The origin and pathogenesis of epithelial ovarian cancer: a proposed unifying theory

HERV-K hypomethylation in ovarian clear cell carcinoma is associated with a poor prognosis and platinum resistance

INTRODUCTION

In general, ovarian clear cell carcinoma (OCCC) has a history of poor response to standard platinum-based chemotherapy regimens, and advanced cases have short survival periods. Therefore, the discovery of a biomarker for the pretreatment prediction of OCCC is crucial. Loss of methylation of a retrotransposable sequence, such as long interspersed repetitive sequence 1 (LINE-1), frequently occurs in cancers, including ovarian cancer, and it has been proven to be associated with poor survival. The expressions of human endogenous retrovirus (HERV) K and E were found to be increased in tissues from patients with OCCC. Here, we propose that methylation levels of HERV are associated with treatment response and prognosis of OCCC.

METHODS

Twenty-nine patients with OCCC were enrolled. Methylation levels of HERV-K, HERV-E, and LINE-1 were measured from microdissected cancer and normal ovarian tissues. The methylation levels were correlated with stage, treatment response, and prognosis.

RESULTS

Methylation levels of HERV-K, HERV-E, and LINE-1 were decreased in tissues from patients with advanced stage cancer (P = 0.0179, P = 0.0021, and P = 0.0307, respectively). Human endogenous retrovirus K demonstrated significantly lower methylation levels in the platinum-resistant group (P = 0.0004). Patients with lower levels of methylated (hypomethylated) HERV-K had a shorter mean overall survival (P = 0.006). In advanced OCCC cases, patients with hypomethylated HERV-K had shorter mean progression-free survival (P = 0.018) and mean overall survival (P = 0.018) than did patients with higher methylation levels of HERV-K.

CONCLUSIONS

Methylation levels of HERV-K, HERV-E, and LINE-1 are decreased during OCCC multistep carcinogenesis. Moreover, HERV-K hypomethylation is a promising biomarker for predicting OCCC treatment response and prognosis.

What are the individual perceptions of patients with borderline tumours of the ovary in regard to pathogenesis and prognosis? A structured survey on 60 women

Limited data exist about the perception of patients with borderline ovarian tumours (BOT). We assessed the individual perception of patients with BOT, with special focus on the biological-behaviour of the disease. Sixty patients with BOT who underwent surgery during January 2001 to June 2009 were interviewed by a 9-item-questionnaire, at the earliest, 12 months postoperatively. The aim was to assess their estimation regarding the malignant potential of BOT, its impact on their future fertility, the risk of recurrence and death and the possible causes of BOT. Seventeen women incriminated occupational-stress as a causative factor; 8 women genetic-predisposition, and 7 women personal-stress. Only 10 (16.7%) patients evaluated the BOT malignant potential as equivalent to that of a benign ovarian-cyst, while 28 (46.7%) and 20 (33.3%) patients believed carrying the same or equivalent recurrence- and mortality-risk, respectively, like patients with ovarian cancer (OC). Most fertile patients (19/23; 82.6%) felt adequately informed about the impact of BOT on their future fertility, while four patients stated being insufficiently informed. Despite the overall favourable BOT prognosis, affected patients appear to correlate their malignant potential close to that of OC with an equivalent high risk of recurrence. However, patients do not expect to die of BOT. There is a high need to intensify information process regarding BOT. Future trials are warranted to evaluate whether this may substantially influence the patients' perspectives.

Enhancer of zeste homolog 2 promotes the proliferation and invasion of epithelial ovarian cancer cells

Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressive complex 2 (PRC2) that includes noncatalytic subunits suppressor of zeste 12 (SUZ12) and embryonic ectoderm development (EED). When present in PRC2, EZH2 catalyzes trimethylation on lysine 27 residue of histone H3 (H3K27Me3), resulting in epigenetic silencing of gene expression. Here, we investigated the expression and function of EZH2 in epithelial ovarian cancer (EOC). When compared with primary human ovarian surface epithelial (pHOSE) cells, EZH2, SUZ12, and EED were expressed at higher levels in all 8 human EOC cell lines tested. Consistently, H3K27Me3 was also overexpressed in human EOC cell lines compared with pHOSE cells. EZH2 was significantly overexpressed in primary human EOCs (n = 134) when compared with normal ovarian surface epithelium (n = 46; P < 0.001). EZH2 expression positively correlated with expression of Ki67 (P < 0.001; a marker of cell proliferation) and tumor grade (P = 0.034) but not tumor stage (P = 0.908) in EOC. There was no correlation of EZH2 expression with overall (P = 0.3) or disease-free survival (P = 0.2) in high-grade serous histotype EOC patients (n = 98). Knockdown of EZH2 expression reduced the level of H3K27Me3 and suppressed the growth of human EOC cells both in vitro and in vivo in xenograft models. EZH2 knockdown induced apoptosis of human EOC cells. Finally, we showed that EZH2 knockdown suppressed the invasion of human EOC cells. Together, these data demonstrate that EZH2 is frequently overexpressed in human EOC cells and its overexpression promotes the proliferation and invasion of human EOC cells, suggesting that EZH2 is a potential target for developing EOC therapeutics.

Reproductive and hormonal factors in association with ovarian cancer in the Netherlands cohort study

Parity, oral contraceptive use, and hysterectomy are known to protect against ovarian cancer, whereas the effect of other reproductive factors remains unclear. The authors investigated the association between several reproductive and hormonal factors and the risk of epithelial invasive ovarian cancer among postmenopausal women participating in the Netherlands Cohort Study on Diet and Cancer. Information on reproductive history and exogenous hormone use was obtained through a self-administered questionnaire at baseline in 1986. After 16.3 years of follow-up, 375 cases and 2,331 subcohort members were available for case-cohort analysis. Ovarian cancer risk was reduced for parous women, with increasing parity, and for hysterectomized women. Moreover, the authors found evidence that oral contraceptive use is protective against ovarian cancer, even when initiated at an older age. In addition, a reduced risk was observed for each year reduction in age at natural menopause and per year reduction in total menstrual life span. A small increased risk was observed with prolonged time to pregnancy, but no difference was found between ever-married nulliparous women and never-married nulliparous women. Moreover, no associations were observed for age at first birth, age at menarche, age at first and last use of oral contraceptives, and use of hormone replacement therapy.

Study of the molecular recognition of aptamers selected through ovarian cancer cell-SELEX

BACKGROUND

Ovarian cancer is the most lethal gynecological malignancy, and the ovarian clear cell carcinoma subtype (OCCA) demonstrates a particularly poor response to standard treatment. Improvements in ovarian cancer outcomes, especially for OCCA, could be expected from a clearer understanding of the molecular pathology that might guide strategies for earlier diagnosis and more effective treatment.

METHODOLOGY/PRINCIPAL FINDINGS

Cell-SELEX technology was employed to develop new molecular probes for ovarian cancer cell surface markers. A total of thirteen aptamers with K(d)'s to ovarian cancer cells in the pico- to nanomolar range were obtained. Preliminary investigation of the targets of these aptamers and their binding characteristics was also performed.

CONCLUSIONS/SIGNIFICANCE

We have selected a series of aptamers that bind to different types of ovarian cancer, but not cervical cancer. Though binding to other cancer cell lines was observed, these aptamers could lead to identification of biomarkers that are related to cancer.

Are all pelvic (nonuterine) serous carcinomas of tubal origin?

It has been proposed that the presence of tubal intraepithelial carcinoma (TIC), in association with one-third to nearly half of pelvic serous carcinomas, is evidence of fallopian tube origin for high-grade serous carcinomas that would have been otherwise classified as primary ovarian or peritoneal. To address this hypothesis, we evaluated a series of 114 consecutive pelvic (nonuterine) gynecologic carcinomas at our institution (2006 to 2008) to determine the frequency of TIC in 52 cases in which all the resected fallopian tube tissue was examined microscopically. These 52 cases were classified as ovarian (n=37), peritoneal (n=8), or fallopian tube (n=7) in origin as per conventional criteria based on disease distribution. The presence of TIC and its location and relationship to invasive carcinoma in the fallopian tubes and ovaries were assessed. Among the 45 cases of ovarian/peritoneal origin, carcinoma subtypes included 41 high-grade serous, 1 endometrioid, 1 mucinous, 1 high-grade, not otherwise specified, and 1 malignant mesodermal mixed tumor. TIC was identified in 24 cases (59%) of high-grade serous carcinoma but not among any of the other subtypes; therefore, the term serous TIC (STIC) is a more specific appellation. STICs were located in the fimbriated end of the tube in 22 cases (92%) and in the ampulla in 2 (8%); they were unilateral in 21 (88%) and bilateral in 3 (13%). STICs in the absence of an associated invasive carcinoma in the same tube were detected in 7 cases (30%) and with invasive carcinoma in the same tube in 17 (71%). Unilateral STICs were associated with bilateral ovarian involvement in 15 cases and unilateral (ipsilateral) ovarian involvement in 5 (the remaining case with a unilateral STIC had a primary peritoneal tumor with no ovarian involvement); the bilateral STICs were all associated with bilateral ovarian involvement. Six of the 7 primary tubal tumors were high-grade serous carcinomas, and 4 of these 6 (67%) had STICs. Based on conventional criteria, 70%, 17%, and 13% of high-grade serous carcinomas qualified for classification as ovarian, peritoneal, and tubal in origin, respectively; however, using STIC as a supplemental criterion to define a case as tubal in origin, the distribution was modified to 28%, 8%, and 64%, respectively. Features of tumors in the ovary that generally suggest metastatic disease (bilaterality, small size, nodular growth pattern, and surface plaques) were identified with similar frequency in cases with and without STIC and were, therefore, not predictive of tubal origin. The findings, showing that nearly 60% of high-grade pelvic (nonuterine) serous carcinomas are associated with STICs, are consistent with the proposal that the fallopian tube is the source of a majority of these tumors. If these findings can be validated by molecular studies that definitively establish that STIC is the earliest form of carcinoma rather than intraepithelial spread from adjacent invasive serous carcinoma of ovarian or peritoneal origin, they will have important clinical implications for screening, treatment, and prevention.

Epithelial ovarian carcinoma: current evidences and future perspectives in the first-line setting

Epithelial ovarian carcinoma is still the most common cause of death from gynaecological cancer in USA and western Europe. The optimal therapy of epithelial ovarian carcinoma requires participation of a multidisciplinary team - from diagnosis through the entire natural history of each individual patient. Only 20-30% of patients are diagnosed at the initial stage, when appropriate staging surgery in combination with adjuvant chemotherapy for high-risk patients can be curative. Treating patients with advanced disease consists of a staging surgery with maximum cytoreductive effort, followed by chemotherapy with a combination of taxane and carboplatin. Unfortunately, the majority of patients with advanced disease will relapse and become candidates for therapy that comprises individualised chemotherapy, and surgery in selected cases. For this reason, there is still a need for new treatments and strategies in the first-line setting.

Asian society of gynecologic oncology workshop 2010

This workshop was held on July 31-August 1, 2010 and was organized to promote the academic environment and to enhance the communication among Asian countries prior to the 2nd biennial meeting of Australian Society of Gynaecologic Oncologists (ASGO), which will be held on November 3-5, 2011. We summarized the whole contents presented at the workshop. Regarding cervical cancer screening in Asia, particularly in low resource settings, and an update on human papillomavirus (HPV) vaccination was described for prevention and radical surgery overview, fertility sparing and less radical surgery, nerve sparing radical surgery and primary chemoradiotherapy in locally advanced cervical cancer, were discussed for management. As to surgical techniques, nerve sparing radical hysterectomy, optimal staging in early ovarian cancer, laparoscopic radical hysterectomy, one-port surgery and robotic surgery were introduced. After three topics of endometrial cancer, laparoscopic surgery versus open surgery, role of lymphadenectomy and fertility sparing treatment, there was a special additional time for clinical trials in Asia. Finally, chemotherapy including neo-adjuvant chemotherapy, optimal surgical management, and the basis of targeted therapy in ovarian cancer were presented.

AXL is an essential factor and therapeutic target for metastatic ovarian cancer

The receptor tyrosine kinase AXL is thought to play a role in metastasis; however, the therapeutic efficacy of an AXL-targeting agent remains largely untested in metastatic disease. In this study, we defined AXL as a therapeutic target for metastatic ovarian cancer. AXL is primarily expressed in metastases and advanced-stage human ovarian tumors but not in normal ovarian epithelium. Genetic inhibition of AXL in human metastatic ovarian tumor cells is sufficient to prevent the initiation of metastatic disease in vivo. Mechanistically, inhibition of AXL signaling in animals with metastatic disease results in decreased invasion and matrix metalloproteinase activity. Most importantly, soluble human AXL receptors that imposed a specific blockade of the GAS6/AXL pathway had a profound inhibitory effect on progression of established metastatic ovarian cancer without normal tissue toxicity. These results offer the first genetic validation of GAS6/AXL targeting as an effective strategy for inhibition of metastatic tumor progression in vivo. Furthermore, this study defines the soluble AXL receptor as a therapeutic candidate agent for treatment of metastatic ovarian cancer, for which current therapies are ineffective.

Ovarian cancer development and metastasis

The biology of ovarian carcinoma differs from that of hematogenously metastasizing tumors because ovarian cancer cells primarily disseminate within the peritoneal cavity and are only superficially invasive. However, since the rapidly proliferating tumors compress visceral organs and are only temporarily chemosensitive, ovarian carcinoma is a deadly disease, with a cure rate of only 30%. There are a number of genetic and epigenetic changes that lead to ovarian carcinoma cell transformation. Ovarian carcinoma could originate from any of three potential sites: the surfaces of the ovary, the fallopian tube, or the mesothelium-lined peritoneal cavity. Ovarian cacinoma tumorigenesis then either progresses along a stepwise mutation process from a slow growing borderline tumor to a well-differentiated carcinoma (type I) or involves a genetically unstable high-grade serous carcinoma that metastasizes rapidly (type II). During initial tumorigenesis, ovarian carcinoma cells undergo an epithelial-to-mesenchymal transition, which involves a change in cadherin and integrin expression and up-regulation of proteolytic pathways. Carried by the peritoneal fluid, cancer cell spheroids overcome anoikis and attach preferentially on the abdominal peritoneum or omentum, where the cancer cells revert to their epithelial phenotype. The initial steps of metastasis are regulated by a controlled interaction of adhesion receptors and proteases, and late metastasis is characterized by the oncogene-driven fast growth of tumor nodules on mesothelium covered surfaces, causing ascites, bowel obstruction, and tumor cachexia.

Shortened telomeres in serous tubal intraepithelial carcinoma: an early event in ovarian high-grade serous carcinogenesis

Short telomeres are one of the main genetic manifestations in human cancer, as they have been shown to play an important role in inducing chromosomal instability and in contributing to tumor progression. The purpose of this study was to determine if changes in telomere length occur in serous tubal intraepithelial carcinoma (STIC), the putative precursor of "ovarian" high-grade serous carcinoma (HGSC). Twenty-two STICs from 15 patients with concurrent but discrete HGSCs were analyzed for telomere length on formalin-fixed, paraffin-embedded sections by conducting p53 immunofluorescence to assist in identifying STICs and telomere-specific FISH. Telomere length (short, long, or no change) in STICs was compared with HGSCs using normal fallopian tube epithelium and stromal cells as controls. We found that STICs had the shortest telomeres, as 18 (82%) of 22 STICs had short telomeres, whereas only 2 (9%) showed no change and 2 (9%) had long telomeres compared with the normal-looking tubal epithelium. In contrast, among 12 paired HGSCs and STICs, 6 HGSCs showed an increase in telomere length, one showed a decrease in length and 5 did not show any change when compared with their matched STICs, although, such as STICs, the majority of HGSCs had shorter telomeres than the associated normal tubal epithelial cells. These differences in telomere length between normal tubal epithelial cells and STICs, and between STICs and HGSCs were statisticaly significant (P<0.05). In conclusion, the finding of short telomeres, which have been shown to be one of the earliest molecular changes in carcinogenesis, in a vast majority of STICs provides further support to the proposal that STICs are precursors of HGSC and opens new areas of research in elucidating the early events of ovarian high-grade serous carcinogenesis.

Genetic analysis of the early natural history of epithelial ovarian carcinoma

Background

The high mortality rate associated with epithelial ovarian carcinoma (EOC) reflects diagnosis commonly at an advanced stage, but improved early detection is hindered by uncertainty as to the histologic origin and early natural history of this malignancy.

Methodology/Principal Findings

Here we report combined molecular genetic and morphologic analyses of normal human ovarian tissues and early stage cancers, from both BRCA mutation carriers and the general population, indicating that EOCs frequently arise from dysplastic precursor lesions within epithelial inclusion cysts. In pathologically normal ovaries, molecular evidence of oncogenic stress was observed specifically within epithelial inclusion cysts. To further explore potential very early events in ovarian tumorigenesis, ovarian tissues from women not known to be at high risk for ovarian cancer were subjected to laser catapult microdissection and gene expression profiling. These studies revealed a quasi-neoplastic expression signature in benign ovarian cystic inclusion epithelium compared to surface epithelium, specifically with respect to genes affecting signal transduction, cell cycle control, and mitotic spindle formation. Consistent with this gene expression profile, a significantly higher cell proliferation index (increased cell proliferation and decreased apoptosis) was observed in histopathologically normal ovarian cystic compared to surface epithelium. Furthermore, aneuploidy was frequently identified in normal ovarian cystic epithelium but not in surface epithelium.

Conclusions/Significance

Together, these data indicate that EOC frequently arises in ovarian cystic inclusions, is preceded by an identifiable dysplastic precursor lesion, and that increased cell proliferation, decreased apoptosis, and aneuploidy are likely to represent very early aberrations in ovarian tumorigenesis.

UK external quality assessment scheme for immunoassays in endocrinology

UK EQAS provide the UK with a comprehensive system for EQA in endocrinology, as well as in other aspects of clinical chemistry and laboratory medicine. UK EQAS in endocrinology are scientifically designed to yield an objective assessment of participants' performance and stimulate improvements in between-laboratory agreement. The design uses appropriate specimens, based on liquid human serum and prepared with minimal processing and additives in the organising centres to enable detailed study of recovery and other important factors. Target values are validated by reproducibility on repeated distribution and by recovery and parallelism studies. Reports are presented informatively, and emphasise the cumulative scoring system (bias and variance) for performance assessment. Computerised data processing and data presentation form an integral part of these schemes, and a common core computing system is in use throughout these UK EQAS. Participants receive advice and assistance in the interpretation of performance data and, when appropriate, in the resolution of problems.

The fiber arrangement of the pathological human tympanic membrane

Aerobic glycolysis is an important metabolic adaptation of cancer cells. There is growing evidence that oxidative phosphorylation is also an active metabolic pathway in many tumors, including in high grade serous ovarian cancer. Metastasized ovarian tumors use fatty acids for their energy needs. There is also evidence of ovarian cancer stem cells privileging oxidative phosphorylation (OXPHOS) for their metabolic needs. Metformin and thiazolidinediones such as rosiglitazone restrict tumor growth by inhibiting specific steps in the mitochondrial electron transport chain. These observations suggest that strategies to interfere with oxidative phosphorylation should be considered for the treatment of ovarian tumors. Here, we review the literature that supports this hypothesis and describe potential agents and critical control points in the oxidative phosphorylation pathway that can be targeted using small molecule agents. In this review, we also discuss potential barriers that can reduce the efficacy of the inhibitors of oxidative phosphorylation.