OBJECTIVE  To investigate the effect and mechanism of icotinib(ICO) on renal fibrosis(RF).

METHODS  A unilateral ureteral obstruction(UUO) model was established by ligating the left ureter of mice. The mice were randomly divided into: Sham group, UUO group, ICO(20 mg· kg⁻¹)-treated UUO group and ICO (40 mg· kg⁻¹)-treated UUO group, eight mice in each group. The renal function was evaluated by blood urea nitrogen(BUN), serum creatinine(Scr) and kidney injury molecule-1(KIM-1). The degree of renal fibrosis was assessed by HE and Masson staining. The level of epidermal growth factor receptor(EGFR) phosphorylation in kidney tissue was detected by immunohistochemistry. The ultrastructure of renal mitochondria was observed by transmission electron microscopy. In vitro, the mouse renal tubular epithelial cells were cultured and divided into control group, transforming growth factor-β1(TGF-β1) group, TGF-β1combined with ICO (5, 10, 20 μmol·L⁻¹) groups. Detection of mitochondrial membrane potential by JC-1 fluorescent probe. DCFH-DA fluorescent probe was used to detect ROS levels. The contents of adenosine triphosphate(ATP) and malondialdehyde(MDA) were determined by kits. The expression of related proteins was detected by immunofluorescence and(or) Western blotting.

RESULTS  In vivo, ICO inhibited UUO-induced renal damage(the levels of BUN, Scr and KIM-1 were reduced), alleviated renal fibrosis(collagen deposition and type I and III collagen expression were decreased), reversed epithelial-mesenchymal transition(EMT)(The expression of E-cadherin rose, while the expressions of α-smooth muscle actin and fibronectin declined), inhibited EGFR phosphorylation and Snail expression, and alleviated mitochondrial damagethe expression of silent information regulator 3(SIRT3) was significantly up-regulated while the expression of uncoupling protein 2(UCP2) was significantly down-regulated in mice. In vitro, ICO significantly inhibited TGF-β1-induced EGFR phosphorylation and Snail expression, repressed EMT, decreased the levels of ROS and MDA, and alleviated mitochondrial damage(mitochondrial membrane potential and the level of ATP were increased, SIRT3 expression was significantly increased while UCP2 expression was significantly decreased).

CONCLUSION  This study indicates that icotinib can alleviate renal fibrosis, and the anti-fibrotic mechanism is related to the inhibition of oxidative stress-mediated mitochondrial damage and thereby the reversal of EMT in renal tubular epithelial cells.