The potential of peripheral blood HERV-K expression as a biomarker for diagnosis with prostate cancer in older men.

5049 Background: Aberrant expression of human endogenous retrovirus-k (HERV-K) has been observed in prostate cancer (PCa). HERV-K is unique as it encodes sequences in the human genome containing open reading frames for near intact retroviruses. We hypothesized that HERV-K reactivation could serve as a non-invasive early disease detection marker. Methods: We evaluated HERV-K gag mRNA expression in PBMCs of African-American (AA) and European-American (EA) men via qRT-PCR (294 PCa cases and 135 male controls). We examined HERV-K env protein expression in PCa by immunohistochemistry. Fisher's exact test and logistic regression were used to analyze continuous and dichotomized data and calculate odds ratios (ORs). Multivariable models adjusted for age at diagnosis and race/ethnicity. Mann-Whitney test was used to compare HERV-K Ct-based expression values between groups. Results: HERV-K gag expression in PBMCs was significantly higher in PCa cases than controls (Table). Men with gag in the highest quartile had >...