Determination of dimethylated nucleosides in serum from colorectal cancer patients by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

[Display omitted] • A sensitive, accurate and reliable HILIC-MS/MS method for determination of dimethylated nucleosides was developed and validated. • The method was successfully applied to quantify dimethylated nucleosides in human serum samples. • Levels of N 6-2′-O-dimethyladenosine and N 2, N 2-dimethylguanosine were elevated, while 5,2′-O-dimethyluridine was diminished in the serum from colorectal cancer patients. RNA modifications play a crucial regulatory role in a variety of biological processes and are closely related to numerous diseases, including cancer. The diversity of metabolites in serum makes it a favored biofluid for biomarkers discovery. In this work, a robust and accurate hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) approach was established for simultaneous determination of dimethylated nucleosides in human serum. Using the established method, we were able to accurately quantify the concentrations of N 6-2′-O-dimethyladenosine (m6A m), N 2, N 2-dimethylguanosine (m2,2G), and 5,2′-O-dimethyluridine (m5U m) in serum samples from 53 healthy controls, 57 advanced colorectal adenoma patients, and 39 colorectal cancer (CRC) patients. The results showed that, compared with healthy controls and advanced colorectal adenoma patients, the concentrations of m6A m and m2,2G were increased in CRC patients, while the concentration of m5U m was decreased in CRC patients. These results indicate that these three dimethylated nucleosides could be potential biomarkers for early detection of colorectal cancer. Interestingly, the level of m5U m was gradually decreased from healthy controls to advanced colorectal adenoma patients to CRC patients, indicating m5U m could also be used to evaluate the level of malignancy of colorectal tumor. In addition, this study will contribute to the investigation on the regulatory mechanisms of RNA dimethylation in the onset and development of colorectal cancer. [ABSTRACT FROM AUTHOR]