Evaluation of microsatellite instability, MLH1 expression and hMLH1 promoter hypermethylation in colorectal carcinomas among Tunisians patients.

Background: About 10% to 15% of sporadic colorectal cancers demonstrate high level of microsatellite instability that is generally associated with aberrant methylation of hMLH1 promoter.

Aim: To investigate the association between MSI status, hMLH1 protein expression and methylation status of the hMLH1 promoter in a cohort of Tunisian sporadic colorectal cancer.

Methods: Expression of MLH1 and MSH2 was determined by immunohistochemistry and the MSI status was analysed by microfluid-based on-chip electrophoresis.

Relationship between expression of ras p21 oncoprotein and mutation status of the K-ras gene in sporadic colorectal cancer patients in Tunisia.

Introduction: The K-ras proto-oncogene encodes a protein (p21-ras) belonging to the family of GTP/GDP-binding proteins with GTPase activity. The activation of ras family genes plays an important role in colorectal tumorigenesis. Frequency of K-ras mutations and overexpression of the protein in colorectal cancer (CRC) vary between 14% and 50% and between 29% and 76%, respectively.

The prognostic value of the immunohistochemical expression and mutational pattern of the key mediator of Wnt signaling: beta-catenin in Tunisian patients with colorectal carcinoma.

Beta-catenin plays a critical role with E-cadherin in cell-cell adhesion and is also a key molecule of the highly conserved Wnt signaling pathway that regulates cell proliferation and differentiation. Abrogation of this pathway is implicated in the carcinogenesis of several malignancies, especially colorectal cancer. The objective of this study was to determine the prognostic value of β-catenin/E-cadherin complex in Tunisian patients with colorectal cancer.