Interactions between E-cadherin and microRNA deregulation in head and neck cancers: the potential interplay.

E-cadherin expression in the head and neck epithelium is essential for the morphogenesis and homeostasis of epithelial tissues. The cadherin-mediated cell-cell contacts are required for the anchorage-dependent growth of epithelial cells. Further, survival and proliferation require physical tethering created by proper cell-cell adhesion. Otherwise, the squamous epithelial cells will undergo programmed cell death. Head and neck cancers can escape from anoikis and enter into the epithelial-mesenchymal transition stages via the modulation of E-cadherin expression with epigenetic mechanisms. At epigenetic level, gene expression control is not dependent on the DNA sequence. In the context of E-cadherin regulation in head and neck cancers, 2 major mechanisms including de novo promoter hypermethylation and microRNA dysregulation are most extensively studied. Both of them control E-cadherin expression at transcription level and subsequently hinder the overall E-cadherin protein level in the head and neck cancer cells. Increasing evidence suggested that microRNA mediated E-cadherin expression in the head and neck cancers by directly/indirectly targeting the transcription suppressors of E-cadherin, ZEB1 and ZEB2.