Fallopian Tube Secretory Cells Research Articles

Innate Immune Program in Formation of Tumor-Initiating Cells from Cells-of-Origin of Breast, Prostate, and Ovarian Cancers.

Tumor-initiating cells (TICs), also known as cancer stem cells (CSCs), are cancer cells that can initiate a tumor, possess self-renewal capacity, and can contribute to tumor heterogeneity. TICs/CSCs are developed from their cells-of-origin. In breast, prostate, and ovarian cancers, progenitor cells for mammary alveolar cells, prostate luminal (secretory) cells, and fallopian tube secretory cells are the preferred cellular origins for their corresponding cancer types. These luminal progenitors (LPs) express common innate immune program (e.g., Toll-like receptor (TLR) signaling)-related genes. Microbes such as bacteria are now found in breast, prostate, and fallopian tube tissues and their corresponding cancer types, raising the possibility that their LPs may sense the presence of microbes and trigger their innate immune/TLR pathways, leading to an inflammatory microenvironment. Crosstalk between immune cells (e.g., macrophages) and affected epithelial cells (e.g., LPs) may eventually contribute to formation of TICs/CSCs from their corresponding LPs, in part via STAT3 and/or NFκB pathways. As such, TICs/CSCs can inherit expression of innate-immunity/TLR-pathway-related genes from their cells-of-origin; the innate immune program may also represent their unique vulnerability, which can be explored therapeutically (e.g., by enhancing immunotherapy via augmenting TLR signaling).

L1CAM is required for early dissemination of fallopian tube carcinoma precursors to the ovary

Most ovarian high-grade serous carcinomas (HGSC) arise from Serous Tubal Intraepithelial Carcinoma (STIC) lesions in the distal end of the fallopian tube (FT). Formation of STIC lesions from FT secretory cells leads to seeding of the ovarian surface, with rapid tumor dissemination to other abdominal structures thereafter. It remains unclear how nascent malignant cells leave the FT to colonize the ovary. This report provides evidence that the L1 cell adhesion molecule (L1CAM) contributes to the ability of transformed FT secretory cells (FTSEC) to detach from the tube, survive under anchorage-independent conditions, and seed the ovarian surface. L1CAM was highly expressed on the apical cells of STIC lesions and contributed to ovarian colonization by upregulating integrins and fibronectin in malignant cells and activating the AKT and ERK pathways. These changes increased cell survival under ultra-low attachment conditions that mimic transit from the FT to the ovary. To study dissemination to the ovary, we developed a tumor-ovary co-culture model. We showed that L1CAM expression was important for FT cells to invade the ovary as a cohesive group. Our results indicate that in the early stages of HGSC development, transformed FTSECs disseminate from the FT to the ovary in a L1CAM-dependent manner.

The fallopian tube as origin of ovarian cancer: Change of diagnostic and preventive strategies.

Ovarian cancer is the leading cause of gynecologic cancer death in the world, and its prevention and early diagnosis remain the key to its treatment, especially for high‐grade serous carcinoma (HGSC). Accumulating epidemiological and molecular evidence has shown that HGSC originates from fallopian tube secretory cells through serous tubal intraepithelial carcinoma. Comprehensive molecular analyses and mouse studies have uncovered the key driver events for serous carcinogenesis, providing novel molecular targets. Risk‐reducing bilateral salpingo‐oophorectomy (RRSO) has been proposed to reduce the subsequent occurrence of serous carcinoma in high‐risk patients with BRCA mutations. However, there is no management strategy for isolated precursors detected at RRSO, and the role of subsequent surgery or chemotherapy in preventing serous carcinoma remains unclear. Surgical menopause due to RRSO provides a variety of problems related to patients’ quality of life, and the risks and benefits of hormone replacement are under investigation, especially for women without a previous history of breast cancer. An additional surgical option, salpingectomy with delayed oophorectomy, has been proposed to prevent surgical menopause. The number of opportunistic salpingectomies at the time of surgery for benign disease to prevent the future occurrence of HGSC has increased worldwide. Thus, the changing concept of the origin of serous carcinoma has provided us a great opportunity to develop novel diagnostic and therapeutic approaches.

PAX8 expression in high-grade serous ovarian cancer positively regulates attachment to ECM via Integrin \u03b23

BackgroundOvarian cancer is the third most common cause of death among gynecologic malignancies worldwide. Understanding the biology and molecular pathogenesis of ovarian epithelial tumors is key to developing improved prognostic indicators and effective therapies. We aimed to determine the effects of PAX8 expression on the migrative, adhesive and survival capabilities of high-grade serous carcinoma cells.MethodsPAX8 depleted Fallopian tube secretory cells and ovarian cancer cells were generated using short interfering siRNA. Anoikis resistance, cell migration and adhesion properties of PAX8 silenced cells were analyzed by means of specific assays. Chromatin immunoprecipitation (ChIP) was carried out using a PAX8 polyclonal antibody to demonstrate that PAX8 is able to bind to the 5′-flanking region of the ITGB3 gene positively regulating its expression.ResultsHere, we report that RNAi silencing of PAX8 sensitizes non-adherent cancer cells to anoikis and affects their tumorigenic properties. We show that PAX8 plays a critical role in migration and adhesion of both Fallopian tube secretory epithelial cells and ovarian cancer cells. Inhibition of PAX8 gene expression reduces the ability of ovarian cancer cells to migrate and adhere to the ECM and specifically to fibronectin and/or collagen substrates. Moreover, loss of PAX8 strongly reduces ITGB3 expression and consequently the correct expression of the αvβ3 heterodimer on the plasma membrane.ConclusionsOur results demonstrate that PAX8 modulates the interaction of tumor cells with the extracellular matrix (ECM). Notably, we also highlight a novel pathway downstream this transcription factor. Overall, PAX8 could be a potential therapeutic target for high-grade serous carcinoma.

Abstract AP03: DISTINCT CELL/TISSUE SOURCES OF HIGH-GRADE SEROUS OVARIAN CANCER

Abstract The cell-of-origin of high grade serous ovarian carcinoma (HGSC) has been a focus of debate. Here, by using genetic mouse models as well as cognate organoid systems, we assessed the tumor forming capacity and properties of the fallopian tube epithelium (FTE) and ovarian surface epithelium (OSE) bearing the same oncogenic abnormalities. Combined RB family inactivation (via T121 expression) and Tp53 mutation in Pax8+ fallopian tube secretory cells causes transformation and characteristics of Serous Tubal Intraepithelial Carcinoma (STIC). This genetically engineered mouse HGSC model is faithfully recapitulated in fallopian organoids, from which serous ovarian cancer with broad abdominal metastasis is generated upon orthotropic injection. The same genetic events in Lgr5+ OSE cells organdies derived from these cells also result in an apparent neoplastic process, expressing markers of early serous carcinoma (but not Pax8), which subsequently develop into serous-like tumors. Hence, both Pax8+ fallopian tube epithelial cells and Lgr5+ ovarian surface epithelial cells can undergo similar neoplastic transformation, suggesting that HGSC might derive from distinct cell and tissue sources. Similar organoid systems can be used to rapidly model other gene combinations associated with HGSC. Citation Format: Shuang Zhang, Benjamin G. Neel. DISTINCT CELL/TISSUE SOURCES OF HIGH-GRADE SEROUS OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP03.

Ovarian Cancer Stem Cell Heterogeneity.

Ovarian carcinoma features pronounced clinical, histopathological, and molecular heterogeneity. There is good reason to believe that parts of this heterogeneity can be explained by differences in the respective cell of origin, with a self-renewing fallopian tube secretory cell being likely responsible for initiation of an overwhelming majority of high-grade serous ovarian carcinomas (i.e., type II tumors according to the recent dualistic classification), whereas there are several mutually non-exclusive possibilities for the initiation of type I tumors, including ovarian surface epithelium stem cells, endometrial cells, or even cells of extra-Müllerian origin. Interestingly, both fallopian tube self-renewing secretory cells and ovarian surface epithelium stem cells seem to be characterized by an overlapping array of stemness signaling pathways, especially Wnt/β-catenin. Apart from this variability in the respective cell of origin, the particular clinical behavior of ovarian carcinoma strongly suggests an underlying stem cell component with a crucial impact. This becomes especially evident in high-grade serous ovarian carcinomas treated with classical chemotherapy, which entails a gradual evolution of chemoresistant disease without any apparent selection of clones carrying obvious chemoresistance-associated mutations. Several cell surface markers (e.g., CD24, CD44, CD117, CD133, and ROR1) as well as functional approaches (ALDEFLUOR™ and side population assays) have been used to identify and characterize putative ovarian carcinoma stem cells. We have recently shown that side population cells exhibit marked heterogeneity on their own, which can hamper their straightforward therapeutic targeting. An alternative strategy for stemness-depleting interventions is to target the stem cell niche, i.e., the specific microanatomical structure that secures stem cell maintenance and survival through provision of a set of stem cell-promoting and differentiation-antagonizing factors. Besides identifying direct or indirect therapeutic targets, profiling of side population cells and other ovarian carcinoma stem cell subpopulations can reveal relevant prognostic markers, as exemplified by our recent discovery of the Vav3.1 transcript variant, which filters out a fraction of prognostically unfavorable ovarian carcinoma cases.

Selective Targeting of Cyclin E1-Amplified High-Grade Serous Ovarian Cancer by Cyclin-Dependent Kinase 2 and AKT Inhibition.

Purpose: Cyclin E1 (CCNE1) amplification is associated with primary treatment resistance and poor outcome in high-grade serous ovarian cancer (HGSC). Here, we explore approaches to target CCNE1-amplified cancers and potential strategies to overcome resistance to targeted agents.Experimental Design: To examine dependency on CDK2 in CCNE1-amplified HGSC, we utilized siRNA and conditional shRNA gene suppression, and chemical inhibition using dinaciclib, a small-molecule CDK2 inhibitor. High-throughput compound screening was used to identify selective synergistic drug combinations, as well as combinations that may overcome drug resistance. An observed relationship between CCNE1 and the AKT pathway was further explored in genomic data from primary tumors, and functional studies in fallopian tube secretory cells.Results: We validate CDK2 as a therapeutic target by demonstrating selective sensitivity to gene suppression. However, we found that dinaciclib did not trigger amplicon-dependent sensitivity in a panel of HGSC cell lines. A high-throughput compound screen identified synergistic combinations in CCNE1-amplified HGSC, including dinaciclib and AKT inhibitors. Analysis of genomic data from TCGA demonstrated coamplification of CCNE1 and AKT2 Overexpression of Cyclin E1 and AKT isoforms, in addition to mutant TP53, imparted malignant characteristics in untransformed fallopian tube secretory cells, the dominant site of origin of HGSC.Conclusions: These findings suggest a specific dependency of CCNE1-amplified tumors for AKT activity, and point to a novel combination of dinaciclib and AKT inhibitors that may selectively target patients with CCNE1-amplified HGSC. Clin Cancer Res; 23(7); 1862-74. ©2016 AACR.

Abstract A69: The PAX8 cistrome in benign and malignant Mullerian epithelia.

Abstract Background: PAX8 is a highly evolutionarily conserved transcription factor with essential roles in both Mullerian development as well as high grade serous ovarian cancer. While PAX8 has emerged as a common clinical tool to identify Mullerian primary tumors, the transcriptional network directed by PAX8 in Mullerian epithelia is unknown. In this study, we sought to understand how PAX8 interacts with chromatin in the context of both benign fallopian tube secretory epithelial cells as well as in high grade serous carcinomas. Methods: This study examined PAX8 using six cell lines: three immortalized fallopian tube secretory cell lines (FT33TAg, FT194, FT246) generated by our laboratory and three high grade serous ovarian cancer cell lines (KURAMOCHI, OVSAHO, and JHOS4) with high genomic fidelity to human tumors according to The Cancer Genome Atlas. First, we used chromatin immunoprecipitation combined with DNA sequencing (ChIP-Seq) to map PAX8 binding sites along the genome. Overlapping peaks among the cell lines were aligned to define a minimum consensus binding motif for PAX8. Unsupervised hierarchical clustering then segregated the peaks into groups. The nearest gene within 50000 base pairs to each peak was identified. Next, we used a series of RNAi experiments to knockdown PAX8 in all six cell lines using three independent siRNA sequences plus a pool and examined the effect on the transcriptome in each cell line using RNA-seq. Finally, we used pathway analysis software and gene ontology tools to map the signaling networks directed by PAX8. Results: Among the six cell lines, there were 11,361 unique PAX8 peaks by ChIP-seq. Approximately half of all PAX8 binding sites were located in intergenic sequences and about a 40% were in intronic sequences. The consensus DNA binding motif was almost identical between benign and malignant cell lines and was consistent with a predicted PAX homology motif. Unsupervised clustering identified 3 sets of peaks: 1) a highly conserved set of peaks among all six cell lines comprised of 558 peaks; 2) a common set of peaks common to benign cell lines but absent in cancer cell lines comprised of 3013 peaks; and 3) a very heterogeneous pattern of DNA binding unique to each cancer cell line ranging from few PAX8 peaks (JHOS4) to more than 3000 PAX8 peaks (both KURAMOCHI and OVSAHO). By gene ontology analysis, the common set of peaks for all six cell lines clustered around apoptosis and programmed cell death. Using the combination of RNAi with RNA-seq, few genes (ranging from 1 – 32 genes) were affected by loss of PAX8 in the fallopian tube cell lines or JHOS4, while more than 200 genes were altered in KURAMOCHI and OVSAHO. While in KURAMOCHI these genes were more likely to involve metabolic processes, in OVSAHO these genes were more likely to involve cell cycle regulation. Conclusions: PAX8 expression is shared among benign fallopian tube secretory cells and high grade serous carcinoma, but PAX8 function appears to be context dependent. While there is a shared set of PAX8 binding sites in benign and malignant Mullerian epithelia, PAX8 appears to be essential for the expression of very few targets in benign cells compared to cancer. In addition, PAX8 appears to have greater access to chromatin in the setting of cancer as evidenced by an increase in the number of PAX8 binding sites, while at the same time losing affinity for a set of binding sites seen only in benign fallopian tube cells. Together, these data suggest a dynamic reorganization of chromatin in the process of malignant transformation. Citation Format: Kevin M. Elias, Megan Emori, Myles Brown, Ronny Drapkin. The PAX8 cistrome in benign and malignant Mullerian epithelia. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: Exploiting Vulnerabilities; Oct 17-20, 2015; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2016;22(2 Suppl):Abstract nr A69.

Pathogenesis and heterogeneity of ovarian cancer

Purpose of reviewThe most common type of ovarian cancer, high-grade serous ovarian carcinoma (HGSOC), was originally thought to develop from the ovarian surface epithelium. However, recent data suggest that the cells that undergo neoplastic transformation and give rise to the majority of HGSOC are from the fallopian tube. This development has impacted both translational research and clinical practice, revealing new opportunities for early detection, prevention, and treatment of ovarian cancer.Recent findingsGenomic studies indicate that approximately 50% of HGSOC are characterized by mutations in genes involved in the homologous recombination pathway of DNA repair, especially BRCA1 and BRCA2. Clinical trials have demonstrated successful treatment of homologous recombination-defective cancers with poly-ribose polymerase inhibitors through synthetic lethality. Recently, amplification of CCNE1 was found to be another major factor in HGSOC tumorigenesis, accounting for approximately 20% of all cases. Interestingly, amplification of CCNE1 and mutation of homologous recombination repair genes are mutually exclusive in HGSOC.SummaryThe fallopian tube secretory cell is the cell of origin for the majority of ovarian cancers. Although it remains unclear what triggers neoplastic transformation of these cells, certain tumors exhibit loss of BRCA function or amplification of CCNE1. These alterations represent unique therapeutic opportunities in ovarian cancer.

Abstract POSTER-TECH-1108: A novel spontaneously transformed model of early-stage serous cancer from murine oviductal epithelial cells

Abstract High-grade serous carcinoma (HGSC) is the most lethal gynecological malignancy. Many studies have implicated the ovarian surface epithelia as the origin of HGSC origin. Newer studies suggest other sources of HGSC, such as the distal fallopian tube (oviduct in mice). Current models have to use multiple genetic manipulations of either isolated human fallopian tube secretory cells (FTSECs) or in transgenic mice to form HGSC-like tumors. While these models are vital for identifying and understanding the key players in HGSC, they do not provide information regarding the step-wise development of HGSC. This information is critical for earlier diagnosis and treatments, since most women develop HGSC spontaneously (85%-90% of cases). Thus, development of a spontaneous transformation model offers the potential to interrogate, in a step-wise manner, premalignant changes that initially drive HGSC progression. A murine oviductal epithelial (MOE) cell line was developed from oviducts of CD-1 mice that were validated using known markers: oviductal glycoprotein 1, Pax8, and acetylated tubulin. The low passage cells, designated MOELOW, (<25 passages) contain both epithelial cell subtypes, ciliated and secretory cells. A subpopulation of the MOELOW cells was then continuously passaged in culture to simulate the aging process, designated MOEHIGH (<85 passages). Molecular comparisons were done by Western blot and next-generation RNA sequencing (RNA-Seq). These cell lines were compared using cellular assays, like proliferation, cell death, 2D foci formation, soft agar growth, and xenografted into nude mice to evaluate tumorgenicity. As compared to MOELOW cells, MOEHIGH cells were significantly more proliferative, resistant to damage by bulky DNA adducts, displayed increased clonogenicity, and anchorage-independent colony formation. RNA-Seq analysis elicited 7,425 differentially expressed transcripts. Database comparisons uncovered several well-known pathways altered in HGSC and a few unique pathways altered upon MOE transformation. Consistent with the results from The Cancer Genome Atlas (TCGA) both the Rb and FoxM1 pathways were altered with increased expression of cyclin E1, c-Myc, PCNA; and reduced expression of p16INK4A and hyperphosphorylation of Rb. Remarkably, the MOEHIGH cells do not contain a mutation in Trp53, the HGSC hallmark expressed in 96% of all cases, but rather an alternatively spliced transcript. This p53 transcript, termed p53AS, has both a frameshift and truncation within the negative-regulation domain at the C-terminus. This region loses the lysine residues for MDM2-mediated degradation thereby stabilizing the protein. When wild-type p53 is transiently transfected back into MOEHIGH cells, the cells still cannot induce p21 expression, functioning similar to a p53 DNA-binding mutation. Nude mice injected subcutaneously with MOEHIGH cells all formed tumors but MOELOW mice did not. MOEHIGH forms densely packed and necrotic tumors, stained for Ki67, Pax8, and OVGP1. Intraperitoneal injections of MOEHIGH cells did not metastasize in any mice. This spontaneous transformation model allows for the evaluation of the stepwise progression of HGSC and since tumors are not metastatic, this will be one of the oviductal-derived first early stage serous carcinoma cell lines. Citation Format: Michael P. Endsley, Georgette Moyle-Heyrman, Suzanne M. Quartuccio, Daniel D. Lantvit, Joanna E. Burdette. A novel spontaneously transformed model of early-stage serous cancer from murine oviductal epithelial cells [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-TECH-1108.

Efficient analyses of DNA double-strand breaks and the cell cycle in the secretory epithelial cells of fallopian tube fimbriae

ObjectiveReactive oxygen species (ROS)-induced DNA double-strand breaks (DSBs) are a feature of cancer initiation. Recently, the cells of origin of ovarian high-grade serous carcinoma (HGSC) have been identified as secretory cells in fallopian tube fimbriae, which might be heavily exposed to ROS after ovulation. Establishing a sensitive detection method for measuring DSBs and the cell cycle in fallopian tube secretory cells after ovulation is essential for facilitating research on ovarian cancer formation. Materials and methodsFimbrial epithelial cells from a prophylactically removed human fallopian tube were primarily cultured and immortalized by TP53/Rb-null and hTERT overexpression (FE25 cell line). Hydrogen peroxide (H2O2) was used to treat the FE25 cells to induce DNA DSBs. The DSBs and cell cycle were analyzed using flow cytometry. In addition, human specimens of fimbrial scrapings were subjected to the flow cytometry-based analysis. ResultsWe report an efficient flow cytometry-based method for analyzing the DSBs and cell cycle in immortalized fallopian tube secretory cells as well as in clinical specimens. ConclusionThis analysis method would facilitate the investigation of cancer initiation in fallopian tube fimbriae and other tissues with DSBs.

Cyclin E1 Deregulation Occurs Early in Secretory Cell Transformation to Promote Formation of Fallopian Tube–Derived High-Grade Serous Ovarian Cancers

The fallopian tube is now generally considered the dominant site of origin for high-grade serous ovarian carcinoma. However, the molecular pathogenesis of fallopian tube-derived serous carcinomas is poorly understood and there are few experimental studies examining the transformation of human fallopian tube cells. Prompted by recent genomic analyses that identified cyclin E1 (CCNE1) gene amplification as a candidate oncogenic driver in high-grade serous ovarian carcinoma, we evaluated the functional role of cyclin E1 in serous carcinogenesis. Cyclin E1 was expressed in early- and late-stage human tumor samples. In primary human fallopian tube secretory epithelial cells, cyclin E1 expression imparted malignant characteristics to untransformed cells if p53 was compromised, promoting an accumulation of DNA damage and altered transcription of DNA damage response genes related to DNA replication stress. Together, our findings corroborate the hypothesis that cyclin E1 dysregulation acts to drive malignant transformation in fallopian tube secretory cells that are the site of origin of high-grade serous ovarian carcinomas.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Abstract IA5: Discovering the distal fallopian tube as the origin for high-grade serous ovarian cancer

Abstract 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 (FT) epithelium, may harbor the coveted cell of origin and could therefore contribute significantly to the development of high-grade serous ovarian carcinoma (HGSOC). Our ability to validate these emerging genomic and pathologic observations and characterize the early transformation events of HGSOC hinges on the development of novel model systems. The tubal hypothesis of serous tumorigenesis has led us to develop a number of experimental platforms. These platforms provide us with a unique view into the susceptibilities of the FT epithelium to neoplastic transformation and provide a vehicle to query the contribution of any given genetic alteration to tumor development in vitro and in vivo. These models include the ex-vivo bioanalytical platform of benign FT epithelium, the in vitro FT secretory cell transformation model, a series of patient-derived primary tumor xenograft (PDX) models that retain the phenotypic and genotypic properties of the original patient tumors, and a genetically-engineered mouse model (GEMM) that specifically targets the FT epithelium in vivo. Our GEM model specifically targets the Müllerian secretory cell. It uses the Pax8 promoter to drive expression of the Cre recombinase in the fallopian tube (FT) secretory cells. Pax8 is a lineage marker for the Müllerian system. It is necessary for the development of the female reproductive tract and its expression is retained in the adult FT secretory cell and in nearly all HGSOCs. By crossing our Pax8-Cre deletor mouse with mice carrying floxed alleles of BRCA genes, TP53 (or mutant) and/or PTEN, we could specifically manipulate the expression of these genes in the FT secretory cell. Using this approach, in collaboration with the laboratory of Daniela Dinulescu, we showed that HGSOC can originate in secretory cell of the FT and also established that serous tubal intraepithelial carcinoma (STIC) is the precursor lesion to high-grade serous ovarian and peritoneal carcinomas. Importantly, the tumors that arise in this model not only look like high-grade serous carcinomas but they also retain the genomic complexity that is a hallmark of human HGSOC. In addition to providing mechanistic insight into the origin and pathogenesis of HGSC, this model provides a platform to explore HGSOC sensitivity to novel therapeutic strategies and to develop better detection strategies for early tumor diagnosis in high-risk women. Citation Format: Ronny Drapkin. Discovering the distal fallopian tube as the origin for high-grade serous ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA5.

Abstract PR03: Oxidants and antioxidants in the follicular fluid in initiation of fimbriae carcinogenesis

Abstract High grade serous carcinoma (HGSC) of the ovary constitutes the majority of incidence and death of ovarian cancer, mainly because of the elusive etiology and cell of origin. Ovulation has been regarded as a strong risk factor and use of oral contraceptives (OC) as a protective factor for ovarian cancer with obvious dose (the span of ovulation life and duration of OC use) effect, but the mechanism is unknown. Meanwhile, more and more evidences have indicated the fallopian tube fimbriae to be the tissue of origin of HGSC. We hypothesize that high level of reactive oxygen species (ROS), which is indispensible for ovulation, as well as abundant mitogens in the mature follicular fluid is responsible for the initiation (DNA double strand breaks, DSB) and promotion (proliferation) of carcinogenesis to the fallopian tube secretory cells. We first tested the scrapped cells of the human fallopian tube epithelium for the extending of DSB. By flow cytometry with gating for the secretory cell marker PAX8 and DSB marker γH2AX, we found the secretory cells in the fimbriae harbored significantly more DSB than the those in the proximal tube. In an immortalized cell line of the human fimbriae secretory cell (we named FE25), we tested the mutagenic and mitogenic effects of the ROS and antioxidant in human follicular fluids at ovulation (FF). We found a balanced activity of of ROS and antioxidants in the undiluted follicular fluid with the antioxidants to be limited, such that, upon serial dilution, the intracellular ROS level raised proportionally. This dilution-raised effect of ROS was able to induce γH2Ax accumulation in the FE25 cells. Upon treating with sub-nM level of melatonin, the most potent and major antioxidant in FF, the level of intracellular ROS and γH2Ax readily decreased. Temporally, we found a two-stage effect of FF on the survival and proliferation of FE25, with an early phase of cell death, which occurred within 12 hours after FF treatment, followed by a cell expansion phase occurring at day 2. We interpret this two-stage effect to be an immediate ROS-induced DSB and cell apoptosis followed by a mitogen-induced proliferation of the survived cells. These survived cells carried the DSB and may be clonally expanded and move on to the carcinogenic road. We conclude that an imbalance favoring the ROS activity in the FF, likely from a significant dilution of FF by an unknown pathological status (such as fimbriae inflammation or ascites), may induce an oxidative stress and DSB in the fallopian tube fimbriae. Cells that survive this stress with some carrying DSB are expanded by the rich mitogens in the same FF. When enough mutations of critical genes were accumulated in a stem cell in this secretory population, cancer lesion such as STIC can thus arise. This abstract is also presented as Poster B5. Citation Format: Hsuan-Shun Huang, Che-Fang Hsu, Taolan Zhang, Tang-Yuan Chu. Oxidants and antioxidants in the follicular fluid in initiation of fimbriae carcinogenesis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr PR03.

Ovarian Brenner tumour: A morphologic and immunohistochemical analysis suggesting an origin from fallopian tube epithelium

BackgroundBrenner tumours (BTs), like other epithelial ovarian tumours, are thought to develop from the ovarian surface epithelium. Aim and MethodsWe hypothesised that BTs arise from transitional metaplasia near the tuboperitoneal junction which, when embedded in the ovary as Walthard cell nests, may progress to BTs. The aim of this study was to validate this hypothesis by a morphologic and immunohistochemical (IHC) analysis. ResultsThe IHC analysis revealed that fallopian tube secretory cells, transitional metaplasia, Walthard cell nests and the epithelial component of BTs shared a similar IHC profile, consistently expressing AKR1C3 (an enzyme involved in androgen biosynthesis) and androgen receptor, but not calretinin. The tumour stromal cells that immediately surrounded the epithelial nests showed strong expression of calretinin, inhibin and steroidogenic factor 1 (markers of steroidogenic cells) in the majority of BTs. Using a highly sensitive immunofluorescent staining method, we detected small groups of cilia in transitional metaplasia and Walthard cell nests, multifocal stretches of cilia and/or ciliated vacuoles in benign BTs and well-developed cilia in atypical proliferative BTs. ConclusionsOur findings suggest a tubal origin of BTs through transitional metaplasia and Walthard cell nests, based on their anatomic proximity, similar IHC profile and the presence of cilia. In addition, we hypothesise a role of androgenic stimulation in the pathogenesis of BT, based on the IHC staining pattern of calretinin, inhibin and steroidogenic factor 1 expressed in the luteinised stromal cells surrounding the epithelial nests of the tumours, and AKR1C3 and androgen receptor expressed in both the epithelial and stromal components.

MiR‐182 overexpression in tumourigenesis of high‐grade serous ovarian carcinoma

Molecular pathogenesis of high-grade serous ovarian carcinoma (HG-SOC) is poorly understood. Recent recognition of HG-SOC precursor lesions, defined as serous tubal intraepithelial carcinoma (STIC) in fimbria, provides a new venue for the study of early genetic changes in HG-SOC. Using microRNA profiling analysis, we found that miR-182 expression was significantly higher in STIC than in matched normal Fallopian tube. Further study revealed that miR-182 was significantly overexpressed in most HG-SOC cases. To test whether miR-182 plays a major role in early tumourigenesis of HG-SOC, we overexpressed miR-182 in immortalized ovarian surface, Fallopian tube secretory cells and malignant ovarian cell lines, and found that miR-182 overexpression resulted in increased tumour transformation in vitro, and enhanced tumour invasiveness in vitro and metastasis in vivo. Mechanistically, we demonstrated that the oncogenic properties of miR-182 in ovarian cancer were mediated in part by its impaired repair of DNA double-strand breaks and negative regulation of breast cancer 1 (BRCA1) and metastasis suppressor 1 (MTSS1) expression as well as its positive regulation of the oncogene high-mobility group AT-hook 2 (HMGA2). Our findings suggest that miR-182 dysregulation confers powerful oncogenic potential in the tumourigenesis of HG-SOC. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.