Metastasizing Melanoma Cells Exhibit Increased Dependence On The Pentose Phosphate Pathway To Manage Oxidative Stress.

Abstract To study distant metastasis we developed a patient-derived xenograft (PDX) assay in which melanoma cells from patients spontaneously metastasize in NOD/SCID IL2Rγnull (NSG) mice in a manner that correlates with metastatic behavior in patients (Sci Transl Med 4:159). Using this assay, we discovered that distant melanoma metastasis is limited by oxidative stress (Nature 527:186). Reactive Oxygen Species (ROS) increase dramatically in melanoma cells as they metastasize through the blood. The rare cells that survive undergo reversible metabolic changes that confer oxidative stress resistance. We found that metastatic melanomas had significant increases in metabolites from the pentose phosphate pathway as compared to primary cutaneous melanomas. Metabolites in the oxidative branch of the pentose phosphate pathway, downstream of the NADPH-regenerating enzyme Glucose-6-Phosphate Dehydrogenase (G6PD), were the most dramatically increased in metastatic nodules. We hypothesized that metastasizing melanoma cells increase their dependence on the pentose phosphate pathway in order to manage oxidative stress. We used CRISPR gene editing to create loss-of-function mutations in G6PD in patient-derived melanomas. When transplanted into NSG mice, the tumors formed by G6PD mutant melanomas showed significantly reduced oxidative pentose phosphate pathway activity, increased ROS levels, decreased NADPH/NADP ratios, and reduced metastatic potential as compared to parental control melanomas. Our results demonstrate that metastasizing melanoma cells exhibit increased dependence upon the pentose phosphate pathway as compared to primary cutaneous tumors. Untargeted metabolomics revealed that G6PD mutant melanomas exhibit increased glutamine utilization, perhaps to compensate for increased oxidative stress. Citation Format: Arin B. Aurora, VIshal Khivansara, Ashley Leach, Misty Martin-Sandoval, Thomas Mathews, Sean J. Morrison. Metastasizing melanoma cells exhibit increased dependence on the pentose phosphate pathway to manage oxidative stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 85.