Ovarian surface epithelium: family history and early events in ovarian cancer

Identification and characterization of multipotential stem cells in immortalized normal ovarian surface epithelial cells

The ovarian surface epithelium (OSE) is a single layer of squamous-to-cuboidal epithelial cells that experience repetitive ovulatory rupture and subsequent repair. However, the characteristics of human immortalized ovarian surface epithelial cells (IOSE80) remain elusive. This study aims to determine whether IOSE80 cells have the characteristics of stem cell proliferation and multilineage differentiation and their application in regenerative medicine. IOSE80 cells are sequenced by high-throughput transcriptome analysis, and 5 sets of public data are used to compare the differences between IOSE80 cells and bone marrow mesenchymal stem cells, pluripotent stem cells, and oocytes in transcriptome profiling. The IOSE80 cells present a cobblestone-like monolayer and express the epithelial cell marker KRT18; the stem cell markers IFITM3, ALDH1A1, and VIM; lowly express stem cell marker LGR5 and germ cell markers DDX4 and DAZL. In addition, the GO terms "regulation of stem cell proliferation", "epithelial cell proliferation", etc., are significantly enriched ( P<0.05). IOSE80 cells have the potential to act as mesenchymal stem cells to differentiate into adipocytes with lipid droplets, osteoblasts, and chondroblasts in vitro. IOSE80 cells express pluripotent stem cell markers, including OCT4, SSEA4, TRA-1-60, and TRA-1-81, and they can be induced into three germ layers in vitro. IOSE80 cells also form oocyte-like cells in vitro and in vivo. In addition, IOSE80 cells exhibit robust proliferation, migration, and ovarian repair functions after in vivo transplantation. This study demonstrates that IOSE80 cells have the characteristics of pluripotent/multipotent stem cells, indicating their important role in tissue engineering and regenerative medicine.

Treatment Outcomes of Epithelial Ovarian Cancers Following Maximum Cytoreduction and Adjuvant Paclitaxel-Carboplatin Chemotherapy: Egyptian NCI Experience

BACKGROUND

Epithelial ovarian cancer (EOC) is the commonest malignancy involving the ovaries. Maximum surgical cytoreduction (MCR) followed by adjuvant taxane-platinum chemotherapy are the standard of care treatments.

AIMS

To study treatment outcomes of EOC patients that were maximally cyto-reduced and received adjuvant paclitaxel-carboplatin (PC) chemotherapy.

MATERIALS AND METHODS

This retrospective cohort study included 174 patients with EOC treated at the Egyptian National Cancer Institute between 2006 and 2010. For inclusion, they should have had undergone MCR with no-gross residual followed by adjuvant PC chemotherapy. MCR was total abdominal hysterectomy/bilateral salpingo-oophorectomy [TAH/BSO] or unilateral salpingo- oophorectomy [USO] plus comprehensive staging.

RESULTS

The median age was 50 years. Most patients were married (97.1%), had offspring (92.5%), were postmenopausal (53.4%), presented with abdominal/pelvic pain and swelling (93.7%), had tumors involving both ovaries (45.4%) without extra-ovarian extension i.e. stage I (55.2%) of serous histology (79.9%) and grade II (87.4%). TAH/BSO was performed in 97.7% of cases. A total of 1,014 PC chemotherapy cycles were administered and were generally tolerable with 93.7% completing 6 cycles. Alopecia and numbness were the commonest adverse events. The median follow up period was 42 months. The 2-year rates for disease free survival (DFS) and overall survival (OS) were 70.7% and 94.8%, respectively. The respective 5-year rates were 52.6% and 81.3%. Advanced stage and high-grade were significantly associated with poor DFS and OS (p<0.001). Age >65 years was associated with poor OS (p =0.008). Using Cox-regression, stage was independent predictor of poor DFS and OS. Age was an independent predictor of poor OS.

Tubal origin of ovarian endometriosis

Endometriosis is a puzzling and debilitating disease that affects millions of women around the world. Ovary is the most common organ site involved by endometriosis. Despite various hypotheses about its cell of origin, uncertainty remains. On the basis of our clinicopathologic observations, we hypothesize that fallopian tube may contribute the histogenesis of ovarian endometriosis. To examine if the hypothesis, tubal origin of ovarian endometriosis, has scientific supporting evidence, we identified a set of novel genes, which are either highly expressed in the normal fallopian tube or in the endometrium through a gene differential array study. Among many differentially expressed genes, FMO3 and DMBT1 were selected as the initial biomarkers to test the hypothesis. These biomarkers were then validated in ovarian sections with foci of endometriosis by comparing their expression levels in the fallopian tube and the endometrium within the same patients with real-time PCR, western blot and immunohistochemistry analysis. FMO3 was highly expressed in the tubal epithelia while low in the paired endometrium. In contrast, DMBT1 was high in the endometrium but low in the fallopian tube. In 32 ovarian endometriosis cases analyzed by real-time PCR, 18 (56%) showed a high level of FMO3 and a low level of DMBT1 expression. However, 14 (44%) endometriosis cases showed a reversed expression pattern with these two markers. Results were similarly seen in the methods of western blot and immunohistochemistry. The findings suggest that approximately 60% of the ovarian endometriosis we studied may be derived from the fallopian tube, whereas about 40% of the cases may be of endometrial origin. The fallopian tube epithelia may represent one of the tissue sources contributing to ovarian endometriosis. Such novel findings, which require confirmation, may have a significant clinical impact in searching for alternative ways of prevention and treatment of endometriosis.

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.

BRCA1 deficiency induces protective autophagy to mitigate stress and provides a mechanism for BRCA1 haploinsufficiency in tumorigenesis

Stress adaptation has profound impacts on malignant progression and response to treatment. BRCA1 is an important modulator of cellular stress, but our understanding of its mechanisms of action remains incomplete. Here we identify autophagy as an essential mechanism protecting BRCA1 deficient cancer cells from metabolic stress and allow their survival, which may underlie its significant cancer-promoting properties. We showed that targeted inhibition of endogenous BRCA1 using small interfering RNA caused significant autophagy in response to serum starvation and endoplasmic reticulum stress, whereas overexpression of BRCA1 did not, confirming that the effect was BRCA1 specific. We demonstrated that Beclin 1 was activated in BRCA1 deficient cells, suggesting involvement of a canonical pathway. Importantly, BRCA1 deficient cells were highly dependent on autophagy for survival, and rapidly underwent cell death upon disruption of autophagy. Notably, this dependence on protective autophagy extended to their tissue of origin, as ovarian surface epithelial cells from women testing positive for BRCA1 mutations, in contrast to those with no mutations, robustly induced autophagy to mitigate the stress and promote their survival. These findings highlight a novel role for BRCA1 in protective autophagy, which may make its essential contribution to tumorigenesis and prognosis.

Induction of estrogen-sensitive epithelial cells derived from human-induced pluripotent stem cells to repair ovarian function in a chemotherapy-induced mouse model of premature ovarian failure

The incidence of premature ovarian failure (POF), a condition causing amenorrhea and hypergonadotropic hypoestrogenism in women before the age of 40, has been increasing in recent years. As an irreversible pathological change, improved treatment strategies for this disease are urgently needed. In this study, a type of microRNA (miR-17-3p) was used to guide the differentiation of human-induced pluripotent stem (iPS) cells into hormone-sensitive ovarian epithelial (OSE)-like cells in vitro. To prevent their morphological transformation into fibroblast-like cells, MiR-17-3p, a microRNA that suppresses vimentin expression, was transfected into human iPS cells. Subsequently, these cells were successfully induced into OSE-like cells in vitro after treatment with estrogen and cell growth factors. Compared with controls, iPS cells transfected with miR-17-3p expressed higher levels of epithelial markers (cytokeratin 7, AE1, AE3, and E-cadherin) and estrogen receptors (ERα and ERβ) while levels of mesenchymal markers (fibronectin, vimentin, and N-cadherin) lowered after the induction. The human iPS cell-derived OSE-like cells were then injected into cyclophosphamide-induced POF model mice to determine their potential benefit as grafts to repair ovarian tissues. The OSE-like cells survived within POF mouse ovaries for at least 14 days in vivo. Compared with the negative controls, expressions of cytokeratin 7 and ERβ proteins were elevated while fibronectin and vimentin levels in ovarian tissues were downregulated in the OSE-like cell transplantation group. Moreover, the ovarian weight and plasma E2 level increased over time in the transplantation with OSE-like cells, compared with control groups. Hence, we can draw the conclusion that iPS cells can be induced to differentiate into OSE-like cells in vitro.

Imaging in gynecological disease (8): ultrasound characteristics of recurrent borderline ovarian tumors

OBJECTIVES

To describe the sonographic characteristics of borderline ovarian tumor (BOT) recurrence.

METHODS

From the databases of five ultrasound centers, we retrospectively identified 68 patients with histological diagnosis of recurrent BOT who had undergone preoperative ultrasound examination. All recurrences were detected during planned follow-up ultrasound examinations. Recurrent lesions were described using the terms and definitions of the International Ovarian Tumor Analysis (IOTA) group.

RESULTS

Sixty-two patients had a serous BOT recurrence and six a mucinous BOT recurrence. All patients except one were premenopausal, 84% of them being < 40 years old. All but one patient were asymptomatic at diagnosis of the recurrence. Fertility-sparing surgery of the recurrent tumor was performed in 57/68 (84%) patients. The most frequent ultrasound feature of recurrent serous BOT was a unilocular solid cyst (49/62, 79%) and almost half of the recurrent serous BOTs (29/62, 47%) had multiple papillary projections. In 89% of the recurrent serous BOTs there was at least one papillation with irregular surface and in 73% there was at least one papillation vascularized at color Doppler examination. Recurrent mucinous BOTs appeared mainly as multilocular or multilocular solid cysts (5/6, 83%).

CONCLUSION

Sonographic features of recurrent BOT resemble those described by others for different subtypes of primary BOT.

Modulation of gene expression in ovarian cancer by active and repressive histone marks

DNA methylation and histone modifications often function concomitantly to drive an aberrant program of gene expression in most cancers. Consequently, they have also been identified as being associated with ovarian cancer. However, several basic issues remain unclear - are these marks established early during normal ovarian functioning, or at a preneoplastic stage, or through a gradual accumulation, or do they arise de novo during transformation? Such issues have been difficult to address in ovarian cancer wherein preneoplastic lesions and progression models have not yet been established and drug-refractive disease progression is rapid and aggressive. The review presents an overview of the known involvement of histone modifications in various cellular states that might contribute to our understanding of epithelial ovarian cancer.

Chicken pleiotrophin: regulation of tissue specific expression by estrogen in the oviduct and distinct expression pattern in the ovarian carcinomas

Pleiotrophin (PTN) is a developmentally-regulated growth factor which is widely distributed in various tissues and also detected in many kinds of carcinomas. However, little is known about the PTN gene in chickens. In the present study, we found chicken PTN to be highly conserved with respect to mammalian PTN genes (91–92.6%) and its mRNA was most abundant in brain, heart and oviduct. This study focused on the PTN gene in the oviduct where it was detected in the glandular (GE) and luminal (LE) epithelial cells. Treatment of young chicks with diethylstilbesterol induced PTN mRNA and protein in GE and LE, but not in other cell types of the oviduct. Further, several microRNAs, specifically miR-499 and miR-1709 were discovered to influence PTN expression via its 3′-UTR which suggests that post-transcriptional regulation influences PTN expression in chickens. We also compared expression patterns and CpG methylation status of the PTN gene in normal and cancerous ovaries from chickens. Our results indicated that PTN is most abundant in the GE of adenocarcinoma of cancerous, but not normal ovaries of hens. Bisulfite sequencing revealed that 30- and 40% of −1311 and −1339 CpG sites are demethylated in ovarian cancer cells, respectively. Collectively, these results indicate that chicken PTN is a novel estrogen-induced gene expressed mainly in the oviductal epithelia implicating PTN regulation of oviduct development and egg formation, and also suggest that PTN is a biomarker for epithelial ovarian carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease.

Allelic transcripts dosage effect in morphologically normal ovarian cells from heterozygous carriers of a BRCA1/2 French Canadian founder mutation

We hypothesized that the transcriptome of primary cultures of morphologically normal ovarian surface epithelial cells could be altered by the presence of a heterozygous BRCA1 or BRCA2 mutation. We aimed to discover early events associated with ovarian carcinogenesis, which could represent putative targets for preventive strategies of this silent killer tumor. We identified the first molecular signature associated with French Canadian BRCA1 or BRCA2 founder mutations in morphologically normal ovarian epithelial cells. We discovered that wild-type and mutated BRCA2 allelic transcripts were expressed not only in morphologically normal but also in tumor cells from BRCA2-8765delAG carriers. Further analysis of morphologically normal ovarian and tumor cells from BRCA1-4446C>T carriers lead to the same observation. Our data support the idea that one single hit in BRCA1 or BRCA2 is sufficient to alter the transcriptome of phenotypically normal ovarian epithelial cells. The highest level of BRCA2-mutated allele transcript expression was measured in cells originating from the most aggressive ovarian tumor. The penetrance of the mutation and the aggressiveness of the related tumor could depend on a dosage effect of the mutated allele transcript.

Differential analysis of ovarian and endometrial cancers identifies a methylator phenotype

Despite improved outcomes in the past 30 years, less than half of all women diagnosed with epithelial ovarian cancer live five years beyond their diagnosis. Although typically treated as a single disease, epithelial ovarian cancer includes several distinct histological subtypes, such as papillary serous and endometrioid carcinomas. To address whether the morphological differences seen in these carcinomas represent distinct characteristics at the molecular level we analyzed DNA methylation patterns in 11 papillary serous tumors, 9 endometrioid ovarian tumors, 4 normal fallopian tube samples and 6 normal endometrial tissues, plus 8 normal fallopian tube and 4 serous samples from TCGA. For comparison within the endometrioid subtype we added 6 primary uterine endometrioid tumors and 5 endometrioid metastases from uterus to ovary. Data was obtained from 27,578 CpG dinucleotides occurring in or near promoter regions of 14,495 genes. We identified 36 locations with significant increases or decreases in methylation in comparisons of serous tumors and normal fallopian tube samples. Moreover, unsupervised clustering techniques applied to all samples showed three major profiles comprising mostly normal samples, serous tumors, and endometrioid tumors including ovarian, uterine and metastatic origins. The clustering analysis identified 60 differentially methylated sites between the serous group and the normal group. An unrelated set of 25 serous tumors validated the reproducibility of the methylation patterns. In contrast, >1,000 genes were differentially methylated between endometrioid tumors and normal samples. This finding is consistent with a generalized regulatory disruption caused by a methylator phenotype. Through DNA methylation analyses we have identified genes with known roles in ovarian carcinoma etiology, whereas pathway analyses provided biological insight to the role of novel genes. Our finding of differences between serous and endometrioid ovarian tumors indicates that intervention strategies could be developed to specifically address subtypes of epithelial ovarian cancer.

Avian SERPINB11 gene: a marker for ovarian endometrioid cancer in chickens

As serine and cysteine proteinase inhibitors, serpins, such as SERPINB5, cause ovarian, colorectal and pancreatic adenocarcinomas. We identified SERPINB11 as a novel estrogen-induced gene in chickens during oviduct development. The chicken is a unique animal model for research on human ovarian cancer, because it spontaneously develops epithelial cell-derived ovarian cancer as in women. Therefore, this study investigated the expression pattern, CpG methylation status, and miRNA regulation of the SERPINB11 gene in normal and cancerous ovaries from chickens. Our results indicate that SERPINB11 is most abundant in the glandular epithelium of endometrioid adenocarcinoma of cancerous, but not normal, ovaries of hens. In addition, bisulfite sequencing revealed that about 30% of -110 CpG sites are methylated in ovarian cancer cells, whereas -110 CpG sites are demethylated in normal ovarian cells. Next, we determined whether miR-1582 influences SERPINB11 expression via its 3'UTR and found that it does not directly target the 3'UTR of SERPINB11 mRNA. Therefore, it is unlikely that post-transcriptional regulation influences SERPINB11 expression in the chicken ovary. On the other hand, in human ovarian cancer cells such as OVCAR-3, SKOV-3 and PA-1 cells, immunoreactive SERPINB11 protein was predominant in the cytoplasm and had a similar expression pattern to that in chicken ovarian cancer cells. Collectively, these results suggest that SERPINB11 is a biomarker for chicken ovarian endometrioid carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease in women.

Differential expression of alpha 2 macroglobulin in response to dietylstilbestrol and in ovarian carcinomas in chickens

BACKGROUND

Alpha 2 macroglobulin (A2M; also known as ovostatin), a homotetrameric protein with four disulfide-linked subunits, has the unique feature of inactivating/inhibiting most known proteases including serine-, threonine-, cysteine-, aspartic- and metalloproteases. In chickens, A2M has been identified and characterized biochemically, but little is known of its functional role(s) in the oviduct, hormonal regulation of expression or its expression in ovarian carcinomas in chickens. Therefore, we investigated estrogen regulation of A2M gene expression during development of the chicken oviduct, and its expression in normal and cancerous ovaries from chickens.

METHODS

To determine tissue-specific expression of A2M in chickens, we collected various organs from male and female chickens and performed RT-PCR analyses. To examine A2M gene expression in the oviduct of 1-week-old female chicks that received a subcutaneous implant of 15 mg DES in the abdominal region for 20 days, we performed RT-PCR, qPCR and in situ hybridization analyses using cDNAs from control- (n=5) and DES-treated oviducts (n=5), and then each segment of the oviduct from DES-treated chicks. To determine if A2M is a biomarker of ovarian cancer in hens, we collected cancerous (n=10) ovaries from a total of 136 chickens which had completely stopped egg-laying and performed RT-PCR and in situ hybridization analyses.

RESULTS

We found that A2M is most abundant in the chicken oviduct, specifically luminal (LE) and glandular epithelia (GE), but it was not detected in any other tissues of either sex. We then determined that DES (dietylstilbestrol, a synthetic nonsteroidal estrogen) increased A2M mRNA only in LE and GE of the oviduct of chicks. Further, expression of A2M was most abundant in GE of endometrioid adenocarcinoma of cancerous, but not normal ovaries of hens.

CONCLUSIONS

Collectively, results of the present study indicate that A2M is novel estrogen-stimulated gene expressed in LE and GE of the chicken oviduct and may be used for monitoring effects of therapies for ovarian cancer in laying hens.

Avian SERPINB11 gene: characteristics, tissue-specific expression, and regulation of expression by estrogen

Serpins, a group of proteins with similar structural and functional properties, were first identified based on their unique mechanism of action: their inhibition of proteases. While most serpins have inhibitory roles, certain serpins are not involved in canonical proteolytic cascades but perform diverse functions including storage of ovalbumin in egg white, transport of hormones (thyroxine- and cortisol-binding globulin), and suppression of tumors. Of these, serpin peptidase inhibitor, clade B, member 11 (SERPINB11) is not an inhibitor of known proteases in humans and mice, and its function is unknown. In the present study, the SERPINB11 gene was cloned, and its expression profile was analyzed in various tissues from chickens. The chicken SERPINB11 gene has an open reading frame of 1346 nucleotides that encode a protein of 388 amino acids that has moderate homology (38.8%-42.3%) to mammalian SERPINB11 proteins. Importantly, SERPINB11 mRNA is most abundant in the chicken oviduct, specifically luminal and glandular epithelia, but it was not detected in any other chicken tissues of either sex. We then determined effects of diethylstilbestrol (DES; a synthetic nonsteroidal estrogen) on SERPINB11 expression in the chicken oviduct. Treatment of young chicks with DES induced SERPINB11 mRNA and protein only in luminal and glandular epithelial cells of the oviduct. Collectively, these results indicate that the novel estrogen-induced SERPINB11 gene is expressed only in epithelial cells of the chicken oviduct and implicate SERPINB11 in regulation of oviduct development and differentiated functions.

Immunohistochemical and ultrastructural characterization of the ovarian surface epithelium of Japanese quail (Coturnix japonica)

Contrary to humans, most ovarian tumors in other species do not arise from the ovarian surface epithelium but are of follicular-, stromal- or germ-cell origin. One of the few species where ovarian cancer arises from the ovarian surface epithelium (OSE) is chicken (Gallus domesticus). Little is known about the morphology of the OSE in other avian species. In our study we analyzed the OSE morphology of Japanese quail (Coturnix japonica) using ultrastructural and histochemical techniques. Carbohydrate residues have been studied by using a panel of fluorescein isothiocyanate labeled lectins. Japanese quails are commonly used animal models in biomedical research as their housing is comparatively inexpensive and they show a short generation interval. Our ultrastructural and histochemical results demonstrate that the quail ovarian surface epithelium shows characteristic features which resemble the epithelia of both chicken and human. Additionally, the ovarian surface epithelium of the Japanese quail contains cytokeratin as well as vimentin intermediate filaments in their cytoplasm. Therewith and among other parts the quail OSE shows many characteristic features also seen in those of humans, which may qualify quail's ovary as a potential animal model for human ovarian carcinomas.

MUC4 stabilizes HER2 expression and maintains the cancer stem cell population in ovarian cancer cells

Background

Recent evidence has suggested that the capability of cancer to grow, propagate and relapse after therapy is dependent on a small subset of the cell population within the tumor, called cancer stem cells. Therefore, this subpopulation of cells needs to be targeted with different approaches by identification of unique stem-cell specific target antigens. One of the well known tumor antigens is the epithelial cell mucin MUC4, which is aberrantly expressed in ovarian cancer as compared to the normal ovary and plays a pivotal role in the aggressiveness and metastasis of ovarian cancer cells. In the present study, we aimed to analyze the cancer stem cell population in MUC4 overexpressed ovarian cancer cells.

Methods

MUC4 was ectopically overexpressed in SKOV3 ovarian cancer cells. Western blot analysis was performed for MUC4, HER2, CD133, ALDH1 and Shh expression in MUC4 overexpressed cells. Confocal analysis of MUC4, HER2 and CD133 was also done in the MUC4 overexpressed cells. CD133 and Hoechst33342 dye staining was used to analyze the cancer stem cell population via FACS method in SKOV3-MUC4 cells.

Results

MUC4 overexpressed SKOV3 cells showed an increased expression of HER2 compared to control cells. MUC4 overexpression leads to increased (0.1%) side population (SP) and CD133-positive cancer stem cells compared to the control cells. Interestingly, the tumor sphere type circular colony formation was observed only in the MUC4 overexpressed ovarian cancer cells. Furthermore, the cancer stem cell marker CD133 was expressed along with MUC4 in the isolated circular colonies as analyzed by both confocal and western blot analysis. HER2 and cancer stem cell specific marker ALDH1 along with Shh, a self-renewal marker, showed increased expression in the isolated circular colonies compared to MUC4-transfected cells.

Conclusion

These studies demonstrate that MUC4 overexpression leads to an enriched ovarian cancer stem cell population either directly or indirectly through HER2. In future, this study would be helpful for MUC4-directed therapy for the ovarian cancer stem cell population.

Dynamics of the primate ovarian surface epithelium during the ovulatory menstrual cycle

BACKGROUND

Epithelial ovarian cancer (EOC) risk correlates strongly with the number of ovulations that a woman experiences. The primary source of EOC in women is the ovarian surface epithelium (OSE). Mechanistic studies on the etiology of OSE transformation to EOC cannot be realistically performed in women. Selecting a suitable animal model to investigate the normal OSE in the context of ovulation should be guided by the model's reproductive similarities to women in natural features that are thought to contribute to EOC risk.

METHODS

We selected the non-human primate, rhesus macaque, as a surrogate to study the normal OSE during the natural menstrual cycle. We investigated OSE morphology and marker expression, plus cell proliferation and death in relation to menstrual cycle stage and ovulation.

RESULTS

OSE cells displayed a morphological range from squamous to columnar. Cycle-independent parameters and cycle-dependent changes were observed for OSE histology, steroid receptor expression, cell death, DNA repair and cell adhesion. Contrary to findings in non-primates, primate OSE cells were not manifestly cleared from the site of ovulation, nor were proliferation rates affected by ovulation or stage of the menstrual cycle. DNA repair proteins were more highly expressed in OSE than in other ovarian cells.

CONCLUSIONS

This study identifies significant differences between primate and non-primate OSE. In contrast to established views, ovulation-induced death and proliferation are not indicated as prominent contributors to EOC risk, but disruption of OSE cadherin-mediated adhesion may be, as could the loss of ovary-mediated chronic suppression of proliferation and elevation of DNA repair potential.

CCL25-CCR9 interaction modulates ovarian cancer cell migration, metalloproteinase expression, and invasion

BACKGROUND

Ovarian carcinoma (OvCa) is the most lethal gynecological malignancy among women and its poor prognosis is mainly due to metastasis. Chemokine receptor CCR9 is primarily expressed by a small subset of immune cells and its only natural ligand, CCL25, is largely expressed in the thymus, which involutes with age. Other than the thymus, CCL25 is expressed by the small bowel. Interactions between CCL25 and CCR9 have been implicated in leukocyte trafficking to the small bowel, a frequent metastatic site for OvCa cells. The current study shows OvCa tissue and cells significantly express CCR9, which interacts with CCL25 to support carcinoma cell migration and invasion.

METHODS

RT-PCR and flow cytometry techniques were used to quantify the expression CCR9 by OvCa cells. OvCa tissue microarrays (TMA) was used to confirm CCR9 expression in clinical samples. The Aperio ScanScope scanning system was used to quantify immunohistochemical staining. Cell invasion and migration assays were performed using cell migration and matrigel invasion chambers. Matrix metalloproteinase (MMP) mRNAs were quantified by RT-PCR and active MMPs were quantified by ELISA.

RESULTS

Our results show significantly (p<0.001) higher expression of CCR9 by mucinous adenocarcinoma, papillary serous carcinoma, and endometriod ovarian carcinoma cases, than compared to non-neoplastic ovarian tissue. Furthermore, CCR9 expression was significantly elevated in OvCa cell lines (OVCAR-3 and CAOV-3) in comparison to normal adult ovarian epithelial cell mRNA. OvCa cells showed higher migratory and invasive potential towards chemotactic gradients of CCL25, which was inhibited by anti-CCR9 antibodies. Expression of collagenases (MMP-1, -8, and -13), gelatinases (MMP-2 and -9), and stromelysins (MMP-3, -10, and -11) by OvCa cells were modulated by CCL25 in a CCR9-dependent fashion.

CONCLUSIONS

These results demonstrate both biological significance and clinical relevance of CCL25 and CCR9 interactions in OvCa cell metastasis.

BRCA1 16 years later: risk-associated BRCA1 mutations and their functional implications

Mutations in the tumor suppressor breast cancer susceptibility gene 1 (BRCA1), an important player in the DNA damage response, apoptosis, cell cycle regulation and transcription, confer a significantly elevated lifetime risk for breast and ovarian cancer. Although the loss of wild-type BRCA1 function is an important mechanism by which mutations confer increased cancer risk, multiple studies suggest mutant BRCA1 proteins may confer functions independent of the loss of wild-type BRCA1 through dominant negative inhibition of remaining wild-type BRCA1, or through novel interactions and pathways. These functions impact various cellular processes and have the potential to significantly influence cancer initiation and progression. In this review, we discuss the functional classifications of risk-associated BRCA1 mutations and their molecular, cellular and clinical impact for mutation carriers.

Natural immunity enhances the activity of a DR5 agonistic antibody and carboplatin in the treatment of ovarian cancer

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis specifically in cancer cells with little effect on normal cells. We have previously shown that TRAIL signaling is altered in most ovarian cancer patients and that resistance to TRAIL contributes to ovarian cancer progression. In this study, we investigated whether resistance to TRAIL may be overcome by a monoclonal TRAILR2 (DR5) agonistic antibody (AD5-10). We found that the joint presence of AD5-10 with TRAIL and natural killer (NK) cells expressing TRAIL resensitizes ovarian cancer cells to apoptosis in vitro and in vivo, respectively. The combination of AD5-10 with carboplatin exerts a more than additive effect in vitro, which may at least partially be explained by the fact that carboplatin triggers DR5 expression on ovarian cancer cells. Moreover, AD5-10 restores the sensitivity of platin-resistant ovarian cancer to carboplatin in vivo. In addition, we found that TRAIL expression and NK cells are abundant in the tumor microenvironment and that depletion of NK cells abolishes the antitumor activity of AD5-10. This indicates that NK-mediated immunosurveillance against ovarian cancer might be mediated by TRAIL and that apoptosis induced by AD5-10 requires the presence of NK cells. In conclusion, this study indicates a key role and strong antitumorigenic effect of DR5 and highlights a novel link between NK-mediated immunosurveillance and activation of DR5-mediated apoptosis in ovarian cancer. Mol Cancer Ther; 9(4); 1007-18. (c)2010 AACR.

Mucins in ovarian cancer diagnosis and therapy

Ovarian cancer is the most lethal gynecologic malignancy and the five-year survival rate is only 35% after diagnosis. Epithelial ovarian cancer is a highly metastatic disease characterized by widespread peritoneal dissemination and ascites. The death incidences from ovarian cancer could be significantly lowered by developing new methods for the early diagnosis and treatment of this fatal disease. Several potential markers have been identified recently. However, mucins are the most promising markers for ovarian cancer diagnosis. Mucins are large extracellular, heavily glycosylated proteins and their aberrant expression has been implicated in the pathogenesis of a variety of cancers, including ovarian cancer. This review will summarize known facts about the pathological and molecular characteristics of ovarian cancer, the current status of ovarian cancer markers, as well as general information about mucins, the putative role of mucins in the progression of ovarian cancer and their potential use for the early diagnosis and treatment of this disease.

Association of the ARLTS1 variants with familial ovarian cancer risk in China

ARLTS1 has been identified in chromosome 13q14 as a tumor suppressor gene of the adenosine diphosphate-ribosylation factor family with pro-apoptotic characteristics. The ARLTS1 mutation Trp149Stop and Cys148Arg have been shown to be associated with familial cancers, but limited information is available regarding the impact of ARLTS1 variants on familial ovarian cancer (OC). The aim of this study was to evaluate the ARLTS1 genetic variants associated with familial OC risk in China. We genotyped 85 OC patients with family ovarian/breast history, 80 sporadic OC patients, and 120 controls from general population by denaturing high-performance liquid chromatography screening analysis followed by direct sequencing of the conspicuous polymerase chain reaction products. ARLTS1 Cys148Arg revealed a significant association with an increased risk of familial OC compared with both sporadic cases and controls in a dose-dependent manner (P = 0.0031 and 0.012, respectively). In the clinical-pathological study, our results support previous data in demonstrating that familial OC was associated with younger age at diagnosis (49.7 years vs 53.3 years; P = 0.014), higher proportion of tumors of advanced stages (81.2% vs 67.5%; P = 0.033), and higher rates of serous adenocarcinomas (76.4% vs 53.8%; P = 0.028) compared with sporadic OC cases. To investigate the association between genetic variants of ARLTS1 and the clinical-pathological characteristics of familial OC, we identified a significantly higher proportion of serous adenocarcinoma (55/67, 82.1%) and higher rates of advanced stage tumors (88.1% vs 55.6%; P = 0.004) in ARLTS1 Cys148Arg carriers. We showed a significantly increased risk of familial OC for ARLTS1 Cys148Arg variant, which indicate that ARLTS1 may play a role in familial OC.

Candidate serous cancer precursors in fallopian tube epithelium of BRCA1/2 mutation carriers

Occult invasive and intraepithelial carcinomas have been identified in the tubal fimbria of BRCA mutation carriers undergoing prophylactic surgery, and recently described lesions overexpressing p53 in the distal tubes of mutation carriers, and non-carriers, have been proposed as histological precursors of high-grade serous carcinoma. The aim of this study was to confirm these findings in a larger, independent case set, to further characterize the cancer precursor lesions, and to determine their frequency in BRCA mutation-positive (n=176) and control groups (n=64). For the purposes of this study, we excluded cases without documentation of a germline mutation of BRCA1/2, and without histological examination of the entire tube, and cases with a diagnosis of invasive carcinoma. Controls included salpingectomies from women undergoing surgery for reasons other than ovarian malignancy. Diagnostic categories were assigned based on combined histological review and immunostaining results. Histological abnormalities were identified in 23% of the BRCA group and in 25% of the control group, and included localized p53 overexpression in 20% of the BRCA group and 25% of the control group. Tubal intramucosal carcinoma was identified in 8% of the BRCA cases and in 3% of the control group. Four cases of intraepithelial carcinoma (21%) did not overexpress p53. There was no significant difference in the median age, frequency of histological abnormalities, p53 signatures, or tubal intraepithelial carcinoma between the BRCA mutation-positive and control groups. This large, blinded review of tubes from BRCA mutation carriers confirms previous reports of putative cancer precursors in distal tubal mucosa, and that p53 signatures occur with similar frequency in women at low and high genetic risk of tubal/ovarian carcinoma. Tubal intraepithelial carcinoma, which, like invasive serous cancer, usually but not always overexpresses p53 protein, is more frequent in BRCA mutation carriers.

Effects of pharmacological concentrations of estrogens on growth of 3AO human ovarian cancer cells

During the past two decades, the knowledge of the molecular mechanism by which estrogens exert various functions in different tissues and organs has evolved rapidly. Recent reports demonstrated that estrogen could decrease the cell growth in several types of cancer cells, including ovarian cancer cells. Though experiments explored the possible mechanism of the inhibitory effect, the exact mechanism is responsible for the effect, which remains unclear. The ovary is the main source of the estrogen, estrogen receptor is expressed in several ovarian cell types, including ovarian surface epithelium, the tissue of origin of approximately 90% of the ovarian cancers. It was of great interest to analyze the effects of 17beta-estradiol (E2) on apoptosis of ovarian cancer cells, and the identification of E2-regulated specific genes involved in epithelial proliferation apoptosis, thus may be a clue for understanding the progression of ovarian cancer and for the design of new target therapies. To elucidate the mechanism involved, effects of pharmacological concentrations of estrogen were studied in human ovarian cancer cell line 3AO cells. Inhibition of cellular growth of 3AO cells was seen with E2 at concentrations higher than 0.1 micromol/L. The estrogen receptor inhibitor ICI 182780 cannot block the inhibitory effect of E2. It was surprising to find that ICI 182780 itself can inhibit the growth of 3AO cells, and had a collaborative effect with E2. The decreased cell growth induced by E2 was shown to be apoptosis as analyzed by flow cytometry. ERbeta was detected in the 3AO ovarian cancer cell line but not ERalpha. The expression of ERbeta was weak, which may partially explain why high but not low dose of E2 needed to induce the apoptosis of 3AO cells. We also observed that membrane impermeable E2, E2-BSA have lost growth inhibitory on 3AO cells, which excluded the membrane effect of E2 as previously reported by many investigators. The p38 kinase inhibitor, SB203580 were partially protected 3AO cells against growth inhibition by E2, while inhibitor of JNK, SP600125 enhanced cell death induced by E2. These results showed that MAPK is implicated in cellular processes involving apoptosis.

Immune physiology in tissue regeneration and aging, tumor growth, and regenerative medicine

The immune system plays an important role in immunity (immune surveillance), but also in the regulation of tissue homeostasis (immune physiology). Lessons from the female reproductive tract indicate that immune system related cells, such as intraepithelial T cells and monocyte-derived cells (MDC) in stratified epithelium, interact amongst themselves and degenerate whereas epithelial cells proliferate and differentiate. In adult ovaries, MDC and T cells are present during oocyte renewal from ovarian stem cells. Activated MDC are also associated with follicular development and atresia, and corpus luteum differentiation. Corpus luteum demise resembles rejection of a graft since it is attended by a massive influx of MDC and T cells resulting in parenchymal and vascular regression. Vascular pericytes play important roles in immune physiology, and their activities (including secretion of the Thy-1 differentiation protein) can be regulated by vascular autonomic innervation. In tumors, MDC regulate proliferation of neoplastic cells and angiogenesis. Tumor infiltrating T cells die among malignant cells. Alterations of immune physiology can result in pathology, such as autoimmune, metabolic, and degenerative diseases, but also in infertility and intrauterine growth retardation, fetal morbidity and mortality. Animal experiments indicate that modification of tissue differentiation (retardation or acceleration) during immune adaptation can cause malfunction (persistent immaturity or premature aging) of such tissue during adulthood. Thus successful stem cell therapy will depend on immune physiology in targeted tissues. From this point of view, regenerative medicine is more likely to be successful in acute rather than chronic tissue disorders.

Clinical potential of mucins in diagnosis, prognosis, and therapy of ovarian cancer

Knowledge of mucins and their multiple roles in various normal and pathological processes has improved greatly in the past two decades. Mucins belong to a family of glycoproteins characterised by densely O-glycosylated repetitive domains and expressed by various surface epithelial cells. Altered expression of mucins is present in various diseases, including cancer. Ovarian cancer is the sixth most common cancer worldwide and the seventh leading cause of cancer-related deaths in women. The most common ovarian cancer is epithelial ovarian carcinoma, which is characterised by few early symptoms, widespread peritoneal dissemination, and ascites at advanced stages that result in poor prognosis. After diagnosis, 5 year survival is only 35-45%. Therefore, improved strategies for early diagnosis and treatment are needed. Because of the surface epithelial origin of epithelial ovarian cancer, mucins are obvious biomolecules for investigation as markers for early diagnosis and as therapeutic targets. We discuss the potential role and clinical usefulness of mucins in early diagnosis, prognosis, and treatment of ovarian cancer.

New insights into the pathogenesis of serous ovarian cancer and its clinical impact

There are only a handful of concepts concerning cancer and carcinogenesis that are currently beyond dispute. One such dogma is the adenoma-carcinoma sequence and that a multistep accumulation of genetic alterations is required for transformation from a benign to a neoplastic tissue. The inevitable derivative of this dogma is that every invasive carcinoma is in fact a missed intraepithelial tumor, and furthermore, a late evolutionary stage in the sequence of development from a precursor lesion. Until fairly recently, high-grade serous ovarian carcinoma seemed to be one of the only known deviants of these concepts. In this article, we discuss the emergence of the fallopian tube fimbria as a field of origin for high-grade serous carcinomas and present a binary model of ovarian cancer pathogenesis that takes into consideration prior epidemiologic, morphologic, and genetic data. With the rise of the fallopian tube secretory epithelial cell as a cell of origin for high-grade pelvic serous carcinomas, the need to develop tools and model systems to characterize the biology and physiology of this cell is recognized.

Primary culture of ovarian surface epithelial cells and ascites-derived ovarian cancer cells from patients

Our laboratory has refined the technique for isolating primary cultures of normal human ovarian surface epithelial (OSE) cells by combining two different protocols involving the enzymatic and mechanical removal of OSE cells from ovarian biopsies. A simple protocol of obtaining primary epithelial ovarian cancer (EOC) cells from the ascites fluid removed from patients with high-grade ovarian cancer is also described. These methods allow for the direct application of many molecular and cellular analyses of normal versus cancer cells isolated freshly from patients, with the added potential for retrospective analyses of archived cells and tissues. Thus, we have included optional steps for the immediate preparation of ascites-derived EOC cells to be used for subsequent cytological analyses. Initial isolation of OSE or EOC cells can be completed in 1 h, and primary cells are further expanded in culture for several weeks.

Macrophages in human fallopian tube and ovarian epithelial inclusion cysts

Epithelial inclusion cysts (EICs) are considered a preferential site for ovarian carcinogenesis. Local inflammation, associated to ovulatory wound repair and epithelial inflammatory conditions, facilitates EIC formation and involves activation of macrophages. The aim of this study was to analyse the presence and numbers of macrophages in the ovarian surface epithelium (OSE), in EICs, and in the fallopian tubes, as tubal metaplasia is a common finding in EICs. Immunohistochemical analysis of macrophages was performed in 25 fallopian tubes in different phases of the menstrual cycle, and in 30 ovaries showing EICs from cycling and postmenopausal women. In the fallopian tube, macrophages were abundant and underwent cyclic changes during the menstrual cycle, being particularly abundant within the epithelium at early and mid-luteal phases. Macrophages were not found in the normal OSE. However, OSE areas and EICs showing tubal metaplasia were invariably associated with infiltration by abundant macrophages. Macrophages were present among epithelial cells, infiltrating the cyst wall, as well as free in the cyst lumen. No significant differences existed between follicular and luteal phases of the cycle, or between cycling and postmenopausal women. This study has demonstrated that macrophages are associated with metaplastic EICs, and raises the possibility that these cells contribute to the particular microenvironment of EICs through secretion of cytokines and growth factors that may reach bioactive concentrations in the confined space of the EICs.

Activated epidermal growth factor receptor induces integrin alpha2 internalization via caveolae/raft-dependent endocytic pathway

Elevated expression or activity of the epidermal growth factor (EGF) receptor is common in ovarian cancer and is associated with poor patient prognosis. Our previous studies demonstrated that expression of the constitutively active mutant form of the EGF receptor (EGFRvIII) in ovarian cancer cells led to reduction in integrin alpha2 surface expression, defects in cell spreading, and disruption of focal adhesions. Inhibition of EGFRvIII catalytic activity reversed the response, suggesting that EGF receptor activation regulates integrin alpha2. In this study we found that EGF treatment resulted in a transient loss of integrin alpha2 from the cell surface. Before EGF stimulation, integrin alpha2 and EGF receptors were associated based on biochemical and immuno-colocalization approaches. After EGF treatment, EGF receptor and integrin alpha2 were internalized and segregated into different compartments. Integrin alpha2, but not EGF receptor, was associated with caveolin-1 and GM1 (Gal_1,3GalNAc_1,4(Neu5Ac-_ 2,3)Gal_1,4Glc_1,1-ceramide) gangliosides, suggesting caveolae-mediated endocytosis. Moreover, integrin alpha2 was subsequently targeted to the Golgi apparatus and the endoplasmic reticulum. Together, these findings demonstrate that activated EGF receptor transiently modulates integrin alpha2 cell surface expression and stimulates integrin alpha2 trafficking via caveolae/raft-mediated endocytosis, representing a novel mechanism by which the EGF receptor may regulate integrin-mediated cell behavior.

Structural changes and cell properties of human ovarian surface epithelium in ovarian pathophysiology

The surface epithelial cells of the ovary, which are modified peritoneal cells, form a single, focally pseudostratified layer. The Müllerian ducts differentiate after invagination of the coelomic mesothelium over the gonadal ridges during the 6th week of embryonic life. On the basis of the embryologically putative Müllerian potential of this epithelium, endometriosis can be explained by coelomic metaplasia from the peritoneum, including ovarian surface epithelium. Some pelvic endometriosis specimens have shown that epithelial cells on the ovary or pelvis are serially changed to endometriotic gland cells. Immunohistochemistry as well as scanning electron microscopy also reinforce the light-microscopical findings. A three-dimensional culture system demonstrated that human ovarian surface epithelial cells exhibited a glandular-stromal structure when they were cocultured with endometrial stromal cells in an estrogen-rich environment. Ovarian carcinomas in the epithelial-stromal category are thought to arise from the surface epithelium and its inclusions. The ovarian surface epithelium is physiologically involved in follicular rupture, oocyte release, and the subsequent repair of follicle wall during reproductive age. Simultaneously, ovulation may cause a loss of integrity of the surface epithelium, followed by accumulation of multiple mutations. The cortical invagination, surface stromal proliferation, and Müllerian differentiation of these cells are likely not to be an early step in the cancer development. However, the inclusion cysts are closely related with carcinogenesis because they are significantly more common in ovaries contralateral to those containing epithelial cancers than in control ovaries. As an in vitro study, ovarian carcinoma cell lines were established from simian virus 40 large T antigen-transformed human surface epithelial cells of the ovary. Further investigations of these cell lines may lead to insights into the preneoplastic and early stages of carcinomas. To clarify the pathogenesis of endometriosis and epithelial ovarian cancer, specifically designed studies of ovarian surface epithelium are required.

4-HPR modulates gene expression in ovarian cells

Ovarian cancer has a high rate of recurrence and subsequent mortality following chemotherapy despite intense efforts to improve treatment outcomes. Recent trials have suggested that retinoids, especially 4-(N-hydroxyphenyl) retinamide (4-HPR), play an important role as a chemopreventive agent and are currently being used in clinical trials for ovarian cancer chemoprevention as well as treatment. This study examines the mechanism of its activity in premalignant and cancer cells. We investigated the modulation of gene expression by 4-HPR in immortalized ovarian surface epithelial (IOSE) cells and ovarian cancer (OVCA433) cells with DNA microarray. Real time RT-PCR and western blotting were used to confirm the microarray results and metabolic changes were examined with optical fluorescence spectroscopy. 4-HPR resulted in an up-regulation of expression of proapoptotic genes and mitochondrial uncoupling protein in OVCA433 cells and modulation of the RXR receptors in IOSE cells, and down-regulation of mutant BRCA genes in both IOSE and OVCA433 cells. 4-HPR had a larger effect on the redox in the 433 cells compared to IOSE. These findings suggest that 4-HPR acts through different mechanisms in premalignant ovarian surface cells and cancer cells, with a preventive effect in premalignant cells and a treatment effect in cancer cells.

Glyceraldehyde-3-phosphate dehydrogenase binds to the AU-Rich 3' untranslated region of colony-stimulating factor-1 (CSF-1) messenger RNA in human ovarian cancer cells: possible role in CSF-1 posttranscriptional regulation and tumor phenotype

The overexpression of the colony-stimulating factor-1(CSF-1) by epithelial ovarian cancer cells enhances invasiveness and metastatic properties, contributing to the poor prognosis of the patients. It has been suggested that CSF-1 3' untranslated region containing AU-rich elements (ARE) could regulate CSF-1 posttranscriptional expression and be responsible for its aberrant abundance in such cancer cells. In this study, normal (NOSE.1) and malignant (Hey) ovarian epithelial cells were used to examine CSF-1 expression and regulation. CSF-1 overexpression in Hey cells was found to associate with increased invasiveness, motility, urokinase activity, and virulence of tumorigenicity, compared with NOSE.1 cells, which expressed little CSF-1. CSF-1 ARE was further found to serve as an mRNA decay element that correlates with down-regulation of protein translation. Moreover, such down-regulation was found more prominent in NOSE.1 than in Hey cells, suggesting differences in posttranscriptional regulation. As a variety of trans-acting factors [AU-binding protein (AUBP)] are known to modulate messenger stability through binding to such elements, we examined the protein content of both cell lines for their ability to bind the CSF-1 ARE. Our results strongly suggested the abundance of such AUBP activity in Hey cells. We isolated a 37-kDa AUBP, which was identified as glyceraldehyde-3-phosphate dehydrogenase (GAPDH). To summarize, our study identified GAPDH as an AUBP abundant in Hey cells, where it binds to CSF-1 ARE that imparts mRNA decay. These data suggest that GAPDH binding to CSF-1 ARE sequence prevents CSF-1 mRNA decay and subsequent down-regulation of CSF-1 protein translation, leading to CSF-1 overexpression and increased metastatic properties seen in ovarian cancer.

Biology of LPA in health and disease

The functions of lysophosphatidic acid (LPA) can be broadly divided into two classes: (1) physiological and (2) pathological roles. The role of LPA in embryonic development can be seen as early as oocyte formation. It continues in postnatal homeostasis, through its ability to impart a level of protection from both stress and local injury, by regulating cellular proliferation, apoptosis, and the reorganization of cytoskeletal fibers. LPA may function as a double-edged sword. While it helps maintain homeostasis against stress and insult, it may also augment the development and spread of pathological processes, including cancers.

Expression of candidate tumor markers in ovarian carcinoma and benign ovary: evidence for a link between epithelial phenotype and neoplasia

EpCAM, epithelial membrane antigen (EMA)-mucin 1 (MUC1), mesothelin, and CD9 have been reported to be overexpressed at the RNA level in ovarian carcinomas. By using immunohistochemistry, we profiled the protein expression of these gene products in ovarian carcinoma tissues and compared them with benign ovarian surface epithelium (OSE) and cortical inclusion cysts (CICs). Immunoreactivity for EMA and calretinin were used to define epithelial and mesothelial differentiation in nontumor tissues, respectively. Papillary serous (n = 16) and endometrioid (n = 10) tumors were immunopositive for EMA/MUC1 (100%), mesothelin (75% and 30%, respectively), CD9 (88% and 90%, respectively), and EpCAM (100%). All ovarian carcinomas and carcinoma cell lines tested were negative for calretinin. In nonneoplastic ovary, both OSE and CICs ranged from flat-to-cuboidal to stratified and ciliated in appearance. OSE with a cuboidal morphology had a similar immunoreactivity as omental peritoneum, expressing calretinin, mesothelin, and CD9. In contrast, CICs with stratified and ciliated epithelium show expression patterns similar to those in fallopian tubes. They frequently expressed EMA, EpCAM, mesothelin, and CD9. This immunophenotype is preserved in ovarian carcinomas, suggesting that Müllerian metaplasia signals the acquisition of these markers and that their expression is maintained in ovarian carcinomas that originate from this epithelium.