Electron Microscopy of Pancreatic Beta Cell Neuroendocrine Tumors (NETs) in Multiple Endocrine Neoplasia Type 1 (MEN1) Knockout Mice Reveal an Adenomatous Phenotype with Depletion of Insulin Granules and Increased Mitochondrial Content

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Introduction: Insulinomas are β cell neuroendocrine tumors (NETs) that secrete insulin, and ~4% of insulinoma patients have multiple endocrine neoplasia type 1 (MEN1). One in ten MEN1 patients present with an insulinoma. Previous reports describe insulinomas as possibly having typical granules (46.4%) or atypical smaller granules (34.3%), both associated with adenomas, or agranular cells (14.3%) associated with carcinomas. MEN1 knockout (Men1+/-) mice develop pancreatic NETs that are mostly insulinomas, and their ultrastructural phenotype is unknown. We hypothesized that these may resemble the adenoma phenotype with atypical granules.

Aim(s): To investigate the ultrastructure of NETs from Men1+/- mice, compared to normal beta cells from wild type (Men1+/+) mice, by electron microscopy.

Materials and methods: Pancreatic NETs and normal islets (n=4 per group) were examined by transmission electron microscope at x 8000 magnification and organelle density quantified per unit cytoplasmic area.

Conference: 11th Annual ENETSConcerence (2014)

Presenting Author:

Authors: Walls G, Clark A, Thakker R,

Keywords: GEP-NET,