Objective: To determine the role of vascular response in the castration-induced regression of benign and malignant human prostate tissue, as recent studies show that castration rapidly decreases blood flow and induces endothelial cell death, which may be important for subsequent epithelial cell death and involution of the glandular tissue of the prostate.
Materials and methods: The expression of vascular endothelial growth factor (VEGF) and its receptors was analysed using the quantitative reverse transcriptase-polymerase chain reaction, in benign and tumour areas of core biopsies taken before, and approximately 1 week after castration therapy. The castration-induced VEGF response was related to therapy-induced changes in tumour cell apoptotic index and subsequent response in serum prostate-specific antigen (PSA). In another set of patients, serum VEGF was quantified by enzyme-linked immunosorbent assay before, and at 3--6 months after castration therapy.
Results: VEGF mRNA was down-regulated after castration in benign prostate tissue (P < or = 0.05), whereas in tumour tissue, VEGF levels were reduced in some of the patients but unchanged or increased in others. In most patients whose tumour tissue responded with VEGF reduction, there was a corresponding increase in tumour cell apoptosis. Serum VEGF levels were not significantly changed after castration. Almost all patients responded with a substantial reduction in serum PSA after castration.
Conclusion: Castration reduces VEGF mRNA expression in benign prostate tissue and generally in those prostate tumours where castration also induces tumour cell apoptosis. This suggests that a therapy-induced down-regulation of VEGF could be important for tumour cell death.