GST gene family polymorphism and the risk of colorectal cancer in patients with type 2 diabetes

Aim
To investigate whether the polymorphisms of GSTP1, GSTT1 and GSTM1 genes are associated with colorectal cancer in a sample of Polish patients with and without type 2 diabetes.

Material and methods
Over 200 patients aged > 40 years were recruited and divided into 4 age-matched groups: patients with diagnosed type 2 diabetes, patients with diagnosed type 2 diabetes and colorectal cancer, patients with colorectal cancer and without type 2 diabetes and patients without type 2 diabetes and without colorectal cancer. DNA for genetic testing was isolated from blood samples. The GST gene polymorphism was examined using qPCR method, with TaqMan probes. It included GSTP1 SNP Ile105Val (rs1695) polymorphism, and deletion of copies of GSTT1 and GSTM1 genes (genotypes GSTT1 null/null and GSTM1 null/null).

Results
The analysis of the frequency of GST gene polymorphisms in the group of patients with type 2 diabetes and colorectal cancer compared to patients with type 2 diabetes showed no statistically significant differences. There were also no statistically significant differences in the distribution of GST gene polymorphisms between patients with diabetes or/and colorectal cancer and population without these diseases.

Conclusions
Extending the analysis to further genetic and environmental factors and taking into account their mutual interactions is needed to search for the relationship between type 2 diabetes and an increased risk of colorectal cancer.