Ornithine decarboxylase (ODC) expression pattern in human prostate tissues and ODC transgenic mice

Ornithine decarboxylase (ODC) is the key enzyme in the polyamine synthesis pathway and is overexpressed in a variety of cancers. We have performed a detailed immunostaining analysis of the expression of ODC in normal, benign prostatic hyperplasia (BPH), and cancerous prostate tissues. We conclude that ODC is overexpressed in both BPH and neoplastic tissues and that ODC overexpression appears to be an early event in prostate carcinogenesis. The extent of overexpression decreases as cancer progresses. Interestingly, ODC overexpression was also detected in patients who underwent androgen ablation therapy, suggesting ODC overexpression may contribute to the androgen-independent survival of prostate cancer cells. ODC is perinuclear localized in BPH samples but is diffusely cytoplasmic in cancer samples. Having shown ODC overexpression in human prostate cancer, we developed prostate-specific ODC transgenic mice to further investigate whether ODC overexpression alone is a causal factor in prostate carcinogenesis. RT-PCR and immunostaining confirmed that ODC was overexpressed in a subset of prostate epithelial cells. Although minor nucleoli enlargements in some tissues were detected, gross morphological changes were not observed in transgenic prostates. Therefore, overexpression of ODC alone in this subset of prostate epithelial cells is not sufficient to induce prostate carcinogenesis.