Epigenetics of gastroenteropancreatic neuroendocrine tumors: A clinicopathologic perspective

Table 1 Overview of epigenetic mechanisms

Mechanism	Effect	Regulation	Ref.
DNA Methylation		DNMTs
Hypomethylation	Chromosomal instability, reactivation of transposable elements, loss of imprinting		[12]
Hypermethylation	Inactivation of tumor suppressor genes		[12]
Histone modification		HDACs, histone methyltransferases
Lysine acetylation	Transcription activation		[12]
Methylation	Transcription activation or suppression		[12]
Noncoding RNAs		Variable
LncRNAs	Pre-transcriptional regulation		[17]
MiRNAs	Post-transcriptional binding to 3’-untranslated regions to inhibit translation or promote mRNA degradation		[18]

DNMTs: DNA methyltransferase enzymes; HDACs: Histone acetyltransferases and deacetylases; LncRNA: Long non-coding RNA.