Endometriosis: a new cellular and molecular genetic approach for understanding the pathogenesis and evolutivity

Abstract

Endometriosis is a benign disease with high prevalence in women of reproductive age estimated between 10 and 15% and is associated with considerable morbidity. Its etiology and pathogenesis are controversial but it is believed to involve multiple genetic, environmental, immunological, angiogenic, and endocrine processes. Altered expressions of growth factors, cytokines, adhesion molecules, matrix metalloproteinases, and enzymes for estrogen synthesis and metabolism have been frequently observed in this condition. The possibility of genetic basis of endometriosis is demonstrated in studies of familial disease, in which the incidence of endometriosis is higher for first-degree relatives of probands as compared to controls. This review describes mainly the cellular, cytochemical, cytogenetic, and molecular genetic features of endometriotic lesions and cultured endometriotic cells. In attempts to identify candidate gene (s) involved in the pathogenesis of endometriosis, a tissue-based approaches including conventional cytogenetics (RHG-banding), loss of heterozygosity (LOH), and comparative genomic hybridization (CGH) were employed. In addition to the karyotypic anomalies, consistent chromosome instability was confirmed by CGH and fluorescence in situ hybridization (FISH). The nature and significance of the molecular genetic aberrations in relation to the locations and function of oncogenes and tumor suppressor genes will be discussed. At last, a possible pathogenic role of embryonic duct remnants was observed in seven female fetal reproductive tract in endometriosis and may induce a discussion about the beginning of ovarian tumors and malignant proliferations.

Keywords: chromosome; comparative genomic hybridization; embryonic duct remnants; endometriosis; fluorescence in situ hybridization; permanent cell line.

Figure 1

Phase contrast microscopy of a primary culture of a fragment from ovarian endometrioma (A). Note presence of an endometriotic gland giving rise to a monolayer of epithelial-like cells (A). In (B), aspect of elongated fibroblast-like cultured cells obtained from the stromal component of a large peritoneal endometriotic implant (B).

Figure 2

Immuno-cytochemical localization of cytokeratin (A), vimentin (B), estrogen receptor (C), progesterone receptor (D), androgen receptor (E) and factor VIII (F) proteins in cultured endometriotic cells (second passage). The culture was established from a large peritoneal implant (black lesion). Note presence of large polymorphic adherent cells growing in monolayer. Original magnification ×400; in B,C,D,E,F (× 280).

Figure 3

Aspect on phase contrast microscopy of untreated (A) and endometriotic cells treated with 2-Ethoxyestradiol (1 mM) during 24 h (B). A striking morphological change was obtained after 12 h of treatment. The 2-Ethoxyestradiol induced decrease of DNA synthesis by 68% after 48 h of treatment (BrDU incorporation).

Figure 4

Representative metaphase spreads obtained from four different endometriotic lesions. Note presence of structural chromosomal alterations expressed as aneuploid metaphase with homogeneous staining region (HSR) in (A), dicentric chromosomes (DICs) (B), double minute chromosomes D-MIN (C), premature centromeric disjunctions (D).

Figure 5

DNA was extracted from a tissue section of a large peritoneal endometriotic implant with presence of an endometriotic gland containing papillary projections [Hematoxylin Eozin stained (A), and from a gland of tissue section from rectovaginal endometriotic nodule (B)].

Figure 6

Complete CGH analysis of one large endometriotic peritoneal implant presented in (A). Compilation of fluorescence ratio profiles from 10 different metaphases was used to calculate the average ratio profiles of this sample. As shown, copy number losses are distributed along chromosomes 1p, 7p and 22q. DAPI staining on the left, and digitized fluorescent image on the right. More detailed representation of the deleted chromosomal segments located on chromosomes 1, 7 and 22 (B).

Figure 7

Hematoxylin and eosin stained sections with areas of ectopic endometrial glands and embryonic ducts. Histological appearance of ectopic glands and stroma observed (insert at higher magnification) in fetal uterine wall (A). Presence of embryonic ducts located in the broad ligament (B), under the fallopian tube serosa (C) and ducts located in the ovarian ligament (D). Note presence of a stromal component surrounding the duct residues in a, b, c, and d. Scale bars, and 100 μm.

Figure 8

Immuno-histo-chemical analysis of ectopic endometrial glands and embryonic ducts in fetal reproductive tract. Immunolabeling with anti-PR antibody of uterine cavity wall lining cells [(A) arrows]. Immunostaining of the fetal ectopic glands located in the uterine myometrium with anti-PR (B), anti ER-alpha (C), and anti CD10 antibodies (D). Expression of the PR in embryonic duct located in the ovarian ligament; insert at higher magnification (E), expression of ER-α in a duct located under the fallopian tube serosa (F), and expression of alpha-1-foetoprotein (G) and CD10 molecules (H). D = duct; St = stromal layer. Scale bars; 500 μm in (A) and 100 μm in (B–H).

Figure 9

Typical aspect of small red peritoneal excrescences in a context of extensive endometriosis.