4-Octyl Itaconate Attenuates Cell Proliferation by Cellular Senescence Glutathione Metabolism Disorders and Mitochondrial Dysfunction in Melanoma

Itaconate (IA) is synthesized in the citric acid cycle cis-aconitate decarboxylase (ACOD1); however, its biological significance in cancer remains incompletely understood. In previous studies, 4-octyl itaconate (OI) was used as a membrane-permeable form of IA, but little detailed verification of the difference in biological activities between IA and OI exists. Here, we investigated the direct effects of IA and OI on melanoma. The proliferation of melanoma cells treated with OI was significantly suppressed , and our transcriptomic analysis revealed drastic changes in the expression of glutathione metabolism-related genes in OI-treated cells. Indeed, OI treatment decreased intracellular glutathione levels, followed by increased production of reactive oxygen species and expression of γH2AX, a marker of DNA damage, and β-galactosidase, a marker of cellular senescence. We further showed that the mitochondrial respiratory capacity in B16 cells was significantly decreased by OI treatment. OI administration also suppressed the growth of B16 tumor transplants , and the expression of γH2AX was increased in tumor tissues of OI-treated mice. In addition, minimal effects of OI treatment were observed in melanocytes and normal tissues. We also proved that not only exogenous IA, which enters intracellularly, but also endogenous IA has little effect on melanoma proliferation activity, an investigation using -overexpressing transfectants and -deficient mice. This work revealed that OI disrupts the antioxidant system the collapse of glutathione metabolism and inhibits cancer cell proliferation. 00, 000-000.