Genetic analysis of the early natural history of epithelial ovarian carcinoma

High-grade Serous Carcinoma Occurring in a Serous Cystadenoma on the Background of a Serous Tubal Intraepithelial Carcinoma (STIC)-like Lesion: A Case Report With Literature Review

At present, the prevailing concept is that high-grade serous carcinoma (HGSC) arises from the fallopian tubes (FTs). We report an HGSC case occurring in a serous ovarian cyst against the background of a serous tubal intraepithelial carcinoma (STIC)-like lesion. We also provide a literature review that contains references to clinical cases of the occurrence of STIC-like lesions in the ovary and phylogenetic studies that do not always reveal obvious bonds between early dysplastic serous lesions and HGSC. The article discusses cases of association between HGSCs of serous borderline tumors (SBTs) and low-grade serous carcinomas (LGSCs) in the context of their possible histogenetic relationship. We propose a concept in which high-grade serous carcinogenesis, represented by the p53-signature-STIC-HGSC continuity, occurs in the serous epithelium of both the FT and other locations.

[Morphological precursors of high-grade serous ovarian cancer]

At the beginning of this century, there was a paradigm shift in understanding the histogenesis of high-grade serous carcinomas. The theory of the origin of these tumors from the ovarian surface epithelium was replaced by the concept of their origin from the secretory epithelium of the fallopian tubes. In recent years, researchers have put forward the hypothesis of the "escape" of the precursor of high-grade serous carcinomas. It allows looking at the carcinogenesis of these neoplasms as a natural history of tumor transformation of the serous epithelium without reference to a specific localization.

Molecular, cellular and systemic aspects of epithelial ovarian cancer and its tumor microenvironment

Ovarian cancer encompasses a heterogeneous group of malignancies that involve the ovaries, fallopian tubes and the peritoneal cavity. Despite major advances made within the field of cancer, the majority of patients with ovarian cancer are still being diagnosed at an advanced stage of the disease due to lack of effective screening tools. The overall survival of these patients has, therefore, not substantially improved over the past decades. Most patients undergo debulking surgery and treatment with chemotherapy, but often micrometastases remain and acquire resistance to the therapy, eventually leading to disease recurrence. Here, we summarize the current knowledge in epithelial ovarian cancer development and metastatic progression. For the most common subtypes, we focus further on the properties and functions of the immunosuppressive tumor microenvironment, including the extracellular matrix. Current and future treatment modalities are discussed and finally we provide an overview of the different experimental models used to develop novel therapies.

Proliferation of the Fallopian Tube Fimbriae and Cortical Inclusion Cysts: Effects of the Menstrual Cycle and the Levonorgestrel Intrauterine Contraceptive System

BACKGROUND

The objectives of this study were (i) to explore whether differences in cell proliferation may help explain why most high-grade serous ovarian cancers (HGSOC) arise in the fallopian tube fimbriae (FTF) rather than in ovarian cortical inclusion cysts (CIC); (ii) to compare premenopausal and postmenopausal FTF proliferation as a reason why the age incidence of HGSOC increases at a slower rate after menopause; and (iii) to compare FTF proliferation in cycling women and women using the levonorgestrel intrauterine contraceptive system (Lng-IUS) to see whether proliferation on the Lng-IUS was lower.

METHODS

We studied 60 women undergoing a salpingo-oophorectomy. We used Ki67, paired-box gene 8 (PAX8, Müllerian marker), and calretinin (mesothelial marker) to study FTF and CIC proliferation.

RESULTS

FTF Ki67%+ was greater in the follicular than in the luteal phase (4.9% vs. 1.5%; P = 0.003); postmenopausal Ki67%+ was 1.7%. Ki67%+ in PAX8 negative (PAX8-) CICs was extremely low. Proliferation in PAX8+ CICs did not vary by menstrual phase or menopausal status. Follicular Ki67%+ was 2.6-fold higher in FTF than PAX8+ CICs. FTF Ki67%+ from 10 women using the Lng-IUS was not lower than in cycling women.

CONCLUSIONS

Overall FTF Ki67%+ is greater than overall CIC Ki67%+. Overall FTF Ki67%+ in postmenopausal women is lower than in premenopausal women. The Lng-IUS is not associated with lower FTF Ki67%+.

IMPACT

Ki67%+ provides an explanation of the preponderance of FTF-derived HGSOCs, and of the slower increase of HGSOCs after menopause. The Lng-IUS may not be associated with a protective effect against HGSOCs.

Molecular catastrophe, the peritoneal cavity and ovarian cancer prevention

The current theory of carcinogenesis for the deadliest of "ovarian" cancers - high-grade serous carcinoma (HGSC) - holds that the malignancy develops first in the fallopian tube and spreads to the ovaries, peritoneum and/or regional lymph nodes. This is based primarily on the observation of early forms of serous neoplasia (serous tubular intraepithelial lesions (STILs), and serous tubular intraepithelial carcinomas (STICS)) in the fimbria of women undergoing risk reduction surgery. However, these lesions are uncommon in the general population, confer a low risk (5%) of HGSC following their removal in at-risk women with germ-line BRCA1/2 mutations and require 4 or more years to recur as intraperitoneal HGSC. These features suggest that isolated STILs and STICs behave as precursors with uncertain cancer risk rather than carcinomas. Their evolution to HGSC after escape from the tube could proceed step-wise with multiple biologic events; however, it is unclear whether immediately adjacent HGSCs in the setting of advanced disease evolved in the same fashion. The latter scenario could also be explained by a "catastrophic" model in which STICs suddenly develop with invasive and metastatic potential, overwhelming or obscuring the site of origin. Moreover, a similar model might explain the sudden emergence of HGSC in the peritoneal cavity following escape of precursor cells years before. Long term follow-up data from opportunistic or prophylactic salpingectomy should shed light on where malignant transformation occurs, as well as the time-line from precursor to metastatic HGSC. This article is protected by copyright. All rights reserved.

MicroRNAs as Biomarkers for Early Diagnosis, Prognosis, and Therapeutic Targeting of Ovarian Cancer

Ovarian cancer is the major cause of gynecologic cancer-related mortality. Regardless of outstanding advances, which have been made for improving the prognosis, diagnosis, and treatment of ovarian cancer, the majority of the patients will die of the disease. Late-stage diagnosis and the occurrence of recurrent cancer after treatment are the most important causes of the high mortality rate observed in ovarian cancer patients. Unraveling the molecular mechanisms involved in the pathogenesis of ovarian cancer may help find new biomarkers and therapeutic targets for ovarian cancer. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression, mostly at the posttranscriptional stage, through binding to mRNA targets and inducing translational repression or degradation of target via the RNA-induced silencing complex. Over the last two decades, the role of miRNAs in the pathogenesis of various human cancers, including ovarian cancer, has been documented in multiple studies. Consequently, these small RNAs could be considered as reliable markers for prognosis and early diagnosis. Furthermore, given the function of miRNAs in various cellular pathways, including cell survival and differentiation, targeting miRNAs could be an interesting approach for the treatment of human cancers. Here, we review our current understanding of the most updated role of the important dysregulation of miRNAs and their roles in the progression and metastasis of ovarian cancer. Furthermore, we meticulously discuss the significance of miRNAs as prognostic and diagnostic markers. Lastly, we mention the opportunities and the efforts made for targeting ovarian cancer through inhibition and/or stimulation of the miRNAs.

Mechanisms of High-Grade Serous Carcinogenesis in the Fallopian Tube and Ovary: Current Hypotheses, Etiologic Factors, and Molecular Alterations

Ovarian high-grade serous carcinomas (HGSCs) are a heterogeneous group of diseases. They include fallopian-tube-epithelium (FTE)-derived and ovarian-surface-epithelium (OSE)-derived tumors. The risk/protective factors suggest that the etiology of HGSCs is multifactorial. Inflammation caused by ovulation and retrograde bleeding may play a major role. HGSCs are among the most genetically altered cancers, and TP53 mutations are ubiquitous. Key driving events other than TP53 mutations include homologous recombination (HR) deficiency, such as BRCA 1/2 dysfunction, and activation of the CCNE1 pathway. HR deficiency and the CCNE1 amplification appear to be mutually exclusive. Intratumor heterogeneity resulting from genomic instability can be observed at the early stage of tumorigenesis. In this review, I discuss current carcinogenic hypotheses, sites of origin, etiologic factors, and molecular alterations of HGSCs.

Molecular Targets and Associated Signaling Pathways of Jingshu Granules in Ovarian Cysts Based on Systemic Pharmacological Analysis

Background

More than a third of women could develop ovarian cysts during their lifetime. Jingshu granules are used for the treatment of gynecological disease of primary dysmenorrhea. However, the molecular mechanisms of Jingshu granules in ovarian cysts are still unreported. We aimed to find the active ingredients, molecular targets, and potential signaling pathways of Jingshu granules in ovarian cysts by using the systemic pharmacological analysis.

Methods

Firstly, the effect of Jingshu granules on female hormones and reproductive organs of young female rats was evaluated. Secondly, candidate pharmaceutical ingredients of Jingshu granules were retrieved from the traditional Chinese medicine systems pharmacology (TCMSP) database and analysis platform. Potential protein targets for the active ingredients in Jingshu granules were then identified according to the oral bioavailability and drug-likeness indices. Thirdly, ovarian cyst-related gene targets were screened based on different databases. Finally, enrichment analysis was used to analyze the potential biological function of intersection targets between Jingshu granules and ovarian cysts.

Results

In young female rats, Jingshu granules reduced the secretion of estradiol, progesterone, and prolactin and could affect the development of the uterus. This suggested that Jingshu granules played roles in hormone secretion and reproduction. From the TCMSP, a total of 1021 pharmaceutical ingredients of Jingshu granules were retrieved. After further screening, a total of 166 active ingredients and 159 protein targets of Jingshu granules were identified. In addition, 4488 gene targets of ovarian cysts were screened out. After taking the intersection, a total of 110 intersection targets were identified between potential protein targets of Jingshu granules and gene targets of ovarian cysts. In the functional analysis of 110 intersection targets, 8 signaling pathways including progesterone-mediated oocyte maturation (MAPK8 and CDK1 involved), GnRH signaling pathway (JUN involved), T cell receptor signaling pathway and Toll-like receptor signaling pathway (MAPK1 involved), NOD-like receptor signaling pathway (TNF, IL6, and IL1B involved), p53 signaling pathway (CDK2 and CDK4 involved), VEGF signaling pathway (MAPK14 involved), and PPAR signaling pathway (PPARG involved) were obtained.

Conclusion

Our study revealed that Jingshu granules could function in patients with ovarian cysts through a number of molecular targets and signaling pathways. Our study may provide a new field into the mechanisms of Jingshu granules in ovarian cysts, from the molecular to the signaling pathway level.

Ovarian High-Grade Serous Carcinoma: Assessing Pathology for Site of Origin, Staging and Post-neoadjuvant Chemotherapy Changes

High-grade serous (HGSC) stands apart from the other ovarian cancer histotypes in being the most frequent, in occurring as part of a genetic predisposition in a significant proportion of cases, and in having the poorest clinical outcomes. Although the pathologic diagnosis of HGSC is now made with high accuracy, there remain areas of disagreement regarding viewpoints on tissue site of origin and designation of primary site, with impact on staging in low-stage cases, as well as difficulties in reproducible and clinically relevant reporting of HGSC in specimens taken after neoadjuvant chemotherapy. These areas are discussed in the current article.

Both fallopian tube and ovarian surface epithelium are cells-of-origin for high-grade serous ovarian carcinoma

The cell-of-origin of high grade serous ovarian carcinoma (HGSOC) remains controversial, with fallopian tube epithelium (FTE) and ovarian surface epithelium (OSE) both considered candidates. Here, by using genetically engineered mouse models and organoids, we assessed the tumor-forming properties of FTE and OSE harboring the same oncogenic abnormalities. Combined RB family inactivation and Tp53 mutation in Pax8 + FTE caused Serous Tubal Intraepithelial Carcinoma (STIC), which metastasized rapidly to the ovarian surface. These events were recapitulated by orthotopic injection of mutant FTE organoids. Engineering the same genetic lesions into Lgr5 + OSE or OSE-derived organoids also caused metastatic HGSOC, although with longer latency and lower penetrance. FTE- and OSE-derived tumors had distinct transcriptomes, and comparative transcriptomics and genomics suggest that human HGSOC arises from both cell types. Finally, FTE- and OSE-derived organoids exhibited differential chemosensitivity. Our results comport with a dualistic origin for HGSOC and suggest that the cell-of-origin might influence therapeutic response.

The Association and Significance of p53 in Gynecologic Cancers: The Potential of Targeted Therapy

Dysfunction of p53 is observed in the many malignant tumors. In cervical cancer, p53 is inactivated by degradation through the complex with human papilloma virus (HPV) oncoprotein E6 and E6-associated protein (E6AP), an E3 ubiquitin protein ligase. In endometrial cancer, overexpression of p53 in immunohistochemistry is a significant prognostic factor. A discrepancy between p53 overexpression and TP53 mutations is observed in endometrioid endometrial cancer, indicating that the accumulation of p53 protein can be explained by not only gene mutations but also dysregulation of the factors such as ERβ and MDM2. Furthermore, the double-positive expression of immunoreactive estrogen receptor (ER) β and p53 proteins is closely associated with the incidence of metastasis and/or recurrence. High-grade serous ovarian carcinoma (HGSC) arises from secretary cells in the fallopian tube. The secretary cell outgrowth (SCOUT) with TP53 mutations progresses to HGSC via the p53 signature, serous intraepithelial lesion (STIL), and serous intraepithelial carcinoma (STIC), indicating that TP53 mutation is associated with carcinogenesis of HGSC. Clinical application targeting p53 has been approved for some malignant tumors. Gene therapy by the adenovirus-mediated p53 gene transfer system is performed for head and neck cancer. A clinical phase III trial using MDM2/X inhibitors, idasanutlin (RG7388) combined with cytarabine, is being performed involving relapse/refractory acute myeloid leukemia patients. The use of adenoviruses as live vectors which encode wild-type p53 has given promising results in cervical cancer patients.

Evaluation of Microscopic Changes in Fallopian Tubes of BRCA Mutation Carriers by Morphometric Analysis of Histologic Slides: A Preliminary Pilot Study

Mutations in BRCA genes increase the risk of ovarian cancer, yet no method for early diagnosis is available. Some serous ovarian tumors are hypothesized to stem from cells of the fallopian tube fimbria. Using a novel method of computerized morphometry of the fimbrial epithelium, this study aimed to detect morphologic differences in noncancerous fimbriae between BRCA mutation carriers and noncarriers, and between healthy and serous ovarian cancer patients. Twenty-four fimbriae from healthy women (13 BRCA+, 11 BRCA-) and 21 fimbriae from women with serous ovarian cancer (10 BRCA+, 11 BRCA-), all reported as "normal" by hematoxylin and eosin examination, were subjected to computerized histomorphometric analysis. A Fast Fourier Transformation was applied to images of fimbrial epithelium and the Fast Fourier Transformation 2-dimensional frequency maps were subsequently quantified for nuclear orientation and planar distribution by a cooccurrence matrix analysis. Additional analysis of nuclear contour was applied to the fimbriae of the healthy women. Among the healthy women, significant differences were found in morphometric characteristics between the BRCA mutation carriers and noncarriers. Among the women with ovarian cancer, no significant differences were found between BRCA mutation carriers and noncarriers. Between healthy women and those with ovarian cancer, significant differences were detected, regardless of BRCA mutational status. A novel method, which combined Fast Fourier Transformation with cooccurrence matrix analysis, demonstrated differences in morphometric characteristics in the fimbriae between healthy and ovarian cancer patients, and between BRCA mutation carriers and noncarriers. The clinical significance of these observations should be investigated.

The fallopian tube, "precursor escape" and narrowing the knowledge gap to the origins of high-grade serous carcinoma

Most ovarian carcinomas are high-grade serous carcinomas (HGSC) that contain TP53 mutations, present at advanced stage, and eventually become resistant to chemotherapy. The rapid evolution of this disease has been attributed to an origin in the distal fallopian tube, in the form of serous tubal intraepithelial carcinomas (STICs). This has led to a disease model where malignancy develops first in the tube and spreads to the peritoneum or regional lymph nodes. However, although most early or incidentally discovered HGSCs manifest in the tube with STICs, many advanced HGSCs are not accompanied by a malignancy in the fimbria. To resolve this paradox, the focus has shifted to earlier, premalignant serous proliferations (ESPs) in the tubes, which lack the cytomorphologic features of malignancy but contain TP53 mutations. These have been termed p53 signatures or serous tubal intraepithelial lesions (STILs). Although they have not been presumed to have cancer-causing potential by themselves, some ESPs have recently been shown to share identical TP53 mutations with concurrent HGSCs, indicating a shared lineage between these early mucosal changes and metastatic malignancy. This discovery supports a paradigm by which HGSCs can emerge not only from STICs but also from exfoliated precursor cells (precursor escape) that eventually undergo malignant transformation within the peritoneal cavity. This paradigm unifies both localized and widespread HGSCs to a visible pre-existing cellular alteration in the tubal epithelium, and highlights a consistent and necessary biologic event (TP53 mutation) rarely encountered in the ovary or secondary Mullerian system. This dual pathway to HGSCs underscores the subtle nature of many serous cancer origins in the tube, explains contrasting clinico-pathologic presentations, and explains why, until recently, the fallopian tube was unappreciated as the principal origin of HGSCs. Moreover, it highlights additional challenges faced in preventing or intercepting HGSCs at a curable stage.

Back to the Future? The Fallopian Tube, Precursor Escape and a Dualistic Model of High-Grade Serous Carcinogenesis

Beginning with the discovery of the BRCA-associated ovarian cancer susceptibility genes and subsequent detailed examination of risk-reducing salpingo-oophorectomy (RRSO) specimens, a new paradigm of ovarian carcinogenesis has unfolded with attention to the distal fallopian tube. The primary focus has been an early cancer or neoplasm in the fallopian tube which is seen in virtually all incidentally discovered high-grade serous cancers in asymptomatic women. This high-frequency of tubal involvement in early serous neoplasm (usually in the form of serous tubal intraepithelial carcinoma—STIC) has galvanized attention to this organ as a primary source of this disease. However, an enduring mystery has been the relatively low frequency of STIC in the fallopian tubes of women with advanced malignancy. This paradox, a high frequency of tubal involvement early on and a low frequency of involvement later in the disease process, has spurred interest in other potential sources, such as the ovarian surface epithelium or cortical inclusions and the secondary Mullerian system. However, because essentially all high-grade serous carcinomas are linked by TP53 mutations, and because fallopian tubes frequently contain early serous proliferations (ESPs) with these mutations, attention has turned to the possibility that the nonmalignant but TP53 mutated tubal epithelium could be responsible for an eventual malignancy. Recent data have shown evidence of a lineage continuity between ESPs and concurrent serous carcinomas prompting the concept of “precursor escape”. This creates a second component of the paradigm by which cells from early precursors are shed from the tube and undergo subsequent malignant transformation, emerging suddenly as widespread intraperitoneal malignancy. This dualistic model thus provides a unique pathway by which the future outcome (wide spread high-grade serous carcinomas—HGSC) is ultimately explained by going back in time to an early serous proliferation. This paradigm also brings the peritoneal cavity into focus, raising new questions about the potential co-variables or exposures that might facilitate the occasional malignant transformation of an ESP in the peritoneal cavity or on the peritoneal surface.

Defective Nuclear Lamina in Aneuploidy and Carcinogenesis

Aneuploidy, loss or gain of whole chromosomes, is a prominent feature of carcinomas, and is generally considered to play an important role in the initiation and progression of cancer. In high-grade serous ovarian cancer, the only common gene aberration is the p53 point mutation, though extensive genomic perturbation is common due to severe aneuploidy, which presents as a deviant karyotype. Several mechanisms for the development of aneuploidy in cancer cells have been recognized, including chromosomal non-disjunction during mitosis, centrosome amplification, and more recently, nuclear envelope rupture at interphase. Many cancer types including ovarian cancer have lost or reduced expression of Lamin A/C, a structural component of the lamina matrix that underlies the nuclear envelope in differentiated cells. Several recent studies suggest that a nuclear lamina defect caused by the loss or reduction of Lamin A/C leads to failure in cytokinesis and formation of tetraploid cells, transient nuclear envelope rupture, and formation of nuclear protrusions and micronuclei during the cell cycle gap phase. Thus, loss and reduction of Lamin A/C underlies the two common features of cancer—aberrations in nuclear morphology and aneuploidy. We discuss here and emphasize the newly recognized mechanism of chromosomal instability due to the rupture of a defective nuclear lamina, which may account for the rapid genomic changes in carcinogenesis.

Preclinical Models of Ovarian Cancer: Pathogenesis, Problems, and Implications for Prevention

Preclinical models are relatively underutilized and underfunded resources for modeling the pathogenesis and prevention of ovarian cancers. Several reviews have detailed the numerous published models of ovarian cancer. In this review, we will provide an overview of experimental model systems, their strengths and limitations, and use selected models to illustrate how they can be used to address specific issues about ovarian cancer pathogenesis. We will then highlight some of the preclinical prevention studies performed to date and discuss experiments needed to address important unanswered questions about ovarian cancer prevention strategies.

BRCA Mutation Status Is Not Associated With Increased Hematologic Toxicity Among Patients Undergoing Platinum-Based Chemotherapy for Ovarian Cancer

OBJECTIVE

Women with an inherited BRCA1 or BRCA2 mutation may have an impaired ability to repair chemotherapy-induced damage as a result of a state of haploinsufficiency and may experience greater treatment-related toxicity. The objective of this study was to compare the hematologic adverse effect profiles associated with platinum-based chemotherapy in ovarian cancer patients with and without germline BRCA mutations.

METHODS

We conducted a retrospective analysis of patients treated for high-grade serous ovarian cancer at Princess Margaret Cancer Center, Toronto, Ontario between January 2000 and December 2015. We included only women with known BRCA mutation status and who received first-line platinum-based chemotherapy. We compared 3 primary measures of myelosuppression (ie, hemoglobin levels, platelet counts, and neutrophil counts) before each cycle of chemotherapy in patients with and without a BRCA mutation.

RESULTS

We included 130 BRCA mutation carriers and 302 noncarriers who met the eligibility criteria. There were no significant differences in baseline hemoglobin levels, neutrophil counts, or platelet counts between the groups (P ≥ 0.31). We found no significant difference in 3 measures of hematologic toxicity (ie, neutropenia, anemia, or thrombocytopenia) based on BRCA mutation status across all chemotherapy cycles (P ≥ 0.06). Although BRCA mutation carriers were more likely to experience an absolute neutrophil count below 1.0 × 10/L than noncarriers (P = 0.02), this did not translate to an increased frequency of dose reduction or dose delay.

DISCUSSION

Among women with ovarian cancer, hematologic toxicity does not appear to be more frequent in BRCA mutation carriers than in noncarriers. This is reassuring for clinicians treating ovarian cancer patients with respect to dosing regimens. These findings do not support the hypothesis that a haploinsufficiency phenotype exists with respect to the repair of chemotherapy-induced double-strand DNA breaks in this high-risk population.

Extrauterine high-grade serous carcinomas with bilateral adnexal involvement as the only two disease sites are clonal based on tp53 sequencing results: implications for biology, classification, and staging

A previous multicenter study of 67 cases of Stage I/II tubo-ovarian high-grade serous carcinoma with complete tubal sampling identified 7 cases in which there were only two disease sites, comprising tumor involving opposite adnexa with no extra-adnexal involvement. This study aimed to determine whether such low-stage extrauterine high-grade serous carcinomas with only two sites of involvement, located on opposite adnexa, have identical or different TP53 mutations in order to investigate their clonal relationship. DNA extracted from both sites of involvement was subjected to TP53 sequencing (n=6) or sequencing of one site and mutation confirmation by droplet digital PCR for the other site (n=1). Of the 7 cases analyzed, 1 case had unilateral serous tubal intraepithelial carcinoma with contralateral ovarian high-grade serous carcinoma, 3 had tubal high-grade serous carcinomas (±serous tubal intraepithelial carcinoma) with contralateral ovarian high-grade serous carcinoma, 2 had bilateral ovarian high-grade serous carcinomas with normal tubes, and 1 had bilateral fallopian tube high-grade serous carcinoma with normal ovaries. All 7 cases showed identical TP53 mutations in tumor from both disease sites. Therefore, these rare cases of high-grade serous carcinoma confined to opposite adnexa all show clonal identity between the two sites of involvement, suggesting unifocal origin and metastasis rather than multifocal origin. Our results suggest that serous tubal intraepithelial carcinoma or adnexal high-grade serous carcinoma can metastasize to the contralateral adnexa without peritoneal involvement. Given the clonal relationship between the two sites, such cases should be considered stage II, with stage I reserved for cases with unilateral and unifocal adnexal involvement. Furthermore, serous tubal intraepithelial carcinoma without invasion should be taken to constitute a disease site for staging purposes.

Observations on the origin of ovarian cortical inclusion cysts in women undergoing risk-reducing salpingo-oophorectomy

AIMS

Evidence suggests that up to 70% of high-grade serous ovarian carcinomas (HGSCs) arise potentially from fallopian tube fimbriae, and that many of the remaining cases arise from within the ovary in cortical inclusion cysts (CICs) with a Müllerian phenotype (Müllerian-CICs). It has been proposed that Müllerian-CICs arise either from metaplasia of mesothelial ovarian surface epithelium (OSE) entrapped within the ovary after ovulation or from normal tubal cells entrapped postovulation. However, this proposal is controversial. We therefore conducted a study of CICs in women, most of them BRCA1/2 mutation carriers, undergoing risk-reducing salpingo-oophorectomy at our institution from 2000 to 2014.

METHODS AND RESULTS

We used immunohistochemistry for PAX8, a Müllerian marker, and calretinin, a mesothelial marker to classify CIC cells. In 499 CICs from 59 women, 72.3% were positive for PAX8 (PAX8⁺ ): ≥10% of CIC cells positive; 43.5% positive for calretinin (calretinin⁺ ). The proportion of PAX8⁺ CICs increased from 62.9% in premenopausal to 80.5% in postmenopausal patients. The proportion of calretinin⁺ CICs decreased from 52.6% to 35.6%, respectively. There was significant overlap of PAX8 and calretinin positivity: 82 (16.4%) CICs were PAX8⁺ /calretinin⁺ ; 43 (40.2%) of these 82 demonstrated PAX8⁺ /calretinin⁺ in the same cells.

CONCLUSIONS

These results, and the increased ratio of PAX8⁺ to calretinin⁺ CICs from premenopausal to postmenopausal, show that many PAX8⁺ CICs probably arise from metaplasia of OSE-derived CICs. The proportion of PAX⁺ /calretinin^- CICs arising from OSE-derived CICs is unclear, but our results strongly support the proposal that many Müllerian-CICs arise from OSE via metaplasia.

Low-Stage High-Grade Serous Ovarian Carcinomas: Support for an Extraovarian Origin

Many adnexal high-grade serous carcinomas (HGSCs) may derive from microscopic precursors in the fallopian tube. By studying a series of low-stage ovarian carcinomas, we anticipated that HGSCs would be distributed in a pattern suggesting secondary involvement, helping to indirectly validate the fallopian tube origin theory, and that most ovarian carcinomas other than serous carcinomas would demonstrate features consistent with derivation from precursors located in or transplanted to the ovary. Seventy-six patients with low-stage (FIGO I/II) sporadic ovarian carcinoma who underwent primary surgical management at Memorial Sloan Kettering Cancer Center from 1980 to 2000 were included in the study. Histologic type was assigned using Gilks' criteria. Similar to the approach taken when distinguishing primary and metastatic mucinous or endometrioid carcinoma involving ovary, cases interpreted as showing a "primary" pattern of ovarian involvement had ≥3 of the following features: unilateral tumor, size >12 cm, no surface involvement, no multinodularity, and no destructive stromal invasion. All other cases were considered to show a "metastatic" pattern of ovarian involvement. Cases were evaluated for p53 and WT-1 expression, using standard techniques on a tissue microarray. TP53 gene sequencing was also performed. Cases comprised HGSC (n=22), endometrioid carcinoma (n=30), clear cell carcinoma (n=13), and mucinous carcinoma (n=11). HGSCs displayed substantially more "metastatic features" than the non-HGSC group and a mean overall size that was smaller (8.85 vs. 14.1 cm). Statistically significant differences were found for bilaterality (63% vs. 7.3%), P=0.0001; multinodularity (55% vs. 7.3%), P=0.0001; tumor size, P=0.003; and surface involvement (50% vs. 13%), P=0.002. Five of 22 (23%) of HGSCs showed a "primary pattern" of ovarian involvement. There were no significant differences between these cases and "metastatic pattern" HGSCs when comparing morphology, immunophenotype, TP53 mutational status, and clinical outcomes. Most low-stage HGSCs demonstrate patterns of ovarian involvement that suggest metastasis from another source, such as the fallopian tube. Both metastatic pattern HGSCs and unilateral, low-stage HGSCs can behave aggressively.

Molecular analysis of high-grade serous ovarian carcinoma with and without associated serous tubal intra-epithelial carcinoma

Many high-grade serous carcinomas (HGSCs) of the pelvis are thought to originate in the distal portion of the fallopian tube. Serous tubal intra-epithelial carcinoma (STIC) lesions are the putative precursor to HGSC and identifiable in ~ 50% of advanced stage cases. To better understand the molecular etiology of HGSCs, we report a multi-center integrated genomic analysis of advanced stage tumors with and without STIC lesions and normal tissues. The most significant focal DNA SCNAs were shared between cases with and without STIC lesions. The RNA sequence and the miRNA data did not identify any clear separation between cases with and without STIC lesions. HGSCs had molecular profiles more similar to normal fallopian tube epithelium than ovarian surface epithelium or peritoneum. The data suggest that the molecular features of HGSCs with and without associated STIC lesions are mostly shared, indicating a common biologic origin, likely to be the distal fallopian tube among all cases.High-grade serous carcinomas (HGSCs) are associated with precursor lesions (STICs) in the fallopian epithelium in only half of the cases. Here the authors report the molecular analysis of HGSCs with and without associated STICs and show similar profiles supporting a common origin for all HGSCs.

Cells of origin of ovarian cancer: ovarian surface epithelium or fallopian tube?

OBJECTIVE

Ovarian cancer is the fifth most common cancer in women and one of the leading causes of death from gynecological malignancies. Despite of its clinical importance, ovarian tumorigenesis is poorly understood and prognosis remains poor. This is particularly true for the most common type of ovarian cancer, high-grade serous ovarian cancer.

RESULTS

Two models are considered, whether it arises from the ovarian surface epithelium or from the fallopian tube. The first model is based on (1) the pro-inflammatory environment caused by ovulation events, (2) the expression pattern of ovarian inclusion cysts, and (3) biomarkers that are shared by the ovarian surface epithelium and malignant growth. The model suggesting a non-ovarian origin is based on (1) tubal precursor lesions, (2) genetic evidence of BRCA1/2 mutation carriers, and (3) recent animal studies. Neither model has clearly demonstrated superiority over the other. Therefore, one can speculate that high-grade serous ovarian cancer may arise from two different sites that undergo similar changes. Both tissues are derived from the same embryologic origin, which may explain how progenitor cells from different sites can respond similar to stimuli within the ovaries. However, distinct molecular drivers, such as BRCA deficiency, may still preferentially arise from one site of origin as precancerous mutations are frequently seen in the fallopian tube.

CONCLUSIONS

Confirming the origin of ovarian cancer has important clinical implications when deciding on cancer risk-reducing prophylactic surgery. It will be important to identify key biomarker to uncover the sequence of ovarian tumorigenesis.

Serous tubal intraepithelial neoplasia: the concept and its application

In recent years it has become clear that many extra-uterine (pelvic) high-grade serous carcinomas (serous carcinomas) are preceded by a precursor lesion in the distal fallopian tube. Precursors range from small self-limited 'p53 signatures' to expansile serous tubal intraepithelial neoplasms that include both serous tubal epithelial proliferations (or lesions) of uncertain significance and serous tubal intraepithelial carcinomas. These precursors can be considered from three perspectives. The first is biologic underpinnings, which are multifactorial, and include the intersection of DNA damage with Tp53 mutations and disturbances in transcriptional regulation that increase with age. The second perspective is the morphologic discovery and classification of intraepithelial neoplasms that are intercepted early in their natural history, either incidentally or in risk-reduction surgeries for germline mutations. For the practicing pathologist, as well as the investigators, a distinction between a primary intraepithelial neoplasm and an intramucosal carcinoma must be made to avoid misinterpreting (or underestimating) the significance of these proliferations. The third perspective is the application of this information to intervention, devising strategies that will actually lower the ovarian cancer death rate by opportunistic salpingectomy, widespread comprehensive genetic screening and early detection. Central to this issue are the questions of (1) whether some STICs are metastatic, (2) whether lower-grade epithelial proliferations can invade prior to evolving into intraepithelial carcinoma, or (3) metastasize and become malignant elsewhere ('precursor escape'). An important caveat is the persistent and unsettling reality that many high-grade serous carcinomas are not associated with an obvious point of initiation in the fallopian tube. The pathologist sits squarely in the midst of all of these issues, and has a pivotal role in managing expectations for stemming the death rate from this lethal disease.

The disparate origins of ovarian cancers: pathogenesis and prevention strategies

Ovarian cancer is the fifth cause of cancer-related death in women and comprises a histologically and genetically broad range of tumours, including those of epithelial, sex cord-stromal and germ cell origin. Recent evidence indicates that high-grade serous ovarian carcinoma, clear cell carcinoma and endometrioid carcinoma primarily arise from tissues that are not normally present in the ovary. These histogenetic pathways are informing risk-reduction strategies for the prevention of ovarian and ovary-associated cancers and have highlighted the importance of the seemingly unique ovarian microenvironment.

Redefining the origin and evolution of ovarian cancer: a hormonal connection

Ovarian cancer has the highest mortality of all female reproductive cancers. Late diagnosis, tumour heterogeneity and the development of chemoresistance contribute to this statistic and work against patient survival. Current studies have revealed novel concepts that impact our view on how ovarian cancer develops. The greatest impact is on our understanding that, as a disease, ovarian cancer has multiple cellular origins and that these malignant precursors are mostly derived from outside of the ovaries. In this review, we propose a new concept of a step-wise developmental process that may underwrite ovarian tumorigenesis and progression: (1) migration/recruitment to the ovaries; (2) seeding and establishment in the ovaries; (3) induction of a dormant cancer stage; and (4) expansion and tumor progression. We will discuss the relationship of each step with the changing ovarian function and milieu during the reproductive age and the subsequent occurrence of menopause. The realization that ovarian cancer development and progression occurs in distinct steps is critical for the search of adequate markers for early detection that will offer personalized strategies for prevention and therapy.

Rationale for Developing a Specimen Bank to Study the Pathogenesis of High-Grade Serous Carcinoma: A Review of the Evidence

Women with clinically detected high-grade serous carcinomas (HGSC) generally present with advanced-stage disease, which portends a poor prognosis, despite extensive surgery and intensive chemotherapy. Historically, HGSCs were presumed to arise from the ovarian surface epithelium (OSE), but the inability to identify early-stage HGSCs and their putative precursors in the ovary dimmed prospects for advancing our knowledge of the pathogenesis of these tumors and translating these findings into effective prevention strategies. Over the last decade, increased BRCA1/2 mutation testing coupled with performance of risk-reducing surgeries has enabled studies that have provided strong evidence that many, but probably not all, HGSCs among BRCA1/2 mutation carriers appear to arise from the fallopian tubes, rather than from the ovaries. This shift in our understanding of the pathogenesis of HGSCs provides an important opportunity to achieve practice changing advances; however, the scarcity of clinically annotated tissues containing early lesions, particularly among women at average risk, poses challenges to progress. Accordingly, we review studies that have kindled our evolving understanding of the pathogenesis of HGSC and present the rationale for developing an epidemiologically annotated national specimen resource to support this research. Cancer Prev Res; 9(9); 713-20. ©2016 AACR.

Integrative proteomic profiling of ovarian cancer cell lines reveals precursor cell associated proteins and functional status

A cell line representative of human high-grade serous ovarian cancer (HGSOC) should not only resemble its tumour of origin at the molecular level, but also demonstrate functional utility in pre-clinical investigations. Here, we report the integrated proteomic analysis of 26 ovarian cancer cell lines, HGSOC tumours, immortalized ovarian surface epithelial cells and fallopian tube epithelial cells via a single-run mass spectrometric workflow. The in-depth quantification of >10,000 proteins results in three distinct cell line categories: epithelial (group I), clear cell (group II) and mesenchymal (group III). We identify a 67-protein cell line signature, which separates our entire proteomic data set, as well as a confirmatory publicly available CPTAC/TCGA tumour proteome data set, into a predominantly epithelial and mesenchymal HGSOC tumour cluster. This proteomics-based epithelial/mesenchymal stratification of cell lines and human tumours indicates a possible origin of HGSOC either from the fallopian tube or from the ovarian surface epithelium.

High-grade serous ovarian cancer is the most common and aggressive ovarian cancer, with uncertain cell of origin. Here, the authors undertake a mass spectrometric analysis of 26 cancer cell lines and identify a protein signature that classifies ovarian cancer tissues into epithelial and mesenchymal groups.

Application of multiplex nested methylated specific PCR in early diagnosis of epithelial ovarian cancer

OBJECTIVE

To explore the application of multiplex nested methylated specific polymerase chain reaction (PCR) in the early diagnosis of epithelial ovarian carcinoma (EOC).

MATERIALS AND METHODS

Serum and fresh tissue samples were collected from 114 EOC patients. RUNX3, TFPI2 and OPCML served as target genes. Methylation levels of tissues were assessed by multiplex nested methylated specific PCR, the results being compared with those for carcinoma antigen 125 (CA125).

RESULTS

The serum free deoxyribose nucleic acid (DNA) methylation spectrum of EOC patients was completely contained in the DNA spectrum of cancer tissues, providing an accurate reflection of tumor DNA methylation conditions. Serum levels of CA125 and free DNA methylation in the EOC group were evidently higher than those in benign lesion and control groups (p<0.05). Patients with early EOC had markedly lower serum CA125 than those with advanced EOC (p<0.05), but there was no significant difference in free DNA methylation (p>0.05). The sensitivity, specificity and positive predicative value (PPV) of multiplex nested methylated specific PCR were significantly higher for detection of all patients and those with early EOC than those for CA125 (p<0.05). In the detection of patients with advanced EOC, the PPV of CA125 detection was obviously lower than that of multiplex nested methylated specific PCR (p>0.05), but there was no significant difference in sensitivity (p>0.05).

CONCLUSIONS

Serum free DNA methylation can be used as a biological marker for EOC and multiplex nested methylated specific PCR should be considered for early diagnosis since it can accurately determine tumor methylation conditions.

[Importance of the tumor stem cell hypothesis for understanding ovarian cancer]

BACKGROUND

Despite complex surgical and systemic therapies epithelial ovarian cancer has a poor prognosis. A small quantity of tumorigenic cells termed cancer stem cells (CSC) are responsible for the development of chemoresistance and high rates of recurrence.

OBJECTIVES

This review presents the CSC hypothesis and describes methods of identification and enrichment of CSCs as well as approaches for the therapeutic use of these findings.

MATERIAL AND METHODS

A systematic literature review based on PubMed and Web of Science was carried out.

RESULTS

The CSC model is based on a hierarchical structure of tumors with few CSCs and variably differentiated tumor cells constituting the tumor bulk. Only the CSCs possess tumorigenic potential. Other essential functional characteristics of CSCs are their potential for self-renewal and their ability to differentiate into further cell types. The CSCs are structurally characterized by different surface markers and changes in certain signaling pathways. Currently there are phase I and II studies in progress investigating specific influences on CSCs.

CONCLUSION

Various clinical characteristics of the course of disease in ovarian cancer are aptly represented by the tumor stem cell model. In spite of precisely defined functional characteristics of CSCs, surface markers and signaling pathways show individual differences and vary between tumor entities. This complicates identification and enrichment. Current experimental findings in various approaches and even first clinical studies raise hopes for a personalized cancer therapy targeting CSCs.

PAX8 expression in ovarian surface epithelial cells

High-grade serous ovarian carcinoma (HGSOC) is usually diagnosed at a late stage and is associated with poor prognosis. Understanding early stage disease biology is essential in developing clinical biomarkers to detect HGSOC earlier. While recent studies indicate that HGSOCs arise from fallopian tube secretory epithelial cells, a considerable body of evidence suggests that HGSOC can also arise from ovarian surface epithelial cells (OSECs). PAX8 is overexpressed in HGSOCs and expressed in fallopian tube secretory epithelial cells, but there are conflicting reports about PAX8 expression in OSECs. The purposes of this study were to comprehensively characterize PAX8 expression in a large series of OSECs and to investigate the role of PAX8 in early HGSOC development. PAX8 protein expression was analyzed in the OSECs of 27 normal ovaries and 7 primary OSEC cultures using immunohistochemistry and immunofluorescent cytochemistry. PAX8 messenger RNA expression was quantified in 66 primary OSEC cultures. Cellular transformation was evaluated in OSECs expressing a PAX8 construct. PAX8 was expressed by 44% to 71% of OSECs. Calretinin and E-cadherin were frequently coexpressed with PAX8. Expression of PAX8 in OSECs decreased cellular migration (P = .028), but had no other effects on cellular transformation. In addition, PAX8 expression was significantly increased (P = .003) in an in vitro stepwise model of neoplastic transformation. In conclusion, PAX8 is frequently expressed by OSECs, and endogenous levels of PAX8 expression are non-transforming. These data indicate that in OSECs, PAX8 expression may represent a normal state and that OSECs may represent an origin of HGSOCs.

Role of the stem cell niche in the pathogenesis of epithelial ovarian cancers

Ovarian cancer is the fifth leading cause of cancer-related deaths among women in the United States. Recent extensive genomic analyses of epithelial ovarian cancer (EOC), particularly the most common and deadly form of high-grade serous ovarian carcinoma, have provided important insights into the repertoire of molecular aberrations that are characteristic for this malignancy. However, interpretation of the discovered aberrations is complicated because the origin and mechanisms of progression of EOC remain uncertain. Here, we summarize current views on the cell of origin of EOC and discuss recent findings of a cancer-prone stem cell niche for ovarian surface epithelium, one of the major likely sources of EOC. We also outline future directions and challenges in studying the role of stem cell niches in EOC pathogenesis.

Epithelial ovarian cancer stem cells: underlying complexity of a simple paradigm

The lack of significant progress in the treatment of epithelial ovarian cancer (EOC) underscores the need to gain a better understanding of the processes that lead to chemoresistance and recurrence. The cancer stem cell (CSC) hypothesis offers an attractive explanation of how a subpopulation of cells within a patient's tumour might remain refractory to treatment and subsequently form the basis of recurrent chemoresistant disease. This review examines the literature defining somatic stem cells of the ovary and fallopian tube, two tissues that give rise to EOC. In addition, considerable research has been reviewed, that has identified subpopulations of EOC cells, based on marker expression (CD133, CD44, CD117, CD24, epithelial cell adhesion molecule, LY6A, ALDH1 and side population (SP)), which are enriched for tumour initiating cells (TICs). While many studies identified either CD133 or CD44 as markers useful for enriching for TICs, there is little consensus. This suggests that EOC cells may have a phenotypic plasticity that may preclude the identification of universal markers defining a CSC. The assay that forms the basis of quantifying TICs is the xenograft assay. Considerable controversy surrounds the xenograft assay and it is essential that some of the potential limitations be examined in this review. Highlighting such limitations or weaknesses is required to properly evaluate data and broaden our interpretation of potential mechanisms that might be contributing to the pathogenesis of ovarian cancer.

The association of serous tubal intraepithelial carcinoma with gynecologic pathologies and its role in pelvic serous cancer

OBJECTIVES

Possible primary sites of pelvic serous cancers are, fallopian tubes, ovaries or peritoneum. Recent studies have revealed that a portion of these tumors originates from serous tubal intraepithelial carcinoma (STIC) at the distal end of fallopian tubes. In this study, the association of STIC with pelvic serous carcinomas and the pathologic parameters that indicate the tubes as the primary site were assessed.

METHODS

In total, 495 pairs of fallopian tubes obtained via total abdominal hysterectomy and bilateral salpingo-oophorectomy between 2011 and 2013 were examined according to SEE-FIM protocol. Hematoxylin and eosin-stained slides were examined by pathologists. Suspicious areas were immunostained with p53 and Ki-67 to diagnose STIC precisely.

RESULTS

Of the 495 cases, 110 cases were malignant. Among 34 cases of non-uterine serous carcinomas, 13 were diagnosed with STIC. STIC was located at the fimbrial end of the fallopian tubes in 12 cases. No STIC was identified in the gynecologic malignancies other than non-uterine serous pelvic carcinomas and benign gynecologic pathologies. Comparison of the ovarian and tubal cancer cases with and without STIC did not reveal a factor that helps to define the primary site. STIC was an important factor associated in a higher portion of the cases with bilateral ovarian cancer.

CONCLUSION

The role of STIC in carcinogenesis continues to be discussed as it is unknown whether STIC is the precursor lesion or just associates with the malignancies. Discovering the accurate precursor lesions and tumor carcinogenesis is essential to prevent these malignancies and to develop early diagnostic methods.

Origin and molecular pathogenesis of ovarian high-grade serous carcinoma

A new paradigm for the pathogenesis of ovarian cancer has recently been proposed which helps to explain persistent problems in describing the development and diverse morphology of these neoplasms. The paradigm incorporates recent advances in our understanding of the molecular pathogenesis of epithelial 'ovarian' cancer with new insights into the origin of these tumors. Correlated clinicopathologic and molecular genetic studies led to the development of a dualistic model that divides all the various histologic types of epithelial ovarian carcinomas into two broad categories designated 'type I' and 'type II'. The prototypic type I tumor is low-grade serous carcinoma and the prototypic type II tumor is high-grade serous carcinomas (HGSCs). As the serous tumors comprise ∼70% of all epithelial ovarian tumors and account for the majority of deaths, the serous tumors will be the subject of this review. There are marked differences between the low-grade and high-grade serous tumors. Briefly, the former are indolent, present in stage I (tumor confined to the ovary) and develop from well-established precursors, so-called 'atypical proliferative (borderline) tumors,' which are characterized by specific mutations, including KRAS, BRAF and ERBB2; they are relatively genetically stable. In contrast, HGSCs are aggressive, present in the advanced stage, and develop from intraepithelial carcinomas in the fallopian tube. They harbor TP53 mutations in over 95% of cases, but rarely harbor the mutations detected in the low-grade serous tumors. At the time of diagnosis they demonstrate marked chromosomal aberrations but over the course of the disease these changes remain relatively stable. Along with the recent advances in understanding the molecular pathogenesis of these tumors, studies have demonstrated that the long sought for precursor of ovarian HGSC appears to develop from an occult intraepithelial carcinoma in the fimbrial region of the fallopian tube designated 'serous tubal intraepithelial carcinoma (STIC)' and involves the ovary secondarily. Another possible mechanism for the development of ''ovarian'' HGSC is implantation of normal fimbrial epithelium on the denuded ovarian surface at the site of rupture when ovulation occurs. We speculate that this tubal epithelium can result in the formation of a cortical inclusion cyst (CICs) that can then undergo malignant transformation. Thus, serous tumors may develop from inclusion cysts, as has been previously proposed, but by a process of implantation of tubal (müllerian-type) tissue rather than by a process of metaplasia from ovarian surface epithelium (OSE, mesothelial). The dualistic model serves as a framework for studying ovarian cancer and can assist investigators in organizing this complex group of neoplasms. In conjunction with the recognition that the majority of 'ovarian' carcinomas originate outside the ovary, this model also facilitates the development of new and novel approaches to prevention, screening and treatment of this devastating disease.

Early preinvasive lesions in ovarian cancer

Faced with the catastrophic prognosis for ovarian cancer due to the fact that it is most often diagnosed late at the peritoneal carcinomatosis stage, screening and early detection could probably reduce the mortality rate. A better understanding of the molecular characteristics of the different ovarian cancer subtypes and their specific molecular signatures is indispensable prior to development of new screening strategies. We discuss here the early natural history of ovarian cancer and its origins.

CDKN2D-WDFY2 is a cancer-specific fusion gene recurrent in high-grade serous ovarian carcinoma

Ovarian cancer is the fifth leading cause of cancer death in women. Almost 70% of ovarian cancer deaths are due to the high-grade serous subtype, which is typically detected only after it has metastasized. Characterization of high-grade serous cancer is further complicated by the significant heterogeneity and genome instability displayed by this cancer. Other than mutations in TP53, which is common to many cancers, highly recurrent recombinant events specific to this cancer have yet to be identified. Using high-throughput transcriptome sequencing of seven patient samples combined with experimental validation at DNA, RNA and protein levels, we identified a cancer-specific and inter-chromosomal fusion gene CDKN2D-WDFY2 that occurs at a frequency of 20% among sixty high-grade serous cancer samples but is absent in non-cancerous ovary and fallopian tube samples. This is the most frequent recombinant event identified so far in high-grade serous cancer implying a major cellular lineage in this highly heterogeneous cancer. In addition, the same fusion transcript was also detected in OV-90, an established high-grade serous type cell line. The genomic breakpoint was identified in intron 1 of CDKN2D and intron 2 of WDFY2 in patient tumor, providing direct evidence that this is a fusion gene. The parental gene, CDKN2D, is a cell-cycle modulator that is also involved in DNA repair, while WDFY2 is known to modulate AKT interactions with its substrates. Transfection of cloned fusion construct led to loss of wildtype CDKN2D and wildtype WDFY2 protein expression, and a gain of a short WDFY2 protein isoform that is presumably under the control of the CDKN2D promoter. The expression of short WDFY2 protein in transfected cells appears to alter the PI3K/AKT pathway that is known to play a role in oncogenesis. CDKN2D-WDFY2 fusion could be an important molecular signature for understanding and classifying sub-lineages among heterogeneous high-grade serous ovarian carcinomas.

High-grade serous carcinoma (HG-SC) is the most common subtype of ovarian cancer observed in women. This subtype of ovarian cancer is typically detected at advanced stages due to lack of effective early screening tools. Recurrent cancer-specific gene fusions resulting from chromosomal translocations have the potential to serve as effective screening tools as well as therapeutic targets. Here we identified CDKN2D-WDFY2 as a cancer-specific fusion gene present in 20% of HG-SC tumors, by far the most frequent gene recombinant event found in this highly heterogeneous disease. We also presented evidence that the expression of this fusion may affect the PI3K/AKT pathway that is important for cancer progression. Thus CDKN2D-WDFY2 could very well represent a major cellular lineage important for detecting and classifying heterogeneous ovarian carcinomas, and could provide insight into the underlying mechanism of this deadly disease. This is critical, given that ovarian cancer kills 140,200 women worldwide each year, and few ovarian cancer-specific molecular alterations are currently available for targeting and screening.

Biomarkers and endosalpingiosis in the ovarian and tubal microenvironment of women at high-risk for pelvic serous carcinoma

INTRODUCTION

BRCA mutations increase the risk for development of high-grade pelvic serous carcinomas. Tissue biomarkers distinguishing women at high-risk (HR) for ovarian cancer from those at low-risk (LR) may provide insights into tumor initiation pathways.

METHODS

A prospective study of 47 HR women (40% BRCA carriers) undergoing risk-reducing salpingo-oophorectomy and 48 LR controls undergoing salpingo-oophorectomy was performed. Ovarian/tubal tissues were harvested. Immunohistochemical analysis of candidate proteins CSF-1, CSF-1R, ErbB4 is presented, with scores separately analyzed in epithelium and stroma, in ampulla, fimbria, ovary, and ovarian endosalpingiosis (ES). Comparison was performed between HR and LR groups.

RESULTS

Elevated levels of CSF-1 (p=0.005) or ErbB4 (p=0.005) in the ovarian epithelium, or ErbB4 (p=0.005) in the ovarian stroma, were significantly associated with both the HR status and carrying a BRCA mutation, as was nuclear ErbB4 staining. Ovarian ES, an entity which likely derives from the tubal mucosal epithelium, was also associated with HR (p=0.038) and BRCA mutation status (p=0.011). Among the BRCA carriers only, markers also found association when present in the tube as well as in ovarian ES (p < 0.05). ROCs were generated including in the regression model both CSF-1 and ErbB4 expression levels. A model including CSF-1 in ovarian epithelium, ErbB4 in ovarian stroma, and younger age achieves AUC=0.87 (73% sensitivity, 93% specificity) of detection of the HR status. In BRCA carriers, CSF-1 in ovarian epithelium alone achieves AUC=0.85.

CONCLUSIONS

Our data suggest that elevated levels of CSF-1/ErbB4 in the adnexae correlate with HR/BRCA carrier status. CSF-1/CSF-1R signaling is active in ovarian cancer progression; our data suggests a role in its initiation. ErbB4, in particular nuclear ErbB4, may have a role in tumor initiation as well. Ovarian ES, an entity which may represent a latent precursor to low-grade pelvic serous carcinomas, was surprisingly associated with both HR status and the BRCA carrier cohort. In line with these findings, both ErbB4 and CSF-1R expression in ovarian ES correlated with carrying a BRCA mutation. This analysis, which needs to be validated, indirectly suggests a potential link between ovarian ES and the development of pelvic serous carcinoma in women who are BRCA mutation carriers.

Through the glass darkly: intraepithelial neoplasia, top-down differentiation, and the road to ovarian cancer

It is currently hoped that deaths from extra-uterine high-grade serous cancer (HGSC) will be reduced via opportunistic salpingectomy in healthy women. Accumulated data implicate the fimbria as a site of origin and descriptive molecular pathology and experimental evidence strongly support a serous carcinogenic sequence in the Fallopian tube. Both direct and indirect ('surrogate') precursors suggest that the benign tube undergoes important biological changes after menopause, acquiring abnormalities in gene expression that are often shared with malignancy, including PAX2, ALDH1, LEF1, RCN1, RUNX2, beta-catenin, EZH2, and others. However, the tube can be linked to only some HGSCs, recharging arguments that nearby peritoneum/ovarian surface epithelium (POSE) also hosts progenitors to this malignancy. A major sticking point is the difference in immunophenotype between POSE and Müllerian epithelium, essentially requiring mesothelial to Müllerian differentiation prior to or during malignant transformation to HGSC. However, emerging evidence implicates an embryonic or progenitor phenotype in the adult female genital tract with the capacity to differentiate, normally or during neoplastic transformation. Recently, a putative cell of origin for cervical cancer has been identified in the squamo-columnar (SC) junction, projecting a model whereby Krt7+ embryonic progenitors give rise to immunophenotypically distinct progeny under stromal influences via 'top down' differentiation. Similar differentiation can be seen in the endometrium with a parallel in juxtaposed mesothelial and Müllerian differentiation in the ovary. Abrupt mesothelial-Müllerian transitions remain to be proven, but would explain the rapid evolution, short asymptomatic interval, and absence of a defined epithelial starting point in many HGSCs. Resolving this question will require accurately distinguishing progenitor from progeny tumour cells in HGSC and pinpointing where initial transformation and trans-differentiation occur, whether in the tube or POSE. Both will be critical to expectations from prophylactic salpingectomy and future approaches to pelvic serous cancer prevention.

Estrogen and androgen receptor expression in surface epithelium and inclusion cyst in the ovary of premenopausal and postmenopausal women

BACKGROUND

The importance of surface epithelium and epithelial inclusion cysts in the ovary arises from studies demonstrating that these structures are susceptible to epithelial ovarian cancer development. The expression of estrogen receptor alpha (ER alpha), androgen receptor (AR), in epithelial cells of the ovary from premenopausal and postmenopausal women is interesting because sexual steroid hormones are involved in cell growth and differentiation.

METHODS

The presence of ER alpha, AR, and the orphan G protein-coupled receptor 30 (GPR30) was demonstrated by immunofluorescence in ovaries obtained from 79 pre and postmenopausal patients, undergoing histero-salpingo-oophorectomy for proliferative gynecological diseases. The proportion of patients that displayed positive reaction for estrogen and androgen receptors in epithelial cells of the ovary was evaluated according to menopausal status and associated pathology.

RESULTS

The proportion of patients that displayed a positive receptor expression in the epithelial cells of the ovarian surface and cortical inclusion cysts shows that ER alpha is present in 20 of 79 patients (0.25), AR in 33 of 79 (0.42) and GPR30 in 38 of 55 (0.69). There are no differences in ER alpha, AR, and GPR30 expression between pre and postmenopausal patients and considering the associated pathology, proportions for ER alpha and GPR30 are similar. The patients with cervical cancer show a higher proportion of AR expression in epithelial cells of the ovary, which is statistically significant (P < 0.01) compared with patients with other proliferative diseases.

CONCLUSIONS

The presence of ER alpha, AR, and GPR30 in the surface epithelial ovarian cells and its derivatives are observed with a proportion that is specific for each receptor. The proportion of expression for these receptors in the epithelial cells of the ovary does not change after menopause. The proportion of ovaries with AR positive epithelial cells in patients with cervical squamous carcinoma is higher compared with other gynecological pathologies.

Origin and pathogenesis of pelvic (ovarian, tubal, and primary peritoneal) serous carcinoma

A new paradigm for the pathogenesis of female pelvic cancer helps explain persistent problems in describing the development and diverse morphology of these neoplasms. This paradigm incorporates recent advances in the molecular pathogenesis of epithelial ovarian cancer (EOC) with new insights into the origin of these tumors. Correlated clinicopathologic and molecular genetic studies gave rise to a dualistic model that divides the various histologic types of EOCs into two broad categories designated type I and type II. Because serous carcinomas are the most common EOC and account for the vast majority of deaths, they form the subject of this review. Recent studies indicate that the precursor of ovarian high-grade serous carcinoma appears to develop from an occult intraepithelial carcinoma in the fimbria of the fallopian tube and involves the ovary secondarily. Another possible mechanism is implantation of normal fimbrial epithelium on the denuded ovarian surface at the site of rupture when ovulation occurs, causing the development of cortical inclusion cysts. The dualistic model serves as a framework for the study of ovarian cancer and can help investigators organize this complex group of neoplasms. It also facilitates the development of novel approaches to prevention, screening, and treatment of this devastating disease.

Apolipoprotein concentrations are elevated in malignant ovarian cyst fluids suggesting that lipoprotein metabolism is dysregulated in epithelial ovarian cancer

SELDI-TOF MS analysis of ovarian cyst fluids revealed that peaks m/z 8696 and 8825 discriminate malignant, borderline, and benign tumors. These peaks correspond to isoforms of apoA2. ELISA demonstrates that apoA1, A2, B, C2, C3, and E cyst fluid concentrations are uncorrelated and higher in malignant ovarian tumors, but only apoA2, apoE, and age are independent classifiers of malignant ovarian tumors, yielding 55.1% sensitivity, 95% specificity, and 88.1% accuracy to discern malignant from benign and borderline tumors. These data suggest that lipoprotein metabolism is dysregulated in ovarian cancer and that apoA2 and apoE warrant further investigation as ovarian tumor biomarkers.

The molecular fingerprint of high grade serous ovarian cancer reflects its fallopian tube origin

High grade serous ovarian cancer (HGSC), the most lethal and frequent type of epithelial ovarian cancer (EOC), has poor long term prognosis due to a combination of factors: late detection, great metastatic potential and the capacity to develop resistance to available therapeutic drugs. Furthermore, there has been considerable controversy concerning the etiology of this malignancy. New studies, both clinical and molecular, strongly suggest that HGSC originates not from the surface of the ovary, but from the epithelial layer of the neighboring fallopian tube fimbriae. In this paper we summarize data supporting the central role of fallopian tube epithelium in the development of HGSC. Specifically, we address cellular pathways and regulatory mechanisms which are modulated in the process of transformation, but also genetic changes which accumulate during disease progression. Similarities between fallopian tube mucosa and the malignant tissue of HGSC warrant a closer analysis of homeostatic mechanisms in healthy epithelium in order to elucidate key steps in disease development. Finally, we highlight the importance of the cancer stem cell (CSC) identification and understanding of its niche regulation for improvement of therapeutic strategies.

Tu-be or not tu-be: that is the question… about serous ovarian carcinogenesis

Our understanding of the early natural history of epithelial ovarian carcinoma is limited by the access to early lesions as the disease is very often diagnosed at advanced stages. The incessant ovulation theory from the last century that indicated the ovary as the site for the initiation of high-grade serous cancers is contrary to the newly emerging idea that ovarian cancer could arise from the distal fallopian tube. In view of the recent pathological and molecular studies, we propose to discuss the genesis of high-grade serous ovarian cancer.