Abstract 3560: Application of metabolomics to assess serum profiles in limonene-treated breast cancer patients

Abstract

Abstract Background. Limonene is a highly lipophilic monoterpene found in citrus peel that has demonstrated anticancer effects in preclinical models. Limonene likely affects multiple targets with varying potency. Advanced techniques to obtain metabolomic profiles from biofluids have the potential to provide a non-invasive means to assess these multiple effects. This strategy was applied to a clinical trial with women with early stage breast cancer receiving limonene treatment. Methods. Forty women with stage 0 - 2 breast cancer received 2 g QD limonene daily for 2 - 6 weeks (21.5 + 8.8 days) before scheduled surgical resection of their tumor. Pre/post intervention blood draws were taken for metabolomics analysis. Metabolomics profiling was conducted using ultra performance liquid chromatography tandem time-of-flight mass spectrometry (UPLC-QToF). Chromatographic separation was achieved using a gradient of two mobile phases; A: 0.1% formic acid in water, and B: 0.1% formic acid in methanol with a flow rate of 0.4 mL/min. A Waters Aquity UltraPerformance LC HSS T3 column was used. Metabolomics data was preprocessed with XCMS. Preliminary metabolite identification was conducted by mining the Human Metabolome Database (HMDB). Results. Over 1,000 metabolite features were identified by metabolomic profiling. In negative ion mode, three metabolites exhibited a 48-fold change or higher from pre to post-intervention; 183.1 m/z at 9.4 min, 177.0 m/z at 10.0 min, and 345.1 m/z 8.9 min (P's<0.001). Two distinct peaks with m/z of 103.0 elute at 1.9 and 2.25 minutes respectively and changed >20% (P's<0.05). Twenty potential metabolites were identified in positive ion mode with >20% change by the intervention (P's< 0.05), of these, two exhibited 10-fold change or higher; 312.2 m/z at 8.7 min, and 369.2 m/z at 9.0 min (P's<0.001). Discussion. This study demonstrates that 2 g QD daily oral limonene results in significant changes in approximately 20 metabolites in serum. Candidate compounds include limonene metabolites, carnitines and end products of arachindonic acid metabolism. Efforts are ongoing to identify these metabolites for analyte specific verification and quantitation. Further clinical trials with limonene are necessary to establish its potential role as a chemopreventive agent in breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3560. doi:1538-7445.AM2012-3560