Expression of Osteocalcin in Prostate Cancer before and after Hormonal Therapy

Background: Osteocalcin (OC), a noncollagenous bone matrix protein, is specifically produced by osteoblasts. Previously, we demonstrated that OC immunohistochemical staining was found in primary prostate cancer (PC) and PC metastasis to lymph node and bone. Advanced and metastatic PC is commonly treated by hormonal therapy (H/T). Inevitably, these patients will relapse and develop hormone-refractory (HR) PC. The aim of this study was to realize the OC expression in PC before H/T and after H/T when HRPC developed. Materials and Methods: Twenty patients with PC received H/T and later developed HRPC. The interval of androgen-response was classified by good response (Group A, ≥30 months) and poor response (Group B, <30 months). The mean interval of androgen-response was 48.8 months in Group A (10 patients) and 17.5 months in Group B (10 patients). Formalin-fixed paraffin-embedded PC before H/T and HRPC for each patient were stained for osteocalcin. Results: Osteocalcin immunohistochemical stain was detected in 18 of 20 PC before H/T and 19 of 20 of HRPC. Compared to PC before H/T, the expression of OC in HRPC increased in 5 cases (4 of Group A, 1 of Group B), did not change in 3 (2 of Group A, 1 of Group B) and decreased in 12 (4 of Group A, 8 of Group B). Conclusion: Our data suggest the expression of OC in PC is not correlated to the response of H/T. OC expression was still noted in 95% of HRPC. OC may be a target for treatment of HRPC.