Biological factors may drive tumor aggressiveness in African-Americans

Researchers analyzing prostate tumors have identified differences in gene expression between African-American and Caucasian men that show the existence of distinct tumor microenvironments in these two patient groups. The study, conducted by investigators at the National Cancer Institute, Bethesda, MD, appears in Cancer Research (2008; 68:927-36).

Many of the genes that are differentially expressed between the tumors of African-American and Caucasian men are related to the immune system. The results of this study suggest that biological differences may, in part, underlie the disparity in prostate cancer survival rates observed between the two groups.

“Although preliminary, our findings are novel and could have implications for cancer therapy,” said Stefan Ambs, PhD, of NCI’s Breast and Prostate Unit. “Our data suggest that African-Americans and Caucasians might respond differently to immunotherapies currently under study for prostate cancer. Understanding the biological differences that play a role in the development and progression of cancer among racial and ethnic groups may aid in the development of therapies tailored to these differences.”

Lead author Tiffany Wallace, PhD, and colleagues analyzed differences in gene expression in prostate tumors from 33 African-American and 36 Caucasian men. Their analysis revealed higher expression of numerous genes that influence immune responses and metastasis in the tumors of African-American men compared with Caucasian men. Among the genes with elevated expression in prostate tumors from African-American men were genes that encode different types of chemokines and their receptors.

In addition, expression of a number of genes that are induced by interferon was found to be elevated in the African-American prostate tumor tissues. This observation suggests the possibility that viral infections could be associated with the development of prostate tumors in African-Americans.