Da Pieve, Chiara; Moore, Sharon and Velasco, Maria
Screening for colorectal cancer risk biomarkers related to diet.
In: Nutrition, Physical Activity & Cancer Prevention: Current Challenges, New Horizons, 12-13 Sep 2010, Royal College of Physicians, London, UK.
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Background: Red and processed meat are associated with high risks of colorectal cancer due to the endogenous formation of O6-carboxymethyl guanine (O6CMG), a potent carcinogen. The aim of our research is to develop liquid chromatography tandem mass spectrometry (LC-MS/MS) analytical methods for the measurement of the DNA adducts, such as O6CMG and its nucleoside O6-carboxymethyl deoxyguanosine (O6CMdG), in urine samples and correlate it to different diets.
Methods: Urine samples were collected from volunteers on three different diets (vegetarian as the control, with red and processed meat as the experimental group) over a period of 15 days at the Medical Research Council, Cambridge. Samples were analysed by LC-MS/MS either by direct injection or using a column-switching system with an on-line solid phase extraction (SPE) column.
Results: An LC-MS/MS method was developed and used initially to monitor and quantify O6CMdG and O6CMG using standards in synthetic urine. O6CMG elutes at 4.7 min and have a limit of detection (LOD) of 0.3ng/mL, and O6CMdG elutes at 14.1 min and have a LOD of 0.03ng/mL. The LC-MS/MS direct injection analysis of the clinical samples showed low sensitivity and the need for sample clean-up.
Conclusions: An efficient method for the separation and quantification of O6CMdG and O6CMG was developed. An on-line SPE column system is under development to allow an efficient and rapid processing of a large number of clinical urine samples.
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