Expression of X-linked inhibitor of apoptosis protein in human prostate cancer specimens with and without neo-adjuvant hormonal therapy.

PURPOSE: X-linked inhibitor of apoptosis (XIAP) has high affinity and strong inhibitory activity on apoptosis-related caspase-3. The relationships between expression of XIAP and cleaved caspase-3, and response to neo-adjuvant hormonal therapy (NHT) remain elusive. The aim was to investigate whether NHT influences with XIAP expression in prostate cancer patients. In addition, the relationship between XIAP expression and apoptosis in patients who did or did not receive NHT was also investigated. METHODS: Eighty-three patients who had undergone radical prostatectomy were examined retrospectively and divided into NHT group (n = 40) and non-NHT group (n = 43). Immunohistochemistry was used to analyze the expressions of XIAP and cleaved caspase-3. The apoptotic cells reconfirmed the number of terminal deoxynucleotidyl transferase-mediated nick and labeling (TUNEL)-positive cells. RESULTS: In the non-NHT group, the proportion of TUNEL-positive cells correlated with expression of cleaved caspase-3 (r = 0.592, P < 0.001), and the expression of XIAP correlated negatively with that of cleaved caspase-3 and TUNEL-positive cells (r = -0.464, P < 0.001 and r = 0.431, P = 0.002, respectively). The expression of cleaved caspase-3, but not that of XIAP, was higher in NHT group than non-NHT group (P = 0.017). In the NHT group, there was no significant correlation between XIAP expression and cleaved caspase-3 expression or the proportion of TUNEL-positive cells. CONCLUSIONS: NHT did not influence XIAP expression. We speculate that the inhibition of XIAP expression may reinforce the apoptotic effect of NHT and improve the prognosis in patients with prostate cancer.