Cysteinyl leukotrienes synthesis is involved in aristolochic acid I-induced apoptosis in renal proximal tubular epithelial cells

Aristolochic acid I (AAI) is a primary nephrotoxin and carcinogen that is found in some Chinese herbal medicines, and AAI is responsible for the progression of aristolochic acid nephropathy. The membrane associated proteins in the eicosanoid and glutathione metabolism (MAPEG) superfamily are associated with cysteinyl leukotrienes (cysLTs) synthesis. The present study investigated whether cysLTs synthesis was involved in AAI-induced renal proximal tubular epithelial cell injury in LLC-PK1 cells. Based on MAPEG and related molecular events, the potential mechanisms of AAI-induced LLC-PK1 cell injury were explored. AAI triggered the mitochondrial/caspase apoptotic pathway in LLC-PK1 cells, which was indicated by an enhanced Bax/Bcl-2 ratio, loss of mitochondrial membrane potential, cytochrome C release, and caspase 3 activation. In addition, AAI-induced cysLTs release was accompanied by selective upregulation of 5-lipoxygenase activating protein (FLAP) and microsomal glutathione S-transferase 3 (mGST3) in a concentration-dependent manner. The FLAP inhibitor MK866 significantly protected cells from AAI-induced apoptosis. Furthermore, activation of extracellular signal-regulated kinase (ERK) 1/2 and inhibition of phosphorylated p38-MAPK were demonstrated at the early phase of AAI treatment. Notably, the MEK/ERK inhibitor U0126 reversed AAI-induced apoptosis and reduced both FLAP, mGST3 and mitochondrial/caspase protein expression. Taken together, these findings suggest that cysLTs synthesis is involved in AAI-induced apoptosis via an ERK activation way.