Regulation of Cyclooxygenase-2 by Environmental and Dietary Factors

Persistent Link:
http://hdl.handle.net/10150/195632
Title:
Regulation of Cyclooxygenase-2 by Environmental and Dietary Factors
Author:
Degner, Stephanie C
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Each year over 260,000 new cases of breast cancer will be diagnosed in the U.S. and approximately 40,000 women will die of metastatic breast cancer. The etiology of breast cancer is poorly understood and only 5 -10% of cases can be attributed to genetic factors. This suggests that the development of breast cancer may involve environmental factors including diet, lifestyle, and exposure to chemicals. Several lines of experimental and epidemiological evidence have highlighted COX-2 as a potential target for breast cancer prevention. The central hypothesis of this proposal is that activation of COX-2 transcription by epigenetic effectors can be prevented by dietary agents that target the activator protein-1 (AP-1) transcription factor and the aromatic hydrocarbon receptor (AhR). The first specific aim was to determine the mechanism through which conjugated linoleic acid (CLA) and rosmarinic acid (RA) inhibit TPA-induced COX-2 trancription. These studies documented that CLA and RA repressed COX-2 transcription by antagonizing the AP-1 transcription factor. The second specific aim was to investigate whether or not the AhR plays a role in TCDD-induced COX-2 transcription and effects of chemopreventive agents. Results indicated that AhR agonists induced the binding of the AhR to COX-2 and was prevented by CLA and the AhR antagonist, resveratrol (RES) and 3-methoxy-4-nitroflavone (3M4NF). The third specific aim was to examine the effects of AhR agonists and dietary selective AhR modulators on chromatin modifications associated with the COX-2 promoter. Chromatin immunoprecipitation (ChIP) assays revealed that the AhR is recruited to the region of the COX-2 promoter containing a xenobiotic response element and accompanied by recruitment of p300 and acetylation of histone H4. Transcriptional regulation of COX-2 by AhR agonists and dietary antagonists may also involve other post-transcriptional modifications of histones, which along with chromatin remodeling factors modulate the structure of chromatin and recruitment of RNA polymerase II. Overall, the results demonstrated that COX-2 transcription can be targeted by a variety of dietary agents that act through different mechanisms. Therefore, inhibition of transcriptional regulation of COX-2 by selected dietary factors may be a breast cancer preventive strategy that bypasses the side effects of drugs that target COX-2.
Type:
text; Electronic Dissertation
Keywords:
Cyclooxygenase-2; breast cancer; chromatin; aromatic hydrocarbon receptor
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Nutritional Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Romagnolo, Donato F.
Committee Chair:
Romagnolo, Donato F.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleRegulation of Cyclooxygenase-2 by Environmental and Dietary Factorsen_US
dc.creatorDegner, Stephanie Cen_US
dc.contributor.authorDegner, Stephanie Cen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractEach year over 260,000 new cases of breast cancer will be diagnosed in the U.S. and approximately 40,000 women will die of metastatic breast cancer. The etiology of breast cancer is poorly understood and only 5 -10% of cases can be attributed to genetic factors. This suggests that the development of breast cancer may involve environmental factors including diet, lifestyle, and exposure to chemicals. Several lines of experimental and epidemiological evidence have highlighted COX-2 as a potential target for breast cancer prevention. The central hypothesis of this proposal is that activation of COX-2 transcription by epigenetic effectors can be prevented by dietary agents that target the activator protein-1 (AP-1) transcription factor and the aromatic hydrocarbon receptor (AhR). The first specific aim was to determine the mechanism through which conjugated linoleic acid (CLA) and rosmarinic acid (RA) inhibit TPA-induced COX-2 trancription. These studies documented that CLA and RA repressed COX-2 transcription by antagonizing the AP-1 transcription factor. The second specific aim was to investigate whether or not the AhR plays a role in TCDD-induced COX-2 transcription and effects of chemopreventive agents. Results indicated that AhR agonists induced the binding of the AhR to COX-2 and was prevented by CLA and the AhR antagonist, resveratrol (RES) and 3-methoxy-4-nitroflavone (3M4NF). The third specific aim was to examine the effects of AhR agonists and dietary selective AhR modulators on chromatin modifications associated with the COX-2 promoter. Chromatin immunoprecipitation (ChIP) assays revealed that the AhR is recruited to the region of the COX-2 promoter containing a xenobiotic response element and accompanied by recruitment of p300 and acetylation of histone H4. Transcriptional regulation of COX-2 by AhR agonists and dietary antagonists may also involve other post-transcriptional modifications of histones, which along with chromatin remodeling factors modulate the structure of chromatin and recruitment of RNA polymerase II. Overall, the results demonstrated that COX-2 transcription can be targeted by a variety of dietary agents that act through different mechanisms. Therefore, inhibition of transcriptional regulation of COX-2 by selected dietary factors may be a breast cancer preventive strategy that bypasses the side effects of drugs that target COX-2.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectCyclooxygenase-2en_US
dc.subjectbreast canceren_US
dc.subjectchromatinen_US
dc.subjectaromatic hydrocarbon receptoren_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineNutritional Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorRomagnolo, Donato F.en_US
dc.contributor.chairRomagnolo, Donato F.en_US
dc.contributor.committeememberBloom, Johnen_US
dc.contributor.committeememberBowden, G. Timothyen_US
dc.contributor.committeememberHowell, Wandaen_US
dc.contributor.committeememberLau, Serrineen_US
dc.identifier.proquest2505en_US
dc.identifier.oclc659748411en_US
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