Clinical Significance of Measuring Global Hydroxymethylation of White Blood Cell DNA in Prostate Cancer: Comparison to PSA in a Pilot Exploratory Study

This is the first study investigating the clinical relevance of 5-hydroxymethylcytosine (5hmC) in genomic DNA from white blood cells (WBC) in the context of prostate cancer (PCa) and other prostate pathologies. Using an enzyme-linked immunosorbent assay, we identified significantly different distributions of patients with low and elevated 5hmC content in WBC DNA across controls and patients with prostate cancer (PCa), atypical small acinar proliferation (ASAP), and benign prostatic hyperplasia (BPH). The measured values were within the normal range for most PCa patients, while the latter category was predominant for ASAP. We observed a wider heterogeneity in 5hmC content in all of the prostate pathologies analyzed when compared to the healthy age-matched controls. When compared to blood levels of prostate-specific antigen (PSA), this 5hmC-based biomarker had a lower performance in PCa detection than the use of a PSA cut-off of 2.5 nanograms per milliliter (ng/mL). Above this threshold, however, it delineated almost three quarters of PCa patients from controls and patients with other prostate pathologies. Overall, genome-wide 5hmC content of WBC DNA appears to be applicable for detecting non-cancerous prostate diseases, rather than PCa. Our results also suggest a potential clinical usefulness of complementing PSA as a PCa marker by the addition of a set of hydroxymethylation markers in the blood, but further studies are necessary to confirm these findings.