Cox-2 expression, PGE(2) and cytokines production are inhibited by endogenously synthesized n-3 PUFAs in inflamed colon of fat-1 mice.

There is great interest in the role of polyunsaturated fatty acids (PUFAs) in promoting (n-6 class) or inhibiting (n-3 class) inflammation. Mammalian cells are devoid of desaturase that converts n-6 to n-3 PUFAs. Consequently, essential n-3 fatty acids must be supplied with the diet.

Dietary calcium and cholecalciferol modulate cyclin D1 expression, apoptosis, and tumorigenesis in intestine of adenomatous polyposis coli1638N/+ mice.

Both epidemiological and experimental findings have indicated that components of Western diets influence colonic tumorigenesis. Among dietary constituents, calcium and cholecalciferol have emerged as promising chemopreventive agents. We have demonstrated that a Western-style diet (WD) with low levels of calcium and cholecalciferol and high levels of (n-6) PUFA, increased the incidence of neoplasia in mouse intestine compared with a standard AIN-76A diet; models included wild-type mice and mice with targeted mutations.

Peroxisome proliferator-activated receptor gamma agonist troglitazone induces colon tumors in normal C57BL/6J mice and enhances colonic carcinogenesis in Apc1638 N/+ Mlh1+/- double mutant mice.

The role of the nuclear peroxisome proliferator-activated receptor-gamma (PPAR-gamma) in colon tumorigenesis remains controversial. Notwithstanding evidence that PPAR-gamma ligands impede murine colorectal carcinogenesis, PPAR-gamma agonists have been shown to enhance in vivo tumor formation in mouse models of human colon cancer. Our study was designed to determine whether troglitazone (TGZ) induces colonic tumor formation in normal C57BL/6J mice and enhances colorectal carcinogenesis in double mutant Apc1638N/+ Mlh1+/- mice fed a standard AIN-76A diet.

Mouse models of gastrointestinal tumorigenesis for dietary cancer prevention studies.

Mouse models have been generated to help identify dietary components that are protective against gastrointestinal tumorigenesis. Some of the models are produced by gene-targeting procedures, whereas others use the normal mouse as an experimental animal. These preclinical mouse models have provided valuable information on the chemopreventive efficacy of specific nutrients greatly enhancing our understanding of the molecular mechanisms involved in gastrointestinal tumorigenesis.

Chemoprevention of colon cancer by calcium, vitamin D and folate: molecular mechanisms.

Recent findings have indicated that dietary calcium, vitamin D and folate can modulate and inhibit colon carcinogenesis. Supporting evidence has been obtained from a wide variety of preclinical experimental studies, epidemiological findings and a few human clinical trials. Important molecular events and cellular actions of these micronutrients that contribute to their tumour-modulating effects are discussed.

Migrating colonic crypt epithelial cells: primary targets for transformation.

It is widely believed that stem cells are the relevant target cells for colonic cell transformation. Evidence is presented that a proliferative transit daughter cell acquiring a mutant adenomatous polyposis coli gene during upward migration from the crypt base can develop retention abnormalities and permanence in the crypt, thus qualifying as a transformed clone which is retained in the colonic epithelium.