Expression of some selected cytokeratins and Ki67 protein in prostatic tumor: can these be used as tumor markers

INTRODUCTION Diagnosis of prostatic diseases with Immunohistochemistry still faces challenges because of the peculiar histology of the prostate and difference(s) in reactivity of Monoclonal antibodies (MoAb) to benign and malignant changes. METHODS Thirty (30) archived paraffin embedded tissue samples from primary prostate tumors (15 Benign Prostatic Hyperplasia (BPH) and 15 Cancer of the prostate (CaP)) were sectioned at thickness of 5 µm and confirmed as BPH or CaP. Sections from each sample were stained by Immunohistochemistry using the Streptavidin-biotin method and using CK5/6, CK7, CK8,CK20 and Ki67 antibodies (Zymed Antibody products). Appropriate positive and negative controls for each antibody were setup alongside the test slides. RESULTS BPH samples were reactive to Ck5/6 (93.3%), Ck7 (80%) and Ck8 (100%). Only 13.3% of BPH samples were reactive to Ki67. The reactivity of Ck5/6, 7, 8 in CaP is a contrast with only 3(20%) of samples positive with Ck5/6, 2(13.3%) positive with Ck7 and 14(93.3%) with Ck8. While reactivity of Ck 8 is similar in BPH and CaP, no reaction was recorded in Ck 20 in both BPH and CaP. Ki67 was only reactive in 2(13.3) of BPH samples and 15(100%) of CaP. Only Ck 8 was expressed in both BPH and CaP. There was co-expression of Ck5/6, 7,8 and Ki67 in 13.3%; Ck7 and Ki67 in 13.3% in both BPH and CaP. CONCLUSION The various cytokeratins are individually expressed in both BPH and CaP. Ck5/6 and Ck7 are co-expressed and may be used in the diagnosis of BPH, Ck5/6,7,8 and Ki67 are co-expressed in Prostatic adenocarcinoma and squamous cell carcinoma of the prostate while Ck8 and Ki67 are co-expressed and may be used for diagnosis of Prostatic adenocarcinoma alone.