Abstract: Objective To investigate the effects of advanced oxidation protein products (AOPP) on epithelial-to-mesenchymal
transition (EMT) in cultured human proximal tubular epithelial cells (HK-2) and explore the mechanism. Methods HK-2 cells
treated with 50, 100, 200, and 400 μg/ml AOPP or 50 μg/m bovine serum albumin (BSA) for 24 h, or with 200 μg/ml AOPP for
0.5, 1, 3, 6, 12, and 24 h were examined for the protein expression of α-SMA and E-cadherin. In cells pretreated with
diphenyleneiodonium (DPI) or cytoplasmic superoxide dismutase (C-SOD), the effects of 50 μg/ml BSA and 200 μg/ml AOPP
were assessed on the expressions of α-SMA and E-cadherin, malondialdehyde (MDA) level, superoxide dismutase (SOD)
activity, catalase (CAT) activity, and glutathione peroxidase (GSH-px) activity. Results AOPP treatment up-regulated α-SMA
expression and down-regulated E-cadherin expression in a dose- and time-dependent fashion. AOPP exposure of the cells
resulted in increased MDA level and lowered activities of SOD, CAT and GSH-PX. DPI and C-SOD partially attenuated the
effects of AOPP on α-SMA, E-cadherin, MDA, SOD, CAT and GSH-px. Conclusion AOPP can induce EMT in cultured HK-2
cells via oxidative stress, and this effect can be attenuated by inhibiting the activation of NADPH oxidase and using
antioxidants to delay the progression of renal interstitial fibrosis.