Abstract A35: Resistant starch inhibition of azoxymethane-induced preneoplastic lesions with and without antibiotic treatment

Abstract

Abstract Colorectal cancer is one of the more prevalent cancers in Western cultures, and previous studies suggest an interaction between diet and colon carcinogenesis. Starches have been modified to be more indigestible. This allows the starch to continue through the digestive tract to the colon where it is fermented by the gut microflora to produce short chain fatty acids (SCFA). SCFA are beneficial to colon health due to their ability to regulate anti-inflammation and apoptotic pathways and inhibit colonic preneoplastic lesions such as aberrant crypt foci (ACF) and mucin depleted foci (MDF), two common lesions associated with colon cancer. By adding an antibiotic regimen, a stronger pressure will be placed on the gut microflora and this added pressure of an altered gut microflora is believed to negate the protective effects of resistant starches. Preneoplastic lesions were induced in rats with azoxymethane (AOM), a known colon cancer carcinogen, with saline used as a control. An antibiotic cocktail of vancomycin and imipenem was administered via drinking water to select groups for three days following AOM treatment. The rats were then fed experimental diets containing either control starch (CS) or high amylose-lipid complexed resistant starch (RS5) for ten weeks. Distal colon sections were collected and stained to observe ACF and MDF. There was no significant difference in ACF numbers between the CS and RS5 diet groups but there was a significant difference between the numbers of MDF observed between the two diets, with the CS rats producing more MDF than RS5 rats. A significant antibiotic effect was also observed between the two diet groups with all RS5 rats producing zero MDF and the CS treatment animals producing between 0.2-1.8 MDF. This result could indicate that RS5 does indeed retain its protective effects with an altered gut microflora. This result could also suggest that MDF may not be a suitable lesion for colon cancer studies as the highest number of MDF were observed in saline treated animals. The deliberate addition of antibiotics was a novel approach in the colon carcinogenesis-diet interaction, but the results suggest that repeated experimentation is needed to confirm the retained protective effects of resistant starch diets. Citation Format: Bridget Nelson, Yongfeng Ai, Carter Roberts, Peng Liu, Jay-lin Jane, Diane Birt. Resistant starch inhibition of azoxymethane-induced preneoplastic lesions with and without antibiotic treatment. [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 A35.