title: Simultaneous detection of six urinary pteridines and creatinine by high-performance liquid chromatography-tandem mass spectrometry for clinical breast cancer detection.
abstract: Recent preliminary studies have implicated urinary pteridines as candidate biomarkers in a growing number of malignancies including breast cancer. While the developments of capillary electrophoresis-laser induced fluorescence (CE-LIF), high performance liquid chromatography (HPLC), and liquid chromatography-mass spectroscopy (LC-MS) pteridine urinalyses among others have helped to enable these findings, limitations including poor pteridine specificity, asynchronous or nonexistent renal dilution normalization, and a lack of information regarding adduct formation in mass spectrometry techniques utilizing electrospray ionization (ESI) have prevented application of these techniques to a larger clinical setting. In this study, a simple, rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and optimized for simultaneous detection of six pteridines previously implicated in breast cancer and creatinine as a renal dilution factor in urine. In addition, this study reports cationic adduct formation of urinary pteridines under ESI-positive ionization for the first time. This newly developed technique separates and detects the following six urinary pteridines: 6-biopterin, 6-hydroxymethylpterin, d-neopterin, pterin, isoxanthopterin, and xanthopterin, as well as creatinine. The method detection limit for the pteridines is between 0.025 and 0.5 μg/L, and for creatinine, it is 0.15 μg/L. The method was also validated by spiked recoveries (81-105%), reproducibility (RSD: 1-6%), and application to 25 real urine samples from breast cancer positive and negative samples through a double-blind study. The proposed technique was finally compared directly with a previously reported CE-LIF technique, concluding that additional or alternative renal dilution factors are needed for proper investigation of urinary pteridines as breast cancer biomarkers.
authors.affiliation: Department of Chemistry and Center for Biomedical Science & Engineering, Missouri University of Science and Technology , 400 West 11th Street, Rolla, Missouri 65409, United States.
authors.forename: Casey
authors.initials: C
authors.lastname: Burton
authors.forename: Honglan
authors.initials: H
authors.lastname: Shi
authors.forename: Yinfa
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000652:urine*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003404:Creatinine / Q000652:urine*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011621:Pteridines / Q000652:urine*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D014408:Biomarkers, Tumor; D011621:Pteridines; D003404:Creatinine