title: Estrogen receptor beta deficiency enhances small intestinal tumorigenesis in ApcMin/+ mice.
abstract: Clinical evidence suggests that estradiol replacement therapy reduces colon cancer risk in 'post'menopausal women. In colon epithelial cells, the estrogen receptor beta (ERbeta) is the predominant ER subtype and is thought to mediate the genomic effect of estrogens. The first aim of this study was to investigate the consequence of ERbeta deficiency on intestinal tumorigenesis in the Apc(Min/+) mouse model. Furthermore, to explore the biological mechanisms by which estrogens may influence the pathogenesis of colorectal cancer, we performed gene expression profiles in colonocytes from ovariectomized wild-type (WT) vs. ERbeta(-/-) mice, treated with estradiol (E(2)) or vehicle. Specifically in female, ERbeta deficiency was found to be associated with higher adenoma multiplicity in the small intestine, but not in the colon. Furthermore, tumors from ERbeta(-/-)Apc(Min/+) female mice were on average significantly larger than those from control Apc(Min/+) mice. Higher steady-state proliferation in epithelial cells of the jejunum and colon from ERbeta(-/-)Apc(Min/+) vs. Apc(Min/+) female mice was confirmed by BrdU incorporation assay. Interestingly, functional categorization of microarray results revealed the TGFbeta signaling pathway to be modulated in colonocytes, especially for the WT + E(2) vs. WT + Vehicle and the ERbeta(-/-) + E(2) vs. WT + E(2) comparisons. Using quantitative PCR analysis, we observed transcripts from ligands of the TGFbeta pathway to be upregulated in colonocytes from E(2)-treated WT and ERbeta(-/-) mice and downregulated in ERbeta-deficient mice, mostly in an E(2)-independent manner. Therefore, our results demonstrate that ERbeta deficiency enhances small intestinal tumorigenesis and suggest that modulation of the TGFbeta signaling pathway could contribute to the protective role of estrogens on intestinal tumorigenesis.
authors.affiliation: Service de gastroentérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Département d'anatomie et de biologie cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Equipe IRSC sur l'épithélium digestif, Sherbrooke, QC, Canada.
authors.forename: Véronique
authors.initials: V
authors.lastname: Giroux
authors.affiliation: Service de gastroentérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lemay
authors.affiliation: Service de gastroentérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Département d'anatomie et de biologie cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Equipe IRSC sur l'épithélium digestif, Sherbrooke, QC, Canada.
authors.forename: Gérald
authors.initials: G
authors.lastname: Bernatchez
authors.affiliation: Service de gastroentérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Département d'anatomie et de biologie cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Equipe IRSC sur l'épithélium digestif, Sherbrooke, QC, Canada.
authors.forename: Yolaine
authors.initials: Y
authors.lastname: Robitaille
authors.affiliation: Service de gastroentérologie, Département de médecine, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Département d'anatomie et de biologie cellulaire, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, QC, Canada.|Equipe IRSC sur l'épithélium digestif, Sherbrooke, QC, Canada.
authors.forename: Julie C
authors.initials: JC
authors.lastname: Carrier
mesh_terms: D000236:Adenoma / Q000209:etiology / Q000378:metabolism*; D000818:Animals; D001973:Bromodeoxyuridine; D003110:Colonic Neoplasms / Q000378:metabolism; D004195:Disease Models, Animal; D047629:Estrogen Receptor beta / Q000172:deficiency* / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D007414:Intestinal Neoplasms / Q000209:etiology / Q000378:metabolism*; D007421:Intestine, Small; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D020411:Oligonucleotide Array Sequence Analysis; D010052:Ovariectomy; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D047629:Estrogen Receptor beta; D016212:Transforming Growth Factor beta; D001973:Bromodeoxyuridine