Transforming growth factor-β (TGF-β) plays a critical role in regulating cell growth and differentiation. Epithelial to mesenchymal transition (EMT) induced by TGF-β promotes cancer cell migration, invasion, and proliferation. Pirfenidone (5-methyl-1-phenyl-2(1 H)-pyridone, PFD), an approved drug for treating pulmonary and renal fibrosis, is a potent TGF-β inhibitor and found reduced incidence of lung cancer and alleviated renal function decline. However, whether PFD plays a role in controlling renal cancer progression is largely unknown. In the present study, we demonstrated that high TGF-β1 expression was negatively associated with ten-year overall survival of patients with renal cancer. Functionally, blockade of TGF-β signaling with PFD significantly suppressed the progression of renal cancer in a murine model. Mechanistically, we revealed that PFD significantly decreased the expression and secretion of TGF-β both in vitro and in vivo tumor mouse model, which further prevented TGF-β-induced EMT and thus cell proliferation, migration, and invasion. Importantly, the downregulation of TGF-β upon PFD treatment shaped the immunosuppressive tumor microenvironment by limiting the recruitment of tumor-infiltrating MDSCs. Therefore, our study demonstrated that PFD prevents renal cancer progression by inhibiting TGF-β production of cancer cells and downstream signaling pathway, which might be presented as a therapeutic adjuvant for renal cancer.
Keywords: Pirfenidone; TGF-β; epithelial-to-mesenchymal transition; myeloid-derived suppressor cells (MDSC); renal cell carcinoma; tumor microenvironment (TME).