Chalcone flavokawain A attenuates TGF- β1-induced fibrotic pathology via inhibition of ROS/Smad3 signaling pathways and induction of Nrf2/ARE-mediated antioxidant genes in vascular smooth muscle cells.

In this study, flavokawain A (FKA, 2-30 μM), a naturally occurring chalcone in kava extracts, was evaluated for its anti-fibrotic and antioxidant properties in TGF-β1-stimulated vascular smooth muscle (A7r5) cells, as well as its underlying molecular mechanism of action. Immunofluorescence data showed down-regulated F-actin expression with FKA treatment in TGF-β1-stimulated A7r5 cells. Western blotting demonstrated that FKA treatment suppressed the expression of α-SMA and fibronectin proteins under TGF-β1 stimulation. Findings from wound-healing and invasion experiments showed that FKA inhibits TGF-β1-mediated migration and invasion. Western blotting demonstrated that treatment with FKA down-regulated MMP-9 and MMP-2 and up-regulated TIMP-1 expression. Further evidence showed that FKA decreased TGF-β1-mediated phosphorylation and the transcriptional activity of Smad3. TGF-β1-induced excessive ROS production was remarkably reversed by FKA treatment in A7r5 cells, and inhibition by FKA or N-acetylcysteine (NAC) substantially diminished TGF-β1-induced p-Smad3 activation and wound-healing migration. Interestingly, FKA-mediated antioxidant properties were associated with increased nuclear translocation of Nrf2 and elevated antioxidant response element (ARE) luciferase activity. Activation of Nrf2/ARE signaling was accompanied by the induction of HO-1, NQO-1 and γ-GCLC genes in FKA-treated A7r5 cells. Notably, silencing of Nrf2 (siRNA transfection) significantly diminish...

Source: J Cell Mol Med - December 13, 2018 Category: Molecular Biology Authors: Hseu YC, Yang TY, Li ML, Rajendran P, Mathew DC, Tsai CH, Lin RW, Lee CC, Yang HL Tags: J Cell Mol Med Source Type: research