DNA demethylation caused by 5-Aza-2'-deoxycytidine induces mitotic alterations and aneuploidy.

Giuseppe Costa,Viviana Barra,Danilo Cilluffo,Laura Lentini,Aldo Di Leonardo

doi:10.18632/oncotarget.6897

Abstract

Aneuploidy, the unbalanced number of chromosomes in a cell, is considered a prevalent form of genetic instability and is largely acknowledged as a condition implicated in tumorigenesis. Epigenetic alterations like DNA hypomethylation have been correlated with cancer initiation/progression. Furthermore, a growing body of evidence suggests the involvement of epigenome-wide disruption as a cause of global DNA hypomethylation in aneuploidy generation.Here, we report that the DNA hypomethylating drug 5-aza-2′-deoxycytidine (DAC), affects the correct ploidy of nearly diploid HCT-116 human cells by altering the methylation pattern of the chromosomes. Specifically, we show that a DAC-induced reduction of 5-Methyl Cytosine at the pericentromeric region of chromosomes correlates with aneuploidy and mitotic defects.Our results suggest that DNA hypomethylation leads to aneuploidy by altering the DNA methylation landscape at the centromere that is necessary to ensure proper chromosomes segregation by recruiting the proteins necessary to build up a functional kinetochore.

Highlights

The majority of human tumours show a form of genome instability called chromosomal instability (CIN) that refers to the high rate of numerical and structural chromosome aberrations found in cancer cells
The methylation status of the CHFR promoter was assessed by Methylation Specific PCR (MSP) in HCT-116 cells treated with DAC (1, 2, 5μM) for 72 hours
As loss of DNA methylation could interfere with chromosome dynamics, we evaluated if the global DNA hypomethylation observed upon the DAC treatment was associated with aneuploidy

Summary

Introduction

The majority of human tumours show a form of genome instability called chromosomal instability (CIN) that refers to the high rate of numerical and structural chromosome aberrations found in cancer cells. Aneuploidy arises by several mechanism(s) including mutations in genes encoding mitotic regulators [1, 2], tumour suppressors or controlling centrosome numbers [3,4,5,6,7], altered expression of mitotic checkpoint proteins, defects in chromatid cohesion and in kinetochore-microtubule attachment [6,7,8,9,10] Epigenetic alterations such as DNA hypomethylation are considered as a cause of aneuploidy [11, 12]. Cells from patients with ICF syndrome exhibit hypomethylation of pericentromeric regions associated with the formation of micronuclei [18]

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