Progesterone and transforming growth factor-beta coordinately regulate suppression of endometrial matrix metalloproteinases in a model of experimental endometriosis.

Endometriosis is a benign, though aggressive, disease of the female reproductive tract that consists of endometrial stromal and epithelial cells growing at an extrauterine site. Although it is widely accepted that the majority of cases of endometriosis result from the ectopic implantation of refluxed menstrual tissue, the precise mechanisms by which this disease becomes established are not well understood. Matrix metalloproteinases (MMPs), enzymes which are important for extracellular matrix turnover, have recently been implicated in the development of endometriosis. MMPs appear to be overexpressed in endometriotic lesions, but expression levels decrease following successful medical therapy. Intriguingly, although transforming growth factor-beta (TGF-beta) mediates progesterone suppression of specific endometrial MMPs, this growth factor is overexpressed in women with endometriosis. In the current study, we used an established experimental model of endometriosis to explore MMP regulation by TGF-beta. Our findings indicate that blocking the action of TGF-beta opposes progesterone-mediated suppression of MMPs and blocks the ability of this steroid to prevent experimental endometriosis. However, we also show that the action of TGF-beta does not lead to a sustained suppression of MMPs as observed following progesterone treatment. Taken together, our data suggest that in the absence of a normal progesterone response, common in ectopic lesions of endometriosis, sensitivity to TGF-beta may be altered, resulting in a failure to regulate MMPs.

Suppression of matrix metalloproteinases inhibits establishment of ectopic lesions by human endometrium in nude mice.

Matrix metalloproteinases of the stromelysin family are expressed in the human endometrium as a consequence of cellular events during the menstrual cycle that require extracellular matrix remodeling. We have recently documented the presence of these enzymes in lesions of endometriosis, a benign disease that presents as persistent ectopic sites of endometrial tissue, usually within the peritoneal cavity. Endometriosis can develop after retrograde menstruation of endometrial tissue fragments, and establishment of ectopic sites within the peritoneal cavity requires breakdown of extracellular matrix. To examine whether matrix metalloproteinases might contribute to the steroid-dependent epidemiology and cellular pathophysiology of endometriosis, we have developed an experimental model of endometriosis using athymic nude mice as recipients of human endometrial tissue. Our results demonstrate that estrogen treatment of human endometrial tissue in organ culture maintains secretion of matrix metalloproteinases, and promotes establishment of ectopic peritoneal lesions when injected into recipient animals. In contrast, suppressing metalloproteinase secretion in vitro with progesterone treatment, or blocking enzyme activity with a natural inhibitor of metalloproteinases, inhibits the formation of ectopic lesions in this experimental model.

Stromal-epithelial interaction mediates steroidal regulation of metalloproteinase expression in human endometrium.

The hallmark of the menstrual cycle is extensive steroid-dependent tissue turnover. Estrogen mediates endometrial cell growth and structural remodeling, whereas progesterone suppresses estrogen-dependent proliferation and promotes cellular differentiation. In nonfertile cycles, tissue degradation and menstruation occur as a consequence of steroidal deprivation as the ovarian corpus luteum fails. Stromal-epithelial interactions are recognized as a necessary component in mediating steroid-induced endometrial turnover. Specific mRNAs for metalloproteinases of the stromelysin family are expressed during endometrial growth and menstrual breakdown but are absent in the progestin-dominated secretory phase. This expression pattern suggests involvement of stromelysins in remodeling the extracellular matrix of the endometrium during tissue growth and breakdown and implicates progesterone in the suppression of these enzymes. We examined the regulation of endometrial stromelysins in explant cultures and found no acute effect of estradiol on their expression, whereas progesterone was a potent inhibitor of stromelysin expression. Progesterone also suppressed stromelysin expression in cultures of isolated stromal cells, but epithelial cells were progesterone insensitive. Coculture of recombined stromal and epithelial cells restored steroidal suppression of the epithelial-specific metalloproteinase. Our data confirm that progesterone inhibits endometrial stromelysins and further demonstrate the necessity for a stromal-derived factor(s) as a mediator of steroid suppression of an epithelial metalloproteinase.

Patterns of matrix metalloproteinase expression in cycling endometrium imply differential functions and regulation by steroid hormones.

Matrix metalloproteinases are a highly regulated family of enzymes, that together can degrade most components of the extracellular matrix. These proteins are active in normal and pathological processes involving tissue remodeling; however, their sites of synthesis and specific roles are poorly understood. Using in situ hybridization, we determined cellular distributions of matrix metalloproteinases and tissue inhibitor of metalloproteinase-1, an inhibitor of matrix metalloproteinases, in endometrium during the reproductive cycle. The mRNAs for all the metalloproteinases were detected in menstrual endometrium, but with different tissue distributions. The mRNA for matrilysin was localized to epithelium, while the others were detected in stromal cells. Only the transcripts for the 72-kD gelatinase and tissue inhibitor of metalloproteinases-1 were detected throughout the cycle. Transcripts for stromelysin-2 and the 92-kD gelatinase were only detected in late secretory and menstrual endometrium, while those for matrilysin, the 72-kD gelatinase, and stromelysin-3 were also consistently detected in proliferative endometrium. These data indicate that matrix metalloproteinases are expressed in cell-type, tissue, and reproductive cycle-specific patterns, consistent with regulation by steroid hormones, and with specific roles in the complex tissue growth and remodeling processes occurring in the endometrium during the reproductive cycle.

Expression and localization of matrilysin, a matrix metalloproteinase, in human endometrium during the reproductive cycle.

OBJECTIVE: We studied the expression of a matrix metalloproteinase, matrilysin, in the human endometrium to determine whether metalloproteinase genes are expressed during the reproductive cycle. Matrix metalloproteinases are a tightly regulated family of enzymes that degrade components of the extracellular matrix and basement membrane; they play important roles in growth and development and in invasion and metastasis of tumors and thus are likely enzymes participating in the dynamic structural changes occurring in endometrium during the reproductive cycle. STUDY DESIGN: In situ and Northern nucleic acid hybridization and immunohistochemistry were used to detect and localize matrilysin ribonucleic acid and protein in normal endometrial tissue. RESULTS: Matrilysin protein and matrilysin messenger ribonucleic acid are abundant in proliferative, late secretory, and menstrual endometrial epithelium but are not detected in early or mid secretory endometrium. CONCLUSION: The expression of the matrilysin gene is regulated in endometrium during the reproductive cycle, implying an important role for matrilysin in endometrial physiologic characteristics.

Distribution of tumor-associated glycoprotein-72 (TAG-72) expression throughout the normal female reproductive tract.

Compared with the degree of investigation of stage-specific expression of tumor-associated glycoprotein-72 (TAG-72) in fundal endometrium, other regions of the female reproductive tract have not received comparable attention. Regional, cell-type-specific, and temporal differences in estrogen receptor and progesterone receptor distribution and concentration among these tissues should make such examination beneficial to our understanding of hormonal regulation of TAG-72 expression. The pattern of monoclonal antibody (MAb) B72.3 recognition in the cervix, uterus, oviduct, and ovary was examined by immunohistochemistry during both the proliferative and secretory intervals of the normal menstrual cycle. Intense immunoreactivity in fundal endometrium was limited to the secretory menstrual interval. Conversely, TAG-72 expression was generally weaker, sporadically distributed, and not stage specific in the lower uterine segment, endocervix, and cervix; no expression was detected in the oviduct or ovary. The disparity in both temporal and spatial distribution of TAG-72 expression throughout the female reproductive tract does not appear to be directly associated with the well-described changes in circulating estradiol or progesterone or the receptors for these steroids. Results suggest that regulation of TAG-72 expression may involve local paracrine/autocrine mechanisms, which in turn may be subject to hormonal influence.

Epithelial cells from normal human endometrium express a tumor-associated glycoprotein (TAG-72) epitope in vitro.

Monoclonal antibody B72.3 identifies a tumor-associated glycoprotein (TAG-72) epitope derived from a human breast carcinoma metastasis. Recently, expression of this epitope was noted in normal endometrium during the secretory, but not proliferative, menstrual interval. In light of known hormonal control of normal endometrial growth and differentiation, we investigated in vitro expression of TAG-72 epitope in purified endometrial epithelium cultured under serum-free conditions on Matrigel biomatrix. Cells from secretory endometrium exhibited homogeneous tumor-associated glycoprotein 72 epitope expression. Unexpectedly, epithelium from the proliferative interval developed expression after 5 to 6 days of culture. Epithelial cells from both intervals maintained expression over 12 days of culture without exogenous estradiol and progesterone. Spontaneous, uniform expression of tumor-associated glycoprotein 72 epitope by normal endometrial epithelial cells in vitro is in marked contrast to the cyclic, heterogeneous expression observed in vivo. Such expression also differs from published in vitro observations of cancer cell lines that express this epitope.