MacroH2A Variant Suppress Uveal Melanoma Progression and Rewires Cancer Metabolic Phenotype

Abstract

Histone are a family of protein conserved among all the eukaryotes. A histone variant part of the H2A histone family is macroH2A1 which is expressed in nearly all cell types and is involved in a number of processes including cell cycle, gene regulation, DNA damage repair and senescence. Melanoma of the uveal tract, or uveal melanoma (UM), though rare, is one the most common primary cancer of the eye. Its incidence is approximately 4.3 new cases per million people in the United States. Metastasis is a frequent occurrence in uveal melanoma, and outcomes are poor once distant spread occurs and no clinically significant chemotherapeutic protocol is so far available.The aim of the present study was to evaluate the relationship between macroH2A1 and UM progression. We established a stable knockdown of the protein, using a specific macroH2A1 shRNA and assessed differences in cell proliferation, migration and metabolic profile.Cell proliferation, migration and colony formation capacity were evaluated by Xcelligence technology, wound healing assay and clonogenic assay. Mitochondrial respiratory chain gene expression was evaluated by RT‐PCR and confirmed by immunocytochemistry whereas metabolic phenotype was determined by Seahorse technology. Our results were further confirmed in a series of human UM biopsies obtained and results were correlated to survival, metastatic outbreak and proliferative index. The study was conducted according to the basic principles of the declaration oh Helsinki. Our results showed that knockdown for macroH2A1 resulted in a reduced proliferation, migration and colony capacity formation rate when compared to their control. Using seahorse assay we also demonstrated that the knockdown of macroH2A1 induced a shift in cell metabolism. These results were confirmed by RT‐PCR and immunocytochemistry showing that knockdown for macroH2A1 had a significant decreased expression of genes implicated in oxidative phosphorylation and in NAD+ metabolism, and a decreased level in TFAM expression. Finally, these data were confirmed in UM biopsies, exhibiting increased expression of macroH2A1 inpatients deceased for metastasis. Furthermore, p16, a well‐established marker of cell proliferation, correlated with macroH2A1 expression. In conclusion, our results showed that macroH2A1 play a major role in UM progression and may represent a possible target for future chemotherapic strategies.Support or Funding InformationThis work was supported by FIR2016/2018 from the University of CataniaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.