Molecular docking combined with in vitro validation study to explore the effect of lupenone on alleviating renal fibrosis based on TGF-β/Smad/CTGF signaling pathway

Hyperglycemia and renal fibrosis play critical roles in the occurrence and development of diabetic complications such as diabetic nephropathy (DN). Lupenone, a stable pentacyclic triterpenoid compound, has anti-hyperglycemic and anti-renal fibrosis activities. Previous research has confirmed that lupenone can improve renal fibrosis in type 2 diabetic nephropathy by regulating TGF-β/Smad/CTGF signaling pathway. However, the binding power of lupenone with its related targets has not been confirmed, and it is unclear whether it exerts anti-renal fibrosis effects as a prototype component. Therefore, the aim of this study was to identify the underlying mechanism of lupenone on anti-renal fibrosis based on the TGF-β/Smad/CTGF signaling pathway and elucidate their binding ability using molecular docking and in vitro cell experiments. Molecular docking results suggested that lupenone combined well with fibronectin, TGF-β1, TβRI, TβRII, Smad2, Smad3, Smad4, Smad7 and Smurf2, respectively. And lupenone could significantly reduce high glucose-induced MCs cytotoxicity. Furthermore, lupenone significantly downregulated the mRNA and protein expression of collagen-I, collagen-IV, fibronectin, TGF-β1, p-TβRI/TβRI, TβRII, p-Smad2/Smad2, p-Smad/Smad3, Smad4, Smurf2, and CTGF in high glucose-induced MCs, with the best effect observed in the high-dose lupenone group. These results concluded that lupenone could inhibit the generation of fibrosis factors collagen-I, collagen-IV, and fibronectin and delay the process of fibrosis by regulating the TGF-β/Smad/CTGF signaling pathway in MCs.