Analysis of molecular pathways in sporadic neuroendocrine tumors of the gastro-entero-pancreatic system

Background & Aims: Little is known about the molecular pathogenesis of neuroendocrine tumors (NET) of the gastro-entero-pancreatic (GEP) system. We therefore analyzed genetic and epigenetic alterations as well as the CpG island methylator phenotype (CIMP) and the functional significance of genes silenced by promoter methylation in GEP-NET. Methods: The study comprised 118 well-differentiated foregut and midgut GEP-NET from 71 patients. In addition to loss of heterozygosity (LOH), microsatellite instability (MSI) and the methylation status of the hMLH1, p16, APC, O6-MGMT, PTEN, HIC1, E-cadherin, RASSF1A, TIMP3, R…