The Effect Of SNF5 On Immune Escape Of Non-small Cell Lung Cancer

SNF5 is the core subunit of the SWI/SNF chromatin-remodeling complex.Mutations or deletions of SNF5 have occurred in various malignant tumors,such as melanoma,malignant rhabdomyomas,familial schwannomatosis,and epithelioid sarcoma.Immune escape plays an important role in the occurrence and development of lung cancer,and lung cancer cells evade the immune system’s anti-tumor response through a variety of mechanisms.Studies have found that SNF5 can directly or selectively block the binding of MYC to PD-L1 promoters,which plays a role in suppressing tumors.However,it is currently unclear that SNF5 regulates the mechanism of lung cancer immune escape.Therefore,this project takes non-small cell lung cancer cells A549 and NCI-H1299 as the experimental research background.First,we analyzed the expression level of SNF5 of lung cancer tissues and normal tissues through the TCGA database,and also analyzed the relationship between the overall survival(OS)and lung cancer patients.Secondly,after overexpression or knockdown of SNF5 in two lung cancer cell lines A549 and NCI-H1299,we detected the expression levels of immune escape related factors through western blot and q RT-PCR to explore the effect of SNF5 on the immune escape of lung cancer cells.Because overexpression of SNF5 in A549 cells can activate STAT3 phosphorylation.Therefore,after adding P-STAT3 inhibitor S3I-201 to A549 cells overexpressing SNF5,we explore SNF5 whether to regulate the immune escape of lung cancer cells through the P-STAT3 signaling pathway.Finally,we detected the expression of proliferation-related factors and the proliferate ability of lung cancer cells by western blot,q RT-PCR,and CCK8 after overexpressing SNF5 in A549 cells and knocking down SNF5 in NCI-H1299 cells.The following experiment results conclusions were obtained:Results:(1)SNF5 is highly expressed in lung cancer tissues.The overall survival of lung cancer patients with high SNF5 expression is significantly lower than with low SNF5 expression.(2)The protein expression level of SNF5 in NCI-H1299 cells was significantly higher than in A549 cells.O verexpression of SNF5 in A549 lung cancer cells can up-regulate the expression levels of immune escape-related factors PD-L1,PD-L2,IDO1,and TGFβ1.Knockdown of SNF5 in NCI-H1299 lung cancer cells can inhibit the expression levels of PD-L1,PD-L2,IDO1,and TGFβ1.(3)Overexpression of SNF5 can promote the expression of P-STAT3,PD-L1 and PD-L2 in A549 lung cancer cells,but does not effect the expression of STAT3.Knockdown of SNF5 can inhibit the expression of P-STAT3,PD-L1,and PD-L2 in NCI-H1299 lung cancer cells,and also does not effect the expression of STAT3.Therefore,after adding the P-STAT3 inhibitor S3I-201 to A549 lung cancer cells overexpressing SNF5,the up-regulated expression of PD-L1 and PD-L2 was alleviated or inhibited,indicating that the SNF5 regulates the expression of PD-L1/PD-L2 by STAT3 signaling pathway in lung cancer cells and participates in tumor immune escape.(4)Overexpression of SNF5 can promote the expression of cyclin D1 in A549 lung cancer cells,while inhibiting the expression of P21.It can enhance the proliferation ability of A549 lung cancer cells.O n the contrary,knocking down SNF5 can inhibit the expression of Cyclin D1 in NCI-H1299 lung cancer cells at the protein and gene level,but promote the expression of P21,and inhibit the proliferation of NCI-H1299 lung cancer cel s.