Plk2 Loss Commonly Occurs in Colorectal Carcinomas but not Adenomas: Relationship to mTOR Signaling.

Plk2 Loss Commonly Occurs in Colorectal Carcinomas but not Adenomas: Relationship to mTOR Signaling. Neoplasia. 2018 Feb 12;20(3):244-255 Authors: Matthew EM, Yang Z, Peri S, Andrake M, Dunbrack R, Ross E, El-Deiry WS Abstract Plk2 is a target of p53. Our previous studies demonstrated that with wild-type p53, Plk2 impacts mTOR signaling in the same manner as TSC1, and Plk2-deficient tumors grew larger than control. Other investigators have demonstrated that Plk2 phosphorylates mutant p53 in a positive feedback loop. We investigated Plk2's tumor suppressor functions in relationship to mTOR signaling. Archival specimens from 12 colorectal adenocarcinomas were stained for markers including Plk2, phosphorylated mTOR (serine 2448) and ribosomal S6 (Serine 235/236). We show that Plk2 is expressed in normal colon, with a punctate staining pattern in supranuclear cytoplasm. In colorectal adenocarcinoma, Plk2 demonstrates complete or partial loss of expression. Strong expression of phosphorylated mTOR is observed in the invasive front. Phosphorylated S6 expression partially correlates with phosphorylated mTOR expression but appears more diffuse in some cases. p53 and Ki67 expression is diffuse, in the subset of cases examined. In order to determine whether Plk2 is lost prior to the development of invasive cancer, 8 colon polyps from 6 patients were evaluated for Plk2 expression. All polyps are positive for Plk2. A Cancer Genome Atlas search i...
Source: Neoplasia - Category: Cancer & Oncology Authors: Tags: Neoplasia Source Type: research