O101 : Histone variant macroH2A1 orchestrates escape from hepatocyte senescence during ageing and cancer

Histone Variant MacroH2A1 Marks Liver Aging and Orchestrates the Escape from Senescence Induced by DNA Hypomethylation in Hepatocellular Carcinoma

The epigenetic basis of age-associated progression of liver diseases towards hepatocellular carcinoma (HCC) is unclear. MacroH2A1 is a variant of histone H2A1, present in the two isoforms, with fundamental roles in cell homeostasis. MacroH2A1 is a marker of senescence associated heterochromatic foci (SAHF) and synergizes with DNA demethylating chemotherapic agent 5-aza-2'-deoxycytidine (5-aza-dC) in silencing tumor suppressor genes in human fibroblasts. We show that protein levels of macroH2A1 isoforms are increased in the livers of old rodents and humans, and in human HCC tissue. Human HCC cells overexpressing macroH2A1 escape a 5-aza-dC-induced senescent phenotype, as determined by cell p…