Gene polymorphisms in antioxidant enzymes correlate with the efficacy of androgen-deprivation therapy for prostate cancer with implications of oxidative stress

ABSTRACT

Background

Oxidative stress mitigated by antioxidant enzymes is thought to be involved in the progression to castration-resistant prostate cancer (CRPC) during androgen-deprivation therapy (ADT). This study investigated the association between genetic variations in antioxidant enzymes and the efficacy of ADT as well as its biological background.

Patients and methods

The non-synonymous or promoter-locating polymorphisms of antioxidant enzymes were examined as well as the time to CRPC progression and overall survival in 104 and 92 patients treated with ADT for metastatic and non-metastatic prostate cancer, respectively. In addition, intracellular reactive oxygen species and expression levels of antioxidant enzymes were examined in castration-resistant and enzalutamide-resistant cells.

Results

In metastatic prostate cancer, the AG/GG allele inGSTM3 rs7483 and CT/TT allele inCAT rs564250 were associated with a significantly lower risk of progression to CRPC and all-cause death compared with homozygotes of the major AA allele (hazard ratio [HR]; [95% confidence interval (CI)], 0.55 [0.34–0.86],P = 0.0086) and CC allele (HR; [95% CI], 0.48 [0.24–0.88],P = 0.016), respectively. On multivariate analyses, onlyGSTM3 rs7483 was associated with significant progression risk (AG/GG versus AA; HR; [95% CI], 0.45 [0.25–0.79],P = 0.0047) even after Bonferroni adjustment. In non-metastatic prostate cancer, the AG/GG allele inGSTM3 rs7483 was associated with a significantly lower risk of progression to CRPC (HR; [95% CI], 0.35 [0.10–0.93],P = 0.034) and all-cause death (HR; [95% CI], 0.26 [0.041–0.96],P = 0.043) compared with the AA allele. Intracellular reactive oxygen species levels were increased, accompanied with augmentedGSTM3 expression in both castration-resistant and enzalutamide-resistant cells.

Conclusions

Differential activity of antioxidant enzymes caused by the polymorphism inGSTM3 may contribute to resistance to hormonal therapy through oxidative stress. TheGSTM3 rs7483 polymorphism may be a promising biomarker for prostate cancer patients treated with ADT.