Enhanced hepatocyte growth factor level in human prostate cancer treated with endocrine therapy

Hepatocyte growth factor (HGF) has been revealed to have various functions such as regeneration, cancer invasion and tumor suppression in normal and cancer cells of different organs. To compare HGF expression in non-malignant prostate tissues and prostate cancers pretreated with or without neoadjuvant endocrine therapy (pretreated PC and non-treated PC), the amounts of HGF protein and mRNA were quantitated by Western blot analysis and reverse transcription-competitive polymerase chain reaction. The biologically active HGF (baHGF), which was converted by an HGF activator protein from secretory type proHGF, showed significantly higher expression in pretreated PC than in non-treated PC. The amounts of baHGF in pretreated PC were similar to those in non-malignant prostate tissues. There was no difference in the expression level of full-length HGF mRNA encoding secretory type HGF among the three groups. No variance of tissue content of short variant HGF mRNA encoding a competitive HGF antagonist among the three groups indicated that short variant HGF protein in prostate cancer seemed not to function similarly to a competitive HGF antagonist in benign prostate tissues. These results suggest that the tissue level of baHGF in non-treated and pretreated PC depends on activation of proHGF supplied from distal organs rather than de novo HGF mRNA synthesis in prostate glands. Increased baHGF in pretreated PC is expected to relate to tumor suppression in vivo.