Decreased Expression Of Histone Deacetylase 9 Lead To Poor Prognosis And Inhibit Immune Cell Infiltration In Clear Cell Renal Cell Carcinoma

Objective:It is well known that clear cell renal cell carcinoma(ccRCC)is considered the main type of renal cell carcinoma(RCC).At present,surgical resection is the most frequently recommended treatment for ccRCC,but the clinical outcomes of advanced and metastatic ccRCC have not improved.The literature indicates that ccRCC is highly immunogenic and treatment resistant.Hence,screening novel targets and combinations with immunotherapy could provide a novel approach for the treatment of ccRCC.Currently,histone deacetylation has been validated as an important epigenetic modification.Histone deacetylase 9(HDAC9)is in the IIa subtype of histone deacetylases(HDACs),regulating a variety of biofunctions and playing a dual role in tumors.In current study,we evaluated the expression level of HDAC9 in clear cell renal cell carcinoma(ccRCC),investigated the correlations between the prognosis of ccRCC patients and HDAC9,and examined the association between immunological parameters and HDAC9.Materials&Methods:1.The differences between HDAC9 expression in ccRCC tissues and normal tissues were evaluated with reverse transcription-quantitative polymerase chain reaction(RT-qPCR),western blotting and immunohistochemistry(IHC).The relationship of the expression of HDAC9 and overall survival(OS)was estimated using UCSC Xena database.2.After the construction of stably transfected cell lines using the recombinant plasmid carrying HDAC9 and the negative control plasmid,the proliferation and metastasis of ccRCC cells,786-O and ACHN,were examined with colony formation assays and 5-ethynyl-2’deoxyuridine(EdU)assays,and transwell assays.3.Gene set enrichment analysis(GSEA)was conducted to examine the potential biofunctions of HDAC9.4.To assess the relationship between HDAC9 expression and immunological parameters,we used the Tumor IMmune Estimation Resource(TIMER)database.Results:1.The results of RT-qPCR,western blotting,and IHC consistently confirmed that HDAC9 was downregulated in ccRCC tissues.And decreased expression of HDAC9lead to poor prognosis in ccRCC.2.By performing colony formation assays and EdU assays,we found that the upregulation of HDAC9 inhibited ccRCC cell proliferation.In addition,the migration and invasion of ccRCC cells were significantly suppressed by HDAC9 overexpression based on transwell assays.3.A subset of the GSEA results associated with the immune response and inflammation were positively correlated with HDAC9 expression.4.The levels of B cells,CD8~+T cells,CD4~+T cells,macrophages,neutrophils,and dendritic cells were significantly positively correlated with HDAC9 expression.Furthermore,the significant positive correlations between the expression of HDAC9and the expression of common immune checkpoints were also found.ConclusionThe decreased expression of HDAC9 was confirmed in ccRCC and lead to poor prognosis.Overexpressed HDAC9 inhibited ccRCC cell proliferation migration and invasion.Additionally,HDAC9 can activate immune cell infiltration in ccRCC.Hence,HDAC9 can be identified as a novel target for ccRCC treatment,but further studies are needed.