Study about Predominance of ERG-Negative High-Grade Prostate Cancers in African American Men

The most common and well-documented prostate cancer (CaP) genome alteration, erythroblast transformation-specific-related gene (ERG) fusions, cause changes in the expression of the ERG oncoprotein. ERG frequencies are significantly lower in African American (AA) men's tumours than in Caucasian American (CA) men's tumours. Evaluations of the ERG alterations at the genomic, transcriptional and protein levels have continued to suggest lower frequencies of ERG in AA CaP in comparison to CA CaP. Based on our preliminary findings, we focused this study on the increased association of ERG-negative status with higher-grade prostate tumours in AA men. Representative whole-mount prostate sections from a matched cohort of 63 AA and 63 CA men with Gleason scores of 4+3 and those with Gleason scores of 8-10 were analyzed for ERG oncoprotein by immunohistochemistry. The striking finding of this study was that ERG expression was 3 times more likely to be present in the higher-grade index tumors of CA men compared to AA men (31 of 63 vs. 10 of 63 patients, respectively; P<0.0001). Even though the mechanisms underlying such disparities have not been identified, the current study, along with our previous findings, suggests that ERG typing may improve understanding of ethnic differences and future CaP targeted therapy.