Fallopian tube correlates of ovarian serous borderline tumors

Ciliated Cells in Ovarian Cancer Decrease with Increasing Tumor Grade and Disease Progression

Ciliated cell markers expressed in epithelial ovarian cancers (EOC) are associated with improved survival. We examined the distribution of cells expressing ciliated cell markers in various EOC histologies and stages. Immunohistochemistry and/or multiplex immunofluorescence were used to determine the expression of FOXJ1 and/or CAPS (ciliated cell markers) in tissue microarrays including 4 normal fallopian tubes, 6 normal endometria, 16 cystadenomas, 25 borderline tumors, 21 low-grade carcinomas, and 118 high-grade carcinomas (HGSOC) (46 serous, 29 endometrioid, 30 clear cell, 13 mucinous). CAPS+ cells were observed in normal fallopian tubes and endometria and in ~85% of serous benign and borderline tumors and low-grade carcinomas but only in <40% of HGSOC. mRNA data from an independent cohort showed higher FOXJ1 and CAPS expression in serous borderline tumors and low-grade carcinomas compared to HGSOC. In HGSOC, ciliated cell-positive markers were observed in 52% primary tumors compared to 26% of patient-matched synchronous metastases, and 24% metachronous metastases (p = 0.009). mRNA data from an independent HGSOC cohort showed lower levels of CAPS in metastases than in primary tumors (p = 0.03). Overall, the study revealed that ciliated cells were less common in mucinous EOC, the percentage of ciliated cell marker-positive cases decreased with increasing grade, and the percentage of ciliated cells decreased in HGSOC metastases compared to patient-matched primary tumors.

Serous tubal intraepithelial carcinoma: What Do We Really Know at this Point?

Serous tubal intraepithelial carcinoma (STIC) is the earliest morphologically recognizable step in the development of invasive high-grade serous carcinoma of the fallopian tube. Lesions occurring prior to STIC within the carcinogenic sequence for the pathogenesis of invasive high-grade serous carcinoma include the p53 signature and secretory cell outgrowth (SCOUT). Variable histologic criteria have been used for diagnosing STIC, but a combination of morphology and immunohistochemistry for p53/Ki-67 improves interobserver agreement. Half of all carcinomas identified in risk-reducing salpingo-oophorectomy specimens are in the form of STIC; however, STIC also may be incidentally found on occasion in specimens from women at low or average risk of ovarian/tubal/peritoneal carcinoma. TP53 mutation is the earliest known DNA sequence alteration in STIC and almost all invasive high-grade serous carcinomas of the ovary and peritoneum. Data on the clinical behavior of STIC are limited. While the short-term follow-up in the prior literature suggests a low risk of malignant progression, a more recent meta-analysis indicates a 10-year risk of 28%. STIC probably should be best regarded as a lesion with uncertain malignant potential at present, and future molecular analysis will help classify those with higher risk of dissemination. This review article provides an update on the current knowledge of STIC and related issues.

Pathologic Classification of Ovarian Cancer

Optimal use of human tissue for research requires an understanding of basic pathologic principles. Given that the physical assessment of tissue must occur as part of standard clinical examination, it cannot be handled directly by investigators unless they are also a part of the care team. The purpose of this chapter is to provide an overview of the clinical analytic process, from initial gross handling to histologic examination by light microscopy and the use of ancillary studies, in order to provide context for samples that are used in research and to highlight specific considerations that are relevant for obtaining appropriate tissue for experimental purposes. Given that they comprise >95% of ovarian malignancies, there is an emphasis on epithelial tumors.

STING pathway expression in low-grade serous carcinoma of the ovary: an unexpected therapeutic opportunity?

Ovarian carcinoma histotypes are distinct diseases with variable clinical outcomes and response to treatment. There is a need for new subtype-specific treatment modalities, especially for women with widespread and chemo-resistant disease. Stimulator of interferon genes (STING) is a part of the cGAS-STING pathway that mediates innate immune defence against infectious DNA-containing pathogens and also detects tumour-derived DNA and generates intrinsic antitumour immunity. The STING signalling pathway is suppressed by several mechanisms in a variety of malignant diseases and, in some cancers that may be a requirement for cellular transformation. The aim of this study was to use immunohistochemistry to evaluate STING protein expression across normal tissue, paratubal and ovarian cysts, and ovarian tumour histotypes including ovarian carcinomas. Herein, we show that the fallopian tube ciliated cells express STING protein, whereas the secretory cells are negative. STING expression differs among ovarian cancer histotypes; low-grade serous ovarian carcinomas and serous borderline tumours have uniform high STING expression, while high-grade serous and endometrioid carcinomas have heterogeneous expression, and clear cell and mucinous carcinomas show low expression. As low-grade serous carcinomas are known to be genomically stable and typically lack a prominent host immune response, the consistently high STING expression is unexpected. High STING expression may reflect pathway activation or histogenesis and the mechanisms may be different in different ovarian carcinoma histotypes. Further studies are needed to determine whether the STING signalling pathway is active and whether these tumours would be candidates for therapeutic interventions that trigger innate immunity activation.

Motile ciliogenesis and the mitotic prism

Motile cilia of epithelial multiciliated cells transport vital fluids along organ lumens to promote essential respiratory, reproductive and brain functions. Progenitors of multiciliated cells undergo massive and coordinated organelle remodelling during their differentiation for subsequent motile ciliogenesis. Defects in multiciliated cell differentiation lead to severe cilia-related diseases by perturbing cilia-based flows. Recent work designated the machinery of mitosis as the orchestrator of the orderly progression of differentiation associated with multiple motile cilia formation. By examining the events leading to motile ciliogenesis with a methodological prism of mitosis, we contextualise and discuss the recent findings to broaden the spectrum of questions related to the differentiation of mammalian multiciliated cells.

Tubal Origin of "Ovarian" Low-Grade Serous Carcinoma: A Gene Expression Profile Study

Objective

Ovarian low-grade serous carcinomas are thought to evolve in a stepwise fashion from ovarian epithelial inclusions, serous cystadenomas, and serous borderline tumors. Our previous study with clinicopathological approach showed that the majority ovarian epithelial inclusions are derived from the fallopian tubal epithelia rather than from ovarian surface epithelia. This study was designed to gain further insight into the cellular origin of ovarian low-grade serous carcinomas by differential gene expression profiling studies.

Methods

Gene expression profiles were studied in 43 samples including 11 ovarian low-grade serous carcinomas, 7 serous borderline tumors, 6 serous cystadenomas, 6 ovarian epithelial inclusions, 7 fallopian tubal epithelia, and 6 ovarian surface epithelia. Comprehensive analyses with hierarchical clustering, Rank-sum analysis and Pearson correlation tests were performed. Final validation was done on selected genes and corresponding proteins.

Results

The gene expression profiles distinguished ovarian low-grade serous carcinomas from ovarian surface epithelia, but not from fallopian tubal epithelia cells. Hierarchical clustering analysis showed ovarian serous tumors and ovarian epithelial inclusions were clustered closely in a branch, but separated from ovarian surface epithelia. The results were further validated by selected proteins of OVGP1, WT-1, and FOM3, which were highly expressed in the samples of the fallopian tube, ovarian epithelial inclusions, and ovarian serous tumors, but not in ovarian surface epithelia. The reverse was true for the protein expression patterns of ARX and FNC1.

Conclusions

This study provides evidence in a molecular level that ovarian low-grade serous carcinomas likely originate from the fallopian tube rather than from ovarian surface epithelia. Similar gene expression profiles among fallopian tube, ovarian epithelial inclusions, and serous tumors further support that ovarian low-grade serous carcinomas develop in a stepwise fashion. Such findings may have a significant implication for “ovarian” cancer-prevention strategies.

Frontiers in the Pathology and Pathogenesis of Ovarian Cancer: Cancer Precursors and "Precursor Escape"

This article summarizes the pathogenesis of ovarian carcinoma, focusing on the paradox of high-grade serous carcinogenesis. The fallopian tube is the prime site of origin in early serous cancers. Because a subset of serous cancers is associated with early serous proliferations absent intramucosal carcinomas, "precursor escape" is emerging, whereby some advanced cancers trace their roots to early serous proliferations. This has parallels in the endometriosis model and opens up a novel mechanism by which advanced malignancy could emerge without an obvious tubal carcinoma. The impact of this concept on classification of serous cancer and expectations from preventive strategies are discussed.

A guided tour of selected issues pertaining to metastatic carcinomas involving or originating from the gynecologic tract

Epithelial metastases originating from the gynecologic tract or secondarily involving it frequently display a different morphology when compared to the primary tumor. Furthermore, issues such as modes of metastasis, appropriate nomenclature and prognostic significance remain subjects of discussion and some skepticism. In this review, we will discuss: metastases to uterine adnexa; serous tubal intraepithelial carcinoma (STIC); serous borderline tumors; metastases from the uterine corpus; and “synchronous” endometrial and ovarian tumors. Three additional themes that will run through the discussions are those that are peculiar, although not restricted to the gynecologic tract: metastasis from non-invasive primary tumors, metastases that look benign and metastases that are benign or clinically indolent.

PTEN loss in the fallopian tube induces hyperplasia and ovarian tumor formation

The signaling events involved in the onset of ovarian cancer from the fallopian tube epithelium (FTE) are crucial for early detection and treatment of the disease, but they remain poorly defined. Conditional homozygous knockout of PTEN mediated by PAX8-cre recombinase was sufficient to drive endometrioid and serous borderline ovarian carcinoma, providing the first model of FTE-derived borderline tumors. In addition, heterozygous PTEN deletion in the FTE resulted in hyperplasia, providing a model to study early events of human ovarian pathogenesis. To uncover the mechanism underlying the invasion of cancerous oviductal cells to the ovary, PTEN-deficient murine oviductal cells were developed and tagged with green fluorescent protein. Loss of PTEN increased cell migration, invasion, and upregulated WNT4, a key regulator of Müllerian duct development during embryogenesis. Further investigation revealed that WNT4 was required for increased migration and colonization of the ovary by PTEN-deficient oviductal cells in a β-catenin independent manner. Human tumor microarrays and ovarian cancer cells lines confirmed WNT4 expression in cancer and its role in migration. Together, these findings provide a novel model to study the mechanism of fallopian tube tumor initiation and invasion to the ovary mediated by loss of PTEN, which may help to define early events of human ovarian carcinogenesis.

Mucosal Proliferations in Completely Examined Fallopian Tubes Accompanying Ovarian Low-grade Serous Tumors: Neoplastic Precursor Lesions or Normal Variants of Benign Mucosa?

Malignant transformation of the fallopian tube mucosa, followed by exfoliation of malignant cells onto ovarian and/or peritoneal surfaces, has been implicated as the origin of most pelvic high-grade serous carcinoma. Whether a parallel pathway exists for pelvic low-grade serous tumors [ovarian serous borderline tumor (SBT) and low-grade serous carcinoma (LGSC)] remains to be fully elucidated. The literature is challenging to interpret due to variation in the diagnostic criteria and terminology for cytologically low-grade proliferations of the fallopian tube mucosa, as well as variation in fallopian tube specimen sampling. Recently, a candidate fallopian tube precursor to ovarian SBT, so-called papillary tubal hyperplasia, was described in advanced stage patients. The current study was designed to identify fallopian tube mucosal proliferations unique to patients with low-grade serous ovarian tumors (serous cystadenoma, SBT, LGSC) and to determine if they may represent precursors to the ovarian tumors. Fallopian tubes were thinly sliced and entirely examined microscopically, including all of the fimbriated and nonfimbriated portions of the tubes, from patients with ovarian serous cystadenoma (35), SBT (61), and LGSC (11) and from a control population of patients with ovarian mucinous cystadenoma (28), mature cystic teratoma (18) or uterine leiomyoma (14). The slides of the fallopian tubes were examined in randomized order, without knowledge of the clinical history or findings in the ovaries or other organs. Alterations of the mucosa of the fallopian tube were classified as type 1: nonpapillary proliferation of cytologically bland tubal epithelium exhibiting crowding, stratification, and/or tufting without papillary fibrovascular cores or as type 2: papillary alterations consisting of a fibrovascular core lined by a cytologically bland layer of tubal epithelium. A third abnormality, type 3, consisted of detached intraluminal papillae, buds, or nests of epithelium that cytologically resembled the epithelial component of SBT or LGSC. Mucosal proliferations were identified in subsets of all populations, including the control populations. Overall, type 1 proliferations were in 28% to 61% of all patients and type 2 alterations in 4% to 16%. There was no statistically significant difference in the incidence of type 1 or type 2 proliferations between the class of ovarian serous tumors (benign, SBT, LGSC), between early and advanced stage SBT, or between patients with any ovarian serous tumor and the control population of nonserous diagnoses. Type 3 alterations were only identified in patients with advanced stage SBT/LGSC and not in any early stage SBT or cystadenoma. These findings suggest that type 3 alterations floating in the fallopian tube lumen represent exfoliation of tumor cells from ovarian and/or peritoneal origin. Our study did not identify a mucosal-based proliferation of the fallopian tubes that was specific to ovarian low-grade serous tumors. Cytologically bland mucosal proliferations appear to be common in fallopian tubes from patients of all ages and unrelated to ovarian tumorigenesis. A consensus on diagnostic criteria and terminology for these types of proliferations is needed, as well as further study into their etiology, including possible association with hormonal environment.

Frequency of papillary tubal hyperplasia (PTH), salpingoliths and transition from adenoma to borderline ovarian tumors (BOT): A systematic analysis of 74 BOT with different histologic types

Borderline ovarian tumors (BOT) arise from cystadenomas and represent a transition step within the development of low-grade ovarian carcinomas (Type I tumors). That pathway mirrors the adenoma-to-carcinoma sequence known for colorectal cancer. It has been suggested that papillary tubal hyperplasia (PTH) and salpingoliths may be associated with the development of BOT. To evaluate the frequency of the presence of benign cystadenoma and its transition to BOT in a given patient as well as the presence of PTH and salpingoliths we re-valuated in 74 consecutive cases of BOT with different histologic types. The majority of cases represented serous-BOT (60.8%), followed by mucinous BOT (25.7%), other histologic types were rare. 86.5% showed an adenoma-BOT sequence, which was seen in all mucinous BOT but was missed in 15.6% of serous BOT. Two cases had salpingoliths without associated PTH. PTH was seen in four out of the 74 (5.4%) BOT and occurred only in cases with serous histology. The vast majority of BOT represent a transition from benign cystadenoma to BOT in cases with mucinous and serous histology. Salpingoliths are rarely seen in association with BOT and occurred exclusively in BOT with serous histology. PTH may represent a distinct lesion but is rarely seen in association with BOT, especially in those with non-serous histology. Further studies are needed to evaluate the frequency and pathogenetic association of PTH with BOT.

Ovarian borderline tumors in the 2014 WHO classification: evolving concepts and diagnostic criteria

Borderline ovarian tumors (BOT) are uncommon but not rare epithelial ovarian neoplasms, intermediate between benign and malignant categories. Since BOT were first identified >40 years ago, they have inspired controversies disproportionate to their incidence. This review discusses diagnostic criteria for the histologic subtypes of BOT, highlighting areas of diagnostic challenges, ongoing controversies, and changes in terminology implemented by the recent 2014 WHO Classification of Tumours of the Female Genital Organs. Emerging knowledge supports the notion that subtypes of borderline ovarian tumors comprise distinct biologic, pathogenetic, and molecular entities, precluding a single unifying concept for BOT. Serous borderline tumors (SBT) share molecular and genetic alterations with low-grade serous carcinomas and can present at higher stages with peritoneal implants and/or lymph node involvement, which validates their borderline malignant potential. All other (non-serous) subtypes of BOT commonly present at stage I confined to the ovary(ies) and are associated with overall survival approaching that of the general population. An important change in the WHO 2014 classification is the new terminology of non-invasive implants associated with SBT, as any invasive foci (previously called “invasive implants”) are now in line with their biological behavior considered peritoneal low-grade serous carcinoma (LGSC). The controversy regarding the terminology of non-serous borderline tumors, called by some pathologists “atypical proliferative tumor” in view of their largely benign behavior, has not been resolved. The concepts of intraepithelial carcinoma and microinvasion may evolve in further studies, as their presence appears to have no prognostic impact and is subject to considerable inter-observer variability.

Mutant p53 regulates ovarian cancer transformed phenotypes through autocrine matrix deposition

High-grade serous ovarian carcinoma (HGS-OvCa) harbors p53 mutations and can originate from the epithelial cell compartment of the fallopian tube fimbriae. From this site, neoplastic cells detach, survive in the peritoneal cavity, and form cellular clusters that intercalate into the mesothelium to form ovarian and peritoneal masses. To examine the contribution of mutant p53 to phenotypic alterations associated with HGS-OvCA, we developed live-cell microscopy assays that recapitulate these early events in cultured fallopian tube nonciliated epithelial (FNE) cells. Expression of stabilizing mutant variants of p53, but not depletion of endogenous wild-type p53, in FNE cells promoted survival and cell-cell aggregation under conditions of cell detachment, leading to the formation of cell clusters with mesothelium-intercalation capacity. Mutant p53^R175H-induced phenotypes were dependent on fibronectin production, α5β1 fibronectin receptor engagement, and TWIST1 expression. These results indicate that FNE cells expressing stabilizing p53 mutants acquire anchorage independence and subsequent mesothelial intercalation capacity through a mechanism involving mesenchymal transition and matrix production. These findings provide important new insights into activities of mutant p53 in the cells of origin of HGS-OvCa.

Morphologic and Molecular Characteristics of Mixed Epithelial Ovarian Cancers

Epithelial ovarian cancer (EOC) consists of 5 major histotypes: high-grade serous carcinoma (HGSC), endometrioid carcinoma (EC), clear cell carcinoma (CCC), mucinous carcinoma (MC), and low-grade serous carcinoma (LGSC). Each can have a broad spectrum of morphologic appearances, and 1 histotype can closely mimic histopathologic features more typical of another. Historically, there has been a relatively high frequency of mixed, defined by 2 or more distinct histotypes present on the basis of routine histopathologic assessment, histotype carcinoma diagnoses (3% to 11%); however, recent immunohistochemical (IHC) studies identifying histotype-specific markers and allowing more refined histotype diagnoses suggest a much lower incidence. We reviewed hematoxylin and eosin-stained slides from 871 cases of EOC and found the frequency of mixed carcinomas to be 1.7% when modern diagnostic criteria are applied. Through international collaboration, we established a cohort totaling 22 mixed EOCs, consisting of 9 EC/CCC, 4 EC/LGSC, 3 HGSC/CCC, 2 CCC/MC, and 4 other combinations. We interrogated the molecular differences between the different components of each case using IHC, gene expression, and hotspot sequencing analyses. IHC data alone suggested that 9 of the 22 cases were not mixed tumors, as they presented a uniform immuno-phenotype throughout, and these cases most probably represent morphologic mimicry and variation within tumors of a single histotype. Synthesis of molecular data further reduces the incidence of mixed carcinomas. On the basis of these results, true mixed carcinomas with both morphologic and molecular support for the presence of >1 histotype within a given tumor represent <1% of EOCs.

Incidence of serous tubal intraepithelial carcinoma (STIC) by algorithm classification in serous ovarian tumor associated with PAX8 expression in tubal epithelia: a study of single institution in Japan

Serous ovarian carcinoma is now hypothesized to originate from fallopian tube epithelium (FTE). We investigated the FTE abnormalities in the patients with epithelial ovarian tumors. Our study included 55 cases of serous tumors (24 carcinomas, 8 borderline tumors, and 23 adenomas), 14 mucinous carcinomas, 22 endometrioid carcinomas, 5 clear cell carcinomas, and 2 malignant Brenner tumors. FTE was diagnosed by the diagnostic algorithm, which combines the data of morphology, and p53, Ki-67 immunostaining, as serous tubal intraepithelial carcinoma, serous tubal intraepithelial lesion, p53 signature, and normal/reactive. Serous tubal intraepithelial carcinoma, serous tubal intraepithelial lesion, p53 signature, and normal/reactive were observed in 5, 3, 0, and 16 cases in serous carcinoma; 0, 3, 0, and 5 cases in serous borderline tumor; 0, 1, 1, and 21 cases in serous adenoma; 0, 0, 1, and 13 cases in mucinous carcinoma; 0, 0, 3, and 19 cases in endometrioid carcinoma; 0, 0, 0, and 5 cases in clear cell carcinoma; and 0, 1, 0, and 1 case in malignant Brenner tumor. Among tumors of serous histology and between carcinomas, FTE abnormalities differed significantly (P<0.05). Serous tubal intraepithelial carcinomas were only found in serous carcinoma. The incidence of secretory cell proliferation (SCP) was examined by PAX8 expression. The rate of SCP was extremely high in serous carcinoma (96%). Among tumors of serous histology and between carcinomas, an incidence of SCP differed significantly (P<0.05). Patients with SCP were significantly older (P<0.0001). Our observations were concordant with the hypothesis of serous ovarian carcinogenesis. The SCP has a meaningful association with serous ovarian cancer.

Ovarian high-grade serous carcinoma with a noninvasive growth pattern simulating a serous borderline tumor

Ovarian serous borderline tumors (SBTs) being a precursor of low-grade serous carcinomas are morphologically characterized by noninvasive growth and low-grade cytology. On the other hand, many pathologists regard cytologically high-grade, noninvasive (HG-noninv) ovarian serous tumors resembling SBTs in low magnification as conventional high-grade serous carcinomas (HGSCs) by personal experiences. Nonetheless, there are no established molecular characteristic of such tumors. In this study, therefore, we attempted to provide the molecular evidence. We selected 37 ovarian serous tumors that exhibited a cytologically HG-noninv growth pattern, including 36 tumors that coexisted with conventional invasive HGSC components (HG-inv) and a single tumor exclusively composed of pure HG-noninv. Histologically, all HG-noninv showed many mitotic figures, and serous tubal intraepithelial carcinomas were identified in 3 tumors with HG-noninv. Immunohistochemically, most HG-noninv showed aberrant p53 expression, frequent IMP3 positivity, p16 overexpression, a high MIB-1 labeling index, and infrequent PAX2. By molecular analysis, the pure HG-noninv and 13 HGSCs with HG-noninv showed TP53 mutations, but KRAS/BRAF mutations were not detected in any of them. In 1 tumor, we detected an identical TP53 mutation in both HG-noninv and HG-inv components by using laser capture microdissection. These immunohistochemical and molecular features of HG-noninv were similar to those of conventional invasive HGSCs but different from those of SBTs. In conclusion, our results showed that a cytologically HG-noninv growth pattern simulating an SBT is a morphological spectrum of HGSC, but not a true SBT.

Primary fallopian tube carcinoma: correlation between magnetic resonance and diffuse weighted imaging characteristics and histopathologic findings

OBJECTIVE

The aim of this study was to investigate the magnetic resonance (MR) and diffusion-weighted (DW) imaging characteristics of primary fallopian tube carcinoma (PFTC).

METHODS

The clinical, MR, and DW imaging characteristics and pathologic findings of 23 patients with 27 tumors were studied retrospectively. The MR and DW imaging appearance of tumors including laterality, size and shape, architecture, signal intensity, apparent diffusion coefficient (ADC) value, enhancement pattern, hydrosalpinx, and intrauterine fluid collection were evaluated and correlated with pathologic findings.

RESULTS

Histopathologically, all 27 tumors were serous carcinoma with a unilateral tumor in 19 patients and bilateral tumors in 4 patients. Thirteen patients (57%) with PFTC were misdiagnosed preoperatively, 10 of which as epithelial ovarian carcinoma. The mean (SD) largest diameter was 61 (7) mm. The tumor shape was fusiform, sausagelike, or serpentine in 19 patients (70%) and nodular or irregular in 8 patients (30%). Twenty (74%) of the 27 tumors were solid, and 7 (26%) were cystic-solid. The solid components showed hypointensity to isointensity on T1-weighted imaging, and isointensity to slight hyperintensity on T2-weighted imaging. There were obvious hyperintensity on DW imaging; obvious hypointensity on ADC maps with a mean (SD) ADC value of 0.79 (0.22) × 10 mm; and mild (8/27, 30%), moderate (13/27, 48%), and marked (6/27, 22%) enhancement on contrast-enhanced imaging. Ipsilateral hydrosalpinx, intrauterine fluid collection, and ascites were found in 14 tumors (52%) and 7 (30%) and 5 (22%) patients, respectively.

CONCLUSIONS

The PFTC has some characteristic MR imaging features. The DW imaging, ADC maps, and ADC values are helpful for the detection and differentiation of PFTC from other pelvic masses.

The PAX2-null immunophenotype defines multiple lineages with common expression signatures in benign and neoplastic oviductal epithelium

The oviducts contain high-grade serous cancer (HGSC) precursors (serous tubal intraepithelial neoplasia or STINs), which are γ-H2AX(p) - and TP53 mutation-positive. Although they express wild-type p53, secretory cell outgrowths (SCOUTs) are associated with older age and serous cancer; moreover, both STINs and SCOUTs share a loss of PAX2 expression (PAX2(n) ). We evaluated PAX2 expression in proliferating adult and embryonic oviductal cells, normal mucosa, SCOUTs, Walthard cell nests (WCNs), STINs, and HGSCs, and the expression of genes chosen empirically or from SCOUT expression arrays. Clones generated in vitro from embryonic gynaecological tract and adult Fallopian tube were Krt7(p) /PAX2(n) /EZH2(p) and underwent ciliated (PAX2(n) /EZH2(n) /FOXJ1(p) ) and basal (Krt7(n) /EZH2(n) /Krt5(p) ) differentiation. Similarly, non-ciliated cells in normal mucosa were PAX2(p) but became PAX2(n) in multi-layered epithelium undergoing ciliated or basal (WCN) cell differentiation. PAX2(n) SCOUTs fell into two groups: type 1 were secretory or secretory/ciliated with a 'tubal' phenotype and were ALDH1(n) and β-catenin(mem) (membraneous only). Type 2 displayed a columnar to pseudostratified (endometrioid) phenotype, with an EZH2(p) , ALDH1(p) , β-catenin(nc) (nuclear and cytoplasmic), stathmin(p) , LEF1(p) , RCN1(p) , and RUNX2(p) expression signature. STINs and HGSCs shared the type 1 immunophenotype of PAX2(n) , ALDH1(n) , β-catenin(mem) , but highly expressed EZH2(p) , LEF1(p) , RCN1(p) , and stathmin(p) . This study, for the first time, links PAX2(n) with proliferating fetal and adult oviductal cells undergoing basal and ciliated differentiation and shows that this expression state is maintained in SCOUTs, STINs, and HGSCs. All three entities can demonstrate a consistent perturbation of genes involved in potential tumour suppressor gene silencing (EZH2), transcriptional regulation (LEF1), regulation of differentiation (RUNX2), calcium binding (RCN1), and oncogenesis (stathmin). This shared expression signature between benign and neoplastic entities links normal progenitor cell expansion to abnormal and neoplastic outgrowth in the oviduct and exposes a common pathway that could be a target for early prevention.

Coming into focus: the nonovarian origins of ovarian cancer

BACKGROUND

The traditional view of epithelial ovarian cancer asserts that all tumor subtypes share a common origin in the ovarian surface epithelium (OSE) DESIGN: A literature review was carried out to summarize the emerging understanding of extraovarian sources of epithelial ovarian carcinomas.

RESULTS

Historically, there were no diagnostic criteria for documenting the origin of ovarian epithelial carcinomas. Moreover, there are no normal epithelial tissues in the ovary with morphologic similarities to these tumors. In fact, no precursor lesions have ever been reproducibly identified in the ovary. However, there is a strong correlation between extrauterine Müllerian tissue and the development of ovarian carcinomas, tumors of low malignant potential, and cystadenomas. The most recent support for this hypothesis comes from the careful analysis of risk-reducing bilateral salpingo-oopherectomy specimens from BRCA1 or BRCA2 mutation carriers. These studies showed that a significant majority of high-grade serous ovarian carcinomas, the most common subtype, arise from the fallopian tube fimbriae rather than the OSE.

CONCLUSIONS

Mounting evidence indicates that the vast majority of epithelial ovarian carcinomas are not ovarian in origin. Extrauterine Müllerian epithelium from various sites in the reproductive tract likely accounts for the diverse morphology and behavior of these tumors.

Fallopian tube: Its role in infertility and gynecological oncology

Disorders of the fallopian tube play a very important role in both infertility and gynaecological oncology. Tubal factor infertility is considered among the leading causes of female factor infertility. Many tubal disorders are related to infertility including congenital anomalies, acute and chronic inflammatory diseases, endometriosis and other pathologies that result in partial or total fallopian tube obstruction. In the field of gynaecological oncology, ovarian surface epithelial tumors remain one of the most fatal malignancies in women worldwide carrying the worst prognosis among female genital malignancies. For decades, the cell of origin of epithelial tumors has remained controversial and was largely believed to be surface ovarian epithelium. Recently several studies suggested that there is a major role of the fallopian tube in the development of ovarian surface epithelial tumors, mainly high grade serous carcinoma and other tumour types. In this article we review the role of the fallopian tube in both infertility and gynaecological oncology.

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.

Expression of folate receptor-α (FRA) in gynecologic malignancies and its relationship to the tumor type

An immunohistochemical evaluation for folate receptor-α (FRA) was undertaken to evaluate expression in gynecologic malignancies involving ovary, endometrium, and the fallopian tube. Commercial tissue microarrays were assessed using an optimized manual immunohistochemical method using MAb 26B3, a newly described monoclonal antibody. A positive result was defined as ≥5% of the sample demonstrating membranous staining. A semiquantitative staining algorithm, defined as the M-score, was used to analyze staining intensity between sample histotypes. MAb 26B3 showed uniform membranous staining and high levels of expression of FRA in ovarian, fallopian tube, and endometrial cancers. All serous ovarian cancers analyzed (70) were positive for FRA expression and no relationship to stage or grade was found. However, a significant difference for FRA expression, between serous and mucinous ovarian carcinomas, was demonstrated (P=0.014). In addition, approximately 90% of all endometrial adenocarcinomas were positive for FRA expression but, unlike ovarian serous carcinomas, a statistically significant relationship to grade was observed (P=0.0029). Although normal ovary is completely devoid of FRA immunoreactivity, normal fallopian tube and cortical serous/tubal inclusion cysts demonstrated uniform and intense FRA staining of columnar epithelium supporting the hypothesis that serous ovarian carcinoma is similar to the tubal epithelium. The data presented further support the hypothesis that FRA expression in gynecologic tumors is due to the cell of origin normally expressing this receptor. This is possibly due to an associated growth advantage, rather than the process of tumorigenesis resulting in aberrant expression of FRA per se.

Type-specific cell line models for type-specific ovarian cancer research

BACKGROUND

OVARIAN CARCINOMAS CONSIST OF AT LEAST FIVE DISTINCT DISEASES: high-grade serous, low-grade serous, clear cell, endometrioid, and mucinous. Biomarker and molecular characterization may represent a more biologically relevant basis for grouping and treating this family of tumors, rather than site of origin. Molecular characteristics have become the new standard for clinical pathology, however development of tailored type-specific therapies is hampered by a failure of basic research to recognize that model systems used to study these diseases must also be stratified. Unrelated model systems do offer value for study of biochemical processes but specific cellular context needs to be applied to assess relevant therapeutic strategies.

METHODS

We have focused on the identification of clear cell carcinoma cell line models. A panel of 32 "ovarian cancer" cell lines has been classified into histotypes using a combination of mutation profiles, IHC mutation-surrogates, and a validated immunohistochemical model. All cell lines were identity verified using STR analysis.

RESULTS

Many described ovarian clear cell lines have characteristic mutations (including ARID1A and PIK3CA) and an overall molecular/immuno-profile typical of primary tumors. Mutations in TP53 were present in the majority of high-grade serous cell lines. Advanced genomic analysis of bona-fide clear cell carcinoma cell lines also support copy number changes in typical biomarkers such at MET and HNF1B and a lack of any recurrent expressed re-arrangements.

CONCLUSIONS

As with primary ovarian tumors, mutation status of cancer genes like ARID1A and TP53 and a general immuno-profile serve well for establishing histotype of ovarian cancer cell We describe specific biomarkers and molecular features to re-classify generic "ovarian carcinoma" cell lines into type specific categories. Our data supports the use of prototype clear cell lines, such as TOV21G and JHOC-5, and questions the use of SKOV3 and A2780 as models of high-grade serous carcinoma.

Modeling High-Grade Serous Carcinoma: How Converging Insights into Pathogenesis and Genetics are Driving Better Experimental Platforms

Recent developments in the study of epithelial ovarian cancer have called into question the traditional views regarding the site of tumor initiation. Histopathologic studies and genomic analyses suggest that extra-ovarian sites, like the fallopian tube, may harbor the coveted cell of origin and could therefore contribute significantly to the development of high-grade serous ovarian carcinoma (HG-SOC). Our ability to validate these emerging genomic and pathologic observations and characterize the early transformation events of HG-SOC hinges on the development of novel model systems. Currently, there are only a handful of new model systems that are addressing these concerns. This review will chronicle the convergent evolution of these ovarian cancer model systems in the context of the changing pathologic and genomic understanding of HG-SOC.

The DNA methylomes of serous borderline tumors reveal subgroups with malignant- or benign-like profiles

Serous borderline tumors (SBOTs) are a challenging group of ovarian tumors positioned between benign and malignant disease. We have profiled the DNA methylomes of 12 low-grade serous carcinomas (LGSCs), 19 SBOTs, and 16 benign serous tumors (BSTs) across 27,578 CpG sites to further characterize the epigenomic relationship between these subtypes of ovarian tumors. Unsupervised hierarchical clustering of DNA methylation levels showed that LGSCs differ distinctly from BSTs, but not from SBOTs. Gene ontology analysis of genes showing differential methylation at linked CpG sites between LGSCs and BSTs revealed significant enrichment of gene groups associated with cell adhesion, cell-cell signaling, and the extracellular region, consistent with a more invasive phenotype of LGSCs compared with BSTs. Consensus clustering highlighted differences between SBOT methylomes and returned subgroups with malignant- or benign-like methylation profiles. Furthermore, a two-loci DNA methylation signature can distinguish between these SBOT subgroups with benign- and malignant-like methylation characteristics. Our findings indicate striking similarities between SBOT and LGSC methylomes, supporting a common origin and the view that LGSC may arise from SBOT. A subgroup of SBOTs can be classified into tumors with a benign- or a malignant-like methylation profile that may help in identifying tumors more likely to progress into LGSCs.

Digital quantification of precursor frequency in the fallopian tube and its significance

A high frequency of precursor lesions is a risk factor for cancer in many organ systems but must be precisely quantified. Pelvic serous neoplasia is associated with an estimated increase in frequency of secretory cell outgrowths (SCOUTs) with loss of PAX2 protein (PAX2p) expression (PAX2p-null SCOUTs) in the fallopian tube. However, to confirm this, PAX2p-null SCOUTs must be precisely quantified relative to the epithelial surface. We developed a method by which fallopian tube sections were digitized using an iScan brightfield scanner (BioImagene) and uploaded in Adobe Photoshop CS3 Extended. Pixel length was translated into microns and epithelial length measured with the Magic Wand tool. SCOUTs were expressed as a function of total epithelial perimeter. Frequency, required perimeter length, topographic clustering tendency and effects of age were ascertained. SCOUT frequency per 10 cm was 0-4.60 for cases and 0-1.66 for controls, averaging 0.84 and 0.27, respectively, (P=0.007). Required perimeter length for SCOUT detection was less in serous cancer cases and topographic distribution followed a random pattern without aberrant clustering. Age was also associated with SCOUT frequency (P=0.025) and differences between cancers and controls were still significant after adjusting for age (P=0.001). We describe an efficient method for quantifying epithelial perimeter in the fallopian tube and verify its relevance to precursor frequency. This has important implications for assessing precursor frequency both in the fallopian tube and in other organs-such as prostate, pancreas and colon-where epithelial precursors are integral to carcinogenesis.

The oviduct and ovarian cancer: causality, clinical implications, and "targeted prevention"

A novel origin for pelvic serous cancer (ovarian cancer) has been proposed in the distal oviduct. This has important implications, including both early detection in high-risk women and wisdom of relying on serological tests to detect a disease that begins so close to the peritoneal surfaces. With the recent discovery of premalignant disturbances in gene function in the tubal mucosa, the concept of targeted prevention is emerging whereby the interruption of a portion of the carcinogenic pathway will prevent cancer. This alternative to detect early malignancy is a new paradigm in the quest to prevent this deadly disease.

Ovarian serous carcinoma: recent concepts on its origin and carcinogenesis

Recent morphologic and molecular genetic studies have led to a paradigm shift in our conceptualization of the carcinogenesis and histogenesis of pelvic (non-uterine) serous carcinomas. It appears that both low-grade and high-grade pelvic serous carcinomas that have traditionally been classified as ovarian in origin, actually originate, at least in a significant subset, from the distal fallopian tube. Clonal expansions of the tubal secretory cell probably give rise to serous carcinomas, and the degree of ciliated conversion is a function of the degree to which the genetic hits deregulate normal differentiation. In this article, the authors review the evidentiary basis for aforementioned paradigm shift, as well as its potential clinical implications.

Ovarian carcinomas: five distinct diseases with different origins, genetic alterations, and clinicopathological features

Malignant epithelial tumors (carcinomas) are the most common ovarian cancers and also the most lethal gynecological malignancies. Based on histopathology and molecular genetic alterations, ovarian carcinomas are divided into five main types (high-grade serous (70%), endometrioid (10%), clear cell (10%), mucinous (3%), and low-grade serous carcinomas (<5%)) that account for over 95% of cases. These types are essentially distinct diseases, as indicated by differences in epidemiological and genetic risk factors, precursor lesions, patterns of spread, and molecular events during oncogenesis, response to chemotherapy, and prognosis. For a successful specific treatment, reproducible histopathological diagnosis of the tumor cell type is critical. The five tumor types are morphologically diverse and resemble carcinomas of the uterus. Actually, recent investigations have demonstrated that a significant number of cancers, traditionally thought to be primary ovarian tumors (particularly serous, endometrioid, and clear cell carcinomas), originate in the fallopian tube and the endometrium and involve the ovary secondarily. This review summarizes recent advances in the molecular pathology which have greatly improved our understanding of the biology of ovarian carcinoma and are also relevant to patient management.

Papillary tubal hyperplasia: the putative precursor of ovarian atypical proliferative (borderline) serous tumors, noninvasive implants, and endosalpingiosis

In contrast to the controversy regarding the terminology and behavior of ovarian noninvasive low-grade serous tumors [atypical proliferative serous tumor (APST) and serous borderline tumor], little attention has been directed to their origin. Similarly, until recently, proliferative lesions in the fallopian tube had not been extensively studied. The recent proposal that ovarian high-grade serous carcinomas are derived from intraepithelial carcinoma in the fallopian tube prompted us to evaluate the possible role of fallopian tube in the genesis of low-grade serous tumors. We have identified a lesion, designated "papillary tubal hyperplasia (PTH)," characterized by small rounded clusters of tubal epithelial cells and small papillae, with or without associated psammoma bodies, that are present within the tubal lumen and which are frequently associated with APSTs. Twenty-two cases in this study were selected from a population-based study in Denmark of approximately 1000 patients with low-grade ovarian serous tumors in whom implants were identified on the fallopian tube. Seven additional cases were seen recently in consultation at The Johns Hopkins Hospital (JHH). These 7 cases were not associated with an ovarian tumor. PTH was found in 20 (91%) of the 22 cases in the Danish study. On the basis of this association of PTH with APSTs with implants and the close morphologic resemblance of PTH, not only to primary ovarian APSTs but also to noninvasive epithelial implants and endosalpingiosis, we speculate that the small papillae and clusters of cells from the fallopian tube implant on ovarian and peritoneal surfaces to produce these lesions. The 7 JHH cases of PTH that were not associated with an ovarian tumor support the view that PTH is the likely precursor lesion. We propose a model for the development of ovarian and extraovarian low-grade serous proliferations (APST, noninvasive epithelial implants, and endosalpingiosis) that postulates that all of these lesions are derived from PTH, which appears to be induced by chronic inflammation. If this hypothesis is confirmed, it can be concluded that low-grade and high-grade ovarian tumors develop from tubal epithelium and involve the ovary secondarily.