Glucose deprivation promotes lung adenocarcinoma de-differentiation due to unbalanced EZH2 activity

Lung cancer is the most frequent cancer-related cause of death, and adenocarcinoma (LUAD) is the most frequent type. Despite the recent success of immunotherapies, survival of lung cancer patients has not significantly improved in the last decades. New therapies are necessary. We have previously identified sodium-glucose transporter 2 (SGLT2) as the major responsible for glucose uptake in LUAD, and we have showed that treatment with SGLT2 inhibitors significantly delays LUAD development and prolongs survival in murine models. However, our data shows that SGLT2 inhibitors also induce de-differentiation of LUAD cells, leading to a more aggressive phenotype and increased resistance to cisplatin. Glucose deprivation causes reduced aKG levels, leading to reduced activity of aKG-dependent histone demethylases and consequent histone hypermethylation. Supplementation of aKG or inhibition of the histone methyltransferase EZH2 reverse this phenotype, suggesting that this de-differentiated phenotype depends on insufficiency of aKG-dependent histone demethylases and unbalanced EZH2 activity. Consistently, double treatment with an SGLT2 inhibitor and an EZH2 inhibitor significantly reduces the tumor burden in a genetically engineered murine model of LUAD. We further characterized the effect of low glucose-induced tumor de-differentiation, identifying stabilization of hypoxia inducible factor 1a (HIF1a) as a major pathway responsible for the acquisition of a more aggressive phenotype following glucose deprivation. Finally, we identified an HIF1a-dependent transcriptional signature with prognostic significance in human LUAD. Our studies further our knowledge of the relationship between glucose metabolism and cell differentiation in cancer, characterizing the epigenetic adaptation of cancer cells to nutrient deprivation and identifying novel targets to prevent the development of resistance to metabolic therapies.