Chemo‐Enzymatic Fluorescence Labeling Of Genomic DNA For Simultaneous Detection Of Global 5‐Methylcytosine And 5‐Hydroxymethylcytosine**

Abstract

Abstract5‐Methylcytosine and 5‐hydroxymethylcytosine are epigenetic modifications involved in gene regulation and cancer. We present a new, simple, and high‐throughput platform for multi‐color epigenetic analysis. The novelty of our approach is the ability to multiplex methylation and de‐methylation signals in the same assay. We utilize an engineered methyltransferase enzyme that recognizes and labels all unmodified CpG sites with a fluorescent cofactor. In combination with the already established labeling of the de‐methylation mark 5‐hydroxymethylcytosine via enzymatic glycosylation, we obtained a robust platform for simultaneous epigenetic analysis of these marks. We assessed the global epigenetic levels in multiple samples of colorectal cancer and observed a 3.5‐fold reduction in 5hmC levels but no change in DNA methylation levels between sick and healthy individuals. We also measured epigenetic modifications in chronic lymphocytic leukemia and observed a decrease in both modification levels (5‐hydroxymethylcytosine: whole blood 30 %; peripheral blood mononuclear cells (PBMCs) 40 %. 5‐methylcytosine: whole blood 53 %; PBMCs 48 %). Our findings propose using a simple blood test as a viable method for analysis, simplifying sample handling in diagnostics. Importantly, our results highlight the assay‘s potential for epigenetic evaluation of clinical samples, benefiting research and patient management.