FOXP3 influences recruitment and polarization of macrophages via regulating CCL5 in non-small cell lung cancer

Forkhead box P3 (FOXP3) plays a key role in the malignant progression of non-small cell lung cancer (NSCLC).However, the regulatory effect of FOXP3 on the biological activity of macrophages in NSCLC has not yet been reported.In the present study, we explored the effects of FOXP3 on the polarization and recruitment of macrophages induced by A549 and H1975 cells.RAW264.7 cells were used as macrophages.The transcription and protein levels of FOXP3, chemokine (C-C motif) ligand 5 (CCL5), and other cytokines were evaluated by reversetranscription quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively.Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays were performed to confirm the regulatory relationship between FOXP3 and CCL5.Immunofluorescence staining was used to detect the expression of differentiation 206 (CD206) in the macrophages.The capacity of cancer cells to recruit macrophages was evaluated using a macrophage chemotaxis assay.Downregulation of FOXP3 expression inhibits macrophage recruitment by lung cancer cells.Low FOXP3 expression also decreased the expression levels of M2 macrophage markers (CD206, CD163, and interleukin-10 (IL-10)) in macrophages.Inhibition of FOXP3 expression downregulates CCL5 transcription in A549 and H1975 cells.The promotion of macrophage chemotaxis and M2 polarization in lung cancer cells overexpressing FOXP3 was reversed by downregulation of CCL5.Our study revealed that FOXP3 promoted chemotaxis and M2 polarization of macrophages in NSCLC.This effect is caused by the regulation of CCL5 secretion by cancer cells.