The Role And Mechanism Of ARID1A In Regulating Immune Microenvironment And Protein Translation In Hepatocellular Carcinoma

Study objectives:We aimed to explore the regulation of at rich interacting domain protein 1A(ARID1A)gene in the development of liver cancer and the correlation between ARID1A gene variants or expression level changes and the immune microenvironment of liver cancer,in order to provide clues for optimizing liver cancer immunotherapy strategies.Research methods:In this study,the somatic mutation profiles of 81 patients with hepatocellular carcinoma were examined by hybrid capture analysis of key genes associated with high tumor mutational burden.Using public data,different ARID1A expression levels were analyzed for correlation with the tumor immune microenvironment,and differentially expressed genes were screened and subjected to functional enrichment analysis.In parallel,we performed biological functional experiments and RNA seq analysis of ARID1A knockdown liver cancer cell lines in vitro,and qRT-PCR was used to initially validate the analysis.Public databases were used to analyze the correlation between ARID1A and other differentially expressed genes and the prognosis of HCC patients.Result:Mutation profiling of 81 HCC patients revealed that ARID1A,MLL,NCOR1,TP53 and CTNNB1 mutations were associated with higher tumor mutational burden in hepatocellular carcinoma(HCC).Public database analysis revealed that ARID1A underexpression was significantly associated with higher immune scores,immune cell infiltration,cytotoxicity,and immune checkpoint protein expression levels in hepatocellular carcinoma.The differential gene functions among different ARID1A expression groups were mainly enriched in cell components such as intercellular junctions,focal adhesions,and mitochondrial matrix,as well as tumor related signaling pathways such as RAP1 and PI3K-AKT.Although in vitro assays showed that liver cancer cells with ARID1A knockdown had higher invasive migration ability,analysis of public databases showed that liver cancer patients with ARID1A and low expression of ribosomal proteins had better prognosis,which is inconsistent with the results of cell experiments,and may be associated with ARID1A gene exerting tumor suppressor or anticancer effects in a condition dependent manner.RNA-seq analysis showed that the differentially expressed genes after ARID1A knockdown were mainly enriched in the ribosome synthesis and protein translation pathways.The expression levels of ribosomal proteins were significantly decreased in ARID1A knockdown liver cancer cells.Conclusions:In this study,we found that ARID1A mutation or low expression was strongly associated with the more active tumor microenvironment and might serve as a predictive marker for the efficacy of immunotherapy in hepatocellular carcinoma.We first propose that ARID1A is involved in the regulation of protein translation and that low ARID1A expression causes a widespread decrease in ribosomal protein synthesis.Significance:This study may provide clues for optimizing liver cancer immunotherapy strategies in the clinic and further exploring combination therapy with immune checkpoint inhibitors and protein translation regulation.