Chemopreventive Effects of Edible Canna (Canna edulis Kerr.) Against Colorectal Carcinogenesis: Effects on Expression of Adenomatous Polyposis Coli and Inducible Nitric Oxide Synthase in Rat Inflammatory Model

Objective: Dietary high fibre and calcium intake has been suggested to reduce colorectal cancer risk. However, there is limited information available regarding the potential of edible canna (Ganyong), with high dietary fibre and calcium content, to act as a preventive agent for colorectal cancer. This experimental study was conducted to investigate the preventive effect of Ganyong in reducing colorectal carcinogenesis with attention to effects on adenomatous polyposis coli (APC) and inducible nitric oxide synthase (iNOS) expression. Methods: Thirty male Wistar rats were divided into 5 equal groups; a normal control group without azoxymethane/dextran sodium sulphate (AOM/DSS) induction and Ganyong, a ‘cancer’ control group with AOM/DSS induction only, and three treatment groups with AOM/DSS induction and different percentages (5%, 10% and 20%) of Ganyong. Paraffin-embedded sections of rat colon tissue were analysed by haematoxylin-eosin and immunohistochemical staining against antibodies against APC and iNOS. Variation in rates of APC and iNOS expression were analyzed using the Kruskal-Wallis test followed by the Dunn’s test (SPSS statistic version 24). P<0.05 was considered statistically significant. Results: AOM/DSS induction increased the expression of APC (p=0.013) and iNOS (p=0.013) compared to the normal control group. APC expression in the treated groups was lower than in the ‘cancer’ control group (p=0.049), especially in the 10% Ganyong group (p=0.02). In contrast, there was no significant variation among the treated groups regarding iNOS expression. Histopathological features of the colon supported the data for APC and iNOS expression. Conclusion: This study indicated potential chemopreventive effects of Ganyong reducing expression of factors contributing to colorectal carcinogenesis.