Mitochondrial Dysfunction and Aberrant Methylation of Cancer Related Genes

MAYORGA L; LAURITO S; CAMPOY E; LOOS M; EIROA H; TAGLIAVINI C; LUBIENIECKI F; ROQUE M

santiago

Congreso; X Congreso Latinoamericano de Errores Innatos del metabolismo y pesquisa neonatal; 2015

Cancer cells experience an energetic reprogramming called ?aerobic glycolysis? or Warburg effect. They choose glycolysis over OXPHOS even in the presence of Oxygen. Why this occurs is yet to be completely elucidated. Epigenetic modifications might play a role in this energetic reprogramming. Mitochondrial (MT) diseases have OXPHOS naturally impaired. Our objective was to study whether mt dysfunction could play a role in epigenetic modifications, specifically methylation of cancer related genes. MATERIALS AND METHODSMethylation of cancer related genes was explored using the Methyl-Specific Multiplex Ligation-dependent Probe amplification assay (MS-MLPA, MRC-Holland®). This was carried out in: 1) 19 samples from 13 MT disease patients using probe kits which covered 94 CpG sites in 55 genes. These samples came from low (leukocytes) and high (muscle and bone marrow) energy demanding tissues that had been used for patient diagnosis. 2) Human skeletal muscle cell line (hSKM) that was used as a high energy demanding tissue model which had been treated 24h with an OXPHOS Complex 1 inhibitor (Rotenone) to analyze methylation alterations on 26 CpG sites from 24 tumor suppressor genes . OXPHOS function was determined after Rotenone treatment by measuring MT membrane potential using Trimethylrodamine esther (TMRE) stain visualized with Confocal Microscopy. RESULTSIn patients´ samples, a gene was considered methylated when the methylation ratio sample/control was above 8%. Aberrant methylation profiles were encountered in the majority of the samples. The mean methylation index (n° of methylated CpG sites/n° of CpG sites explored) differed significantly among tissues of different energy demand(4.9% inleukocytes vs 15.6% in muscle/bone marrow, p