Creatine riboside (CR) is a novel metabolite of
cancer metabolism. It is a urinary diagnostic
biomarker of lung and
liver cancer risk and prognosis. The level of CR is highly positive correlated in
tumor and urine indicating that it is derived from human lung and
liver cancers. A precise and sensitive ultra-pressure liquid chromatography-tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for simultaneous quantification of the noninvasive
biomarker CR, along with
creatinine riboside (CNR), and their precursors
creatine and
creatinine, utilizing the labeled internal standard
creatine riboside-13C,15N2 (CR-13C,15N2). Chromatography was carried out on a hydrophilic interaction chromatography column under a gradient mobile phase condition. MRM transitions were monitored for CR (264.1 > 132.1, m/z), CNR (246.1 > 113.9, m/z),
creatine (132.0 > 72.0, m/z),
creatinine (114.0 > 85.8, m/z) and CR-13C,15N2 (267.1 > 134.9, m/z) with a 11.0 min run time in the positive mode ionization. The calibration plot of the method was linear over the concentration range of 4.50-10,000 nM. Method validation was performed according to regulatory guidelines established for sensitivity, selectivity, calibration curve, stability at different storage conditions, reinjection reproducibility, ruggedness with acceptable accuracy, and precision. This assay was applied for the quantification of CR along with CNR,
creatine and
creatinine in a subset of urine and serum samples from the National Cancer Institute - Maryland (NCI-MD) cohort population controls and
lung cancer cases. It can be standardized and used in multiple laboratories for
cancer diagnosis and determining the efficacy of
cancer therapy and monitoring
cancer recurrence.