Downregulation of FOXP3 inhibits cell proliferation and enhances chemosensitivity to cisplatin in human lung adenocarcinoma

Our study aimed to investigate the biological role of FOXP3 expression in human lung adenocarcinoma (LAD) tissues and evaluate its involvement in cell proliferation and chemosensitivity to cisplatin in LAD cells. Paraffin-embedded tissues from 50 LAD patients were collected to detect FOXP3 and Ki-67 expression using immunohistochemistry (IHC). Downregulation of FOXP3 in A549 cells was performed using siRNA transfection. Real-time PCR or western blot assay was performed to analyze FOXP3 expression in A549 cells. Cell proliferation and cisplatin cytotoxicity test were assessed by CCK-8 assay. The expression of FOXP3 was significantly associated with lymph node metastasis and TNM stage of LAD patients. The FOXP3 expression was positively correlated with Ki-67 labelling index(LI)in LAD tissues. The downregulated expression of FOXP3 by siRNA transfection significantly inhibited cell proliferation and enhanced chemosensitivity to cisplatin in A549 cells. The expression of FOXP3 was significantly upregulated following cisplatin treatment in A549 cells. Our study indicates that FOXP3 may potentially be a novel molecular target in combating drug resistance in the chemotherapy of LAD.