Immunohistochemical evaluation of proliferating cell nuclear antigen, prostate‐specific antigen and α1‐antichymotrypsin in human prostate cancer

Abstract

To determine the relationship between growth fractions defined by proliferating cell nuclear antigen (PCNA), prostate-specific antigen (PSA) and alpha 1-antichymotrypsin (ACT) staining in prostate cancer. A total of 96 lesions, including 71 from prostate cancers and 25 from benign prostatic hyperplasia (BPH) were evaluated in microscopic sections of the prostatic tissues from 34 patients with prostate cancer. Immunohistochemical staining was performed with an avidin-biotin system using monoclonal anti-PCNA antibodies, polyclonal anti-PSA and anti-ACT antibodies. There was a significant difference in the mean PCNA labelling index between tissue from prostate cancer (4.2 +/- 7.1) and BPH (0.5 +/- 1.1) (P = 0.002). The mean labelling index of PCNA tended to increase with increasing Gleason score. The proportion of cells positive for PSA was significantly higher in tissue from BPH than from prostate cancer (P = 0.005). While the proportion of cells immunostaining for ACT was significantly higher in tissue from BPH compared to that from prostate cancer (P = 0.02), there was no significant difference in the proportion of ACT-positive cells among prostate cancers of differing Gleason score. The mean labelling index of PCNA decreased significantly with the increase in the proportion of PSA-positive cells (P = 0.013). There was a significant relationship between the proportion of ACT- and PSA-positive cells (P = 0.001). These results indicate a reciprocal relationship between cell growth and tumour differentiation in prostate cancer. Although the significance of ACT deserves further study, there was evidence for the complexing of PSA with ACT from the immunohistochemical studies.