Interaction of cancer cell-derived Foxp3 and tumor microenvironment in human tongue squamous cell carcinoma

The forkhead transcription factor, Foxp3, has been proved essential for differentiation and activation of regulatory T cells (Tregs). Recently, Foxp3 expression in tumor cells (cancer cell-derived Foxp3) has gained increasing interest, but the function has yet to be confirmed. In the current investigation, we identified the interaction of cancer cell-derived Foxp3 and tumor microenvironment in human tongue squamous cell carcinoma (TSCC) by various in vitro methods. We detected cancer cell-derived Foxp3 was closely associated with the infiltration of Foxp3 + lymphocytes in TSCC lesions using immunohistochemical staining. The cytokines secretion (IFN-gamma, TGF beta, IL-2, IL-6, IL-1 beta, IL-10, IL-8, IL-17, IL-23) of PBMC and differentiation of CD4 + T cells were modulated by the expression of Foxp3 in TSCC, shown by ELISA and flow cytometry. As feedback, increasing TGF beta and decreasing IL-17 further up-regulated cancer cell-derived Foxp3. Furthermore, CHIP on chip assay showed that both TGF beta and IL-17 decreased the number of Foxp3-binding genes in TSCC. GO and pathway analysis suggested that, treated with TGF beta or Th17, Foxp3-binding genes were inclined to the negative regulation of TGF beta signal pathway. Taken together, this study showed cancer cell-derived Foxp3 contributed to Tregs expansion in TSCC microenvironment with positive and negative feedbacks.