Bioactive Food Compounds with Cancer Preventing Effects in the Colon Focus on Ferulic Acid, para-Coumaric Acid and Lactoferricin

Sammanfattning: Colorectal cancers are globally ranked as the third most common cancer form in terms of incidence and mortality. Diet has long been considered as one of the main factors affecting population outcome regarding development of cancer in the colon. Numerous epidemiological studies have found links between consumption of dietary fibres and milk and reduced risk of cancers including colon cancer. To be able to understand the full extent of the impact of certain foods and diets on public health, it is important to focus on mechanistic effects exerted by single food compounds. This study concerns the effects of the three food compounds, ferulic acid (FA), para-coumaric acid (p-CA) and lactoferricin on colon. The dietary fibres from cereals, fruits and vegetables are rich sources of the phenolic compounds FA and p-CA. Lactoferricin is a peptide derived from the milk protein lactoferrin. The overall objective of this project was to develop an extended knowledge about the mechanisms of the action of FA, p-CA and lactoferricin in the colon with specific emphasis on colon cancer cells. To that end, the study was performed with the colon cancer-derived cell line Caco-2. The main emphasis was on processes related to cell proliferation, as alterations in cell proliferation are essential in cancer prevention and cancer therapy. The Caco-2 cells were treated with physiologically relevant concentrations of FA, p-CA or lactoferricin based on food content of the compounds and consumption. The main methods used were MTT and AlamarBlue assays for analysis of metabolic activity, flow cytometry for analysis of cell cycle phase distribution and cell cycle kinetics, microarray assay for analysis of global gene expression and Western blot for protein detection. The results showed that all three compounds reduced cell proliferation of Caco-2 cells caused by increased cell cycle duration. Specifically, FA treatment induced a delay in the S phase and affected genes that regulate centrosome assembly and the S phase DNA damage checkpoints such as CEP2, CETN3 and RABGAP1. p-CA treatment induced a delay in the G2/M phase and affected genes in the cell cycle regulating system including MYC, CDKN1A, PCNA, CDC25A, ODC1, CCNA2 and CCNB1. Lactoferricin treatment induced a delay in the S phase and affected cyclin E1 protein expression. A daily dose of one or more compounds over a long time span, years and decades, that decreases the number of total cell divisions substantially, may reduce the overall risk of cancer development. This is probably the most important message in this study to be carried along for the future.