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Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy.

ABSTRACT: Autophagy is the principal catabolic prosurvival pathway during nutritional starvation. However, excessive autophagy could be cytotoxic, contributing to cell death, but its mechanism remains elusive. Arginine starvation has emerged as a potential therapy for several types of cancers, owing to their tumor-selective deficiency of the arginine metabolism. We demonstrated here that arginine depletion by arginine deiminase induces a cytotoxic autophagy in argininosuccinate synthetase (ASS1)-deficient prostate cancer cells. Advanced microscopic analyses of arginine-deprived dying cells revealed a novel phenotype with giant autophagosome formation, nucleus membrane rupture, and histone-associated DNA leakage encaptured by autophagosomes, which we shall refer to as chromatin autophagy, or chromatophagy. In addition, nuclear inner membrane (lamin A/C) underwent localized rearrangement and outer membrane (NUP98) partially fused with autophagosome membrane. Further analysis showed that prolonged arginine depletion impaired mitochondrial oxidative phosphorylation function and depolarized mitochondrial membrane potential. Thus, reactive oxygen species (ROS) production significantly increased in both cytosolic and mitochondrial fractions, presumably leading to DNA damage accumulation. Addition of ROS scavenger N-acetyl cysteine or knockdown of ATG5 or BECLIN1 attenuated the chromatophagy phenotype. Our data uncover an atypical autophagy-related death pathway and suggest that mitochondrial damage is central to linking arginine starvation and chromatophagy in two distinct cellular compartments.

SUBMITTER: Changou CA

PROVIDER: S-EPMC4191793 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature

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Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy.

Changou Chun A CA Chen Yun-Ru YR Xing Li L Yen Yun Y Chuang Frank Y S FY Cheng R Holland RH Bold Richard J RJ Ann David K DK Kung Hsing-Jien HJ

Proceedings of the National Academy of Sciences of the United States of America 20140813 39

Autophagy is the principal catabolic prosurvival pathway during nutritional starvation. However, excessive autophagy could be cytotoxic, contributing to cell death, but its mechanism remains elusive. Arginine starvation has emerged as a potential therapy for several types of cancers, owing to their tumor-selective deficiency of the arginine metabolism. We demonstrated here that arginine depletion by arginine deiminase induces a cytotoxic autophagy in argininosuccinate synthetase (ASS1)-deficient ...[more]

PMID: 25122679

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Project description:One of the most common metabolic defects of cancer cells is the deficiency in arginine synthesis due to suppressed expression of argininosuccinate synthetase 1 (ASS1) which renders cancer cells auxotrophic to external arginine supply. Arginine deprivation has been effectively used as a treatment for leukemias, with several clinical trials on solid tumors underway. We previously showed that in prostate cancer arginine depletion induced mitochondrial dysfunction and excessive ROS production resulting in chromatin autophagy, nuclear DNA leakage, and cellular death, but the detailed mechanism of arginine starvation-induced cell death remains unclear. In this study, we demonstrated that arginine deprivation coordinately suppressed metabolic genes, including those responsible for mitochondrial oxidative phosphorylation (OXPHOS), nucleotide metabolism, and DNA repair. The consequent ROS production and impaired DNA damage response resulted in nuclear DNA leakage and cGAS-STING activation which is accompanied by upregulation of type I interferon response. We also showed that coordinated silencing of OXPHOS and DNA repair genes is caused in part by the depletion of α-ketoglutarate (αKG) and inactivation of histone demethylases. Supplementing cell-permeable dimethyl α-ketoglutarate (DMKG) both reduced repressive histone methylations and partially restored OXPHOS gene expressions, mitochondrial functions, and mitigated nuclear DNA leakage. Using our dietary arginine-restriction model, we demonstrate that arginine starvation slows prostate cancer growth with evidence of enhanced interferon responses and recruitment of immune cells. Our data suggests arginine starvation induces cell killing of ASS1-low cancer cells by metabolic depletion and epigenetic silencing of metabolic genes, leading to DNA damage and leakage. Resulting cGAS-STING activation may further enhance these killing effects. We used microarray to analyze the expression difference between control and arginine-depleted cells to find out what genes involved in the regulation of mitochondrial function and arginine deprivation-induced cell death.

Dataset Information

Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy.

Publications

Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy.

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