BAP1 modulates gene-environment interaction in carcinogenesis

We discovered that heterozygous germline BAP1 mutations (BAP1 +/- ) cause a novel cancer syndrome that we named “The BAP1 cancer syndrome” characterized by development of malignant mesothelioma (MM), uveal and cutaneous melanoma, and other cancers. We demonstrated how germline BAP1 mutations are transmitted over the centuries across generations and found that 100% of individuals who inherited germline BAP1 mutations have developed one or more malignancies in their lifetime. Very recently we demonstrated that the potent BAP1 tumor-suppressor activity is linked to its dual function in the nucleus, where it regulates DNA repair, and in the cytoplasm, where it regulates apoptosis by deubiquitylating and stabilizing the IP3R3 endoplasmic reticulum (ER) Ca 2+ channel. In parallel we discovered that cells carrying heterozygous BAP1 mutations derive energy largely via aerobic glycolysis, Warburg effect. Now we have found the mechanisms regulated by BAP1 that are responsible for the changes in metabolism. We discovered that reduced BAP1 levels lead to reduced release of Ca 2+ from the ER into the cytoplasm and reduced intra-mitochondrial Ca 2+ levels. Reduced mitochondrial Ca 2+ levels directly impair aerobic respiration and cells switch to glycolysis even in the presence of oxygen. We demonstrate that aerobic glycolysis can be induced in apparently any human cell type by reducing BAP1 levels using siRNAs or other strategies, and that in these cells glycolysis can be reverted to aerobic respiration upon re-establishing normal Ca 2+ levels. In conclusion, our findings indicate how BAP1 deficiency regulates DNA repair and apoptosis and how low BAP1 levels induce the Warburg effect, an effect seen in all “normal” cell types from individuals born with inherited germline heterozygous BAP1 mutations. In these individuals aerobic glycolysis predates by many years malignant transformation. Citation Format: Michele Carbone, Angela Bononi, Carlotta Giorgi, Simone Patergnani, Harvey I. Pass, Wei Jia, Paolo Pinton, Haining Yang. BAP1 modulates gene-environment interaction in carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5519.