Urinary Measurement of Epigenetic DNA Modifications and 8-oxodG as Possible Noninvasive Markers of Colon Cancer Evolution

Abstract

The active DNA demethylation mechanism involves 5-methylcytosine (5-mCyt) enzymatic oxidation with the subsequent formation of 5-hydroxymethylcytosine (5-hmCyt), which can be further oxidized to 5-formylcytosine (5-fCyt) and 5-carboxylcytosine (5-caCyt). The products of active DNA demethylation are released into the bloodstream and eventually also appear in urine. We used online two-dimensional ultraperformance liquid chromatography with tandem mass spectrometry (2D-UPLC-MS/MS) to compare DNA methylation marks and 8-oxo-2′-deoxyguanosine (8-oxodG) in colorectal cancer and pre-cancerous condition in urine. The study included four groups of subjects: healthy controls, patients with inflammatory bowel disease (IBD), persons with adenomatous polyps (AD), and individuals with colorectal cancer (CRC). We have found that the level of 5-fCyt in urine was significantly lower for CRC and polyp groups than in the control group. The level of 5-hmCyt was significantly higher only in the CRC group compared to the control (2.3 vs. 2.1 nmol/mmol creatinine). Interestingly, we have found highly statistically significant correlation of 5-hydroxymethyluracil with 5-hydroxymethylcytosine, 5-(hydroxymethyl)-2′-deoxycytidine, 5-(hydroxymethyl)-2′-deoxyuridine, and 5-methyl-2′-deoxycytidine in the CRC patients’ group.

The level of active DNA demethylation compounds in leukocytes and urine samples as potential epigenetic biomarkers in breast cancer patients

“…Leukocytes can serve as reliable “carriers” of information, reflecting the changes in tissue milieu, specifically environmentally-induced DNA alterations 20 , 51 , 52 . Moreover, it should be noted that during the active DNA demethylation process, after elimination by BER mechanism, modified deoxynucleosides and nucleobases appear in the bloodstream, followed by their elimination in the urine 53 , 54 . Therefore, the paper focuses on the examination of breast cancer surrogate tissues – leukocytes as well as urine as a source of metabolic elimination products.…”