Molecular pathogenesis of pancreatic neuroendocrine tumors

Abstract

Pancreatic neuroendocrine tumors (PNETs) are rare primary neoplasms of the pancreas and arise sporadically or in the context of genetically determined syndromes. Depending on hormone production and sensing, PNETs clinically manifest due to a hormone-related syndrome (functional PNET) or by symptoms related to tumor bulk effects (non-functional PNET). So far, radical surgical excision is the only therapy to cure the disease. Development of tailored non-surgical approaches has been impeded by the lack of experimental laboratory models and there is, therefore, a limited understanding of the complex cellular and molecular biology of this heterogeneous group of neoplasm. This review aims to summarize current knowledge of tumorigenesis of familial and sporadic PNETs on a cellular and molecular level. Open questions in the field of PNET research are discussed with specific emphasis on the relevance of disease management.

Figure 1

(A) Enucleated pancreatic insulinoma; (B) immunostaining of the insulinoma revealed Ki-67 expression (brown) <2%; (C) weak insulin expression (brown) and (D) strong expression of synaptophysin (brown).

Figure 2

Scheme of mTOR-signaling pathway.