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A high‐fat diet generates alterations in nuclear receptor expression: Prevention by vitamin A and links with cyclooxygenase‐2 and β‐catenin
Author(s) -
Delage Barbara,
Bairras Céline,
Buaud Benjamin,
Pallet Véronique,
Cassand Pierrette
Publication year - 2005
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.21108
Subject(s) - retinoic acid , aberrant crypt foci , endocrinology , medicine , receptor , vitamin , nuclear receptor , tretinoin , peroxisome proliferator activated receptor , downregulation and upregulation , carcinogenesis , cyclooxygenase , retinol , colorectal cancer , biology , cancer , transcription factor , biochemistry , enzyme , colonic disease , gene
Abstract Epidemiologic studies suggest that intake of high energy from fat, inducing overweight, increases the risk of cancer development and promotes colon carcinogenesis. It is therefore important to understand which parameters are affected early on by a high‐fat diet in order to devise and improve protective nutritional strategies. We investigated the effect of high energy/fat intake on colon mucosa of male Wistar rats induced by a single 1,2‐dimethylhydrazine (DMH) injection. Aberrant crypt foci (ACF) were numbered and modifications in cyclooxygenase‐2 (COX‐2) and β‐catenin levels assessed. Peroxisome proliferator– and retinoic acid–activated receptors (PPAR and RAR, RXR) are key transcription factors regulating gene expression in response to nutrient‐activated signals. A short‐term study was designed to evaluate whether alterations in mRNA expression of nuclear receptors can be detected at the beginning of the weight gain phase induced by an appetizing hyperlipidic diet (HLD). HLD consumption induced early downregulation of PPARγ (−33.1%) and RARβ (−53.1%) mRNA expression concomitant with an increase in levels of COX‐2 (+45.5%) and β‐catenin (+84.56%) and in the number of ACF (191.56 ± 88.60 vs. 21.14 ± 11.64, p < 0.05). These findings suggest that HLD increases ACF occurrence, possibly through alterations in the mRNA expression profile of nuclear receptors. Moreover, the use HLD rich in retinyl esters or supplemented with all‐ trans retinoic acid led to a reduction in the number of ACF. Vitamin A also prevented HLD‐induced alterations and the increase in levels of COX‐2 and β‐catenin. The present observations show a protective role for vitamin A against disturbances associated with HLD exposure in induced colon carcinogenesis. © 2005 Wiley‐Liss, Inc.