Phosphorylation of eIF2α suppresses cisplatin-induced p53 activation and apoptosis by attenuating oxidative stress via ATF4-mediated HO-1 expression in human renal proximal tubular cells

• Published in: International journal of molecular medicine Vol. 40; no. 6; pp. 1957 - 1964
• Main Authors: Ju, Sung-Min, Jo, Yong-Seok, Jeon, Yoo-Min, Pae, Hyun-Ock, Kang, Dae-Gill, Lee, Ho-Sub, Bae, Jun-Sang, Jeon, Byung-Hun
• Format: Journal Article
• Language: English
• Published: Greece D.A. Spandidos 01.12.2017; Spandidos Publications UK Ltd
• Subjects: activating transcription factor 4; Activating Transcription Factor 4 - genetics; Antibiotics; Antineoplastic Agents - toxicity; Antioxidants; Apoptosis; Apoptosis - drug effects; Cell Line, Tumor; Chemotherapy; cisplatin; Cisplatin - toxicity; eIF-2 Kinase - genetics; Endoplasmic Reticulum - drug effects; Endoplasmic Reticulum Stress - genetics; Eukaryotic Initiation Factor-2 - genetics; eukaryotic translation initiation factor 2α; Gene Expression Regulation - drug effects; heme oxygenase-1; Heme Oxygenase-1 - genetics; HK-2 cells; Humans; Kidney Tubules, Proximal - metabolism; Kidney Tubules, Proximal - pathology; Kidneys; Kinases; Neoplasms - drug therapy; Neoplasms - genetics; Neoplasms - pathology; nephrotoxicity; Oxidative stress; Oxidative Stress - drug effects; p53; Phosphorylation; reactive oxygen species; Reactive Oxygen Species - metabolism; Signal Transduction - drug effects; Studies; Tumor Suppressor Protein p53 - genetics
• ISSN: 1107-3756; 1791-244X
• DOI: 10.3892/ijmm.2017.3181

Cisplatin is one of the most widely used chemotherapeutic agents for the treatment of human cancers. However, the nephrotoxicity of cisplatin limits its use as a therapeutic agent. It has been suggested that oxidative stress and p53 activation play important roles in cisplatin-induced nephrotoxicity. It has been demonstrated that the eukaryotic translation initiation factor 2α (eIF2α) may protect HK-2 human renal proximal tubular cells against cisplatin-induced apoptosis through inhibition of reactive oxygen species (ROS)-mediated p53 activation. The aim of the present study was to investigate the effects of siRNA-mediated knockdown of the PKR-like endoplasmic reticulum kinase (PERK) gene, which induces the phosphorylation of eIF2α, or Sal003, a selective inhibitor of eIF2α dephosphorylation, on cisplatin-induced apoptosis in HK-2 cells. Cisplatin induced eIF2α phosphorylation as well as p53 activation. In particular, inhibition of p53 by pifithrin-α, and upregulation of eIF2α phosphorylation by Sal003, reduced cisplatin-induced apoptosis. Of note, Sal003-mediated upregulation of eIF2α phosphorylation suppressed cisplatin-induced p53 activation. Furthermore, reduction of eIF2α phosphorylation by PERK knockdown enhanced cisplatin-induced p53 activation and apoptosis. In addition, the ROS scavenger N-acetyl-L-cysteine inhibited eIF2α phosphorylation as well as p53 activation in HK-2 cells treated with cisplatin, suggesting that oxidative stress induced by cisplatin may lead to apoptosis through p53 activation; furthermore, this stress may confer resistance to apoptosis via eIF2α phosphorylation, which was further supported by the finding that cisplatin-induced ROS generation was attenuated by Sal003, whereas it was enhanced by PERK knockdown. Furthermore, cisplatin induced the expression of activating transcription factor 4 (ATF4) and heme oxygenase-1 (HO-1) that were enhanced by Sal003 and reduced by PERK knockdown. Taken together, these results suggest that phosphorylation of eIF2α suppresses cisplatin-induced p53 activation and apoptosis by attenuating oxidative stress via ATF4-mediated HO-1 expression in HK-2 cells, as ATF4 expression is usually dependent on the phosphorylation of eIF2α and may also transcriptionally induce the expression of HO-1 in response to oxidative stress. Therefore, regulation of eIF2α phosphorylation may play an important role in alleviating cisplatin-induced nephrotoxicity.