Genistein is a major component of soybean isoflavone and has multiple functions resulting in antitumor effects. Prostate cancer is 1 of the targets for the preventive role of genistein. We examined the effect of genistein on human prostate cancer (LNCaP and PC-3) cells. Proliferation of both cell lines was inhibited by genistein treatment in a dose-dependent manner. To obtain the gene expression profile of genistein in LNCaP cells, we performed cDNA microarray analysis. The expression of many genes, including apoptosis inhibitor (survivin), DNA topoisomerase II, cell division cycle 6 (CDC6) and mitogen-activated protein kinase 6 (MAPK 6), was downregulated. Expression levels were increased more than 2-fold in only 4 genes. The glutathione peroxidase (GPx)-1 gene expression level was the most upregulated. Quantitative real-time polymerase chain reaction revealed significant elevation of transcript levels of GPx-1 in both LNCaP and PC-3 cells. Upregulation of gene expression levels accompanied elevation of GPx enzyme activities. In contrast, no significant changes were observed in the gene expression levels and enzyme activities of the other antioxidant enzymes, superoxide dismutase and catalase. GPx activation might be one of the important characteristics of the effects of genistein on prostate cancer cells.
An association between the Pro/Pro genotype of p53 codon 72 and a lower risk of prostate cancer in Caucasians was recently reported. However, the association of this polymorphism with prostate cancer risk in a Japanese population has not been clarified. We performed a case-control study consisting of 114 prostate cancer patients and 105 noncancer controls. Sixty-nine percent (79 of 114) of the patients had a positive family history. The genotypic frequencies in the controls were 39.0% for Arg/Arg, 54.3% for Arg/Pro and 6.7% for Pro/Pro; they were in Hardy-Weinberg equilibrium. When a comparison of the distribution of the p53 codon 72 polymorphism was made between patients with a first-degree family history and all control subjects, the adjusted odds ratios (ORs) for prostate cancer associated with the Arg/Arg, Arg/Pro and Pro/Pro genotypes were 1.00, 0.99 [95% confidence interval (CI) 0.53-1.88] and 2.80 (95% CI 1.04-7.53), respectively. When stratification of cases was performed based on clinical stage (localized or metastatic cancer) and pathological grade (a Gleason score of <7 or > or =7), there tended to be a greater number of patients with localized cancers among those patients with the Arg/Pro genotype than among those with the Arg/Arg genotype (overall cases: age-adjusted OR 0.36, 95% CI 0.13-1.00, p = 0.049; positive family history cases: age-adjusted OR 0.25, 95% CI 0.075-0.84, p = 0.025). In addition, there tended to be a greater number of patients with low-grade cancers among those with the Pro/Pro genotype than among those with other genotypes (overall cases: age-adjusted OR 0.41, 95% CI 0.13-1.30, p = 0.13; positive family history cases: age-adjusted OR 0.20, 95% CI 0.004-0.89, p = 0.035). The present findings suggest that the Pro/Pro genotype of p53 codon 72 played a role in prostate cancer susceptibility in a Japanese population. However, the Pro allele did not appear to worsen such clinical parameters as clinical stage or pathological grade.
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