Global DNA Hypomethylation following 5-aza-2'-deoxycytidine treatment induces aneuploidy in HCT-116 tumor cells.

Aneuploidy, the alteration of the normal number of chromosomes, is found in most of the human solid tumors and correlated with to defects in the process of chromosome segregation (1). It was also suggested that the alteration of the 5-methylcytosine (5-mC) pattern in the chromosome pericentromeric region, generated to aneuploid cells (2, 3). To investigate the relationship between hypomethylation and whole chromosome aneuploidy, we treated HCT-116 cells, a near diploid line, with the demethylating agent 5-aza- 2'-deoxycytidine (DAC). The treatment with DAC for 24, 48 and 72 hours produced a progressive reduction of DNA methylation as shown by decrease of 5-mC signal. DNA hypomethylation resulted in a strong change of 5-mC distribution pattern in metaphase chromosomes that was associated with several chromosome abnormalities, such as: highly hypocondensed chromosomes, "rail-road track" chromosomes and endoreduplication. Live imaging experiments of HCT-116 cells expressing H2B-GFP and DAC treated, showed misaligned and lagging chromosomes, micronuclei, and elongation of metaphase-anaphase transition. All together these results provide further strong evidence of the correlation between DNA hypomethylation and aneuploidy in human somatic cells. References 1. H. Rajagopalan, C. Lengauer, Aneuploidy and cancer. Nature 432, 338 (Nov 18, 2004). 2. D. Prada et al., Satellite 2 demethylation induced by 5-azacytidine is associated with missegregation of chromosomes 1 and 16 in human somatic cells. Mutat.Res. 729, 100 (2012). 3. L. A. Herrera, D. Prada, M. A. Andonegui, A. Duenas-Gonzalez, The epigenetic origin of aneuploidy. Curr.Genomics 9, 43 (2008)