ABSTRACT
Background: Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial lung disease with a high mortality rate and limited treatment efficacy. Nintedanib, a tyrosine kinase inhibitor, is clinically used to treat pulmonary fibrosis. At present, only nintedanib is on the market for the treatment of pulmonary fibrosis. Pazopanib is a drug for the treatment of renal cell carcinoma and advanced soft tissue sarcoma. Methods: In this study, we explored whether pazopanib can attenuate bleomycin (BLM)-induced pulmonary fibrosis and explored its antifibrotic mechanism. In vivo and in vitro investigations were carried out to investigate the efficacy and mechanism of action of pazopanib in pulmonary fibrosis. Results: In vivo experiments showed that pazopanib can alleviate pulmonary fibrosis caused by BLM, reduce the degree of collagen deposition and improve lung function. In vitro experiments showed that pazopanib suppressed transforming growth factor-ß1 (TGF-ß1)-induced myofibroblast activation and promoted apoptosis and autophagy in myofibroblasts. Further mechanistic studies demonstrated that pazopanib inhibited the TGF-ß1/Smad and non-Smad signaling pathways during fibroblast activation. Conclusions: In conclusion, pazopanib attenuated BLM-induced pulmonary fibrosis by suppressing the TGF-ß1 signaling pathway. Pazopanib inhibits myofibroblast activation, migration, autophagy, apoptosis, and extracellular matrix (ECM) buildup by downregulating the TGF-ß1/Smad signal route and the TGF-ß1/non-Smad signal pathway. It has the same target as nintedanib and is a tyrosine kinase inhibitor.
ABSTRACT
Idiopathic pulmonary fibrosis (IPF) is a fatal and age-related pulmonary disease. Nintedanib is a receptor tyrosine kinase inhibitor, and one of the only two listed drugs against IPF. Regorafenib is a novel, orally active, multi-kinase inhibitor that has similar targets to nintedanib and is applied to treat colorectal cancer and gastrointestinal stromal tumors in patients. In this study, we first identified that regorafenib could alleviate bleomycin-induced pulmonary fibrosis in mice. The in vivo experiments indicated that regorafenib suppresses collagen accumulation and myofibroblast activation. Further in vitro mechanism studies showed that regorafenib inhibits the activation and migration of myofibroblasts and extracellular matrix production, mainly through suppressing the transforming growth factor (TGF)-ß1/Smad and non-Smad signaling pathways. In vitro studies have also indicated that regorafenib could augment autophagy in myofibroblasts by suppressing TGF-ß1/mTOR (mechanistic target of rapamycin) signaling, and could promote apoptosis in myofibroblasts. In conclusion, regorafenib attenuates bleomycin-induced pulmonary fibrosis by suppressing the TGF-ß1 signaling pathway.
