title: Direct determination of nucleosides in the urine of patients with breast cancer using column-switching liquid chromatography-tandem mass spectrometry.
abstract: We developed an analytical method for a simple, sensitive and simultaneous determination of oxidized nucleosides in urine using column-switching liquid chromatography-electrospray/tandem mass spectrometry (LC-ESI/MS/MS). We connected two columns through a six-way switching valve and effectively separated nucleosides in the urine from the interference by column-switching liquid chromatography. We monitored separated nucleosides using positive ionization tandem mass spectrometry in selective reaction monitoring (SRM) mode. The calibration ranges of nucleosides were 0.2-100 nmol/mL. The linearity of the method was 0.994-0.999, and the limits-of-detection (LOD) at a signal-to-noise (S/N) ratio of 3 were 0.1-0.2 nmol/mL. The coefficients of variation were in the range 2.28-11.74% for within-day variation and 4.36-11.15% for day-to-day variation, respectively. To explore the relationship between breast cancer and the nucleosides level in human urine, we measured the concentrations of nucleosides in female patients with breast cancer (n = 30) and in normal female subjects (n = 30). The concentration of nucleosides was significantly increased in patients with breast cancer when compared with the normal controls (1-methyladenosine; p < 0.005, N(2),N(2)-dimethylguanosine; p < 0.01, 5-hydroxymethyl-2'-deoxyuridine; p < 0.001, 8-hydroxy-2-deoxyguanosine; p < 0.001). Therefore, the elevated levels of nucleosides could be used as an important biomarker for breast-cancer research.
authors.affiliation: Bioanalysis and Biotransformation Research Center, KIST, Chengryang, Seoul 130-605, Korea.
authors.forename: Sung-Hee
authors.initials: SH
authors.lastname: Cho
authors.forename: Byung Hwa
authors.initials: BH
authors.lastname: Jung
authors.forename: Sang Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Won-Yong
authors.initials: WY
authors.lastname: Lee
authors.forename: Gu
authors.initials: G
authors.lastname: Kong
authors.forename: Bong Chul
authors.initials: BC
authors.lastname: Chung
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000652:urine*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009705:Nucleosides / Q000652:urine*; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D009705:Nucleosides