In vitro assessment of the role of endoplasmic reticulum stress in sunitinib-induced liver and kidney toxicity.

Sunitinib, a multi-targeted tyrosine kinase inhibitor, is prescribed for the treatment of metastatic gastrointestinal stromal tumors, advanced metastatic renal cell carcinoma, and pancreatic neuroendocrine tumors. Hepatotoxicity and nephrotoxicity are significant adverse effects of sunitinib administration; however, there is limited information regarding the molecular mechanisms of these adverse effects. The aim of the present study was to elucidate the role of endoplasmic reticulum stress in hepatotoxicity and nephrotoxicity induced by sunitinib. In addition to endoplasmic reticulum stress, oxidative stress and mitochondrial membrane potential were evaluated to investigate the molecular mechanism more comprehensively. Findings revealed that sunitinib exposure significantly increased the reactive oxygen species levels and decreased the Nrf2 gene expression and GSH/GSSG ratio, suggesting oxidative stress induction in normal hepatocyte (AML12) and normal kidney (HK-2) cell lines. Endoplasmic reticulum stress markers, including ATF4, CHOP, IRE1α, XBP1s and ATF6 mRNA expressions, were upregulated in AML12 cells. Furthermore, enhanced intracellular calcium levels also indicate endoplasmic reticulum stress in hepatocytes. In contrast, sunitinib exposure did not alter endoplasmic reticulum-related gene expression levels and intracellular calcium levels in HK-2 cells. In terms of mitochondrial membrane potential and caspase-3 activity, sunitinib induced mitochondrial membrane damage and increased caspase-3 activation not only in AML12 cells but also in HK-2 cells. The research findings indicate that sunitinib may induce cytotoxic effects in hepatocytes through mechanisms involving oxidative stress, endoplasmic reticulum stress, and mitochondrial damage. However, in the kidney, the toxicity mechanism is different from that of liver, and the endoplasmic reticulum stress does not seem to be involved in this mechanism.