Elevated caveolin-1 levels in African-American versus white-American prostate cancer

Clinical studies suggest that African-American (AA) prostate cancer patient s manifest a more aggressive form of the disease compared with white prosta te cancer patients. However, the biological underpinnings of this potential difference remain unresolved. To address this issue, we used specific quan titative immunostaining protocols to determine whether a panel of biomarker s related to apoptosis including caveolin-1, bcl-2, p53, and c-myc were dif ferentially expressed in AA versus white prostate cancer patients with simi lar clinical and pathological characteristics. We further attempted to corr elate biomarker positivity with proliferation-related markers including Ki- 67 labeling index and apoptotic index. Interestingly, our results indicated that only the incidence of caveolin-1 staining was significantly different between these two ethnic/racial groups of prostate cancer patients. The in cidence of caveolin-1 staining in white patients was 17% compared with 39% in AA patients (P = 0.0048; Fisher's exact test). In addition, the percenta ge of caveolin-1-positive prostate cancer cells was also higher in moderate ly differentiated (Gleason score 6) prostate cancer patients in AA versus w hites. Because caveolin-1 has been shown previously to demonstrate antiapop totic activities in prostate cancer cells, our results suggest that differe nces in caveolin-1 expression may in part underlie the apparent differences in the clinical virulence of this disease in AA versus white prostate canc er patients.