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

High Homogeneity of Mesothelin Expression in Primary and Metastatic Ovarian Cancer

To study the extent of heterogeneity of mesothelin overexpression in primary ovarian cancers and their peritoneal and lymph node metastases, a tissue microarray (TMA) was constructed from multiple sites of 220 ovarian cancers and analyzed by immunohistochemistry. One tissue core each was taken from up to 18 different tumor blocks per cancer, resulting in a total of 2460 tissue spots from 423 tumor sites (188 primary cancers, 162 peritoneal carcinosis, and 73 lymph node metastases). Positive mesothelin expression was found in 2041 of the 2342 (87%) arrayed tissue spots and in 372 of the 392 (95%) tumor sites that were interpretable for mesothelin immunohistochemistry. Intratumoral heterogeneity was found in 23% of 168 primary cancer sites interpretable for mesothelin and decreased to 12% in 154 peritoneal carcinosis and to 6% in 71 lymph node metastases ( P <0.0001). Heterogeneity between the primary tumor and matched peritoneal carcinosis was found in 16% of 102 cancers with interpretable mesothelin results. In these cancers, the mesothelin status switched from positive in the primary tumor to negative in the peritoneal carcinosis (3 cancers) in or vice versa (2 cancers), or a mixture of positive and negative peritoneal carcinoses was found (11 cancers). No such switch was seen between the mesothelin-interpretable primary tumors and their nodal metastases of 59 cancers, and only 1 mesothelin-positive tumor had a mixture of positive and negative lymph node metastases. In conclusion, mesothelin expression is frequent and highly homogeneous in ovarian cancer.

Mesothelin Expression in Human Tumors: A Tissue Microarray Study on 12,679 Tumors

Mesothelin (MSLN) represents an attractive molecule for targeted cancer therapies. To identify tumors that might benefit from such therapies, tissue microarrays including 15,050 tumors from 122 different tumor types and 76 healthy organs were analyzed for MSLN expression by immunohistochemistry. Sixty-six (54%) tumor types showed at least occasional weak staining, including 50 (41%) tumor types with at least one strongly positive sample. Highest prevalence of MSLN positivity had ovarian carcinomas (serous 97%, clear cell 83%, endometrioid 77%, mucinous 71%, carcinosarcoma 65%), pancreatic adenocarcinoma (ductal 75%, ampullary 81%), endometrial carcinomas (clear cell 71%, serous 57%, carcinosarcoma 50%, endometrioid 45%), malignant mesothelioma (69%), and adenocarcinoma of the lung (55%). MSLN was rare in cancers of the breast (7% of 1138), kidney (7% of 807), thyroid gland (1% of 638), soft tissues (0.3% of 931), and prostate (0 of 481). High expression was linked to advanced pathological tumor (pT) stage (p < 0.0001) and metastasis (p < 0.0001) in 1619 colorectal adenocarcinomas, but unrelated to parameters of malignancy in 1072 breast-, 386 ovarian-, 174 lung-, 757 kidney-, 171 endometrial-, 373 gastric-, and 925 bladder carcinomas. In summary, numerous important cancer types with high-level MSLN expression might benefit from future anti-MSLN therapies, but MSLN’s prognostic relevance appears to be limited.

CD9, a tetraspanin target for cancer therapy?

In the present minireview, we intend to provide a brief history of the field of CD9 involvement in oncogenesis and in the metastatic process of cancer, considering its potential value as a tumor-associated antigenic target. Over the years, CD9 has been identified as a favorable prognostic marker or predictor of metastatic potential depending on the cancer type. To understand its implications in cancer beside its use as an antigenic biomarker, it is essential to know its physiological functions, including its molecular partners in a given cell system. Moreover, the discovery that CD9 is one of the most specific and broadly expressed markers of extracellular membrane vesicles, nanometer-sized entities that are released into extracellular space and various physiological body fluids and play a role in intercellular communication under physiological and pathological conditions, notably the establishment of cancer metastases, has added a new dimension to our knowledge of CD9 function in cancer. Here, we will discuss these issues as well as the possible cancer therapeutic implications of CD9, their limitations, and pitfalls.

MicroRNA-200 family governs ovarian inclusion cyst formation and mode of ovarian cancer spread

Epidemiologic and histopathologic findings and the laying hen model support the long-standing incessant ovulation hypothesis and cortical inclusion cyst involvement in sporadic ovarian cancer development. MicroRNA-200 (miR-200) family is highly expressed in ovarian cancer. Herewith, we show that ovarian surface epithelial (OSE) cells with ectopic miR-200 expression formed stabilized cysts in three-dimensional (3D) organotypic culture with E-cadherin fragment expression and steroid hormone pathway activation, whereas ovarian cancer 3D cultures with miR-200 knockdown showed elevated TGF-β expression, mitotic spindle disorientation, increased lumenization, disruption of ROCK-mediated myosin II phosphorylation, and SRC signaling, which led to histotype-dependent loss of collective movement in tumor spread. Gene expression profiling revealed that epithelial-mesenchymal transition and hypoxia were the top enriched gene sets regulated by miR-200 in both OSE and ovarian cancer cells. The molecular changes uncovered by the in vitro studies were verified in both human and laying hen ovarian cysts and tumor specimens. As miR-200 is also essential for ovulation, our results of estrogen pathway activation in miR-200-expressing OSE cells add another intriguing link between incessant ovulation and ovarian carcinogenesis.

Ping-Pong-Tumor and Host in Pancreatic Cancer Progression

Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.

Epithelialization of mouse ovarian tumor cells originating in the fallopian tube stroma

Epithelial ovarian carcinoma accounts for 90% of all ovarian cancer and is the most deadly gynecologic malignancy. Recent studies have suggested that fallopian tube fimbriae can be the origin of cells for high-grade serous subtype of epithelial ovarian carcinoma (HGSOC). A mouse HGSOC model with conditional Dicer-Pten double knockout (Dicer-Pten DKO) developed primary tumors, intriguingly, from the fallopian tube stroma. We examined the growth and epithelial phenotypes of the Dicer-Pten DKO mouse tumor cells contributable by each gene knockout. Unlike human ovarian epithelial cancer cells that expressed full-length E-cadherin, the Dicer-Pten DKO stromal tumor cells expressed cleaved E-cadherin fragments and metalloproteinase 2, a mixture of epithelial and mesenchymal markers. Although the Dicer-Pten DKO tumor cells lost the expression of mature microRNAs as expected, they showed high levels of tRNA fragment expression and enhanced AKT activation due to the loss of PTEN function. Introduction of a Dicer1-expressing construct into the DKO mouse tumor cells significantly reduced DNA synthesis and the cell growth rate, with concurrent diminished adhesion and ZO1 epithelial staining. Hence, it is likely that the loss of Dicer promoted mesenchymal-epithelial transition in fallopian tube stromal cells, and in conjunction with Pten loss, further promoted cell proliferation and epithelial-like tumorigenesis.

Similar Characteristics of Endometrial and Endometriotic Epithelial Cells

Epithelial-mesenchymal transition (EMT) is characterized by the loss of epithelial and acquisition of mesenchymal cell characteristics. Our aim was to assess the epithelial phenotype in the pathogenesis of endometriosis with epithelial and mesenchymal markers. We used 2 structural (keratin-18, -19 [K18, K19]), 1 membrane-associated (mucin-1 [MUC1]), and 2 mesenchymal proteins (vimentin; zinc finger E-box-binding homeobox 1, [ZEB1]) to compare epithelial and mesenchymal characteristics in eutopic endometrium with the 3 endometriotic entities, peritoneal, ovarian, and deep infiltrating endometriosis (DIE). Quantitation showed no differences for K18, K19, and MUC1 between endometrium with and without endometriosis. Also, K18 was not different between endometrium and endometriotic lesions. In contrast, K19 and MUC1 were modestly but significantly decreased in the endometriotic lesions compared to endometrium. However, the maintained expression of epithelial markers in all investigated tissues, regardless of the pathological condition, clearly indicates no loss of the epithelial phenotype. This is further supported by the reduced presence of epithelial vimentin in endometriotic lesions which is in contrast to an increase in stromal vimentin in ectopic endometrium, especially in ovarian endometriosis. The ZEB1 increase in endometriotic lesions, especially in DIE, on the other hand suggests a role of partial EMT in the development of endometriotic lesions, possibly connected with the gain of invasive capabilities or stemness. Taken together, although we found some hints for at least a partial EMT, we did not observe a severe loss of the epithelial cell phenotype. Thus, we propose that EMT is not a main factor in the pathogenesis of endometriosis.

Pinin interacts with C-terminal binding proteins for RNA alternative splicing and epithelial cell identity of human ovarian cancer cells

Unlike many other human solid tumors, ovarian tumors express many epithelial markers at a high level for cell growth and local invasion. The phosphoprotein Pinin plays a key role in epithelial cell identity. We showed that clinical ovarian tumors and ovarian cancer cell lines express a high level of Pinin when compared with normal ovarian tissues and immortalized normal ovarian surface epithelial cell lines. Pinin co-localized and physically interacted with transcriptional corepressor C-terminal binding proteins, CtBP1 and CtBP2, in the nuclei of cancer cells. Knockdown of Pinin in ovarian cancer cells resulted in specific reduction of CtBP1 protein expression, cell adhesion, anchorage-independent growth, and increased drug sensitivity. Whole transcriptomic comparison of next-generation RNA sequencing data between control ovarian cancer cell lines and cancer cell lines with respective knockdown of Pinin, CtBP1, and CtBP2 expression also showed reduced expression of CtBP1 mRNA in the Pinin knockdown cell lines. The Pinin knockdown cell lines shared significant overlap of differentially expressed genes and RNA splicing aberrations with CtBP1 knockdown and in a lesser degree with CtBP2 knockdown cancer cells. Hence, Pinin and CtBP are oncotargets that closely interact with each other to regulate transcription and pre-mRNA alternative splicing and promote cell adhesion and other epithelial characteristics of ovarian cancer cells.

Characterization of MicroRNA-200 pathway in ovarian cancer and serous intraepithelial carcinoma of fallopian tube

BACKGROUND

Ovarian cancer is the leading cause of death among gynecologic diseases in Western countries. We have previously identified a miR-200-E-cadherin axis that plays an important role in ovarian inclusion cyst formation and tumor invasion. The purpose of this study was to determine if the miR-200 pathway is involved in the early stages of ovarian cancer pathogenesis by studying the expression levels of the pathway components in a panel of clinical ovarian tissues, and fallopian tube tissues harboring serous tubal intraepithelial carcinomas (STICs), a suggested precursor lesion for high-grade serous tumors.

METHODS

RNA prepared from ovarian and fallopian tube epithelial and stromal fibroblasts was subjected to quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR) to determine the expression of miR-200 families, target and effector genes and analyzed for clinical association. The effects of exogenous miR-200 on marker expression in normal cells were determined by qRT-PCR and fluorescence imaging after transfection of miR-200 precursors.

RESULTS

Ovarian epithelial tumor cells showed concurrent up-regulation of miR-200, down-regulation of the four target genes (ZEB1, ZEB2, TGFβ1 and TGFβ2), and up-regulation of effector genes that were negatively regulated by the target genes. STIC tumor cells showed a similar trend of expression patterns, although the effects did not reach significance because of small sample sizes. Transfection of synthetic miR-200 precursors into normal ovarian surface epithelial (OSE) and fallopian tube epithelial (FTE) cells confirmed reduced expression of the target genes and elevated levels of the effector genes CDH1, CRB3 and EpCAM in both normal OSE and FTE cells. However, only FTE cells had a specific induction of CA125 after miR-200 precursor transfection.

CONCLUSIONS

The activation of the miR-200 pathway may be an early event that renders the OSE and FTE cells more susceptible to oncogenic mutations and histologic differentiation. As high-grade serous ovarian carcinomas (HGSOC) usually express high levels of CA125, the induction of CA125 expression in FTE cells by miR-200 precursor transfection is consistent with the notion that HGSOC has an origin in the distal fallopian tube.

The Functions of MicroRNA-200 Family in Ovarian Cancer: Beyond Epithelial-Mesenchymal Transition

The majority of studies on microRNA-200 family members (miR-200s) in human cancers are based on the premise that miR-200s maintain epithelial cell integrity by suppressing epithelial-mesenchymal transition (EMT) through direct inhibition of mesenchymal transcription factors zinc finger E-box-binding homeobox 1/2 (ZEB1/ZEB2) and transforming growth factor-β (TGF-β), a potent inducer of EMT. Hence, downregulation of miR-200 in cancer cells promotes EMT and cancer metastasis. Yet, miR-200s are highly expressed in ovarian cancer, and ovarian cancer metastasizes primarily by dissemination within the pelvic cavity. In this review, we will refocus the epithelial property of ovarian cancer cells and the role of miR-200s in safeguarding this property, as well as the diverse roles of miR-200s in inclusion cyst formation, cancer cell growth, collective movement, angiogenesis, exosome-mediated cell communication, and chemoresponse. Taken together, miR-200s play a significant role in the initiation, progression and metastasis of ovarian cancer and may serve as diagnostic biomarkers and a target in therapeutic development.

The Functions of MicroRNA-200 Family in Ovarian Cancer: Beyond Epithelial-Mesenchymal Transition

The majority of studies on microRNA-200 family members (miR-200s) in human cancers are based on the premise that miR-200s maintain epithelial cell integrity by suppressing epithelial-mesenchymal transition (EMT) through direct inhibition of mesenchymal transcription factors zinc finger E-box-binding homeobox 1/2 (ZEB1/ZEB2) and transforming growth factor-β (TGF-β), a potent inducer of EMT. Hence, downregulation of miR-200 in cancer cells promotes EMT and cancer metastasis. Yet, miR-200s are highly expressed in ovarian cancer, and ovarian cancer metastasizes primarily by dissemination within the pelvic cavity. In this review, we will refocus the epithelial property of ovarian cancer cells and the role of miR-200s in safeguarding this property, as well as the diverse roles of miR-200s in inclusion cyst formation, cancer cell growth, collective movement, angiogenesis, exosome-mediated cell communication, and chemoresponse. Taken together, miR-200s play a significant role in the initiation, progression and metastasis of ovarian cancer and may serve as diagnostic biomarkers and a target in therapeutic development.

The Functions of MicroRNA-200 Family in Ovarian Cancer: Beyond Epithelial-Mesenchymal Transition

The majority of studies on microRNA-200 family members (miR-200s) in human cancers are based on the premise that miR-200s maintain epithelial cell integrity by suppressing epithelial-mesenchymal transition (EMT) through direct inhibition of mesenchymal transcription factors zinc finger E-box-binding homeobox 1/2 (ZEB1/ZEB2) and transforming growth factor-β (TGF-β), a potent inducer of EMT. Hence, downregulation of miR-200 in cancer cells promotes EMT and cancer metastasis. Yet, miR-200s are highly expressed in ovarian cancer, and ovarian cancer metastasizes primarily by dissemination within the pelvic cavity. In this review, we will refocus the epithelial property of ovarian cancer cells and the role of miR-200s in safeguarding this property, as well as the diverse roles of miR-200s in inclusion cyst formation, cancer cell growth, collective movement, angiogenesis, exosome-mediated cell communication, and chemoresponse. Taken together, miR-200s play a significant role in the initiation, progression and metastasis of ovarian cancer and may serve as diagnostic biomarkers and a target in therapeutic development.

Loss of E-cadherin disrupts ovarian epithelial inclusion cyst formation and collective cell movement in ovarian cancer cells

Increased inclusion cyst formation in the ovary is associated with ovarian cancer development. We employed in vitro three-dimensional (3D) organotypic models formed by normal human ovarian surface epithelial (OSE) cells and ovarian cancer cells to study the morphologies of normal and cancerous ovarian cortical inclusion cysts and the molecular changes during their transitions into stromal microenvironment. When compared with normal cysts that expressed tenascin, the cancerous cysts expressed high levels of laminin V and demonstrated polarized structures in Matrigel; and the cancer cells migrated collectively when the cyst structures were positioned in a stromal-like collagen I matrix. The molecular markers identified in the in vitro 3D models were verified in clinical samples. Network analysis of gene expression of the 3D structures indicates concurrent downregulation of transforming growth factor beta pathway genes and high levels of E-cadherin and microRNA200 (miR200) expression in the cancerous cysts and the migrating cancer cells. Transient silencing of E-cadherin expression in ovarian cancer cells disrupted cyst structures and inhibited collective cell migration. Taken together, our studies employing 3D models have shown that E-cadherin is crucial for ovarian inclusion cyst formation and collective cancer cell migration.

Role of mesothelin in carbon nanotube-induced carcinogenic transformation of human bronchial epithelial cells

Carbon nanotubes (CNTs) have been likened to asbestos in terms of morphology and toxicity. CNT exposure can lead to pulmonary fibrosis and promotion of tumorigenesis. However, the mechanisms underlying CNT-induced carcinogenesis are not well defined. Mesothelin (MSLN) is overexpressed in many human tumors, including mesotheliomas and pancreatic and ovarian carcinomas. In this study, the role of MSLN in the carcinogenic transformation of human bronchial epithelial cells chronically exposed to single-walled CNT (BSW) was investigated. MSLN overexpression was found in human lung tumors, lung cancer cell lines, and BSW cells. The functional role of MSLN in the BSW cells was then investigated by using stably transfected MSLN knockdown (BSW shMSLN) cells. MSLN knockdown resulted in significantly decreased invasion, migration, colonies on soft agar, and tumor sphere formation. In vivo, BSW shMSLN cells formed smaller primary tumors and less metastases. The mechanism by which MSLN contributes to these more aggressive behaviors was investigated by using ingenuity pathway analysis, which predicted that increased MSLN could induce cyclin E expression. We found that BSW shMSLN cells had decreased cyclin E, and their proliferation rate was reverted to nearly that of untransformed cells. Cell cycle analysis showed that the BSW shMSLN cells had an increased G2 population and a decreased S phase population, which is consistent with the decreased rate of proliferation. Together, our results indicate a novel role of MSLN in the malignant transformation of bronchial epithelial cells following CNT exposure, suggesting its utility as a potential biomarker and drug target for CNT-induced malignancies.

Differential expression of p-ERM, a marker of cell polarity, in benign and neoplastic oviductal epithelium

Serous tubal intraepithelial carcinoma (STIC) is a noninvasive phase of pelvic serous cancer at risk for metastasizing. Because of its biologic significance, its accurate distinction from nonmalignant mimics is important. Loss of cell orientation is an important feature of STIC. We sought to determine whether the immunohistochemical localization of cytoskeletal-organizing proteins phospho-ezrin-radaxin-moesin (p-ERM) would be useful in making this distinction. The benign oviductal entities (normal and p53 signatures), premalignant atypias (tubal intraepithelial lesions in transition), serous intraepithelial carcinomas (STICs), and carcinomas were analyzed for 5 staining patterns and compared. Linear or uniform luminal p-ERM staining was strongly associated with benign mucosa in contrast to STICs, in which it was lost and often replaced by nonlinear or nonuniform patterns highlighting individually cell groups or single cells. Premalignant atypias were similar to benign mucosa by p-ERM staining and retained the linear luminal pattern. This study shows, for the first time, that patterns of staining for an immunohistochemical correlate of cell polarity (p-ERM) differ between STICs, their benign counterparts and premalignant atypias that do not fulfill the criteria for STICs. If confirmed, these findings warrant further analysis of indices of cell polarity as objective markers for the diagnosis and mapping of the evolution of pelvic serous precursors.

Endosalpingiosis as it relates to tubal, ovarian and serous neoplastic tissues: an immunohistochemical study of tubal and Müllerian antigens

OBJECTIVE

The origins and clinical significance of endosalpingiosis (ES), ectopic tubal epithelium, are not well understood. These investigations aim to characterize ES as it relates to normal fallopian tube, ovarian surface and serous neoplasms.

METHODS

A retrospective review of pathology reports from all prophylactic gynecologic surgeries from 2000 to 2010 was performed to assess the frequency of ES. Twenty-one archival specimens of ES, 6 normal fallopian tubes, 9 normal ovaries, 21 serous neoplasms and a commercially available ovarian tissue microarray were subjected to immunohistochemistry (IHC) with 11 tubal and Müllerian antigens. IHC staining was evaluated with a quantitative scoring system and scores were analyzed using MINITAB statistical software.

RESULTS

ES was noted in 3.5% of pathologic specimens from 464 prophylactic surgeries. The majority of antigens showed no significant differences (p > 0.05) in median IHC scores between ES and normal fallopian tube epithelium (nFTE), while they were significantly different (p < 0.05) from the ovarian surface epithelium (OSE). Median IHC scores were unchanged in ES tissues regardless of the location of ES or the presence of a concurrent serous neoplasm. Three antigens emerged as contemporary tubal and ES biomarkers: phospho-Smad2, BCL2 and FOXJ1. All 3 biomarkers were expressed in ES, nFTE and serous neoplasms, but not in OSE or other tumor types.

CONCLUSION

This study provides immunophenotypic evidence that ES is more similar to the nFTE than OSE. Further, ES biomarker expression closely resembles serous neoplasms strengthening the growing body of evidence that all Müllerian serous carcinomas arise from tubal-like epithelium.

Fusion-derived epithelial cancer cells express hematopoietic markers and contribute to stem cell and migratory phenotype in ovarian carcinoma

For a long time, the external milieu of cancer cells was considered to be of secondary importance when compared with its intrinsic properties. That has changed now as the microenvironment is considered to be a major contributing factor toward the progression of tumor. In this study, we show that in human and mouse epithelial ovarian carcinoma and mouse lung carcinoma, the interaction between tumor-infiltrating hematopoietic cells and epithelial cancer cells results in their fusion. Intriguingly, even after the fusion event, cancer cells retain the expression of the pan-hematopoietic marker (CD45) and various markers of hematopoietic lineage, including those of hematopoietic stem cells, indicating that the hematopoietic genome is not completely reprogrammed. This observation may have implications on the bone marrow contribution to the cancer stem cell population. Interestingly, it was seen that in both cancer models, the expression of chemokine receptor CXCR4 was largely contributed to by the fused compartment of cancer cells. We hypothesize that the superior migratory potential gained by the cancer cells due to the fusion helps in its dissemination to various secondary organs upon activation of the CXCR4/CXCL12 axis. We are the first to report the presence of a hemato-epithelial cancer compartment, which contributes to stem cell markers and CXCR4 in epithelial carcinoma. This finding has repercussions on CXCR4-based therapeutics and opens new avenues in discovering novel molecular targets against fusion and metastasis.

Conditional inactivation of p53 in mouse ovarian surface epithelium does not alter MIS driven Smad2-dominant negative epithelium-lined inclusion cysts or teratomas

Epithelial ovarian cancer is the most lethal gynecological malignancy among US women. The etiology of this disease, although poorly understood, may involve the ovarian surface epithelium or the epithelium of the fallopian tube fimbriae as the progenitor cell. Disruptions in the transforming growth factor beta (TGFβ) pathway and p53 are frequently found in chemotherapy-resistant serous ovarian tumors. Transgenic mice expressing a dominant negative form of Smad2 (Smad2DN), a downstream transcription factor of the TGFβ signaling pathway, targeted to tissues of the reproductive tract were created on a FVB background. These mice developed epithelium-lined inclusion cysts, a potential precursor lesion to ovarian cancer, which morphologically resembled oviductal epithelium but exhibited protein expression more closely resembling the ovarian surface epithelium. An additional genetic “hit” of p53 deletion was predicted to result in ovarian tumors. Tissue specific deletion of p53 in the ovaries and oviducts alone was attempted through intrabursal or intraoviductal injection of Cre-recombinase expressing adenovirus (AdCreGFP) into p53^flox/flox mice. Ovarian bursal cysts were detected in some mice 6 months after intrabursal injection. No pathological abnormalities were detected in mice with intraoviductal injections, which may be related to decreased infectivity of the oviductal epithelium with adenovirus as compared to the ovarian surface epithelium. Bitransgenic mice, expressing both the Smad2DN transgene and p53^flox/flox, were then exposed to AdCreGFP in the bursa and oviductal lumen. These mice did not develop any additional phenotypes. Exposure to AdCreGFP is not an effective methodology for conditional deletion of floxed genes in oviductal epithelium and tissue specific promoters should be employed in future mouse models of the disease. In addition, a novel phenotype was observed in mice with high expression of the Smad2DN transgene as validated through qPCR analysis, characterized by teratoma-like lesions implicating Smad signaling in teratoma development.

The dichotomy in the histogenesis of endometriosis-associated ovarian cancer: clear cell-type versus endometrioid-type adenocarcinoma

The histogenesis of endometriosis and endometriosis-associated ovarian cancer is one of the most mysterious aspects of pathology. To better understand the histogenesis of endometriosis and endometriosis-associated ovarian cancer, we analyzed the possibility of a link of endometrium, ovarian surface epithelium, and a cortical inclusion cyst to ovarian endometriosis and endometriosis-associated ovarian cancer by immunohistochemistry using the epithelial membrane antigen (an epithelial marker), calretinin (a mesothelial marker), and hepatocyte nuclear factor (HNF)-1β (a clear cell carcinoma-specific transcription factor). During ovarian surface epithelium invagination, cortical inclusion cyst epithelial cells may, in some cases, undergo mesothelial-epithelial transition and subsequently differentiate into endometriosis. This case of endometriosis that has undergone Müllerian metaplasia arises from the HNF-1β-negative cells. The remaining endometriosis may develop from the late secretory and menstrual endometria, with HNF-1β-positive staining, by retrograde menstruation. Endometrioid adenocarcinoma and clear cell carcinoma arise from the HNF-1β-negative and HNF-1β-positive epithelial cells of endometriosis, respectively. It has been proposed that clear cell and endometrioid-type adenocarcinomas arise from distinct types of endometriosis with different cells of origin.

Upregulation of CD9 in ovarian cancer is related to the induction of TNF-α gene expression and constitutive NF-κB activation

Ovarian cancer is a gynecological cancer with a high death rate. We utilized global gene expression profiles of ovarian carcinomas obtained by complementary DNA (cDNA) microarray to identify ovarian cancer-specific proteins. CD9 was upregulated in ovarian carcinomas, and overexpression of the CD9 protein was detected in ovarian carcinomas by immunohistochemistry. CD9 was also overexpressed in several cancer cell lines, including ovarian cancer cells. In order to elucidate the biological significance of highly expressed CD9 in cancer cells, functional studies of CD9 were performed by ectopic expression, knockdown of CD9 using small interfering RNA (siRNA) and blockage of CD9 activity using the CD9-specific monoclonal antibody ALB6. Ectopic CD9 induced cell survival. In order to identify signaling pathways related to CD9, the gene expressions of CD9/SKOV3 cells were analyzed by cDNA microarray. Among the many upregulated genes, tumor necrosis factor (TNF)-α was induced in CD9/SKOV3 cells. The effect of overexpressed CD9 on the downstream signaling events of TNF-α was further investigated. In CD9/SKOV3 cells, the nuclear factor-kappaB (NF-κB)-signaling pathway was constitutively activated. Knockdown of CD9 by siRNA and blockage of CD9 activity by ALB6 in ovarian cancer cells demonstrated that constitutive activation of NF-κB is CD9 dependent and that CD9 is involved in anti-apoptosis. A CD9 functional study was performed in an ovarian cancer-xenograft mouse by injecting ALB6 into the peritoneum. ALB6 resulted in reduced tumor weight compared with that of control IgG(1). Collectively, these results demonstrate that CD9 functions as an oncogene and represents a target for the development of cancer-specific therapeutics.

CXCL12 expression by healthy and malignant ovarian epithelial cells

Background

CXCL12 has been widely reported to play a biologically relevant role in tumor growth and spread. In epithelial ovarian cancer (EOC), CXCL12 enhances tumor angiogenesis and contributes to the immunosuppressive network. However, its prognostic significance remains unclear. We thus compared CXCL12 status in healthy and malignant ovaries, to assess its prognostic value.

Methods

Immunohistochemistry was used to analyze CXCL12 expression in the reproductive tracts, including the ovaries and fallopian tubes, of healthy women, in benign and borderline epithelial tumors, and in a series of 183 tumor specimens from patients with advanced primary EOC enrolled in a multicenter prospective clinical trial of paclitaxel/carboplatin/gemcitabine-based chemotherapy (GINECO study). Univariate COX model analysis was performed to assess the prognostic value of clinical and biological variables. Kaplan-Meier methods were used to generate progression-free and overall survival curves.

Results

Epithelial cells from the surface of the ovary and the fallopian tubes stained positive for CXCL12, whereas the follicles within the ovary did not. Epithelial cells in benign, borderline and malignant tumors also expressed CXCL12. In EOC specimens, CXCL12 immunoreactivity was observed mostly in epithelial tumor cells. The intensity of the signal obtained ranged from strong in 86 cases (47%) to absent in 18 cases (<10%). This uneven distribution of CXCL12 did not reflect the morphological heterogeneity of EOC. CXCL12 expression levels were not correlated with any of the clinical parameters currently used to determine EOC prognosis or with HER2 status. They also had no impact on progression-free or overall survival.

Conclusion

Our findings highlight the previously unappreciated constitutive expression of CXCL12 on healthy epithelia of the ovary surface and fallopian tubes, indicating that EOC may originate from either of these epithelia. We reveal that CXCL12 production by malignant epithelial cells precedes tumorigenesis and we confirm in a large cohort of patients with advanced EOC that CXCL12 expression level in EOC is not a valuable prognostic factor in itself.

Trial Registration

ClinicalTrials.gov: NCT00052468

Comparison of expression profiles in ovarian epithelium in vivo and ovarian cancer identifies novel candidate genes involved in disease pathogenesis

Molecular events leading to epithelial ovarian cancer are poorly understood but ovulatory hormones and a high number of life-time ovulations with concomitant proliferation, apoptosis, and inflammation, increases risk. We identified genes that are regulated during the estrous cycle in murine ovarian surface epithelium and analysed these profiles to identify genes dysregulated in human ovarian cancer, using publically available datasets. We identified 338 genes that are regulated in murine ovarian surface epithelium during the estrous cycle and dysregulated in ovarian cancer. Six of seven candidates selected for immunohistochemical validation were expressed in serous ovarian cancer, inclusion cysts, ovarian surface epithelium and in fallopian tube epithelium. Most were overexpressed in ovarian cancer compared with ovarian surface epithelium and/or inclusion cysts (EpCAM, EZH2, BIRC5) although BIRC5 and EZH2 were expressed as highly in fallopian tube epithelium as in ovarian cancer. We prioritised the 338 genes for those likely to be important for ovarian cancer development by in silico analyses of copy number aberration and mutation using publically available datasets and identified genes with established roles in ovarian cancer as well as novel genes for which we have evidence for involvement in ovarian cancer. Chromosome segregation emerged as an important process in which genes from our list of 338 were over-represented including two (BUB1, NCAPD2) for which there is evidence of amplification and mutation. NUAK2, upregulated in ovarian surface epithelium in proestrus and predicted to have a driver mutation in ovarian cancer, was examined in a larger cohort of serous ovarian cancer where patients with lower NUAK2 expression had shorter overall survival. In conclusion, defining genes that are activated in normal epithelium in the course of ovulation that are also dysregulated in cancer has identified a number of pathways and novel candidate genes that may contribute to the development of ovarian cancer.

Does bilateral salpingectomy with ovarian retention warrant consideration as a temporary bridge to risk-reducing bilateral oophorectomy in BRCA1/2 mutation carriers?

Risk-reducing salpingo-oophorectomy (RRSO) is the most definitive surgical intervention for ovarian cancer risk reduction among BRCA1/2 mutation carriers. For women who have completed child-bearing but who are not ready for RRSO, bilateral salpingectomy with ovarian retention (BSOR) might serve as a temporary measure while definitive risk-reducing surgery is being contemplated. Here we summarize recent insights into the pathogenesis of hereditary ovarian cancer that might provide a basis for consideration of the proposed BSOR management strategy and outline the evidence for and against this potential risk-reducing intervention. Based on the evidence, we suggest that there may be sufficient merit in this proposed intervention to consider evaluating it formally, perhaps through an intergroup-based clinical trial. In the meanwhile, we believe that BSOR should be considered an investigational risk management option of unproven clinical usefulness, particularly because delay in bilateral oophorectomy theoretically could reduce the protective effect against breast cancer that has been documented in women who have undergone RRSO.

Human steroidogenic factor-1 (hSF-1) regulates progesterone biosynthesis and growth of ovarian surface epithelial cancer cells

The majority of cancers derived from ovarian surface epithelial (OSE) cells are lethal. Estrogens promote proliferation of OSE cells, whereas progesterone inhibits proliferation and promotes apoptosis of OSE cells. Human steroidogenic factor-1 (hSF-1) induction of the steroidogenic acute regulatory protein (StAR) gene, and the steroidogenic enzymes CYP11A1 and HSD3B2 is central to progesterone biosynthesis. Whereas hSF-1 and StAR are expressed in human ovarian surface epithelial (HOSE) cells, hSF-1 and StAR protein were not expressed in a panel of malignant ovarian cancer cell lines (SKOV-3, BG-1, and Caov-3), and in human OSE cells immortalized by SV40 large T antigen (IOSE-121). Transient expression of hSF-1 in SKOV-3 cells activated the expression of StAR, p450scc and 3betaHSD-II mRNAs, and induced progesterone biosynthesis. Additionally, hSF-1 suppressed proliferation and promoted apoptosis of SKOV-3 cells and suppressed SKOV-3 cell growth induced by ERalpha and estradiol. These findings suggest that hSF-1 is central to progesterone biosynthesis in OSE cells. Human SF-1 may decrease OSE cancer cell numbers directly by apoptosis, and indirectly by opposing estradiol-induced proliferation. These findings are consistent with the hypothesis, that down-regulation of hSF-1 contributes to progression of ovarian epithelial cancers.

Expression profiling identifies genes involved in neoplastic transformation of serous ovarian cancer

Background

The malignant potential of serous ovarian tumors, the most common ovarian tumor subtype, varies from benign to low malignant potential (LMP) tumors to frankly invasive cancers. Given the uncertainty about the relationship between these different forms, we compared their patterns of gene expression.

Methods

Expression profiling was carried out on samples of 7 benign, 7 LMP and 28 invasive (moderate and poorly differentiated) serous tumors and four whole normal ovaries using oligonucleotide microarrays representing over 21,000 genes.

Results

We identified 311 transcripts that distinguished invasive from benign tumors, and 20 transcripts that were significantly differentially expressed between invasive and LMP tumors at p < 0.01 (with multiple testing correction). Five genes that were differentially expressed between invasive and either benign or normal tissues were validated by real time PCR in an independent panel of 46 serous tumors (4 benign, 7 LMP, 35 invasive). Overexpression of SLPI and WNT7A and down-regulation of C6orf31, PDGFRA and GLTSCR2 were measured in invasive and LMP compared with benign and normal tissues. Over-expression of WNT7A in an ovarian cancer cell line led to increased migration and invasive capacity.

Conclusion

These results highlight several genes that may play an important role across the spectrum of serous ovarian tumorigenesis.

Screening, epidemiology, molecular biology, and treatment strategies for endometriosis-associated ovarian cancer

Objectives

This article reviews recent data on the biology, pathogenesis and pathophysiology of the different entity of epithelial ovarian cancer (EOC).

Study design

The present article reviews the English language literature for screening, epidemiology, clinical diagnosis, natural history, preclinical and clinical trials, and promising molecular targets on EOC, particularly for clear cell EOC (cEOC) based on the gene expression profiling studies.

Results

Prospective ovarian cancer screening trials in Japan showed that (1) serous-type EOC (sEOC) may exhibit a rapid progression possibly through de novo carcinogenesis, (2) the EOC risk was elevated significantly among patients with ovarian endometrioma (SIR = 8.95), (3) advancing age (>40 years) and the diameter of endometriomas (>9 cm) were independent predictors of development of EOC, (4) the benign-appearing ovarian masses are present several years before the EOC diagnosis in patients with endometriosis-associated EOC, and (5) the slightly elevated CA125 level is also typically present many years (>3 years) before the diagnosis in these patients. Upregulation of HNF-1beta and PLK-Emi1 genes were specifically detected in cEOC. In addition, the therapy currently used in renal cell carcinoma (RCC) should be considered as an attractive therapeutic option for cEOC.

Conclusions

Ovarian endometrioma could be viewed as a neoplastic process, particularly in perimenopausal women. Understanding the mechanisms of endometriosis development and elucidating its pathogenesis and pathophysiology are intrinsic to prevention and the search for effective therapies of endometriosis-associated EOC.

Ovarian cancer pathogenesis: a model in evolution

Ovarian cancer is a deadly disease for which there is no effective means of early detection. Ovarian carcinomas comprise a diverse group of neoplasms, exhibiting a wide range of morphological characteristics, clinical manifestations, genetic alterations, and tumor behaviors. This high degree of heterogeneity presents a major clinical challenge in both diagnosing and treating ovarian cancer. Furthermore, the early events leading to ovarian carcinoma development are poorly understood, thus complicating efforts to develop screening modalities for this disease. Here, we provide an overview of the current models of ovarian cancer pathogenesis, highlighting recent findings implicating the fallopian tube fimbria as a possible site of origin of ovarian carcinomas. The ovarian cancer model will continue to evolve as we learn more about the genetics and etiology of this disease.

The role of hepatocyte nuclear factor-1beta in the pathogenesis of clear cell carcinoma of the ovary

PROBLEM

Clear cell carcinoma (CCC) of the ovary has a number of features distinguishing it from other epithelial ovarian carcinomas (EOC) because of its characteristic histology and biology, frequent concurrence with endometriotic lesion, and highly chemoresistant nature resulting in an extremely poor prognosis. The incidence of CCC has been steadily increasing in Japan. They comprise approximately 20% of all EOC. Understanding the mechanisms of CCC development and elucidating pathogenesis and pathophysiology are intrinsic to prevention and effective therapies for CCC.

METHOD OF STUDY

This article reviews the English language literature for biology, pathogenesis, and pathophysiological studies on endometriosis-associated EOC. Several data are discussed in the context of endometriosis and CCC biology.

RESULTS

Recent studies based on genome-wide expression analysis technology have noted specific expression of hepatocyte nuclear factor-1beta (HNF-1beta) in endometriosis and CCC, suggesting that early differentiation into the clear cell lineage takes place in the endometriosis. The HNF-1beta-dependent pathway of CCC will be discussed, which are providing new insights into regulation of apoptosis and glycogen synthesis and resistance of CCC to anticancer agents.

CONCLUSIONS

This review summarizes recent advances in the HNF-1beta and its target genes; the potential challenges to the understanding of carcinogenesis, pathogenesis, and pathophysiology of CCC; and a possible novel model is proposed.

Acquisition of a second mutation of the Tp53 alleles immediately precedes epithelial morphological transformation in ovarian tumorigenicity

OBJECTIVE

Tp53 mutation is frequent and associates with malignant, high-grade ovarian cancer. However, the details about the progression of Tp53 mutation from heterozygous to homozygous, and association between genotypes and morphological transformation are not clear. We further investigated the expression and mutation of Tp53 and associated markers such as p21 and HDM2 in ovarian cancer.

METHOD

Areas of contiguous ovarian surface epithelia linking morphological normal monolayer to multilayer neoplastic cells were analyzed for the correlation of Tp53 pathway alteration in relation to morphological transformation, by immunostaining and sequencing of Tp53 gene in cells from laser captured microdissection.

RESULTS

Consistent with previous reports, Tp53 staining is positive in 78% of the tumors. The staining of p21 is positive in about 12%, and HMD2 is positive in only 1% of the tumors. In 9 out of 10 cases of p21-positive tumors, p53 is also positive. In the majority of cases of epithelial histological transitions, overexpression of Tp53 correlates with morphological transformation: Tp53 is negative in monolayered cells and positive in neoplastic lesions. Morphological transformation also closely correlates with cell proliferation as indicated by Ki-67 staining and loss of p21 expression. We detected heterozygous mutation of Tp53 in the monolayers adjacent to neoplastic cells.

CONCLUSIONS

p21 expression is an indicator of a wild type Tp53 and lack of p21 in the presence of Tp53 expression predicts an inactivated Tp53. Tp53 inactivation immediately precedes morphological transformation of the ovarian surface epithelium in most cases, and the histological transitional epithelia containing a heterozygous Tp53 mutation are thus pre-neoplastic lesions. We propose that the loss of a second allele of Tp53 leading to the loss of p21 expression, and subsequent cell proliferation, compose a sequence of events that lead to morphological transformation and instigation of ovarian epithelial tumor development.

New diagnostic and molecular characteristics of malignant mesothelioma

Malignant mesothelioma is a primary cancer of the serosal cavities, an anatomic site that is also frequently affected by metastatic disease, predominantly from primary carcinomas of the lung, breast, and ovary. Advances in immunohistochemistry have resulted in improved diagnostic sensitivity and specificity in the differential diagnosis between metastatic adenocarcinoma and malignant mesothelioma in both cytological and histological material. Recently, the author's group applied high throughput technology to the identification of new markers that may aid in differentiating malignant mesothelioma from ovarian and peritoneal serous carcinoma, tumors with closely related histogenesis and antigenic profile. In addition to the improved tools available for serosal cancer diagnosis, knowledge regarding the biology of malignant mesothelioma has been accumulating in recent years. This review presents current data regarding the diagnostic and biological aspects of malignant mesothelioma.

Tspan-1 is a tetraspanin preferentially expressed by mucinous and endometrioid subtypes of human ovarian carcinomas

In many human cancers, tumor progression was found to be associated with an altered expression of tetraspanins, a group of transmembrane adaptor proteins that are implicated in fundamental cellular processes. Although recognized as a characteristic of malignant cells of various origins, Tspan-1 has not yet been characterized in detail due to lack of specific antibodies. We describe the generation of Tspan-1-specific antibodies and immunohistochemical staining of different subtypes of ovarian carcinomas (n=72) that revealed significant differences in Tspan-1 expression that was pronounced in mucinous and endometrioid tumors. The observation that immunoreactivity was focused in intracellular vesicles often concentrated at the luminal sides of glandular structures further supported the assumption that Tspan-1 is involved in secretory pathways. In the group of serous ovarian carcinomas, pronounced expression of Tspan-1 was observed in FIGO stage III C-classified tumors of advanced stages. In summary, our results show that Tspan-1 is an important characteristic of malignant ovarian cancer cells and a potential therapeutic target.

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.

Serous tubal intraepithelial carcinoma: its potential role in primary peritoneal serous carcinoma and serous cancer prevention

PURPOSE

A diagnosis of primary peritoneal serous carcinoma (PPSC) requires exclusion of a source in other reproductive organs. Serous tubal intraepithelial carcinoma (STIC; stage 0) has been described in asymptomatic women with BRCA mutations and linked to a serous cancer precursor in the fimbria. This study examined the frequency of STIC in PPSC and its clinical outcome in BRCA-positive women.

PATIENTS AND METHODS

Presence or absence of STIC was recorded in consecutive cases meeting the 2001 WHO criteria for PPSC, including 26 patients with nonuniform sampling of the fallopian tubes (group 1) and 19 patients with complete tubal examination (group 2; sectioning and extensively examining the fimbriated end, or SEE-FIM protocol). In selected cases, STIC or its putative precursor and the peritoneal tumor were analyzed for p53 mutations (exons 1 to 11). Outcome of STIC was ascertained by literature review.

RESULT

Thirteen (50%) of 26 PPSCs in group 1 involved the endosalpinx, with nine STICs (35%). Fifteen (79%) of 19 cases in group 2 contained endosalpingeal involvement, with nine STICs (47%). STIC was typically fimbrial and unifocal, with variable invasion of the tubal wall. In five of five cases, the peritoneal and tubal lesion shared an identical p53 mutation. Of 10 reported STICs in BRCA-positive women, all patients were without disease on follow-up.

CONCLUSION

The fimbria is the source of nearly one half of PPSCs, suggesting serous malignancy originates in the tubal mucosa but grows preferentially at a remote peritoneal site. The generally low risk of recurrence in stage 0 (STIC) disease further underscores STIC as a possible target for early serous cancer detection and prevention.

Use of yeast-secreted in vivo biotinylated recombinant antibodies (Biobodies) in bead-based ELISA

PURPOSE

To measure circulating antigens, sandwich ELISA assays require two complementary affinity reagents. Mouse monoclonal antibodies (mAb) and polyclonal antibodies (pAb) are commonly used, but because their production is lengthy and costly, recombinant antibodies are emerging as an attractive alternative.

EXPERIMENTAL DESIGN

We developed a new class of recombinant antibodies called biobodies (Bb) and compared them to mAb for use in serodiagnosis. Bbs were secreted biotinylated in vivo by diploid yeast and used as affinity reagents after Ni purification. Bead-based assays for HE4 and mesothelin were developed using Bbs in combination with pAbs (Bb/pAb assays). To assess precision, reproducibility studies were done using four runs of 16 replicates at six analyte levels for each marker. Pearson correlations and receiver-operator characteristic analyses were done in 214 patient serum samples to directly compare the Bb/pAb assays to mAb assays. Diagnostic performance of the Bb/pAb assay was further assessed in an expanded set of 336 ovarian cancer cases and controls.

RESULTS

On average across analyte levels, Bb/pAb assays yielded within-run and between-run coefficients of variations of 11.7 and 23.8, respectively, for HE4 and 14.0 and 14.5, respectively, for mesothelin. In the subset (n = 214), Pearson correlations of 0.95 for HE4 and 0.92 for mesothelin were observed between mAb and Bb/pAb assays. The area under the curves for the mAb and Bb/pAb assays were not significantly different for HE4 (0.88 and 0.84, respectively; P = 0.20) or mesothelin (0.74 and 0.72, respectively; P = 0.38).

CONCLUSION

Yeast-secreted Bbs can be used reliably in cost-effective yet highly sensitive bead-based assays for use in large validation studies.

Tubal and ovarian pathways to pelvic epithelial cancer: a pathological perspective

Prolongation of ovarian epithelial cancer survival depends on early detection or improved responses to chemotherapy. Gains in either have been modest at best. Understanding the diverse pathogenesis of this disease is critical to early intervention or prevention. This review addresses six important variables, including (i) cell of origin, (ii) site of origin, (iii) initial genotoxic events, (iv) risks imposed by hereditary and other promoting conditions, (v) subsequent factors that promote different patterns of metastatic spread, and (vi) prospects for intervention. This review proposes two distinct pathways to pelvic epithelial cancer. The first initiates in ovarian surface epithelium (OSE), Mullerian inclusions or endometriosis in the ovary. The second arises from the endosalpinx and encompasses a subset of serous carcinomas. The serous carcinogenic sequence in the distal fallopian tube is described and contrasted with lower grade serous tumors based on tumour location, earliest genetic change and ability (or lack of) to undergo terminal (ciliated) differentiation. Ultimately, a clear understanding of tumour origin and the mechanism(s) leading to the earliest phases of the serous and endometrioid carcinogenic sequences may hold the greatest promise for designing prevention strategies and/or developing new therapies.

Recent advances in the understanding of the pathogenesis of serous carcinoma: the concept of low- and high-grade disease and the role of the fallopian tube

In the past 50 years, the concept of serous ovarian cancer has been progressively refined, with the distinction of the borderline serous tumour, identification of a smaller subset of well-differentiated serous malignancies and, recently, closer attention to the pathogenesis of high-grade serous malignancies. High-grade serous carcinoma, traditionally presumed to arise within Müllerian inclusion cysts of the ovarian surface, cortex and peritoneum, has recently been linked to the distal fallopian tube. This review addresses the disparate forms of serous neoplasia, which reflect both different genetic abnormalities and stages of differentiation of Müllerian epithelium. The significance of these different origins is addressed in the context of ovarian cancer prevention.

Multiplexed Proximity Ligation Assays to Profile Putative Plasma Biomarkers Relevant to Pancreatic and Ovarian Cancer

Background: Sensitive methods are needed for biomarker discovery and validation. We tested one promising technology, multiplex proximity ligation assay (PLA), in a pilot study profiling plasma biomarkers in pancreatic and ovarian cancer.

Methods: We used 4 panels of 6- and 7-plex PLAs to detect biomarkers, with each assay consuming 1 μL plasma and using either matched monoclonal antibody pairs or single batches of polyclonal antibody. Protein analytes were converted to unique DNA amplicons by proximity ligation and subsequently detected by quantitative PCR. We profiled 18 pancreatic cancer cases and 19 controls and 19 ovarian cancer cases and 20 controls for the following proteins: a disintegrin and metalloprotease 8, CA-125, CA 19-9, carboxypeptidase A1, carcinoembryonic antigen, connective tissue growth factor, epidermal growth factor receptor, epithelial cell adhesion molecule, Her2, galectin-1, insulin-like growth factor 2, interleukin-1α, interleukin-7, mesothelin, macrophage migration inhibitory factor, osteopontin, secretory leukocyte peptidase inhibitor, tumor necrosis factor α, vascular endothelial growth factor, and chitinase 3–like 1. Probes for CA-125 were present in 3 of the multiplex panels. We measured plasma concentrations of the CA-125–mesothelin complex by use of a triple-specific PLA with 2 ligation events among 3 probes.

Results: The assays displayed consistent measurements of CA-125 independent of which other markers were simultaneously detected and showed good correlation with Luminex data. In comparison to literature reports, we achieved expected results for other putative markers.

Conclusion:

Multiplex PLA using either matched monoclonal antibodies or single batches of polyclonal antibody should prove useful for identifying and validating sets of putative disease biomarkers and finding multimarker panels.

High Cancer-Specific Expression of Mesothelin (MSLN) Is Attributable to an Upstream Enhancer Containing a Transcription Enhancer Factor–Dependent MCAT Motif

Identification of genes with cancer-specific overexpression offers the potential to efficiently discover cancer-specific activities in an unbiased manner. We apply this paradigm to study mesothelin (MSLN) overexpression, a nearly ubiquitous, diagnostically and therapeutically useful characteristic of pancreatic cancer. We identified an 18-bp upstream enhancer, termed CanScript, strongly activating transcription from an otherwise weak tissue-nonspecific promoter and operating selectively in cells having aberrantly elevated cancer-specific MSLN transcription. Introducing mutations into CanScript showed two functionally distinct sites: an Sp1-like site and an MCAT element. Gel retardation and chromatin immunoprecipitation assays showed the MCAT element to be bound by transcription enhancer factor (TEF)-1 (TEAD1) in vitro and in vivo. The presence of TEF-1 was required for MSLN protein overexpression as determined by TEF-1 knockdown experiments. The cancer specificity seemed to be provided by a putative limiting cofactor of TEF-1 that could be outcompeted by exogenous TEF-1 only in a MSLN-overexpressing cell line. A CanScript concatemer offered enhanced activity. These results identify a TEF family member as a major regulator of MSLN overexpression, a fundamental characteristic of pancreatic and other cancers, perhaps due to an upstream and highly frequent aberrant cellular activity. The CanScript sequence represents a modular element for cancer-specific targeting, potentially suitable for nearly a third of human malignancies.

The distal fallopian tube: a new model for pelvic serous carcinogenesis

PURPOSE OF REVIEW

Research over the past 50 years has yielded little concrete information on the source of pelvic serous cancer in women, creating a knowledge gap that has adversely influenced our ability to identify, remove or prevent the earliest stages of the most lethal form of ovarian cancer.

RECENT FINDINGS

The distal fallopian tube is emerging as an established source of many early serous carcinomas in women with BRCA mutations (BRCA+). Protocols examining the fimbrial (SEE-FIM) end have revealed a noninvasive but potentially lethal form of tubal carcinoma, designated tubal intraepithelial carcinoma. Tubal intraepithelial carcinoma is present in many women with presumed ovarian or peritoneal serous cancer. A candidate precursor to tubal intraepithelial carcinoma, entitled the 'p53 signature', suggests that molecular events associated with serous cancer (p53 mutations) may be detected in benign mucosa.

SUMMARY

A fully characterized precursor lesion is a first and necessary step to pelvic serous cancer prevention. The emerging data offer compelling evidence for a model of 'fimbrial-ovarian' serous neoplasia, and call attention to the distal fallopian tube as an important source for this disease, the study of which could clarify pathways to cancer in both organs and generate novel strategies for cancer prevention.

[MUC1 (EMA): A key molecule of carcinogenesis?]

MUC1 is a large trans-membrane highly glycosylated mucin which is expressed at the apical pole of normal cells in glandular epithelia. MUC1 is implicated in many physiological mechanisms such as adhesion, development and differentiation. Also, MUC1 is frequently deregulated and over-expressed with a membrane circumferential and/or cytoplasmic expression. The intracellular tail of MUC1 is phosphorylated and can interact with many signalling proteins and transcriptional factors. Indeed, MUC1 can interact with B-catenin competitively for E-cadherin, thus destabilizing intercellular junctions and favouring metastatic dissemination. In carcinomas, the overexpression and membrane delocalization of MUC1 is associated with a worse prognosis and a shorter survival in breast, colon, kidney, prostate or gastro-intestinal cancers. MUC1 appears to be a novel therapeutic target for immunotherapy or anti-tumour vaccines.

DNA methylation and histone modification regulate silencing of epithelial cell adhesion molecule for tumor invasion and progression

Epithelial cell adhesion molecule (Ep-CAM) is believed to have a critical role in carcinogenesis and cell proliferation. However, the association of Ep-CAM with cancer invasion and progression is less clear. We found that Ep-CAM was highly expressed on low-invasive cells compared with highly invasive cells. Forced expression of Ep-CAM decreased cancer invasiveness, and silencing Ep-CAM expression elevated cancer invasiveness. Ep-CAM expression was associated with promoter methylation. Treatment with a demethylating agent, and/or the histone deacetylase inhibitor reactivated Ep-CAM expression in Ep-CAM-negative cells and inhibited cancer invasiveness. Using a promoter-reporter construct, we demonstrated methylation of the promoter fragment drive Ep-CAM-silenced transcription. Additionally, silenced Ep-CAM gene in cancer cells was enriched for hypermethylated histone 3 lysine 9. When unmethylated and active, this promoter was associated with acetylated histone 3 lysine 9. Furthermore, we observed an increased association of Ep-CAM promoter with repression components as tumor invasiveness increased. In cancer tissues, Ep-CAM expression significantly correlated with tumor progression and associated with promoter methylation. Our data support the idea that modulation of Ep-CAM plays a pivotal role in tumor invasion and progression. Moreover, aberrant DNA methylation of Ep-CAM is implicated in enhancing invasive/metastatic proclivity of tumors.

Gene expression signatures differentiate ovarian/peritoneal serous carcinoma from diffuse malignant peritoneal mesothelioma

PURPOSE

Ovarian/primary peritoneal serous carcinoma (OC/PPC) and diffuse peritoneal malignant mesothelioma (DMPM) are highly aggressive tumors that are closely related morphologically and histogenetically. It remains unclear whether both tumors are molecularly distinct neoplasms. The current study compared global gene expression patterns in OC/PPC and DMPM.

EXPERIMENTAL DESIGN

Ten OC/PPC and five DMPM effusions were analyzed for gene expression profiles using the Affymetrix U133 Plus 2 arrays and the dCHIP analysis program. Differentially expressed candidate genes were validated using quantitative real-time PCR and immunohistochemistry.

RESULTS

Unsupervised hierarchical clustering using all 54,675 genes in the array classified the samples into two groups: DMPM specimens versus OC/PPC specimens. A total of 189 genes that were differentially expressed in these two groups were selected based on statistical significance. Genes overexpressed in DMPM (n = 68) included calretinin, vitronectin, claudin 15, alpha4 laminin, hyaluronan synthase 1, cadherin 11, RAB7, v-maf, and the epidermal growth factor-containing fibulin-like extracellular matrix protein 1. Genes overexpressed in OC/PPC (n = 121) included insulin-like growth factor II (IGF-II); IGF-II binding protein 3; cyclin E1; folate receptors 1 and 3; RAB25; MUC4; endothelin-1; CD24; kallikreins 6, 7, and 8; claudins 3, 4, and 6; Notch3; and MMP-7. Quantitative real-time PCR validated the differential expression of 13 genes, and immunohistochemistry confirmed the differences for four gene products.

CONCLUSIONS

Expression profiling separates OC/PPC from DMPM and identifies a number of genes that are differentially expressed in these tumors. The molecular signatures unique to OC/PPC and DMPM should provide a molecular basis to study both tumors and new potential markers for facilitating their differential diagnosis.

D2-40 is Not a Specific Marker for Cells of Mesothelial Origin in Serous Effusions

The presence of effusion in a patient with a history of primary malignant tumor elsewhere in the body is generally accepted as a clinical manifestation of metastatic disease. Even in those cases, it is sometimes difficult to differentiate reactive mesothelial cells from carcinoma cells. Another challenging issue especially in the field of serous effusions is the differential diagnosis between malignant mesothelioma and metastatic adenocarcinoma. The aim of this study was to evaluate the potential use of the D2-40 antibody detecting the M2A oncofetal antigen in the diagnosis of malignant serous effusions. Two hundred and ninety effusion specimens (169 ovarian carcinomas, 44 breast carcinomas, 32 malignant mesotheliomas, 6 lung carcinomas, 8 reactive specimens, and 31 tumors of other origin) were assessed. Expression in reactive mesothelial cells was additionally assessed on 145 malignant effusions. Immunohistochemical analysis using the EnVision system was performed. M2A antigen was expressed in malignant mesotheliomas and reactive mesothelial cells in all specimens. Positive membranous staining was observed in 58% of ovarian carcinomas, 33% of lung carcinomas, and 30% of breast carcinomas. Pulmonary, breast, and nonovarian gynecologic tumors usually showed weak focal membranous staining, whereas the ovarian adenocarcinomas showed an expression pattern more similar to mesotheliomas. The results from the present study suggest low specificity for D2-40 as a mesothelial marker, especially in the context of differentiating mesothelial cells from ovarian carcinoma, and argue against its inclusion in the diagnostic panel of serous effusions.

Gene expression profiling of primary cultures of ovarian epithelial cells identifies novel molecular classifiers of ovarian cancer

In order to elucidate the biological variance between normal ovarian surface epithelial (NOSE) and epithelial ovarian cancer (EOC) cells, and to build a molecular classifier to discover new markers distinguishing these cells, we analysed gene expression patterns of 65 primary cultures of these tissues by oligonucleotide microarray. Unsupervised clustering highlights three subgroups of tumours: low malignant potential tumours, invasive solid tumours and tumour cells derived from ascites. We selected 18 genes with expression profiles that enable the distinction of NOSE from these three groups of EOC with 92% accuracy. Validation using an independent published data set derived from tissues or primary cultures confirmed a high accuracy (87–96%). The distinctive expression pattern of a subset of genes was validated by quantitative reverse transcription–PCR. An ovarian-specific tissue array representing tissues from NOSE and EOC samples of various subtypes and grades was used to further assess the protein expression patterns of two differentially expressed genes (Msln and BMP-2) by immunohistochemistry. This study highlights the relevance of using primary cultures of epithelial ovarian cells as a model system for gene profiling studies and demonstrates that the statistical analysis of gene expression profiling is a useful approach for selecting novel molecular tumour markers.

Soluble mesothelin-related peptides in the diagnosis of malignant pleural mesothelioma

BACKGROUND

Diagnosis of malignant pleural mesothelioma is a challenging issue. Potential markers in mesothelioma diagnosis include soluble mesothelin-related peptides (SMRPs) and osteopontin, but no subsequent validation has been published yet.

METHODS

We prospectively evaluated SMRPs in serum and pleural effusion from patients with mesothelioma (n = 74), pleural metastasis of carcinomas (n = 35), or benign pleural lesions associated with asbestos exposure (n = 28), recruited when first suspected for mesothelioma.

FINDINGS

Mean serum SMRP level was higher in patients with mesothelioma (2.05 +/- 2.57 nM/L [median +/- interquartile range]) than in patients with metastasis (1.02 +/- 1.79 nM/L) or benign lesions (0.55 +/- 0.59 nM/L). The area under the receiver operating characteristic curve (AUC) for serum SMRP was 0.872 for differentiating mesothelioma and benign lesions, cut-off = 0.93 nM/L (sensitivity = 80%, specificity = 82.6%). The AUC for serum SMRP differentiating metastasis and mesothelioma was 0.693, cut-off = 1.85 nM/L (sensitivity = 58.3%, specificity = 73.3%). SMRP values in pleural fluid were higher than in serum in all groups (mesothelioma: 46.1 +/- 83.2 nM/L; benign lesions: 6.4 +/- 11.1 nM/L; metastasis: 6.36 +/- 21.73 nM/L). The AUC for pleural SMRP-differentiating benign lesions and mesothelioma was 0.831, cut-off = 10.4 nM/L (sensitivity = 76.7%, specificity = 76.2%). The AUC for pleural SMRP-differentiating metastasis and mesothelioma was 0.793.

INTERPRETATION

We show that SMRPs may be a promising marker for mesothelioma diagnosis when measured either in serum or pleural fluid. The diagnostic value of SMRPs was similar in both types of samples, but pleural fluid SMRPs may better discriminate mesothelioma from pleural metastasis.

The biological differences between ovarian serous carcinoma and diffuse peritoneal malignant mesothelioma

Recent improvements in immunohistochemistry panels used for differentiating ovarian serous carcinoma/primary peritoneal carcinoma (OC/PPC) from diffuse malignant peritoneal mesothelioma (DMPM) have resulted in improved diagnostic rates for these tumors in both cytological and histological material. However, little is known about the biological characteristics that differentiate these two cancer types. We performed a comparative analysis of cancer-associated molecule expression data for a cohort consisting of up to 270 serous OC/PPC specimens (only peritoneal lesions) and 32 peritoneal MM. The molecules studied were nerve growth factor receptors (p75, p-TrkA), angiogenic factors (VEGF, IL-8, bFGF, heparanase), laminin receptors (the 67-kDa receptor and the alpha 6 integrin subunit), proteases (MMP-2), immune response mediators (HLA-G), and signaling molecules (the MAPK members ERK, JNK, and p38). The methods used were immunohistochemistry, Western blotting, and RT-PCR. DMPM specimens showed significantly higher expression of p75 (P < 0.001), p-TrkA (P < 0.001), and bFGF (P < 0.001), and significantly lower expression of the 67-kDa receptor (P < 0.001), alpha 6 integrin subunit (P = 0.025), VEGF (P < 0.001), IL-8 (P < 0.001), and HLA-G (P = 0.039) compared with OC/PPC. DMPM specimens showed higher activation ratio (phosphorylated/total enzyme ratio) of all three MAPK members (ERK, P = 0.017; JNK, P < 0.001; p38, P = 0.009) compared with OC/PPC. These data document significant differences in the expression of cancer- and metastasis-associated molecules in MM compared with ovarian carcinoma, and suggest that different biological pathways are involved in tumorigenesis and disease progression in these two tumors.

Early diagnosis and predictors of malignancy of adnexal masses

PURPOSE OF REVIEW

Ovarian cancer is an important cause of death among women with a malignant gynecological tumor. Cure rates for the disease at an early stage are around 80-90%, but survival is only 50% as the majority of women already show advanced disease upon diagnosis. The combination of gynecological examination, ultrasonography, and systemic tumor marker assay is considered to be a good strategy for the early diagnosis of ovarian neoplasia.

RECENT FINDINGS

Today, new technologies such as ultrasonography and tumor marker assay have increased the diagnosis rate for adnexal masses. These non-invasive methods, however, frequently do not distinguish benign conditions from malignant ones, which results in unnecessary surgery. Transvaginal ultrasonography is useful for diagnosing adnexal masses, but benign and malignant adnexal masses can present similar morphological characteristics. Combination with color Doppler ultrasonography and/or tumor markers may improve the accuracy of the method. Gene-expression array, proteomics and mathematical models form new approaches, but proper prospective studies are needed to validate them.

SUMMARY

The techniques of pelvic examination, ultrasonography, color Doppler ultrasonography, and tumor markers can be indicated for the diagnosis of ovarian cancer. The differentiation between benign and malignant ovarian tumor is, however, a clinical challenge. Until better diagnostic methods become available, patients and their physicians can use these techniques to decide on management.