Génétique des tumeurs endocrines

Parafibromin inhibits cancer cell growth and causes G1 phase arrest

The HRPT2 (hereditary hyperparathyroidism type 2) tumor suppressor gene encodes a ubiquitously expressed 531 amino acid protein termed parafibromin. Inactivation of parafibromin predisposes one to the development of HPT-JT syndrome. To date, the role of parafibromin in tumorigenesis is largely unknown. Here, we report that parafibromin is a nuclear protein that possesses anti-proliferative properties. We show that overexpression of parafibromin inhibits colony formation and cellular proliferation, and induces cell cycle arrest in the G1 phase. Moreover, HPT-JT syndrome-derived mutations in HRPT2 behave in a dominant-negative manner by abolishing the ability of parafibromin to suppress cell proliferation. These findings suggest that parafibromin has a critical role in cell growth, and mutations in HRPT2 can directly inhibit this role.

Tumeurs endocrines gastro-intestinales : particularités morphologiques et clinico-pathologiques

Gastro-intestinal endocrine tumors constitute a heterogeneous group of tumors. Their clinical features, functional properties, and clinical course differ according to their site of origin. From a practical point of view, several topographical groups may be distinguished: (a) stomach, (b) duodenum and proximal jejunum, (c) ileum and caecum, (d) appendix, (a) colon and rectum. In each of these groups, a certain degree of tumor heterogeneity persists, especially between colon and rectal tumors, which would be better considered apart. In this review, we will describe the main functional, morphological and evolutive features of endocrine tumors in each of the topographical groups currently recognized.