Background/aim: The role of neuroendocrine (NE) cells in prostate cancer biology remains unclear. We previously reported a large difference in NE expression in benign prostate tissue among men of different ethnicities; African-American men had significantly fewer NE cells compared to all other groups. This report describes NE expression in malignant prostate tissue.
Patients and methods: Paraffin-embedded tissue from 180 men who underwent radical prostatectomy at the University of Southern California between 1983 and 2003 was stained using standard immunohistochemistry technique for chromogranin A (ChrA), serotonin (Ser) and synaptophysin (Syn). There were 39 specimens from African-American patients, 39 Asian, 57 Hispanic and 45 non-Hispanic White. Staining intensity and the percentage of cells positive were determined by the automated cellular imaging system. Results were analyzed by univariate and multivariate general linear regression models.
Results: There were significant differences in staining intensity for all markers between ethnic groups in univariate analysis. NE expression, judged by ChrA intensity, was highest in Hispanic patients, compared to non-Hispanic Whites and African-Americans. A similar pattern was observed for Syn and Ser. In multivariate analysis, controlling for age, Gleason score, PSA and stage, the differences in ChrA, Syn and Ser remained highly significant. Hispanic men had higher ChrA expression levels than African-Americans and non-Hispanic Whites (p=0.0077 and 0.0038, respectively); the p-values for the comparison were both <0.0001 for Ser. Both Hispanic and Asian patients had higher intensity Ser expression than African-American and Non-Hispanic Whites patients, with all p-values <0.018.
Conclusion: As already shown in benign prostate tissue, we identified significant differences in NE expression among prostate cancer tissues from men of different ethnic backgrounds. The clinical impact of these differences in NE expression warrants exploration.