Abstract 656: High resolution metabolomics of aspirin treatment in colon tissue and adenoma risk: Results from a randomized clinical trial
Authors: Barry Elizabeth L. , Uppal Karan , Ma Chunyu , Jones Dean P. , Baron John A. , Fedirko Veronika 
Published: August 2019

Abstract
Although substantial evidence from cell and animal studies, epidemiological studies, and clinical trials supports the chemopreventive effects of aspirin, especially for colorectal cancer, the molecular mechanisms are uncertain. Aspirin incorporates two bioactive components in one molecule, a reactive acetyl moiety and a salicylate group, and is well known for its pleotropic effects. Its best-characterized pharmacologic activity is the irreversible acetylation of the cyclooxygenases (COX-1 and COX-2). However, there is evidence for numerous COX-independent mechanisms that could also modify colorectal carcinogenesis. This study applied an untargeted, discovery-based approach (metabolomics) to elucidate the effects of aspirin on low molecular weight molecules in human colon tissue and assess their impact on colorectal carcinogenesis. We utilized normal mucosal tissue biopsies collected at colonoscopy after about 3 years of treatment from a sub-set of N=325 participants in the Aspirin/Folate Polyp Prevention Study, a randomized, placebo-controlled trial of aspirin (81 or 325 mg/day) for the prevention of colorectal adenomas. The global metabolic effects of aspirin were assessed using a high-resolution Thermo Fusion mass spectrometer coupled with dual chromatography and dual ionization (HILIC positive and C18 negative electrospray ionization). Multivariable linear regression was used to identify metabolic features associated with aspirin treatment adjusting for age, sex and race. Multivariable Poisson regression was used to assess associations with adenoma outcomes of metabolic features associated with aspirin treatment. Products of aspirin metabolism (salicylate, salicyluric acid) were identified and statistically significantly increased in post treatment compared to baseline plasma samples confirming aspirin treatment status. After quality control exclusions, N=4,879 and N=5,390 features were included in analyses from the C18 and HILIC columns, respectively, of which N=244 and N=222 were associated with aspirin treatment at a raw P&lt;0.05. At the pathway level, aspirin treatment was most strongly associated with perturbations in prostaglandin/arachidonic acid metabolism and the carnitine shuttle, which is involved in energy metabolism from fatty acids. At the metabolite level, only one feature (tentatively identified as a pterosin compound) was statistically significantly associated with aspirin treatment after FDR adjustment, but it was not associated with adenoma risk. Top features associated with aspirin treatment that were associated with adenoma outcomes included creatinine but are mostly of unknown identity at this time. In conclusion, a non-targeted high-resolution metabolomics approach has the potential to identify key downstream effects of aspirin involved in colorectal chemoprevention.
Citation Format: Elizabeth L. Barry, Karan Uppal, Chunyu Ma, Dean P. Jones, John A. Baron, Veronika Fedirko. High resolution metabolomics of aspirin treatment in colon tissue and adenoma risk: Results from a randomized clinical trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 656.