Detection of 5-carboxylcytosine in Mammalian Cells DNA

Abstract

5-carboxylcytosine (5caC) is an important derivative of cytosine modification in DNA demethylation pathway. However, the accurate quantification of 5caC is a challenge, especially in mammalian tissue. This plight probably results from the trace amount of 5caC in mammalian and the inadequate sensitivity of the existing technologies. Herein, we report a novel LC-MS/MS method to precisely quantify 5caC in mammalian cells. The 5caC standard reagent was synthesized, and the genomic DNA was hydrolyzed with formic acid and the target compound 5caC was detected by HILIC LC-MS/MS. The results showed 5caC generally exist in mice organs and cancer tissues. The content of 5caC in mice brain was higher than in lungs and liver, and was obviously decreased in colorectal cancer tissues compared with the adjacent tissue. This result suggests that 5caC probably associates with tumorigenesis and plays a dominated role in epigenetic control of neuronal function.