Prognostic Importance of GSTO2 Polymorphism in Patients With Colorectal Cancer

ABSTRACT

A genetic polymorphism of GSTO2 causes variations in enzyme activity. It was reported that the GSTO2 wild-type (N142) allozyme showed higher levels of expression than the GSTO2 variant (D142) allozyme. Overexpression of GSTO protein has been found in chemo- and radio-resistant cancer cells. In addition, increased GSTO expression in colorectal cancer cells correlated with increased cell invasion and metastasis. Therefore, we investigated the association of GSTO2 polymorphism and prognoses for colorectal-cancer patients. Formalin-fixed, paraffin-embedded cancerous colorectal tissues from 89 patients were used to extract DNA. Gene polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results showed that wild-type GSTO2 (N142/N142) was found mainly in patients aged \> 50 years (P=0.014). No significant difference was found between GSTO2 genotype and sex, tumor stage, tumor differentiation, and EGFR. Patients carrying wild-type GSTO2 (N142/N142) had poorer survival rates than those carrying variant GSTO2 (N142/D142+D142/D142) (P=0.015). This finding suggests that a finding of wild-type GSTO2 was related to a poor prognosis. Therefore, GSTO2 polymorphism may be used as a prognostic indicator for appropriate treatment decisions in patients with colorectal cancer. (Thai Cancer J 2010;3018-23)