DETECTION OF PROSTATE-CANCER CELLS CIRCULATING IN PERIPHERAL-BLOOD BYREVERSE TRANSCRIPTION-PCR FOR HKLK2

Two of the human tissue kallikrein family, hK2 and hK3 (prostate-speci fic antigen), are primarily produced by the prostatic epithelium under the regulation of androgens, In this study, we detected prostate canc er cells that expressed hKLK2 or hKLK3 mRNA in the peripheral blood of patients with prostate cancer using reverse transcription-PCR (RT-PCR ), We then demonstrated some differences in characteristics, such as d ifferentiation of cancer cells and response to antiandrogen therapy, b etween hKLK2 and hKLK3 mRNA-expressing prostate cancer cells, Total RN A was isolated from 41 patients with known prostate cancer, 7 patients with benign prostatic hyperplasia, and 20 normal volunteers, By RT-PC R, hKLK2 mRNA was detected in 7 patients (33%), and hKLK3 mRNA was det ected in 17 (81%) of 21 stage D prostate cancer patients, In contrast, all patients with benign prostatic hyperplasia and healthy volunteers were negative, From comparison of the background of the patients posi tive for hKLK2 and/or hKLK3 mRNA, it became evident that the response to antiandrogen therapy and the expression of hKLK2 mRNA were reciproc ally correlated, in contrast with the expression of hKLK3 mRNA, Additi onally, our study clearly demonstrated that the detection of hKLK2 mRN A in the peripheral blood was useful for screening patients with certa in prostate cancers that did not express hK3. We conclude that taking advantage of the difference between hKLK2 mRNA and hKLK3 mRNA expressi on is clinically useful for following up prostate cancer patients.