Genetic polymorphism in the transforming growth factor beta1 gene (-509 C/T and -800 G/A) and colorectal cancer.

TGF-beta1 is a multifunctional cytokine that acts as both a tumor suppressor and a stimulator of tumor progression. Susceptibility to colorectal carcinoma may be affected by genetic factors. In this study, the association between -800 G/A and -509 C/T polymorphisms of the transforming growth factor beta1 gene, TGFB1, and susceptibility to colorectal cancer in Iranian patients was investigated. This study was conducted with 134 patients with colorectal carcinoma and 138 healthy controls matched for age and sex. Genotyping was performed on genomic DNA using polymerase chain reaction and restriction fragment length polymorphism. The genotype distributions and allele frequencies of the TGFB1 gene polymorphism at -509 C/T were significantly related to colorectal carcinoma. A lower frequency of 509T allele (41.8%) and TT genotype was observed in patients (21.6%) than in control subjects (52.9% and 29.7%, respectively) (P<0.035). At position 800, no significant differences in genotype distribution and allele frequencies between the patients and healthy controls was found (P>0.05). These data suggest that the genetic polymorphism at -509 C/T but not at -800 G/A of the TGFB1 gene may play a role in susceptibility of Iranian subjects for colorectal carcinoma.