mRNA Expressions of Gamma-Glutamyl Transferase Genes in Different Types of Cancer

Sevgi YARDIM-AKAYDIN*,°, Ceren DEVIREN*, Ece MISER-SALIHOGLU*, Emel
CALISKAN-CAN*, M.Can ATALAY**

* Gazi University, Faculty of Pharmacy, Department of Biochemistry, 06330, Etiler, Ankara, Turkey
** Department of General Surgery, Ankara Oncology Training and Research Hospital, 06200, Demetevler, Ankara, Turkey

° Corresponding Author;
Tel: +90-312-2023155
Fax: +90-312 2235018
E-mail: sevgiy@gazi.edu.tr

Summary

Measurement of gamma-glutamyl transferase (GGT) activity in serum has been found useful in showing tissue damages. In addition to GGT1, different related genes or sequences in the human genome have been reported in pre-genome studies. Two of them, GGT5 and GGT6, are active genes and have similar nucleotide or amino acid sequence to GGT1. The aim of this study was to evaluate the gene expression of GGTs in different types of cancer. In the current study, GGT1, GGT5, and GGT6 mRNA expressions were measured in normal and tumor tissues of 26 patients with breast, gastric and colorectal cancers, using quantitative RT-PCR method. Serum GGT levels were measured by a spectrophotometric method. While GGT1 and GGT5 were expressed in almost all the normal and tumor tissues of the patients, GGT6 expressions were observed in half of both the normal and tumor tissues. In all patients, no significant differences were found in mean mRNA expression levels of GGT1, GGT5 and GGT6 (p>0.05), although GGT1 were higher in tumor tissues than those in the normal tissues. GGT1 was overexpressed in half of the patients (13/26) and these over-expressions were positively correlated with gender (p<0.05) and age (p<0.05). In female patients, serum GGT levels were positively correlated with tumor tissue GGT1 (p<0.01) and GGT6 (p<0.05). Mostly increased mRNA expressions for GGT1 and GGT5 in tumor tissues, overexpressions in some, show their roles in carcinogenesis. The results given here may suggest that the tumor GGT1 is mainly responsible for the increase in serum GGT levels in female patients.

Key Words :
Gamma-glutamyl transferase, GGT1, GGT5, GGT6, mRNA expression, cancer