Immunohistochemical analysis of low-grade and high-grade prostate carcinoma: Relative chanqes or parathyroid hormone-related protein and its parathyroid hormone 1 receptor, osteoprotegerin and receptor activator of nuclear factor-kB ligand

Abstract

Aim: To investigate multiple bone cytokines produced by prostate carcinoma (PCa) as a novel strategy to differentiate potential aggressiveness in localised PCa using immunohistochemical analysis. Methods: A total of 47 cases of PCa undergoing radical prostatectomy or transurethral prostatic resection at our institution (Fundación Jiménez Díaz (Grupo Capio), Madrid, Spain) between January 1991 and June 1998 were identified as low-grade (≤4; n = 22) or high-grade (≥7, excluding 7 (3+4) cases; n = 25) PCa according to Gleason grade. PCa specimens were immunostained for: parathyroid hormone (PTH)-related protein (PTHrP), the PTH1 receptor, osteoprotegerin and receptor activator of nuclear factor-κ B ligand (RANKL), as well as Ki67 (a proliferation marker) and CD34 (an angiogenesis marker). Results: PCa samples showed an increased immunostaining for both osteoprotegerin and RANKL, associated with tumour grade and PTHrP positivity, in the tumoral epithelium. Using a score value of 4 - corresponding to moderate staining - as cut-off, the best sensitivity value was for PTHrP (with C-terminal antiserum C6; 100 %); wheras the best specificity value was for RANKL (95 %). Conclusions: All the evaluated factors are overexpressed mainly in the high-grade tumours. Our findings indicate that, in most patients with PCa (with Ki67 values between 1% and 9%), sequential determination of C-terminal PTHrP and RANKL immunoreactivities is a useful approach to discriminate low-grade and high-grade tumours.