Expression Of CHK2 In ARID1A-deficient Tumors And Its Effect On Treatment

Objective: ARID1 A is a component of the evolutionarily conserved chromatin remodeling complex SWI/SNF.The Cancer Genomic Atlas(TCGA)datasets revealed that ARID1 A is one of the most frequently mutated genes in a wide spectrum of human cancers.Our group and others have shown that ARID1 A plays a unique role in regulating DNA damage response.In this study,we will do further work to investigate the role of ARID1 A in DNA damage response and hope to find therapeutic targets for ARID1A-deficient tumors.Methods: The bioinformatics analysis was used to screen differentially expressed proteins in ARID1A-wildtype and ARID1A-mutant endometrioid carcinoma in TCGA databases.And DNA damage repair signaling molecule CHK2 was identified.Immunohistochemical(IHC)staining and Western blot were utilized to verify the correlation between ARID1 A and CHK2/p-CHK2.MTT and colony formation were used to detect cell proliferation and determine the relationship between ARID1 A expression and cell sensitivity to chemotherapeutic drugs and radiation.Flow cytometry and clone formation were used to detect the effects of CHK2 on cell proliferation and apoptosis of ARID1A-deficient ovarian cancer cell in the presence of different IR dosage.Nude mice xenograft model was used to observe the change of ARID1A-deficient ovarian cancer cell proliferation after inhibiting the expression of CHK2.Results: RPPA data showed that the expression of CHK2 and p-CHK2 was significantly higher in ARID1 A mutant tumors than ARID1 A wild-type tumors.Immunohistochemical and Western blot results showed that CHK2 and p-CHK2 were elevated in ARID1A-deficient ovarian cancer cells.MTT and clone formation results showed that ARID1A-deficient ovarian cancer cells were significantly resistant to chemotherapy drugs and radiation.Flow cytometry and clone formation results showed that the radiosensitivity of ARID1A-deficient tumor cells increased after knockdown the expression of CHK2.In addition,knockdown ARID1 A could increase sensitivity of cells to CHK2 inhibitor.And growth of xenografts was significantly suppressed by CHK2 knockdown,which is consistent with the CHK2 function in vitro.Conclusions: These results demonstrated enhanced Chk2 expression and activation in ARID1A-deficient cells.And knockdown CHK2 sensitized ARID1 A deficient cells to IR treatment and inhibited tumors growth in xenograft models.