Description
An alarming disparity still exists in many cancer types, particularly in prostate cancer (PCa), in spite of new cancer therapeutics and substantial improvements in disease diagnostics. African American men have the highest mortality rates in PCa when compared to men of other races. These substantial differences in mortality are attributed to factors that include socioeconomic status, access to healthcare, family history, and biology. Evidence for the immune system’s critical role in cancer has encouraged the development of immunotherapies for cancer treatment. These therapies serve to enhance the immune system’s recognition of malignant tissues to inhibit cancer progression. Although current immunotherapies have significant impact on the immune response to cancer, many of the immune mechanisms in cancer have yet to be characterized. The immune response in PCa, as well as other cancer types, is critical for inhibiting the growth and progression of tumors. Effective anti-tumor immunity is characterized by high prevalence of cytotoxic T lymphocytes (CTLs) in the tumor microenvironment. CTLs have the ability to directly destroy malignant cells, making them crucial for inhibiting tumor development. The prevalence of CTLs within tumor tissues is associated with improved clinical outcomes in colon, breast, and ovarian cancers. Strong adaptive anti-tumor responses involve effective antigen presentation for the efficient activation of immune cells that contribute to high CTL activity. Our work focuses on identifying differences in expression of specific anti-tumor immune markers between African Americans (AA) and Caucasian Americans (CA) to pinpoint the immune mechanisms that contribute to the racial disparities in PCa. Our immunohistochemical studies indicate differences by race in two major aspects of anti-tumor immunity: antigen presentation by tumors and lymphocyte recruitment to tumor tissues. Previous studies from our lab have revealed significant differences in gene expression of various immune markers by race. HLA-DMB and HLA-DPA1, two genes important in antigen presentation, are higher expressed in tumors of CA compared to those of AA. Both immune products are expressed by various tumor types and antigen presenting cells (APCs). CA tumors also had greater numbers of CD8+ cells, which may potentially be cytotoxic. Collectively, these data indicate greater anti-tumor immunity in CA patients.
