Aristolochic acid-induced apoptosis and G2 cell cycle arrest depends on ROS generation and MAP kinases activation

Abstract

Ingestion of aristolochic acids (AAs) contained in herbal remedies results in a renal disease and, frequently, urothelial malignancy. The genotoxicity of AA in renal cells, including mutagenic DNA adducts formation, is well documented. However, the mechanisms of AA-induced tubular atrophy and renal fibrosis are largely unknown. To better elucidate some aspects of this process, we studied cell cycle distribution and cell survival of renal epithelial cells treated with AAI at low and high doses. A low dose of AA induces cell cycle arrest in G2/M phase via activation of DNA damage checkpoint pathway ATM-Chk2-p53-p21. DNA damage signaling pathway is activated more likely via increased production of reactive oxygen species (ROS) caused by AA treatment then via DNA damage induced directly by AA. Higher AA concentration induced cell death partly via apoptosis. Since mitogen-activated protein kinases play an important role in cell survival, death and cell cycle progression, we assayed their function in AA-treated renal tubular epithelial cells. ERK1/2 and p38 but not JNK were activated in cells treated with AA. In addition, pharmacological inhibition of ERK1/2 and p38 as well as suppression of ROS generation with N-acetyl-L-cysteine resulted in the partial relief of cells from G2/M checkpoint and a decline of apoptosis level. Cell cycle arrest may be a mechanism for DNA repair, cell survival and reprogramming of epithelial cells to the fibroblast type. An apoptosis of renal epithelial cells at higher AA dose might be necessary to provide space for newly reprogrammed fibrotic cells.

Transforming growth factor‐β1 stimulates hedgehog signaling to promote epithelial–mesenchymal transition after kidney injury

“…For the injured cell itself, the different mechanisms and the extent of the injury determine the different cellular fates. TEC apoptosis is common and typical, and may be the result of an epithelial G2/M arrest . In the present study, time‐ and concentration‐dependent epithelial apoptosis was also observed in AA‐treated TECs.…”

“…Previous studies have demonstrated that TEC apoptosis, necrosis and autophagy are the main features after injury . After injury, some signaling pathways and kinases may first be activated to stimulate and induce TECs injury, including cell cycle arrest .…”

An Integrated View of Aristolochic Acid Nephropathy: Update of the Literature

“…A few in vitro studies described that cells treated with AA led to generation of high amounts of reactive oxygen and nitrogen species (ROS/RNS) [122,123,124,125]. Oxidative stress therefore constitutes the primary triggering event of AA cytotoxicity and could be responsible for related DNA damage through activation of the MEK/ERK1/2 signaling pathway and depletion of intracellular glutathione (GSH) [122] resulting in cell cycle arrest in G2/M phase [123]. Treatment of the cells with antioxidants showed cytoprotective effects by reducing AA-induced ROS and genotoxicity, indicating that AA may induce DNA damage through oxidative stress [122,124].…”

The critical role of oxidative stress in the toxicity and metabolism of quinoxaline 1,4-di-N-oxides in vitro and in vivo

“…p38 can be phosphorylated in response to oxidative stress, which may block proliferation or promote apoptosis (Watanabe et al, 2015). The JNK pathway could respond to a diverse array of extracellular stimuli, including hormones, growth factors and oxidative stress (Gong et al, 2015;Kim et al, 2015;Liao et al, 2015;Romanov et al, 2015). Zhao et al documented that OLA induced the JNK pathway with ROS production when HepG2 cells were exposed to OLA (200, 400 and 800 lg/mL) for 24 cells (Zhao et al, 2015).…”