The epigenetic effects of exogenous E-cadherin inhibition in MCF7 epithelial cells

UoM administered thesis: Phd

  • Authors:
  • Hassan Kaabi

Abstract

The epithelial cadherin (E-cadherin) mediates lateral adhesion in epithelial tissues and thus organises the epithelial architecture. E-cadherin functions, however, are not limited to cell adhesion. Recent work in our lab using microarray analysis has shown that inhibition of E-cadherin in the human breast cancer cell line MCF7 was sufficient for inducing changes in transcript levels of genes associated with multiple biological processes. Similarities at the transcript level were described between E-cadherin-inhibited MCF7 cells and naïve human embryonic stem cells. EP300, a transcriptional co-activator and an acetyltransferase, was identified as a core modulator driving the transcriptome in E-cadherin-inhibited MCF7 cells, using a network modelling tool. However, the role of EP300 and the epigenetic mechanism underlying the changes observed remain to be elucidated. In the present study, the E-cadherin neutralising antibody SHE78.7 (nAb) has been used to assess how exogenous inhibition of E cadherin affects the epigenome. The genome-wide binding signatures for EP300 and the histone modification H3K27ac, and DNA methylation have been investigated using chromatin immunoprecipitation followed by massive parallel sequencing (ChIP-seq) and reduced representation bisulfite sequencing (RRBS) techniques, respectively. Genome wide EP300 and H3K27ac signatures and CpG methylation were altered upon inhibition of E-cadherin protein function. The putative genes associated with the alteration were related to multiple biological processes among which EMT and cancer stem cell, dedifferentiation phenotypes were identified. Normal human primary gingival keratinocytes (HPGKs) were used to test transcript changes observed in MCF7 cells. The results revealed to some extent a similar trend to MCF7 cells and highlighting an increase in EMT and pluripotency markers, and the differentiation marker SUZ12 upon E-cadherin inhibition. Altogether, these results show that exogenous inhibition of E-cadherin in MCF7 cells is associated with epigenetic alterations as demonstrated by differential genomic binding for EP300 and H3K27ac marks along with differential CpG methylation. Also, preliminary findings indicate a similar behaviour between cancer and normal epithelial cells following E-cadherin inhibition.

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Original languageEnglish
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Award date1 Aug 2019