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Extramural Research

Final Report: Dioxin and Steroid Regulation in an Endometriosis Model

EPA Grant Number: R826300
Title: Dioxin and Steroid Regulation in an Endometriosis Model
Investigators: Osteen, Kevin G.
Institution: Vanderbilt University School of Medicine
EPA Project Officer: Deener, Kacee
Project Period: December 15, 1997 through December 14, 2000
Project Amount: $381,404
RFA: Endocrine Disruptors (1997)
Research Category: Economics and Decision Sciences , Endocrine Disruptors

Description:

Objective:

Endometriosis is a persistent, steroid-mediated disease which develops in 10-15 percent of women in industrialized nations, most often from the ectopic implantation of endometrial fragments which enter the peritoneum by retrograde menstruation. The environmental contaminant, 2,3,7,8-tetrachlorobenzo-p-dioxin (TCDD or dioxin) has been shown by numerous laboratories to disrupt estrogen action in reproductive tissues. This environmental agent also has been linked to the development of endometriosis in primates, however, this observation appears to be in conflict with TCDD's known anti-estrogenic effects and the association of environmental exposures to the development of endometriosis in humans remains uncertain. Since clear epidemiological information in exposed human populations is difficult to obtain, we have attempted to examine the action of TCDD on specific cellular behaviors linked to the pathophysiology of endometriosis. The long-term objectives of our research grant is to identify specific cellular and/or molecular mechanisms which may link TCDD exposure to endometriosis in a more demonstrative manner. Our preliminary data suggested to us that, as a consequence of TCDD exposure, progesterone-mediated regulation of matrix metalloproteinase (MMP) expression may be disrupted in organ cultures of human endometrium. We have previously demonstrated that endometrial MMPs are necessary for mediating the extensive tissue turnover that is a component of the normal menstrual cycle. Unfortunately, the expression of these enzymes also may provide the necessary matrix breakdown that allows endometrial fragments to penetrate the peritoneal wall during establishment of endometriosis. Our laboratory has demonstrated that blocking the expression or action of these enzymes can prevent the ectopic implantation of human endometrial tissue in an experimental model of endometriosis in nude mice.

Although TCDD clearly has an impact on endometrial tissue function via interference or modulation of estrogen action, the ability of this agent to impact progesterone action is less understood. More specifically, our grant seeks to determine if TCDD can interfere with progesterone-mediated MMP regulation via modulation of local endometrial factors. Additionally, we seek to determine if this interference plays a role in the establishment or progression of experimental endometriosis. The project is divided into three specific objectives representing the different elements of our overall goals. The first objective will determine the expression pattern of several cell specific MMPs in endometriotic lesions obtained from women versus experimental endometriosis. The second objective is designed to determine the most relevant cell-specific mechanisms by which TCDD can disrupt progesterone-mediated regulation of endometrial MMPs. Although we have not identified specific actions of estradiol on MMP gene expression, blocking the action of progesterone would prevent the important suppressive role progesterone normally plays in the regulation of these enzymes during the menstrual cycle. The third objective investigates the role of TCDD in altering cell-type specific response of endometrial cells to local immune cytokines which also can interfere with progesterone action and perhaps overstimulate endometrial MMP expression in the inflammatory-like environment within the peritoneal cavity.

Summary/Accomplishments (Outputs/Outcomes):

Analysis of In Vivo MMP Expression Patterns. During the first 2 years of studies, we identified by in situ hybridization a highly variable expression pattern of MMP-3, MMP-7, and MMP-11 mRNA in endometriotic lesions obtained from different ectopic sites of disease growth. Although progesterone is normally a potent suppressor of cell-specific mRNAs for either MMP-3, MMP-7, or MMP-11, expression of each gene as well as protein secretion in vitro was significantly increased in endometriosis tissues compared to our normal donor population. Although, we have not yet determined the reason that MMP expression is altered in endometriosis, this finding is similar to our observations in normal endometrium, treated in vitro with TCDD.

Cellular Mechanisms of TCDD Action. Preliminary observations indicate that exposing human endometrial organ cultures to TCDD can prevent progesterone suppression of MMP-3 or MMP-7, which occurs in vivo during the progesterone-dominated secretory phase of the menstrual cycle. Since progesterone suppression of MMPs may be critical to prevention of experimental endometriosis, we need to ascertain the specific cellular mechanism by which TCDD prevents progesterone suppression of MMPs. We know that progesterone induction of TGF- 2 is a critical factor in the pathway by which progesterone mediates suppression of MMP-7 expression and that blocking this growth factor also will impact patterns of MMP-3 expression. During the first year of the grant, we demonstrated that TCDD exposure prevented the increase in endometrial TGF- 2 protein expression which normally follows exposure to progesterone. In the second year, we demonstrated that TCDD inhibition of TGF- 2 occurs at the level of the gene, as the progesterone associated increase in TGF- 2 mRNA also is blocked. The ability of TCDD to prevent progesterone induction of TGF- 2 may be a critical component of this toxin's ability to alter the normal pathway by which progesterone regulates MMP expression. In the last 2 years of the grant, we have explored in more depth the mechanisms by which progesterone regulates TGF- 2 expression, since this gene does not contain a known progesterone response element.

Molecular Mechanisms of TCDD Action. To investigate the effects of TCDD on endometrial cells, we have obtained expression vectors for the human Ah receptor and human Arnt. We have begun studies to test the effects of AhR and/or Arnt expression on the activity of a progesterone responsive promoter. At this time, we have demonstrated that AhR is present in stromal cells maintained with progesterone, but have not determined if progesterone or decidualization plays a role in AhR regulation. In a second line of experiments, we are investigating the effect of TCDD exposure on endometrial stromal cell expression of progesterone receptor A and B (PR-A, PR-B). Since we have demonstrated that TCDD blocks progesterone induced TGF-?2 expression, it is important to determine at which level of regulation this is occurring. It is possible that TCDD simply downregulates PR expression or alters the ratio between PR-A and PR-B.


Journal Articles on this Report : 7 Displayed | Download in RIS Format

Other project views: All 15 publications 9 publications in selected types All 7 journal articles

Type Citation Project Document Sources
Journal Article Bofinger DP, Feng L, Chi LH, Love J, Stephen FD, Sutter TR, Osteen KG, Costich TG, Batt RE, Koury ST, Olson JR. Effect of TCDD exposure on CYP1A1 and CYP1B1 expression in explant cultures of human endometrium. Toxicological Sciences 2001;62(2):299-314. R826300 (Final)
not available
Journal Article Bruner KL, Etsenberg E, Gorstein F, Osteen KG. Progesterone and transforming growth factor-β coordinately regulate suppression of endometrial matrix metalloproteinases in a model of experimental endometriosis. Steroids 1999;64(9):648-653 R826300 (1999)
R826300 (Final)
not available
Journal Article Bruner-Tran KL, Eisenberg E, Yeaman GR, Anderson TA, McBean J, Osteen KG. Steroid and cytokine regulation of matrix metalloproteinase expression in endometriosis and the establishment of experimental endometriosis in nude mice. Journal of Clinical Endocrinology and Metabolism 2002;87(10):4782-4791. R826300 (Final)
not available
Journal Article Bruner-Tran KL, Rier SE, Eisenberg E, Osteen KG. The potential role of environmental toxins in the pathophysiology of endometriosis. Obstetric and Gynecologic Investigation 1999;48:45-56. R826300 (1999)
R826300 (Final)
not available
Journal Article Curry TE, Osteen KG. Cyclic changes in the matrix metalloproteinase system in the ovary and uterus. Biology of Reproduction 2001;64(5):1285-1296. R826300 (Final)
not available
Journal Article Igarashi TM, Bruner-Tran KL, Yeaman GR, Lessey BA, Edwards DP, Eisenberg E, Osteen KG. Reduced expression of progesteron receptor-B in the endometrium of women with endometriosis and in cocultures of endometrial cells exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Fertility and Sterility 2005;84(1):67-74 R826300 (Final)
not available
Journal Article Osteen KG, Keller NR, Feltus FA, Melner MH. Paracrine regulation of matrix metalloproteinase expression in the normal human endometrium. Gynecologic and Obstetric Investigation 1999;48(Suppl 1):2-8. R826300 (1999)
R826300 (Final)
not available
Supplemental Keywords:

dioxin, TCDD, progesterone action, animal model., RFA, Health, Scientific Discipline, Toxics, Environmental Chemistry, Health Risk Assessment, pesticides, Endocrine Disruptors - Environmental Exposure & Risk, endocrine disruptors, Risk Assessments, Children's Health, Biology, Endocrine Disruptors - Human Health, adverse outcomes, TCDD, dose response, steroid, enzymes, 2, 3, 7, 8-Tetrachloro-dibenzo-p-dioxin (TCDD), animal models, human exposure, toxicity, biochemistry, biological effects, dioxins, endometriosis, chlorinated phenols, ectopic growth, ovary

Progress and Final Reports:
Original Abstract
1999 Progress Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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