FOXP3 and TLR4 protein expression are correlated in non-small cell lung cancer: Implications for tumor progression and escape

NSCLC (non-small cell lung cancer) is the most common type of lung cancer and usually has poor prognosis. FOXP3 in regulatory T cells (Tregs) and toll-like receptor 4 (TLR4) on some tumor cells are known to be important for tumor escape and clinical tumor formation. Since FOXP3 was found recently in some tumor cells, we speculated if lung tumor cells express FOXP3 and then mimic Tregs to promote tumor escape. As TLR4 induces activation of Tregs, we also hypothesized that FOXP3 and TLR4 may have a correlation in NSCLC progression. The expression levels of FOXP3 and TLR4 protein were detected using immunohistochemistry in 53 postoperative specimens of NSCLC patients and in 15 normal lung tissues from excisions of benign lesion. The relationship between protein expression levels and clinical pathology parameters, as well as the relationship between the expression of FOXP3 and TLR4, were analyzed. FOXP3 and TLR4 expression in NSCLC were significantly elevated as compared to normal lung tissue. FOXP3 expression was closely related with lymph node metastasis and TNM staging, whereas TLR4 expression was closely related with tumor differentiation. The Spearman correlation coefficient indicated a significant positive correlation between FOXP3 and TLR4 expression. These results indicate that FOXP3 and TLR4 may coordinate to play a role in tumor escape and subsequent tumor progression.