Glutathione S-transferase Ti and Mi genotypes in normal mucosa, transitional mucosa and colorectal adenocarcinoma

Gene codings for glutathione S-transferase T1 (GSTT1) and M1(GSTM1) are pol ymorphic in humans with null genotypes present in approximately 20 and 50%, respectively. A significant excess of homozygous null GSTT1 and GSTM1 geno types has been demonstrated among individuals with certain types of cancers . This finding suggests that GSTT1 and GSTM1 may play a role in tumour susc eptibility. However, reports concerning colorectal cancer susceptibility ar e controversial. In the present study, we used a multiplex polymerase chain reaction (PCR) approach to identify and analyze simultaneously the genotyp es of both the genes in 99 patients with colorectal cancer and 109 healthy controls. Compared with the control group, a significant excess of homozygo us null genotypes for GSTT1 was found in normal mucosa among the cancer pat ients, but not for GSTM1. Both genes were move frequently deleted in tumour s than in corresponding normal mucosa. Furthermore, GSTT1 null genotype in tumour tissue, was significantly related to old age and to poor differentia tion of tumours. CSTM1 null genotype in tumour was move frequent in the rec tal tumours compared with tumours of left colon and right colon. Our result s suggest that individuals with GSTT1 null genotype may be genetically pred isposed for an increased risk of developing colorectal cancer. Allele loss in tumour tissue, which reflects genetic instability, may be considered as a marker for evaluating clinico-pathological characteristics of the cancer patients. Int. J. Cancer (Pred. Oncol.) 84: 135-138, 1999. (C) 1999 Wiley-L iss, Inc.