EXPRESSION OF C-MET HGF RECEPTOR MESSENGER-RNA AND PROTEIN IN HUMAN NONMALIGNANT AND MALIGNANT PROSTATE TISSUES/

We previously reported the expression of hepatocyte growth factor (HGF ), a ligand for c-MET, at the level of mRNA and protein in human prost ate tissues. The present study was carried out to evaluate the relatio nship between c-MET expression and cancer cell proliferation or effect of cancer therapy. The expression both in mRNA and protein levels of c-MET proto-oncogene was determined semiquantitatively by reverse tran scription-competitive polymerase chain reaction (RT-competitive PCR) a nd Western blot analysis for prostate tissues from 32 Japanese male su bjects. In addition, tissue localization of c-MET translation product was examined by immunohistochemistry for corresponding specimens. Alth ough there was significantly higher c-MET protein expression in malign ant (prostate cancer treated with/without neoadjuvant endocrine therap y) than in nonmalignant prostate tissues (normal prostate and benign p rostate hyperplasia; BPH), unexpectedly, c-MET mRNA showed high expres sion in the non-malignant group. Thus, there was no parallelism betwee n mRNA and protein expressions of c-MET. Endocrine therapy did not alt er c-MET mRNA and protein expressions in human prostate cancer. Immuno histochemical localization and expression of c-MET protein was found t o be intense in cancer cells and weak in epithelia of normal and hyper plastic prostates. Unconcerted expression of mRNA and protein of c-MET , the reason of which is uninterpretable, is supposed to be one of cha racteristics of human prostate cancer.