Distribution and secretory pathways of prostate specific antigen, α1‐antichymotrypsin and prostate secretory granules in prostate cancers

Using 19 radical prostatectomy specimens, we studied the histological distribution of free prostate specific antigen (PSA), total PSA, α1‐antichymotrypsin (ACT) and prostate secretory granules (PSG) in both normal and cancerous cells of the prostate. After glutaraldehyde fixation, numerous fine eosinophilic droplets of PSG could be found mainly in the apical portions of normal acinous epithelial cells, but was markedly decreased in cancer cells. With antibodies against free PSA, normal acinous cells were granularly positive in the apical portion of the epithelium, which corresponded to the PSG, whereas cancer cells were diffusely positive. With antibodies against ACT, normal duct cells and cancer cells were often positive, but few normal acinous cells were positive. Presumably, these findings indicate that free PSA is secreted into the lumen as PSG in normal glands, but not by the same pathway in cancers where free PSA appears to accumulate due to a decrease of PSG, then leak into the blood producing complexed PSA to some extent in the cytoplasm. One factor analysis of variance (anova) on the correlation of tumor differentiation or Gleason score with serum values of total PSA, free PSA and a free/total PSA ratio demonstrated no significant links. Elucidation of secretory mechanisms should provide better comprehension of various PSA indices for prostate cancer screening.