Arsenic-induced downregulation of BRWD3 suppresses proliferation and induces apoptosis in lung adenocarcinoma cells through the p53 and p65 pathways.

Bromodomain and WD-repeat domain-containing protein 3 (BRWD3) exhibits high expression in lung adenocarcinoma (LUAD) tissues and cells; however, its function in arsenic-induced toxicological responses remains unclear. This study aimed to investigate BRWD3 expression in response to arsenic-induced conditions and its impact on the proliferation and apoptosis of LUAD cell line SPC-A1 upon BRWD3 knockdown. The results revealed a decrease in BRWD3 expression in SPC-A1 cells treated with sodium arsenite (NaAsO₂), but not sodium arsenite's metabolites. BRWD3 knockdown suppressed cell proliferation and induced apoptosis in SPC-A1 cells. Western blot analysis revealed that BRWD3 knockdown resulted in the upregulation of p53, phospho-p53-Ser392, and its downstream factors including MDM2, Bak, and Bax. Additionally, we observed the downregulation of p65, phospho-p65-Ser276, phospho-p65-Ser536, and its downstream factors, including IκBα, BIRC3, XIAP and CIAP1. Moreover, polymerase chain reaction analysis showed that BRWD3 knockdown also resulted in the downregulation of proliferation-related genes and upregulation of apoptosis-related genes. In conclusion, BRWD3 mediated proliferation and apoptosis via the p53 and p65 pathways in response to arsenic exposure, suggesting potential implications for LUAD treatment through BRWD3 downregulation by arsenic.