Overexpression of ornithine decarboxylase in prostate cancer and prostaticfluid in humans

Prostate cancer (PCA), the most commonly diagnosed cancer in males in the U nited States, is the second leading cause of cancer-related deaths of males in this country. Because of the poor success rate in the treatment of PCA, an intervention at an early stage may reduce the progression of small carc inoma to large metastatic lesion, thereby reducing PCA-related deaths. Conc erted efforts are needed to establish mechanism-based approaches to develop : (a) the markers for early detection of the disease as well as toward moni toring the efficacy of treatment(s); and (b) novel chemopreventive strategi es against PCA. Using unique samples of pair-matched benign and cancer tiss ue obtained from the same PCA patient, we showed that ornithine decarboxyla se (ODC) activity is significantly (P < 0.001) elevated in PCA (1142 +/- 10 0; mean +/- SE) than in paired benign tissue (427 +/- 51; mean +/- SE). The immunoblot analysis also showed a significant elevation in the protein exp ression of ODC in the PCA tissues as compared with the paired benign tissue . Furthermore, our data showed that the ODC activity in the prostatic fluid obtained by a digital rectal massage from the patients with PCA (3847 +/- 162; mean +/- SE) was significantly higher than in the patients with benign prostatic hyperplasia (2742 +/- 167; mean +/- SE) or normal individuals (1 244 +/- 67; mean +/- SE). This observation might be of significance because the prostatic fluid could be obtained noninvasively by digital rectal mass age. We suggest that ODC could serve as a target for early detection of hum an PCA as well as for monitoring the efficacy of treatment(s). The developm ent of ODC as a target for novel chemopreventive strategies against PCA is an intriguing possibility.