Clin Invest Med 2008; 31 (1): E8-E15.
AbstractObjective: Ki-67 is a proliferation-associated nuclear antigen and is expressed in all cycling cells except for resting cells in the G0-phase. PCNA is an acidic nuclear protein and has been recognized as a histologic marker for the G1/ S phase in the cell cycle. Ki-67and PCNA labeling indices are considered to reflect cell proliferation, particularly, growth fraction. The purpose of this study is to investigate the expression levels of Ki-67 and PCNA in prostate cancer (PCa) and benign prostatic hyperplasia (BPH) and their potential on the early diagnosis of PCa. Methods: Human prostate cancer cell lines LNCaP and PC-3, human normal prostate epithelial cell line HuPEC, tissues from patients with PCa (121 cases) and BPH (45) and 36 normal cases were examined for the expression of Ki-67 and PCNA by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Then, the association of Ki-67 and PCNA expression with clinical grading of PCa was analyzed by immunohistochemistry staining. Results: The ratios of PCNA and Ki-67 expression levels in LNCaP and PC-3 were higher (P<0.05, P<0.001) than that in HuPEC. The two markers were differentially expressed in three tissues and showed increased expression in PCa (P<0.05) and BPH (P<0.05), relative to human normal prostate tissues. Compared with BPH, the ratio of Ki-67 and PCNA expressed in tumour tissue was increased (P<0.05). The increase of Ki-67 was greater than that of PCNA. Expression of the two markers increased after different grading of PCa cases Prostate cancer (PCa) is the second most frequent cause of male cancer-related death in the United States of America (USA) and Western Europe. Its incidence is continuously rising, with over 200 000 new cancers and 35 000~40 000 deaths per year, 1 Carcinogenesis and the mechanisms influencing the progression and prognosis of PCa is a multistep process, involving both genetic insults to epithelial cells and changes in epithelial-stromal interactions. 2 Despite extensive research PCa is not understood.There are two proliferative markers-Ki-67 and proliferating cell nuclear antigen (PCNA). Ki-67 antigen is expressed in proliferative cells throughout the G1, S, G2, and M phases, and provides a reliable index of cellular proliferation 3,4 PCNA is an acidic nuclear protein, expressed mainly in phase S of the cellular cycle. It becomes active, in various tissues par-