Abstract A32: Chemopreventive potential of Grape Seed Extract in azoxymethane-induced colon tumorigenesis in the A/J mouse model: interlinking miRNA expression and inflammatory and cytokine signaling

Abstract

Abstract Colorectal cancer (CRC) is the second leading cause of cancer-related deaths. Overall, CRC is the third most diagnosed cancer in the United States with 150,000 new cases per year. Traditional CRC therapies are associated with severe toxicity, and therefore, natural products are appealing alternatives. Grape seed extract (GSE) is a complex polyphenolic mixture whose beneficial effects have been well documented across species and with various cancer models. Most (∼75%) of CRC develops sporadically, and diet, lifestyle, and/or environmental factors could further contribute to CRC progression. Chemoprevention utilizes an agent, natural or synthetic, to delay or stop cancer progression. Taken together the above discussion, here in we investigate chemoprevention potential of GSE against the Azoxymethane (AOM)-induced colon tumorigenesis. In our study, 6-week old A/J mice were divided into 5 groups: Group 1 received control diet, Group 2 received 0.5% GSE in diet, and the other 3 groups received i.p. injections of AOM (5mg/kg) weekly, for six weeks. Two weeks post AOM injections, one group continued on control diet and the other two groups were supplemented with 0.25% and 0.5% GSE (w/w) in diet. Animals were sacrificed at 32 and 42 weeks of age, or 20 and 30 weeks after last AOM injection. We found that GSE at 0.25% and 0.5% levels in diet did not exhibit toxic side effects with long-term treatment; and resulted in a 55% decrease in colon tumor multiplicity at 42 weeks at 0.5% dose. Furthermore, GSE treatment reduced overall tumor size; tumor burden ranging from 2-3mm was decreased by 85% in AOM-GSE-fed animals compared to control. Tissue analysis revealed GSE' mechanisms of action: apoptotic death, and decreased proliferation and inflammation. Compared to controls, colon tissue from GSE-treated mice showed a 2-fold increase in TUNEL positive apoptotic cells, 30% decrease in PCNA positive proliferative cells, and ∼50% decrease in COX2 and iNOS levels in IHC analysis. Cytokine array of colon mucosal tissue revealed that compared to controls, GSE treatment resulted in approximately a 10-fold induction of GM-CSF, I-309, IL-1α, and BLC. In addition we observed a 10-30-fold decrease of IL-2, IL-1R, and IL-27 cytokine levels after GSE treatment. miRNA analysis of colon mucosal tissue revealed upregulation of miR-19a, miR-20a, and let7a with GSE treatment; a maximum 2500-fold induction was observed with miR-19a. GSE treatment also resulted in a 10-20-fold down regulation of miR-196a, miR-21, miR-148a, and miR-103. These results are consistence with our IHC observations of altered expression and localization of downstream players. GSE treatment resulted in decreased over-all expression of p21, β-catenin, c-myc, VEGF, and ERK 1/2. Altered localization of p21, β-catenin and c-myc was observed after GSE treatment resulting in increased cytosolic expression. In conclusion, our results indicated that GSE is already consumed by humans and is a non-toxic agent that exerts strong chemopreventive effect against sporadic colorectal cancer development, through modulation of apoptosis, proliferation, and inflammation pathways. Citation Format: Molly M. Derry, Komal Raina, Velmurugan Balaiya, Anil Jain, Sangeeta Shrotriya, Rajesh Agarwal, Chapla Agarwal. Chemopreventive potential of grape seed extract in azoxymethane-induced colon tumorigenesis in the A/J mouse model: Interlinking miRNA expression and inflammatory and cytokine signaling. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A32.