNA technology targeted to RUFY4 were implemented to verify its function of predicting immunotherapy response. Results Follicular helper T cells (TFHs) and Regulatory T cells (Tregs) were highly infiltrated in the tumor microenvironment (TME) and their relative proportions were independent prognostic factors for patients. Among IIRGs of TFHs and TREGs, RUFY4 was found to be highly activated in tumor microenvironment and its co-expression network was enriched in PDL1/PD1 checkpoint pathway in cancer. Additionally, knockdown of RUFY4 led to the decline of PDL1 and proliferation ability in ccRCC cell lines. Conclusion TFHs and Tregs were considered as prognostic biomarkers and RUFY4 was an immunotherapeutic predictor of ccRCC patients in a PDL1-Related manner.

BackgroundThe key role of hypoxia‐inducible factor 2alpha (HIF2α) in the process of renal cancer has been confirmed. In the field of tumour research, oxidative stress is also considered to be an important influencing factor. However, the relationship and biological benefits of oxidative stress and HIF2α in ccRCC remain unclear. This research attempts to explore the effect of oxidative stress on the cancer‐promoting effect of HIF2α in ccRCC and reveal its mechanism of action.MethodsThe bioinformatics analysis for ccRCC is based on whole transcriptome sequencing and TCGA database. The detection of the expression level of related molecules is realised by western blot and PCR. The expression of Nucleoside diphosphate‐linked moiety X‐type motif 1 (NUDT1) was knocked down by lentiviral infection technology. The functional role of NUDT1 were further investigated by CCK8 assays, transwell assays and cell oxidative stress indicator detection. The exploration of related molecular mechanisms is realised by Luciferase assays and Chromatin immunoprecipitation (ChIP) assays.ResultsMolecular screening based on knockdown HIF2α sequencing data and oxidative stress related data sets showed that NUDT1 is considered to be an important molecule for the interaction of HIF2α with oxidative stress. Subsequent experimental results showed that NUDT1 can cooperate with HIF2α to promote the progression of ccRCC. And this biological effect was found to be caused by the oxidative stress regulated by NUDT1. Mechanistically, HIF2α transcription activates the expression of NUDT1, thereby inhibiting oxidative stress and promoting the progression of ccRCC.ConclusionsThis research clarified a novel mechanism by which HIF2α stabilises sirtuin 3 (SIRT3) through direct transcriptional activation of NUDT1, thereby inhibiting oxidative stress to promote the development of ccRCC. It provided the possibility for the selection of new therapeutic targets for ccRCC and the study of combination medication regimens.

Background The mechanism of metabolism reprogramming is an unsolved problem in clear cell renal cell carcinoma (ccRCC). Recently, it was discovered that the Hippo pathway altered tumor metabolism and promoted tumor progression. Thus, this study aimed at identifying key regulators of metabolism reprogramming and the Hippo pathway in ccRCC and pinpointing potential therapeutic targets for ccRCC patients. Methods Hippo‐related gene sets and metabolic gene sets were used to screen potential regulators of the Hippo pathway in ccRCC. Public databases and samples from patients were applied to investigate the association of dihydrolipoamide branched chain transacylase E2 ( DBT ) with ccRCC and Hippo signaling. The role of DBT was confirmed by gain or loss of function assays in vitro and in vivo. Mechanistic results were yielded by luciferase reporter assay, immunoprecipitation, mass spectroscopy, and mutational studies. Results DBT was confirmed as a Hippo‐related marker with significant prognostic predictive value, and its downregulation was caused by methyltransferase‐like‐3 (METTL3)‐mediated N6‐methyladenosine (m 6 A) modification in ccRCC. Functional studies specified DBT as a tumor suppressor for inhibiting tumor progression and correcting the lipid metabolism disorder in ccRCC. Mechanistic findings revealed that annexin A2 (ANXA2) interacted with the lipoyl‐binding domain of DBT to activate Hippo signaling which led to decreased nuclear localization of yes1‐associated transcriptional regulator (YAP) and transcriptional repression of lipogenic genes. Conclusions This study demonstrated a tumor‐suppressive role for the DBT/ANXA2/YAP axis‐regulated Hippo signaling and suggested DBT as a potential target for pharmaceutical intervention in ccRCC.