Recent Advances in Endometriosis With Emphasis on Pathogenesis, Molecular Pathology, and Neoplastic Transformation

Ribosome Biogenesis Serves as a Therapeutic Target for Treating Endometriosis and the Associated Complications

Ribosome biogenesis is a cellular process critical for protein homeostasis during cell growth and multiplication. Our previous study confirmed up-regulation of ribosome biogenesis during endometriosis progression and malignant transition, thus anti-ribosome biogenesis may be effective for treating endometriosis and the associated complications. A mouse model with human endometriosis features was established and treated with three different drugs that can block ribosome biogenesis, including inhibitors against mTOR/PI3K (GSK2126458) and RNA polymerase I (CX5461 and BMH21). The average lesion numbers and disease frequencies were significantly reduced in treated mice as compared to controls treated with vehicle. Flow cytometry analyses confirmed the reduction of small peritoneal macrophage and neutrophil populations with increased large versus small macrophage ratios, suggesting inflammation suppression by drug treatments. Lesions in treated mice also showed lower nerve fiber density which can support the finding of pain-relief by behavioral studies. Our study therefore suggested ribosome biogenesis as a potential therapeutic target for treating endometriosis.

Fallopian tube endometriosis in women undergoing operative video laparoscopy and its clinical implications

OBJECTIVE

To determine the incidence of fallopian tube endometriosis in patients undergoing laparoscopic surgery with a preoperative diagnosis of endometriosis, pelvic pain, infertility, or cystic adnexal mass.

DESIGN

Retrospective cross-sectional study.

SETTING

Gynecologic oncology and minimally invasive surgery practice.

PATIENT(S)

All patients who underwent surgery for endometriosis from July 2015 to June 2018 were included. Exclusion criteria were age ≥55 years, diagnosis of cancer, laparotomy, previous bilateral salpingectomy, and preoperative diagnosis other than endometriosis, pelvic pain, infertility, or cystic adnexal mass.

INTERVENTION(S)

Subjects were divided by those who did and those who did not have a salpingectomy at the time of surgery.

MAIN OUTCOME MEASURE(S)

Diagnosis of tubal endometriosis was based on macroscopic evidence of endometrial implants on the fallopian tube(s) noted within the operative report and microscopic evidence of endometriosis noted within the pathology report.

RESULT(S)

A total of 444 surgeries were performed and 185 met the study criteria. Among those, 153 (82.7%) had histologically diagnosed endometriosis within the abdominopelvic cavity. The incidence of tubal endometriosis was 11%-12% macroscopically and 42.5% microscopically after salpingectomy. Patients with tubal endometriosis were more likely to have severe disease.

CONCLUSION(S)

Among patients with endometriosis, the incidence of microscopic tubal endometriosis was significantly greater than that of macroscopic disease.

Up-regulation of ribosome biogenesis by MIR196A2 genetic variation promotes endometriosis development and progression

Aberrant miRNA expression has been reported in endometriosis and miRNA gene polymorphisms have been linked to cancer. Because certain ovarian cancers arise from endometriosis, we genotyped seven cancer-related miRNA single nucleotide polymorphisms (MiRSNPs) to investigate their possible roles in endometriosis. Genetic variants in MIR196A2 (rs11614913) and MIR100 (rs1834306) were found to be associated with endometriosis development and related clinical phenotypes, such as infertility and pain. Downstream analysis of the MIR196A2 risk allele revealed upregulation of rRNA editing and protein synthesis genes, suggesting hyper-activation of ribosome biogenesis as a driving force for endometriosis progression. Clinical studies confirmed higher levels of small nucleolar RNAs and ribosomal proteins in atypical endometriosis lesions, and this was more pronounced in the associated ovarian clear cell carcinomas. Treating ovarian clear cells with CX5461, an RNA polymerase I inhibitor, suppressed cell growth and mobility followed by cell cycle arrest at G2/M stage and apoptosis. Our study thus uncovered a novel tumorigenesis pathway triggered by the cancer-related MIR196A2 risk allele during endometriosis development and progression. We suggest that anti-RNA polymerase I therapy may be efficacious for treating endometriosis and associated malignancies.

The Link Between Endometriosis and Ovarian Cancer: Clinical Implications

Objectives

The objectives of this study were to evaluate the current evidence of the association of endometriosis and subsequent carcinoma of the ovary and to contextualize this evidence into daily practice issues.

Methods

This study is a critical review of observational and in vitro studies.

Results

Although the lifetime risk for ovarian cancer is low in general population and remains low in the broad spectrum of endometriosis, there may be clusters of individuals at higher risk of oncogenesis, whose identification would allow individualized surveillance and prophylactic interventions. Prevalence studies show that specific subtypes of ovarian cancer predominate in women with endometriosis. This has been validated in pathogenetic, genomic, immunobiologic, and hormonal studies.

Conclusions

Taken together, these data provide a strong rationale for identifying, monitoring, counseling, and treating women with endometriosis who are at highest risk for cancer conversion.

Ovarian carcinoma histotype determination is highly reproducible, and is improved through the use of immunohistochemistry

AIMS

To assess the variation in ovarian carcinoma type diagnosis among gynaecological pathologists from Nordic countries, and whether a rationally designed panel of immunohistochemical markers could improve diagnostic reproducibility.

METHODS AND RESULTS

Eight pathologists from four countries (Sweden, Denmark, Norway, and Finland) received an educational lecture on the diagnosis of ovarian carcinoma type. All tumour-containing slides from 54 ovarian carcinoma cases were independently reviewed by the participants, who: (i) determined type purely on the basis of histology; (ii) indicated whether they would apply immunohistochemistry in their routine practice; and (iii) determined type after reviewing the staining results. The results for six markers (WT1, p53, p16, HNF-1β, ARID1A, and progesterone receptor) were determined for all 54 cases, by staining of a tissue microarray. The median concordance with central review diagnosis was 86%, and significantly improved to 90% with the incorporation of immunostaining results (P = 0.0002). The median interobserver agreement was 78%, and significantly improved to 85% with the incorporation of immunostaining results (P = 0.0002).

CONCLUSIONS

Use of the immunostaining results significantly improved both diagnostic accuracy and interobserver agreement. These results indicate that ovarian carcinoma type can be reliably diagnosed by pathologists from different countries, and also demonstrate that immunohistochemistry has an important role in improving diagnostic accuracy and agreement between pathologists.

KRAS mutations in ovarian low-grade endometrioid adenocarcinoma: association with concurrent endometriosis

The association between ovarian endometrioid adenocarcinoma and endometriosis is well established. However, not all endometrioid adenocarcinomas are directly related to endometriosis, and it has been suggested that there may be clinicopathologic differences between endometriosis-positive and endometriosis-negative tumors. Molecular alterations in endometrioid adenocarcinoma include KRAS and BRAF mutations, but the incidence of these abnormalities in previous reports has been highly variable (0%-36% and 0%-24%, respectively). This may be explained by relatively small sample sizes in earlier studies but could also reflect difficulties in accurately classifying high-grade ovarian malignancies. In the current study, we investigated KRAS and BRAF mutations in 78 low-grade (FIGO grade 1 and 2) endometrioid adenocarcinomas and compared the results with the presence of endometriosis in the tumor-associated ovary and/or in other pelvic sites. KRAS mutations were identified in 12 (29%) of 42 endometriosis-associated endometrioid adenocarcinomas with satisfactory analysis but in only 1 (3%) of 29 tumors in which endometriosis was not identified. BRAF mutation was identified only in a single endometriosis-associated case. These findings support the hypothesis that endometriosis-associated and independent endometrioid adenocarcinoma may develop via different molecular pathways and that KRAS mutations have an important role only in the former tumors. In contrast, BRAF mutations do not appear to have a significant role in either endometrioid adenocarcinoma subgroup. This may be relevant to future targeted therapies in patients with high-stage or recurrent disease and indicate that histopathologists should carefully examine endometrioid adenocarcinoma specimens, including nonneoplastic tissues, for the presence of endometriosis.

HMGA gene rearrangement is a recurrent somatic alteration in polypoid endometriosis

The pathogenesis of endometriosis is unclear, and several genetic, endocrine, immune, and environmental agents have been evaluated with no putative causative factors identified. Here, we show somatic genetic alterations involving HMGA1 (6p21) and HMGA2 (12q15) in 3 cases of polypoid endometriosis. The lesions involved the small bowel mesentery and perirectal soft tissue in 1 case and the posterior vaginal fornix and sigmoid colon serosa in 2 other cases, respectively. All had a polypoid configuration with cystically dilated irregular glands and fibrotic stroma, containing thick-walled vessels. Conventional cytogenetic analysis of 1 case showed 46,XX,t(5;12)(q13;q15) in all metaphases. Fluorescence in situ hybridization studies confirmed the balanced rearrangement of HMGA2. HMGA1 rearrangements were present in 2 additional cases. Rearrangements were exclusively found in the stromal component but not in the glandular component. These findings suggest that HMGA rearrangements likely contribute to the pathogenesis of endometriosis. However, additional studies are needed to better define the biologic role of this genetic alteration.

COMT polymorphism and the risk of endometriosis-related infertility

Estrogens are important factors in the development of endometriosis, and can induce cell proliferation and stimulate cell division. COMT constitutes a crucial element in estrogen metabolism and has been suggested to be involved in the development of endometriosis. This study had the objective of to determine whether the presence of COMT val/met polymorphism (rs4680) increases the risk to endometriosis in infertile patients. A case-control study that included 198 infertile women with endometriosis, 71 infertile women without endometriosis, and 168 fertile women as control group of the Faculdade de Medicina do ABC. COMT (val/met) genotypes were identified by real time PCR (genotyping TaqMan assay) and the results were analyzed statistically by χ² test. The data showed no statistical difference in the distribution of COMT genotypes neither between infertile patients with endometriosis and control group (p = 0.567), regardless disease degree, nor between infertile patients without endometriosis and control group (p = 0.460). In conclusion, the COMT val/met polymorphism is not associated to endometriosis-related infertility in the Brazilian population evaluated. However, more studies in larger populations are necessary to confirm these results.

The association between endometriosis and gynecological cancers and breast cancer: a review of epidemiological data

OBJECTIVE

This article critically reviews the literature on the association between endometriosis and gynecological cancers and breast cancer, based on epidemiologic data.

METHODS

Literature review of the English language literature based on searching in the MEDLINE (PubMed) database and additional collection of reports by systematically reviewing all references from retrieved papers.

RESULTS

Data from large cohort and case-control studies indicate that endometriosis patients only have an increased risk of ovarian cancer among the gynecological malignancies and breast cancer, although most of the observed associations are modest. Data on the association between endometriosis and breast cancer are inconsistent. Endometriosis patients have a reduced risk of cervical cancer, and there is no association between endometriosis and endometrial cancer. Endometriosis-associated ovarian cancer seems to be a distinct clinical entity; patients are younger, diagnosed in earlier stages, have lower grade lesions and a better survival. Further, endometriosis-associated ovarian cancers are predominantly clear cell and endometrioid histologic subtypes.

CONCLUSIONS

Endometriosis seems to be a precursor of epithelial ovarian cancer, especially clear cell and endometrioid adenocarcinomas. However, current evidence is insufficient to draw any definitive conclusions whether this association represents causality or the sharing of similar risk factors and/or antecedent mechanisms.

HMGA1 and HMGA2 rearrangements in mass-forming endometriosis

Endometriosis is a common gynecologic disorder characterized by ectopic endometrium associated with pelvic pain and infertility. The pathogenesis of endometriosis is unclear, and several genetic, endocrine, immune, and environmental agents have been studied as putative causative factors. However, consistent somatic genetic alterations have not been identified. Rarely, endometriosis presents as a mass lesion with an infiltrative pattern reminiscent of malignancy. We describe cytogenetic and molecular cytogenetic findings of mass-forming endometriosis. The index case of pulmonary endometriosis underwent conventional and molecular cytogenetics analysis. In addition, 16 cases of mass-forming endometriosis, 11 cases of usual endometriosis, and six endometriomas were investigated by fluorescence in situ hybridization (FISH) for HMGA1 and HMGA2 loci, performed on paraffin-embedded thin tissue sections with custom-designed probes. The index patient had an endometriotic lung nodule, with a 46,XX, t(5;6)(q13;p21) karyotype and HMGA1 rearrangement by FISH. A second patient had decidualized endometriosis forming a large abdominal mass and HMGA1 rearrangement by FISH. Of the 15 other cases of mass-forming endometriosis, one had HMGA1 rearrangement and two had HMGA2 rearrangement. The rearrangements were found in the stromal component exclusively. None of the usual endometriosis cases or endometriomas had HMGA1 or HMGA2 rearrangements. In conclusion, mass-forming endometriosis is an uncommon subset of endometriosis that harbors HMGA1 or HMGA2 rearrangements in up to 29% of cases. The present findings support the concept that endometriosis is clonal and that rearrangement of HMGA genes likely contributes to its pathogenesis.

Pseudoneoplastic Lesions of the Female Genital Tract

Context.—Numerous benign, proliferative, or reactive processes, often related to hormone stimulation or inflammation, occur throughout the female genital tract and may mimic benign or malignant tumors. Several of the more common pseudoneoplastic lesions are discussed in this article, including microglandular hyperplasia of the cervix mimicking well-differentiated endometrial adenocarcinoma, reactive epithelial changes in the fallopian tubes mimicking adenocarcinoma or carcinoma in situ, and pregnancy changes in the ovary including pregnancy luteoma and large solitary luteinized follicular cyst of pregnancy and puerperium that may mimic ovarian neoplasms.

Objectives.—To discuss and illustrate several common lesions of the female genital tract that mimic neoplasms.

Data Sources.—Material derived from consultation cases and review of the literature.

Conclusions.—Many benign hyperplastic or reactive processes that occur in the female genital tract may be mistaken for neoplasms both clinically and pathologically. Awareness of the features of such lesions will aid in their correct diagnosis and prevent overtreatment of benign processes.

Cathepsins B, L and cystatin C in cyst fluid of ovarian tumors

Introduction

In cancer, an extracellular and membrane bound localization of cathepsins contribute to the invasion of tumor cells at the basement membrane.

Methods

This is the first study that explored levels of cathepsins B (CatB), L (CatL) and their inhibitor cystatin C (CysC) in the cystic fluid (CF) of ovarian tumors (n = 110).

Results

CF contained considerable amounts of CatB, CatL and CysC. Remarkable differences in CatB and CatL and CysC CF levels were found between different histopathological tumor subtypes. Levels of CatB and CysC were significantly higher in CF of malignant serous tumors compared to those found in benign serous tumors (p = 0.010 and p = 0.001 respectively), whereas levels of CatL were significantly higher in CF of malignant mucinous tumors compared to those found in benign mucinous tumors (p = 0.035). CatB and CysC showed a strong correlation in the group of patients with malignant serous tumors (p < 0.001; R = 0.921) suggesting that the increase in CatB might be balanced by a corresponding increase in CysC.

Conclusion

Further studies are warranted to investigate cathepsins as possible prognostic biomarkers for the aggressiveness of ovarian cancer.

The relationship of endometriosis and ovarian malignancy: a review

OBJECTIVE

To review the malignant potential of endometriosis based on epidemiologic, histopathologic, and molecular data.

DESIGN

Literature review.

RESULT(S)

The pathogenesis of endometriosis remains unclear. The histopathologic development of endometriosis has undergone long-term investigation. Studies have confirmed histologic transition from benign endometriosis to ovarian malignancy, including malignant transformation of extraovarian endometriosis. The prevalence of endometriosis in patients with epithelial ovarian cancer, especially in endometrioid and clear cell types, has been confirmed to be higher than in the general population. Ovarian cancers and adjacent endometriotic lesions have shown common genetic alterations, such as PTEN, p53, and bcl gene mutations, suggesting a possible malignant genetic transition spectrum. Furthermore, endometriosis has been associated with a chronic inflammatory state leading to cytokine release. These cytokines act in a complex system in which they induce or repress their own synthesis and can cause unregulated mitotic division, growth and differentiation, and migration or apoptosis similar to malignant mechanisms.

CONCLUSION(S)

The malignant potential of endometriosis holds serious implications for management, such as the need for earlier and more meticulous surgical intervention for complete disease treatment.

WT1 expression in endometrioid ovarian carcinoma with and without associated endometriosis

AIMS

To determine how frequently endometrioid ovarian carcinomas (EOC) express WT1 protein, and to correlate the results with the presence of endometriosis and p53 immunoreactivity.

METHODS

Forty-one grade 1-2 EOC were stained immunohistochemically for WT1 and p53 proteins. Twenty-one tumours were associated with endometriosis and 20 cases lacked such an association. WT1 expression in the tumour cell nuclei and/or cytoplasm was recorded. Nuclear p53 staining was assessed as diffuse (>50% cells positive), focal, or negative.

RESULTS

Four of the 20 (20%) tumours in the endometriosis negative group showed nuclear WT1 staining, while none of the endometriosis-associated EOC was positive (p < 0.05). Two of the immunoreactive cases exhibited sertoliform/sex cord-like patterns. Focal cytoplasmic WT1 labelling was present in seven EOC, three of which showed sertoliform, spindle cell or corded and hyaline patterns. There was no correlation between WT1 expression and p53 immunoreactivity.

CONCLUSIONS

Nuclear WT1 expression is present in a minority of EOC and this should be considered if immunohistochemistry is used as an adjunct in sub-typing ovarian carcinomas. The negative correlation of WT1 staining with endometriosis supports the possibility that some EOC, including unusual histological variants, arise from the ovarian surface epithelium. Further studies of EOC should document any association with endometriosis.

Activation of mammalian target of rapamycin in postmenopausal ovarian endometriosis

The purpose of this study was to determine whether Akt and mammalian target of rapamycin (mTOR), downstream targets of phosphatidylinositol 3-kinase, are activated in endometriosis and ovarian cancer specimens. We measured total and phosphorylated levels of Akt and mTOR from 17 frozen ovarian cancers and 15 benign endometriosis specimens (nine from premenopausal women and six from postmenopausal women) by quantitation of signals from western blots using antibodies against these proteins. Elevated phospho-Akt was detected in ovarian cancer versus endometriosis specimens from premenopausal women and endometriosis specimens from postmenopausal women (2.3 +/- 0.45 versus 0.10 +/- 0.06 and 0.17 +/- 0.11; P < 0.05) when the western blot signal of activated kinase was normalized to total kinase levels. Elevated phospho-mTOR was detected in ovarian cancer and postmenopausal endometriosis versus premenopausal endometriosis (0.52 +/- 0.19 and 0.46 +/- 0.29 versus 0.13 +/- 0.08; P < 0.05). Expression of total kinases (normalized to beta-actin) was higher in carcinoma versus endometriosis specimens. Elevation of the active mTOR was specifically detected in postmenopausal endometriosis.

Increased telomerase activity and human telomerase reverse transcriptase mRNA expression in the endometrium of patients with endometriosis

BACKGROUND

Endometriosis is considered a frequent, benign disease with the ability to undergo neoplastic processes. The aim of this study was to evaluate the limitless replication potential of the endometrium in patients with endometriosis by examining human telomerase reverse transcriptase (hTERT) mRNA expression and telomerase activity.

METHODS

Endometrium samples from 30 endometriosis patients and 30 patients without endometriosis were obtained via endometrial biopsy. The expression of hTERT mRNA was determined by real-time RT-PCR assay, and telomerase activity was measured by telomerase repeat amplification protocol (TRAP) assay.

RESULTS

The mean normalized hTERT (N hTERT) mRNA level was significantly higher in the endometriosis than in the control group (P = 0.013). The mean hTERT mRNA levels during the proliferative phase and during the secretory phase were higher in the endometriosis group than in the control group, although the difference was only significant for the secretory phase (P = 0.036). We found a prominent difference in endometrial telomerase activity between moderate-to-severe endometriosis and the control group (P = 0.048). The levels of hTERT mRNA and telomerase activity increased as the disease became more severe (P = 0.038, P = 0.016).

CONCLUSIONS

This study showed the overexpression of hTERT mRNA and telomerase activity in the endometrium of endometriosis patients. These finding suggest that replication potential of endometrial cells may have an important role in the pathogenesis of endometriosis.