Identification of genes associated with ovarian cancer metastasis using microarray expression analysis

Pathway-level mutation analysis in primary high-grade serous ovarian cancer and matched brain metastases

Brain metastases (BMs) in ovarian cancer (OC) are a rare event. BMs occur most frequently in high-grade serous (HGS) OC. The molecular features of BMs in HGSOC are poorly understood. We performed a whole-exome sequencing analysis of ten matched pairs of formalin-fixed paraffin-embedded samples from primary HGSOC and corresponding BMs. Enrichment significance (p value; false discovery rate) was computed using the Reactome, the Kyoto Encyclopedia of Genes and Genomes pathway collections, and the Gene Ontology Biological Processes. Germline DNA damage repair variants were found in seven cases (70%) and involved the BRCA1, BRCA2, ATM, RAD50, ERCC4, RPA1, MLHI, and ATR genes. Somatic mutations of TP53 were found in nine cases (90%) and were the only stable mutations between the primary tumor and BMs. Disturbed pathways in BMs versus primary HGSOC constituted a complex network and included the cell cycle, the degradation of the extracellular matrix, cell junction organization, nucleotide metabolism, lipid metabolism, the immune system, G-protein-coupled receptors, intracellular vesicular transport, and reaction to chemical stimuli (Golgi vesicle transport and olfactory signaling). Pathway analysis approaches allow for a more intuitive interpretation of the data as compared to considering single-gene aberrations and provide an opportunity to identify clinically informative alterations in HGSOC BM.

Chondroitin Sulfate Disaccharides, a Serum Marker for Primary Serous Epithelial Ovarian Cancer

Glycosaminoglycans are long polysaccharidic chains, which are mostly present in connective tissues. Modified GAG expression in tissues surrounding malignant cells has been shown to contribute to tumor progression, aggressive status and metastasis in many types of cancer. Ovarian cancer is one of the most lethal gynecological malignancies due to its late diagnosis because of the absence of clear symptoms and unavailability of early disease markers. We investigated for the first time GAG changes at the molecular level as a novel biomarker for primary epithelial ovarian cancer. To this end, serum of a cohort of 68 samples was digested with chondroitinase ABC, which releases chondroitin sulfate into disaccharides. After labeling and purification, they were measured by HPLC, yielding a profile of eight disaccharides. We proposed a novel GAG-based score named "CS- bio" from the measured abundance of disaccharides present that were of statistical relevance. CS-bio's performance was compared with CA125, the clinically used serum tumor marker in routine diagnostics. CS-bio had a better sensitivity and specificity than CA125. It was more apt in differentiating early-stage patients from healthy controls, which is of high interest for oncologists.

Detecting survival-associated biomarkers from heterogeneous populations

Detection of prognostic factors associated with patients' survival outcome helps gain insights into a disease and guide treatment decisions. The rapid advancement of high-throughput technologies has yielded plentiful genomic biomarkers as candidate prognostic factors, but most are of limited use in clinical application. As the price of the technology drops over time, many genomic studies are conducted to explore a common scientific question in different cohorts to identify more reproducible and credible biomarkers. However, new challenges arise from heterogeneity in study populations and designs when jointly analyzing the multiple studies. For example, patients from different cohorts show different demographic characteristics and risk profiles. Existing high-dimensional variable selection methods for survival analysis, however, are restricted to single study analysis. We propose a novel Cox model based two-stage variable selection method called "Cox-TOTEM" to detect survival-associated biomarkers common in multiple genomic studies. Simulations showed our method greatly improved the sensitivity of variable selection as compared to the separate applications of existing methods to each study, especially when the signals are weak or when the studies are heterogeneous. An application of our method to TCGA transcriptomic data identified essential survival associated genes related to the common disease mechanism of five Pan-Gynecologic cancers.

Molecular mediators of peritoneal metastasis in pancreatic cancer

Pancreatic cancer is the third leading cause of cancer death in the USA, and pancreatic ductal adenocarcinoma (PDA) constitutes 85% of pancreatic cancer diagnoses. PDA frequently metastasizes to the peritoneum, but effective treatment of peritoneal metastasis remains a clinical challenge. Despite this unmet need, understanding of the biological mechanisms that contribute to development and progression of PDA peritoneal metastasis is sparse. By contrast, a vast number of studies have investigated mechanisms of peritoneal metastasis in ovarian and gastric cancers. Here, we contrast similarities and differences between peritoneal metastasis in PDA as compared with those in gastric and ovarian cancer by outlining molecular mediators involved in each step of the peritoneal metastasis cascade. This review aims to provide mechanistic insights that could be translated into effective targeted therapies for patients with peritoneal metastasis from PDA.

Brain Metastases from Ovarian Cancer: Current Evidence in Diagnosis, Treatment, and Prognosis

With this review, we provide the state of the art concerning brain metastases (BMs) from ovarian cancer (OC), a rare condition. Clinical, pathological, and molecular features, treatment options, and future perspectives are comprehensively discussed. Overall, a diagnosis of high-grade serous OC and an advanced disease stage are common features among patients who develop brain metastases. BRCA1 and BRCA2 gene mutations, as well as the expression of androgen receptors in the primary tumor, are emerging risk and prognostic factors which could allow one to identify categories of patients at greater risk of BMs, who could benefit from a tailored follow-up. Based on present data, a multidisciplinary approach combining surgery, radiotherapy, and chemotherapy seem to be the best approach for patients with good performance status, although the median overall survival (<1 year) remains largely disappointing. Hopefully, novel therapeutic avenues are being explored, like PARP inhibitors and immunotherapy, based on our improved knowledge regarding tumor biology, but further investigation is warranted.

Signals from the Metastatic Niche Regulate Early and Advanced Ovarian Cancer Metastasis through miR-4454 Downregulation

Treatment of ovarian cancer is limited by extensive metastasis and yet it remains poorly understood. We have studied the critical step of metastatic colonization in the context of the productive interactions with the metastatic microenvironment with a goal of identifying key regulators. By combining miRNA expression analysis using an organotypic 3D culture model of early ovarian cancer metastasis with that of matched primary and metastatic tumors from 42 patients with ovarian cancer, we identified miR-4454 as a key regulator of both early colonization and advanced metastasis in patients with ovarian cancer. miR-4454 was downregulated in the metastasizing ovarian cancer cells through paracrine signals from microenvironmental fibroblasts, which promoted migration, invasion, proliferation, and clonogenic growth in ovarian cancer cells as well as their ability to penetrate through the outer layers of the omentum. Stable overexpression of miR-4454 decreased metastasis in ovarian cancer xenografts. Its mechanism of action was through the upregulation of its targets, secreted protein acidic and cysteine rich (SPARC) and BCL2 associated athanogene 5 (BAG5), which activated focal adhesion kinase (FAK) signaling, promoted mutant p53 gain of function by its stabilization, and inhibited apoptosis. Because microenvironment-induced downregulation of miR-4454 is essential for early and advanced metastasis, targeting it could be a promising therapeutic approach. IMPLICATIONS: This study identifies a miRNA, miR-4454, which is downregulated by signals from the microenvironment and promotes early and advanced ovarian cancer metastasis through its effects on FAK activation, mutant p53 stabilization, and apoptosis inhibition.

Comparative transcriptome analysis of matched primary and distant metastatic ovarian carcinoma

BACKGROUND

High grade serous ovarian carcinoma (HGSOC) is the most common subtype of epithelial ovarian cancers (EOC) with poor prognosis. In most cases EOC is widely disseminated at the time of diagnosis. Despite the optimal cytoreductive surgery and chemotherapy most patients develop chemoresistance, and the 5-year overall survival being only 25-35%.

METHODS

Here we analyzed the gene expression profiles of 10 primary HGSOC tumors and 10 related omental metastases using RNA sequencing and identified 100 differentially expressed genes.

RESULTS

The differentially expressed genes were associated with decreased embryogenesis and vasculogenesis and increased cellular proliferation and organismal death. Top upstream regulators responsible for this gene signature were NR5A1, GATA4, FOXL2, TP53 and BMP7. A subset of these genes were highly expressed in the ovarian cancer among the cancer transcriptomes of The Cancer Genome Atlas. Importantly, the metastatic gene signature was suggestive of poor survival in TCGA data based on gene enrichment analysis.

CONCLUSION

By comparing the gene expression profiles of primary HGSOC tumors and their matched metastasis, we provide evidence that a signature of 100 genes is able to separate these two sample types and potentially predict patient survival. Our study identifies functional categories of genes and transcription factors that could play important roles in promoting metastases and serve as markers for cancer prognosis.

Genes associated with bowel metastases in ovarian cancer

OBJECTIVE

This study is designed to identify genes and pathways that could promote metastasis to the bowel in high-grade serous ovarian cancer (OC) and evaluate their associations with clinical outcomes.

METHODS

We performed RNA sequencing of OC primary tumors (PTs) and their corresponding bowel metastases (n = 21 discovery set; n = 18 replication set). Differentially expressed genes (DEGs) were those expressed at least 2-fold higher in bowel metastases (BMets) than PTs in at least 30% of patients (P < .05) with no increased expression in paired benign bowel tissue and were validated with quantitative reverse transcription PCR. Using an independent OC cohort (n = 333), associations between DEGs in PTs and surgical and clinical outcomes were performed. Immunohistochemistry and mouse xenograft studies were performed to confirm the role of LRRC15 in promoting metastasis.

RESULTS

Among 27 DEGs in the discovery set, 21 were confirmed in the replication set: SFRP2, Col11A1, LRRC15, ADAM12, ADAMTS12, MFAP5, LUM, PLPP4, FAP, POSTN, GRP, MMP11, MMP13, C1QTNF3, EPYC, DIO2, KCNA1, NETO1, NTM, MYH13, and PVALB. Higher expression of more than half of the genes in the PT was associated with an increased requirement for bowel resection at primary surgery and an inability to achieve complete cytoreduction. Increased expression of LRRC15 in BMets was confirmed by immunohistochemistry and knockdown of LRRC15 significantly inhibited tumor progression in mice.

CONCLUSIONS

We identified 21 genes that are overexpressed in bowel metastases among patients with OC. Our findings will help select potential molecular targets for the prevention and treatment of malignant bowel obstruction in OC.

Ubiquitin-Proteasome Axis, Especially Ubiquitin-Specific Protease-17 (USP17) Gene Family, is a Potential Target for Epithelial-Mesenchymal Transition in High-Grade Serous Ovarian Cancer

OBJECTIVES

To investigate gene expression differences and related functions between primary tumor, malignant cells in ascites, and metastatic peritoneal implant in high-grade serous ovarian cancer.

METHODS

Biopsies from primary tumor, peritoneal implant, and ascites were collected from 10 patients operated primarily for high-grade, advanced-staged serous ovarian cancer. Total RNA isolation was performed from collected tissue biopsy and fluid samples, and RNA expression profile was measured. Messenger RNA expression profiles of 3 different groups were compared. Functional analyses of candidate genes were carried out by gene ontology and pathway analysis.

RESULTS

There were significant differences in the expression of 5 genes between primary tumor and peritoneal implant, 979 genes between primary tumor and malignant cells in ascites, and 649 genes between peritoneal implant and malignant cells in ascites. Three commonly enriched gene ontology functions between "primary tumor and malignant cells in the ascites" and "peritoneal implant and malignant cells in the ascites" were protein deubiquitination, ubiquitin-dependent protein catabolism, and apoptotic processes. All genes related to these functions belonged to USP17 gene family.

CONCLUSION

Gene expression difference between primary tumor and the peritoneal implant is not as much as the difference between primary tumor and free cells in the ascites. These results show that malignant cells in the ascites return into its genetic origin after they invade on the peritoneum. Significantly increased expression of DUB-enzyme genes, SNAR gene family, and ribosomal pathway genes in epithelial-mesenchymal transition suggests that this regulation is ubiquitin-proteasome dependent. Especially, this is the first study that offers USP17 as a potential target for epithelial-mesenchymal transition.

Bilateral ovarian carcinomas differ in the expression of metastasis-related genes

The mechanisms behind bilaterality of ovarian carcinomas are not fully understood, as the two tumors could possibly represent two primary tumors, a primary tumor and a metastasis, or two metastases. The gene expression profiles from bilateral high-grade serous carcinomas (HGSCs) and clear cell carcinomas (CCCs) of the ovary were compared to study the association between the tumors of the two sides. A separate analysis of genes from chromosome 19 was also performed, since this chromosome is frequently rearranged in ovarian carcinomas. Tumors from four patients were included (three pairs of HGSC and one pair of CCC). The gene expression was analyzed at the exon level, and bilateral tumors were compared to identify within-pair differences. Gene expression data were also compared with genomic information on the same tumors. Similarities in gene expression were observed between the tumors within each pair, as expected if the two tumors were clonally related. However, certain genes exhibited differences in expression between the two sides, indicating metastasis involvement. Among the most differently expressed genes, one gene was common to all four pairs: Immunoglobulin J. In all HGSC pairs, serpin peptidase inhibitor, clade B (ovalbumin), member 2, serpin family E member 1 and phospholipase A2, group IIA (platelets, synovial fluid) were also among the differentially expressed genes. The specific analysis of chromosome 19 highlighted expression differences in the zinc finger protein 36 gene. These results indicate that bilateral ovarian tumors represent different stages during progression of a single clonal process. Several of the genes observed to be differently expressed are known to be metastasis-related, and are likely to be also involved in spreading from one side to the other in the bilateral cancer cases examined.

Dynamic changes of tumor gene expression during repeated pressurized intraperitoneal aerosol chemotherapy (PIPAC) in women with peritoneal cancer

BACKGROUND

Intraperitoneal chemotherapy is used to treat peritoneal cancer. The pattern of gene expression changes of peritoneal cancer during intraperitoneal chemotherapy has not been studied before. Pressurized intraperitoneal aerosol chemotherapy is a new form of intraperitoneal chemotherapy using repeated applications and allowing repeated tumor sampling during chemotherapy. Here, we present the analysis of gene expression changes during pressurized intraperitoneal aerosol chemotherapy with doxorubicin and cisplatin using a 22-gene panel.

METHODS

Total RNA was extracted from 152 PC samples obtained from 63 patients in up to six cycles of intraperitoneal chemotherapy. Quantitative real-time PCR was used to determine the gene expression levels. For select genes, immunohistochemistry was used to verify gene expression changes observed on the transcript level on the protein level. Observed (changes in) expression levels were correlated with clinical outcomes.

RESULTS

Gene expression profiles differed significantly between peritoneal cancer and non- peritoneal cancer samples and between ascites-producing and non ascites-producing peritoneal cancers. Changes of gene expression patterns during repeated intraperitoneal chemotherapy cycles were prognostic of overall survival, suggesting a molecular tumor response of peritoneal cancer. Specifically, downregulation of the whole gene panel during intraperitoneal chemotherapy was associated with better treatment response and survival.

CONCLUSIONS

In summary, molecular changes of peritoneal cancer during pressurized intraperitoneal aerosol chemotherapy can be documented and may be used to refine individual treatment and prognostic estimations.

Identification of Cathepsin K in the Peritoneal Metastasis of Ovarian Carcinoma Using In-silico, Gene Expression Analysis

Ovarian carcinomas (OC) are often found in the advanced stage with wide peritoneal dissemination. Differentially-expressed genes (DEGs) between primary ovarian carcinoma (POC) and peritoneal metastatic ovarian carcinomas (PMOC) may have diagnostic and therapeutic values. In this study, we identified 246 DEGs by in-silico analysis using microarrays for 153 POCs and 57 PMOCs. Pathway analysis shows that many of these genes are associated with lipid metabolism. Microfluidic, card-based, quantitative PCR validated 19 DEGs in PMOCs versus POCs (p<0.05). Immunohistochemistry confirmed overexpression of MMP13, CTSK, FGF1 and GREM1 in PMOCs (p<0.05). ELISA detection indicated that serum CTSK levels were significantly increased in OCs versus controls (p<0.001). CTSK levels discriminated between OCs and healthy controls (ROC 0.739; range 0.685-0.793). Combining CA125 and HE4 with CTSK levels produced an improved specificity in the predictive of OCs (sensitivity 88.3%, specificity 92.0%, Youden's index 80.3%). Our study suggests that CTSK levels may be helpful in the diagnosis of primary, ovarian carcinoma.

Versican and vascular endothelial growth factor expression levels in peritoneal metastases from colorectal cancer are associated with survival after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) can increase survival of colorectal cancer (CRC) patients with peritoneal metastases (PM). This treatment is associated with high morbidity and mortality rates. Therefore, improvement of patient selection is necessary. Assuming that the clinical phenotype is dictated by biological mechanisms, biomarkers could play a crucial role in this process. Since it is unknown whether and to what extent angiogenesis influences the course of disease in patients with PM, we investigated the expression of two angiogenesis-related markers and their relation to overall survival (OS) in CRC patients after CRS and HIPEC. Clinicopathological data and tissue samples were collected from 65 CRC patients with isolated metastases to the peritoneum that underwent CRS and HIPEC. Whole tissue specimens from PM were evaluated for versican (VCAN) expression, VEGF expression and microvessel density (MVD) by immunohistochemistry. The relation between these markers and OS was assessed using univariate and multivariate analysis. Associations between VEGF expression, VCAN expression, MVD and clinicopathological data were tested. High stromal VCAN expression was associated with high MVD (p = 0.001), better resection outcome (p = 0.003) and high T-stage (p = 0.027). High epithelial VCAN expression was associated with MVD (p = 0.007) and a more complete resection (p < 0.001). In multivariate analysis, simplified peritoneal cancer index (p = 0.001), VEGF expression levels (p = 0.012), age (p = 0.030), epithelial VCAN expression levels (p = 0.042) and lymph node status (p = 0.053) were associated with OS. Concluding, VCAN and VEGF were associated with survival in CRC patients with PM after CRS and HIPEC. Independent validation in a well-defined patient cohort is required to confirm the putative prognostic role of these candidate biomarkers.

Clinical prospects of IGF-signaling system components study in ovarian cancer patients

Among various auto/paracrine growth-regulating signaling pathways an important role belongs to that of insulin-like growth factors (IGFs) and insulin. IGF-signaling system is actively involved in the regulation of both normal ovarian function and ovarian tumor growth. On the one hand, all members of this system are expressed in malignant ovarian epithelial cells, and the prognostic significance of this expression has been revealed for some of them in ovarian cancer patients in several studies. On the other hand, circulating IGFs/IGFBPs levels have not been undoubtedly associated with ovarian cancer risk or disease progression, but some of them can be regarded as supplementary serological ovarian cancer markers. An important route to the clinical application of IGF-signaling system studies in ovarian cancer is the growing possibility of using specific molecular targeted agents to suppress its growth-stimulating and other activities. However, the introduction of such agents to practical oncology has met serious problems, with the main difficulties resulting from the absence of reliable predictive molecular markers and metabolic side effects due to the tight connection between IGF-signaling and insulin-regulated processes. The prognostic and diagnostic values of various IGF system components and the current state of corresponding molecular targeted therapies development for ovarian cancer are reviewed.

Expression profiling of primary and metastatic ovarian tumors reveals differences indicative of aggressive disease

The behavior and genetics of serous epithelial ovarian cancer (EOC) metastasis, the form of the disease lethal to patients, is poorly understood. The unique properties of metastases are critical to understand to improve treatments of the disease that remains in patients after debulking surgery. We sought to identify the genetic and phenotypic landscape of metastatic progression of EOC to understand how metastases compare to primary tumors. DNA copy number and mRNA expression differences between matched primary human tumors and omental metastases, collected at the same time during debulking surgery before chemotherapy, were measured using microarrays. qPCR and immunohistochemistry validated findings. Pathway analysis of mRNA expression revealed metastatic cancer cells are more proliferative and less apoptotic than primary tumors, perhaps explaining the aggressive nature of these lesions. Most cases had copy number aberrations (CNAs) that differed between primary and metastatic tumors, but we did not detect CNAs that are recurrent across cases. A six gene expression signature distinguishes primary from metastatic tumors and predicts overall survival in independent datasets. The genetic differences between primary and metastatic tumors, yet common expression changes, suggest that the major clone in metastases is not the same as in primary tumors, but the cancer cells adapt to the omentum similarly. Together, these data highlight how ovarian tumors develop into a distinct, more aggressive metastatic state that should be considered for therapy development.

Splice variants of zinc finger protein 695 mRNA associated to ovarian cancer

Background

Studies of alternative mRNA splicing (AS) in health and disease have yet to yield the complete picture of protein diversity and its role in physiology and pathology. Some forms of cancer appear to be associated to certain alternative mRNA splice variants, but their role in the cancer development and outcome is unclear.

Methods

We examined AS profiles by means of whole genome exon expression microarrays (Affymetrix GeneChip 1.0) in ovarian tumors and ovarian cancer-derived cell lines, compared to healthy ovarian tissue. Alternatively spliced genes expressed predominantly in ovarian tumors and cell lines were confirmed by RT-PCR.

Results

Among several significantly overexpressed AS genes in malignant ovarian tumors and ovarian cancer cell lines, the most significant one was that of the zinc finger protein ZNF695, with two previously unknown mRNA splice variants identified in ovarian tumors and cell lines. The identity of ZNF695 AS variants was confirmed by cloning and sequencing of the amplicons obtained from ovarian cancer tissue and cell lines.

Conclusions

Alternative ZNF695 mRNA splicing could be a marker of ovarian cancer with possible implications on its pathogenesis.

Meta-analysis of microarray data identifies GAS6 expression as an independent predictor of poor survival in ovarian cancer

Seeking new biomarkers for epithelial ovarian cancer, the fifth most common cause of death from all cancers in women and the leading cause of death from gynaecological malignancies, we performed a meta-analysis of three independent studies and compared the results in regard to clinicopathological parameters. This analysis revealed that GAS6 was highly expressed in ovarian cancer and therefore was selected as our candidate of choice. GAS6 encodes a secreted protein involved in physiological processes including cell proliferation, chemotaxis, and cell survival. We performed immunohistochemistry on various ovarian cancer tissues and found that GAS6 expression was elevated in tumour tissue samples compared to healthy control samples (P < 0.0001). In addition, GAS6 expression was also higher in tumours from patients with residual disease compared to those without. Our data propose GAS6 as an independent predictor of poor survival, suggesting GAS6, both on the mRNA and on the protein level, as a potential biomarker for ovarian cancer. In clinical practice, the staining of a tumour biopsy for GAS6 may be useful to assess cancer prognosis and/or to monitor disease progression.

Using MKK4's metastasis suppressor function to identify and dissect cancer cell-microenvironment interactions during metastatic colonization

Host tissue microenvironment plays key roles in cancer progression and colonization of secondary organs. One example is ovarian cancer, which colonizes the peritoneal cavity and especially the omentum. Our research indicates that the interaction of ovarian cancer cells with the omental microenvironment can activate a stress-kinase pathway involving the mitogen-activated protein kinase kinase 4 (MKK4). A combination of clinical correlative and functional data suggests that MKK4 activation suppresses growth of ovarian cancer cells lodged in omentum. These findings prompted us to turn our focus to the cellular composition of the omental microenvironment and its role in regulating cancer growth. In this review, in addition to providing an overview of MKK4 function, we highlight a use for metastasis suppressors as a molecular tool to study cancer cell interaction with its microenvironment. We review features of the omentum that makes it a favorable microenvironment for metastatic colonization. In conclusion, a broader, evolutionary biology perspective is presented which we believe needs to be considered when studying the evolution of cancer cells within a defined microenvironment. Taken together, this approach can direct new multi-dimensional lines of research aimed at a mechanistic understanding of host tissue microenvironment, which could be used to realize novel targets for future research.

An ensemble prognostic model for colorectal cancer

Colorectal cancer can be grouped into Dukes A, B, C, and D stages based on its developments. Generally speaking, more advanced patients have poorer prognosis. To integrate progression stage prediction systems with recurrence prediction systems, we proposed an ensemble prognostic model for colorectal cancer. In this model, each patient was assigned a most possible stage and a most possible recurrence status. If a patient was predicted to be recurrence patient in advanced stage, he would be classified into high risk group. The ensemble model considered both progression stages and recurrence status. High risk patients and low risk patients predicted by the ensemble model had a significant different disease free survival (log-rank test p-value, 0.0016) and disease specific survival (log-rank test p-value, 0.0041). The ensemble model can better distinguish the high risk and low risk patients than the stage prediction model and the recurrence prediction model alone. This method could be applied to the studies of other diseases and it could significantly improve the prediction performance by ensembling heterogeneous information.

Data Mining and Meta-Analysis on DNA Microarray Data

Microarray technology enables high-throughput parallel gene expression analysis, and use has grown exponentially thanks to the development of a variety of applications for expression, genetics and epigenetic studies. A wealth of data is now available from public repositories, providing unprecedented opportunities for meta-analysis approaches, which could generate new biological information, unrelated to the original scope of individual studies. This study provides a guideline for identification of biological significance of the statistically-selected differentially-expressed genes derived from gene expression arrays as well as to suggest further analysis pathways. The authors review the prerequisites for data-mining and meta-analysis, summarize the conceptual methods to derive biological information from microarray data and suggest software for each category of data mining or meta-analysis.

Identification of ovarian cancer metastatic miRNAs

Serous epithelial ovarian cancer (EOC) patients often succumb to aggressive metastatic disease, yet little is known about the behavior and genetics of ovarian cancer metastasis. Here, we aim to understand how omental metastases differ from primary tumors and how these differences may influence chemotherapy. We analyzed the miRNA expression profiles of primary EOC tumors and their respective omental metastases from 9 patients using miRNA Taqman qPCR arrays. We find 17 miRNAs with differential expression in omental lesions compared to primary tumors. miR-21, miR-150, and miR-146a have low expression in most primary tumors with significantly increased expression in omental lesions, with concomitant decreased expression of predicted mRNA targets based on mRNA expression. We find that miR-150 and miR-146a mediate spheroid size. Both miR-146a and miR-150 increase the number of residual surviving cells by 2-4 fold when challenged with lethal cisplatin concentrations. These observations suggest that at least two of the miRNAs, miR-146a and miR-150, up-regulated in omental lesions, stimulate survival and increase drug tolerance. Our observations suggest that cancer cells in omental tumors express key miRNAs differently than primary tumors, and that at least some of these microRNAs may be critical regulators of the emergence of drug resistant disease.

High levels of genomic aberrations in serous ovarian cancers are associated with better survival

Genomic instability and copy number alterations in cancer are generally associated with poor prognosis; however, recent studies have suggested that extreme levels of genomic aberrations may be beneficial for the survival outcome for patients with specific tumour types. We investigated the extent of genomic instability in predominantly high-grade serous ovarian cancers (SOC) using two independent datasets, generated in Norway (n = 74) and Australia (n = 70), respectively. Genomic instability was quantified by the Total Aberration Index (TAI), a measure of the abundance and genomic size of copy number changes in a tumour. In the Norwegian cohort, patients with TAI above the median revealed significantly prolonged overall survival (p<0.001) and progression-free survival (p<0.05). In the Australian cohort, patients with above median TAI showed prolonged overall survival (p<0.05) and moderately, but not significantly, prolonged progression-free survival. Results were confirmed by univariate and multivariate Cox regression analyses with TAI as a continuous variable. Our results provide further evidence supporting an association between high level of genomic instability and prolonged survival of high-grade SOC patients, possibly as disturbed genome integrity may lead to increased sensitivity to chemotherapeutic agents.

Delta-protocadherins in health and disease

The protocadherin family comprises clustered and nonclustered protocadherin genes. The nonclustered genes encode mainly δ-protocadherins, which deviate markedly from classical cadherins. They can be subdivided phylogenetically into δ0-protocadherins (protocadherin-20), δ1-protocadherins (protocadherin-1, -7, -9, and -11X/Y), and δ2-protocadherins (protocadherin-8, -10, -17, -18, and -19). δ-Protocadherins share a similar gene structure and are expressed as multiple alternative splice forms differing mostly in their cytoplasmic domains (CDs). Some δ-protocadherins reportedly show cell-cell adhesion properties. Individual δ-protocadherins appear to be involved in specific signaling pathways, as they interact with proteins such as TAF1/Set, TAO2β, Nap1, and the Frizzled-7 receptor. The spatiotemporally restricted expression of δ-protocadherins in various tissues and species and their functional analysis suggest that they play multiple, tightly regulated roles in vertebrate development. Furthermore, several δ-protocadherins have been implicated in neurological disorders and in cancers, highlighting the importance of scrutinizing their properties and their dysregulation in various pathologies.

Survival prediction based on inherited gene variation analysis

There is a significant variation of outcome among ovarian cases. Clinical features such as age, stage, comorbidities, or degree of debulking are known prognostic factors for the disease. However, additional variation remains unexplained, some of which may be due to inherited factors. Here, we describe identification of survival-associated inherited variants in ovarian cancer that can enhance our current prognostic capabilities.

In vivo and in vitro properties of ovarian cancer cells

Specific biological properties of ovarian cancer cells can be modeled and studied using in vitro experiments. Any experimental setting can closely reflect some aspects of the native conditions; however, parameters that differ from in vivo aspects must be considered. Familiarity with existing and well-established, as well as new, cell culture techniques provides a basis for correct experimental design and production of reliable scientific results. This chapter presents a short comparative review of the techniques used for cell culture establishment and maintenance of ovarian cancer cells, as well as laboratory methods used to characterize malignant features of these cells, including the epithelial-mesechymal transition, cell motility and invasiveness, resistance to detachment-induced apoptosis, and stem cell content.

Overexpression of CD157 contributes to epithelial ovarian cancer progression by promoting mesenchymal differentiation

Epithelial ovarian carcinoma (EOC) is an aggressive tumor often diagnosed at an advanced stage, when there is little or no prospect of cure. Despite advances in surgical and chemotherapeutic strategies, only marginal improvements in patient outcome have been obtained. Hence, unraveling the biological mechanisms underpinning EOC progression is critical for improving patients’ survival. Recently, we reported that CD157 (an ectoenzyme regulating leukocyte diapedesis) is expressed in EOC and that high expression of the molecule is negatively correlated with the disease outcome in patients. Here, we demonstrate that forced overexpression of CD157 in OVCAR-3, TOV-21G, A2780 and OV-90 ovarian cancer cell lines promotes morphological and phenotypic changes characterized by disruption of intercellular junctions, downregulation of epithelial markers and upregulation of mesenchymal ones. These changes in cell shape and phenotype bring to reduced sensitivity to anoikis, increased anchorage-independent growth, cell motility and mesothelial invasion. Conversely, knockdown of CD157 in OV-90 and OC314 cells reverts the mesenchymal phenotype and reduces the cells’ migratory potential. Transcriptome profiling analysis highlighted 378 significantly differentially expressed genes, representing the signature of CD157-overexpressing OVCAR-3 and OV-90 cells. The modulation of selected genes translates into alteration of protein expression that give cells a highly malignant phenotype. The overall picture deduced from the analysis of the modulated transcripts is that high expression of CD157 strengthens a number of biological processes favoring tumor progression (including development and cell motility), and weakens several biological processes hindering tumor progression (such as apoptosis, cell death and response to stress). Together, these findings implicate CD157 in the progression of EOC to metastatic disease and suggest that CD157 may represent a valuable therapeutic target.

Gene expression analysis of matched ovarian primary tumors and peritoneal metastasis

Background

Ovarian cancer is the most deadly gynecological cancer due to late diagnosis at advanced stage with major peritoneal involvement. To date most research has focused on primary tumor. However the prognosis is directly related to residual disease at the end of the treatment. Therefore it is mandatory to focus and study the biology of meatastatic disease that is most frequently localized to the peritoneal caivty in ovarian cancer.

Methods

We used high-density gene expression arrays to investigate gene expression changes between matched primary and metastatic (peritoneal) lesions.

Results

Here we show that gene expression profiles in peritoneal metastasis are significantly different than their matched primary tumor and these changes are affected by underlying copy number variation differences among other causes. We show that differentially expressed genes are enriched in specific pathways including JAK/STAT pathway, cytokine signaling and other immune related pathways. We show that underlying copy number variations significantly affect gene expression. Indeed patients with important differences in copy number variation displayed greater gene expression differences between their primary and matched metastatic lesions.

Conclusions

Our analysis shows a very specific targeting at both the genomic and transcriptomic level to upregulate certain pathways in the peritoneal metastasis of ovarian cancer. Moreover, while primary tumors use certain pathways we identify distinct differences with metastatic lesions. The variation between primary and metastatic lesions should be considered in personalized treatment of ovarian cancer.

Expression of KiSS-1 in Epithelial Ovarian Cancer and its Role in Metastasis

Objectives To study expression of KiSS-1 and its role in migration and invasion of ovarian cancer (OC). Methods Expression of KiSS-1 was detected in tissue of 46 cases of OC and 17 cases of benign ovarian neoplasm by immunohistochemistry examination. Human OC cell line HO8910 was transfected by pcDNA3-KiSS-1 vector. The cell proliferation and invasion properties were detected by RT-RCR, MTT, clone formation rate and Boyden Chamber invasion assay. Results (1) Immunostaining showed that expression of KiSS-1protein was significantly higher in OC than that in benign ovarian tumor (P<0.05). (2) KiSS-1 expression was significantly higher in cases of advanced stage and with lymphatic metastasis (P<0.05). KiSS-1 expression was significantly lower in clear cell cancer compared with other histologic types (P<0.05). (3)KiSS-1 gene was successfully integrated into the genomic DNA of ovarian cancer cell line HO8910. Boyden Chamber invasion assay revealed that the number of cells invading through the Matrigel filter was significantly decreased in the transfected group compared with the non-transfected. No differences were observed in cell proliferation between the two groups. Conclusion There was over expression of KiSS-1 in OC compared with that in benign ovarian tumor. The KiSS-1 gene could suppress HO8910 invasion in vitro. To elucidate the contradiction effects of metastasis suppressor genes KiSS-1in vivoandin vitroneeds deeper research.

Potential role of HE4 in multimodal screening for epithelial ovarian cancer

In screening for epithelial ovarian cancer, unnecessary surgery can be reduced by limiting use of transvaginal ultrasound (TVU) to women with increasing CA125 serum levels. Replacing or augmenting TVU with measurement of a serum marker specific for malignancy might further improve screening performance. Serum samples from 112 invasive ovarian cancer patients and 706 matched control subjects from the Prostate, Lung, Colorectal, and Ovarian trial were used to evaluate human epididymis protein 4 (HE4), mesothelin, matrix metalloproteinase 7 (MMP7), SLPI, Spondin2, and insulin-like growth factor binding protein 2 (IGFBP2) for their potential use in screening. TVU results were available for a subset of 84 patients and 516 control subjects used to compare the best marker with TVU. HE4 was found to perform better than TVU as a second-line screen, confirming 27 of 39 cancers with increasing CA125 serum levels compared with 17 cancers confirmed by TVU (P = .03). Serum HE4 levels were found to increase with age and smoking status, suggesting that a longitudinal algorithm might improve its performance.

Potential markers for detection and monitoring of ovarian cancer

This paper reviews current screening techniques as well as novel biomarkers and their potential role in early detection of ovarian cancer. Ovarian cancer is one of the most common reproductive cancers and has the highest mortality rate amongst gynecologic cancers. Because most ovarian cancer diagnoses occur in the late stages of the disease, five-year survival rates fall below 20%. To improve survival rates and to lower mortality rates for ovarian cancer, improved detection at early stages of the disease is needed. Current screening approaches include tumor markers, ultrasound, or a combination. Efforts are underway to discover new biomarkers of ovarian cancer in order to surmount the obstacles in early-stage diagnosis. Among serum protein markers, HE4 and mesothelin can augment CA125 detection providing higher sensitivity and specificity due to the presence of these proteins in early-stage ovarian cancer. Detection testing that includes methylation of the MCJ gene and increased expression of vascular endothelial growth factor is correlated to poor prognosis and may predict patient survival outcome. Detection testing of biomarkers with long-term stability and combination panels of markers, will likely lead to effective screening strategies with high specificity and sensitivity for early detection of ovarian cancer.

Role of versican, hyaluronan and CD44 in ovarian cancer metastasis

There is increasing evidence to suggest that extracellular matrix (ECM) components play an active role in tumor progression and are an important determinant for the growth and progression of solid tumors. Tumor cells interfere with the normal programming of ECM biosynthesis and can extensively modify the structure and composition of the matrix. In ovarian cancer alterations in the extracellular environment are critical for tumor initiation and progression and intra-peritoneal dissemination. ECM molecules including versican and hyaluronan (HA) which interacts with the HA receptor, CD44, have been shown to play critical roles in ovarian cancer metastasis. This review focuses on versican, HA, and CD44 and their potential as therapeutic targets for ovarian cancer.

Microenvironment and pathogenesis of epithelial ovarian cancer

Multiple genetic alterations play a role in the pathogenesis of ovarian cancer. Although many key proteins and pathways involved in ovarian carcinogenesis and metastasis have been discovered, knowledge of the early steps leading to malignancy remains poorly understood. This poor understanding stems from lack of data from early-stage cancers and absence of a well-established premalignant state universal to all ovarian cancer subtypes. Existing evidence suggests that ovarian cancers develop either through a stepwise mutation process (low-grade pathway), through genetic instability resulting in hastened metastasis (high-grade pathway), or more recently through what has been described as the "'fimbrial-ovarian' serous neoplasia theory." In this latter model, ovarian serous cancers evolve from premalignant lesions in the distal fallopian tube called tubal intraepithelial carcinoma. In this manuscript, we review key genetic and molecular changes that occur in cancer cell progression and suggest a model of ovarian cancer pathogenesis involving both tumor cell mutations and microenvironmental factors.

AXL is an essential factor and therapeutic target for metastatic ovarian cancer

The receptor tyrosine kinase AXL is thought to play a role in metastasis; however, the therapeutic efficacy of an AXL-targeting agent remains largely untested in metastatic disease. In this study, we defined AXL as a therapeutic target for metastatic ovarian cancer. AXL is primarily expressed in metastases and advanced-stage human ovarian tumors but not in normal ovarian epithelium. Genetic inhibition of AXL in human metastatic ovarian tumor cells is sufficient to prevent the initiation of metastatic disease in vivo. Mechanistically, inhibition of AXL signaling in animals with metastatic disease results in decreased invasion and matrix metalloproteinase activity. Most importantly, soluble human AXL receptors that imposed a specific blockade of the GAS6/AXL pathway had a profound inhibitory effect on progression of established metastatic ovarian cancer without normal tissue toxicity. These results offer the first genetic validation of GAS6/AXL targeting as an effective strategy for inhibition of metastatic tumor progression in vivo. Furthermore, this study defines the soluble AXL receptor as a therapeutic candidate agent for treatment of metastatic ovarian cancer, for which current therapies are ineffective.

Disseminated superficial porokeratosis in a patient with cholangiocarcinoma: a paraneoplastic manifestation?

Porokeratosis refers to a group of hereditary or acquired disorders of epidermal keratinization and is characterized histologically by the presence of a cornoid lamella. The clinical variant referred to as disseminated superficial porokeratosis has been described in the literature in association with immunosuppressive conditions that include organ transplant, infections and immunosuppressive treatments. The association of disseminated superficial porokeratosis with solid organ malignancies has seldom been described, only 5 such cases having been published. The present report refers to a patient with lesions of disseminated superficial porokeratosis of sudden onset shortly before diagnosis of a cholangiocarcinoma.

Inherited determinants of ovarian cancer survival

PURPOSE

Due to variation of outcome among cases, we sought to examine whether overall survival in ovarian cancer was associated with common inherited variants in 227 candidate genes from ovarian cancer-related pathways including angiogenesis, inflammation, detoxification, glycosylation, one-carbon transfer, apoptosis, cell cycle regulation, and cellular senescence.

EXPERIMENTAL DESIGN

Blood samples were obtained from 325 women with invasive epithelial ovarian cancer diagnosed at the Mayo Clinic from 1999 to 2006. During a median follow-up of 3.8 years (range, 0.1-8.6 years), 157 deaths were observed. Germline DNA was analyzed at 1,416 single nucleotide polymorphisms (SNP). For all patients, and for 203 with serous subtype, we assessed the overall significance of each gene and pathway, and estimated risk of death via hazard ratios (HR) and 95% confidence intervals (CI), adjusting for known prognostic factors.

RESULTS

Variation within angiogenesis was most strongly associated with survival time overall (P = 0.03) and among patients with serous cancer (P = 0.05), particularly for EIF2B5 rs4912474 (all patients HR, 0.69; 95% CI, 0.54-0.89; P = 0.004), VEGFC rs17697305 (serous subtype HR, 2.29; 95% CI, 1.34-3.92; P = 0.003), and four SNPs in VHL. Variation within the inflammation pathway was borderline significant (all patients, P = 0.09), and SNPs in CCR3, IL1B, IL18, CCL2, and ALOX5 which correlated with survival time are worthy of follow-up.

CONCLUSION

An extensive multiple-pathway assessment found evidence that inherited differences may play a role in outcome of ovarian cancer patients, particularly in genes within the angiogenesis and inflammation pathways. Our work supports efforts to target such mediators for therapeutic gain.

Gene expression profiles as prognostic markers in women with ovarian cancer

The purpose was to find a gene expression profile that could distinguish short-term from long-term survivors in our collection of serous epithelial ovarian carcinomas. Furthermore, it should be able to stratify in an external validation set. Such a classifier profile will take us a step forward toward investigations for more individualized therapies and the use of gene expression profiles in the clinical practice. RNA from tumor tissue from 43 Danish patients with serous epithelial ovarian carcinoma (11 International Federation of Gynecology and Obstetrics [FIGO] stage I/II, 32 FIGO stage III/IV) was analyzed using Affymetrix U133 plus 2.0 microarrays. A multistep statistical procedure was applied to the data to find the gene set that optimally split the patients into short-term and long-term survivors in a Kaplan-Meier plot. A 14-gene prognostic profile with the ability to distinguish short-term survivors (median overall survival of 32 months) from long-term survivors (median overall survival not yet reached after a median follow-up of 76 months) with a P value of 3.4 x 10 was found. The prognostic gene set was also able to distinguish short-term from long-term survival in patients with advanced disease. Furthermore, its ability to classify in an external validation set was demonstrated. The identified 14-gene prognostic profile was able to predict survival (short- vs long-term survival) with a strength that is better than any other prognostic factor in epithelial ovarian cancer including FIGO stage. This stratification method may form the basis of determinations for new therapeutic approaches, as patients with poor prognosis could obtain the biggest advantage from new treatment modalities.

Predicting the response of advanced cervical and ovarian tumors to therapy

The management of advanced cervical and ovarian cancers remains a significant challenge as many women fail to respond to recommended therapy, resulting in disease progression and ultimately patient death. Because of tumor heterogeneity, it is rare for all cancers of a particular type to respond to a specific therapy; and, as a result, many patients receive treatment from which they derive little or no benefit, leading to increased morbidity and undue costs. A marker that could rapidly predict or forecast disease outcome would clearly be beneficial in allowing the administration of a tailored regime for each patient while reducing toxicity and cost. Traditional prognostic factors of tumor size, grade, and stage are not ideal for predicting patient outcome, whereas the use of in vitro assays to detect chemosensitivity or resistance has not yet translated into routine clinical practice. Similarly, biomarkers and tumor markers vary in their predictive ability. DNA array technology offers great promise in predicting the response to therapy based on gene expression profiles, and can allow for targeted therapies against specific molecular alterations that cause disease. Imaging techniques, particularly those with the ability to characterize biological tissues and provide functional, structural, and molecular information, have the potential to noninvasively integrate physical and metabolic information. These include F-18-fluorodeoxyglucose positron emission tomography, dynamic contrast-enhanced magnetic resonance imaging, and diffusion weighted magnetic resonance imaging, all techniques that attempt to evaluate and predict therapy response and so influence clinical outcome. This review examines different methods of predicting the response to treatment in advanced cervical and ovarian tumors.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to describe why prediction of response to therapy for cervical and ovarian cancers is important, describe obstacles to use of in vitro assays to predict outcomes for therapy for ovarian and cervical cancers, and explain potentially new predictive markers.

The biological role and regulation of versican levels in cancer

Increased expression of the proteoglycan, versican is strongly associated with poor outcome for many different cancers. Depending on the cancer type, versican is expressed by either the cancer cells themselves or by stromal cells surrounding the tumor. Versican plays diverse roles in cell adhesion, proliferation, migration and angiogenesis, all features of invasion and metastasis. These wide ranging functions have been attributed to the central glycosaminoglycan-binding region of versican, and to the N-(G1) and C-(G3) terminal globular domains which collectively interact with a large number of extracellular matrix and cell surface structural components. Here we review the recently identified mechanisms responsible for the regulation of versican expression and the biological roles that versican plays in cancer invasion and metastasis. The regulation of versican expression may represent one mechanism whereby cancer cells alter their surrounding microenvironment to facilitate the malignant growth and invasion of several tumor types. A greater understanding of the regulation of versican expression may contribute to the development of therapeutic methods to inhibit versican function and tumor invasion.

Gene expression profiling of advanced-stage serous ovarian cancers distinguishes novel subclasses and implicates ZEB2 in tumor progression and prognosis

To elucidate the mechanisms of rapid progression of serous ovarian cancer, gene expression profiles from 43 ovarian cancer tissues comprising eight early stage and 35 advanced stage tissues were carried out using oligonucleotide microarrays of 18,716 genes. By non-negative matrix factorization analysis using 178 genes, which were extracted as stage-specific genes, 35 advanced stage cases were classified into two subclasses with superior (n = 17) and poor (n = 18) outcome evaluated by progression-free survival (log rank test, P = 0.03). Of the 178 stage-specific genes, 112 genes were identified as showing different expression between the two subclasses. Of the 48 genes selected for biological function by gene ontology analysis or Ingenuity Pathway Analysis, five genes (ZEB2, CDH1, LTBP2, COL16A1, and ACTA2) were extracted as candidates for prognostic factors associated with progression-free survival. The relationship between high ZEB2 or low CDH1 expression and shorter progression-free survival was validated by real-time RT-PCR experiments of 37 independent advanced stage cancer samples. ZEB2 expression was negatively correlated with CDH1 expression in advanced stage samples, whereas ZEB2 knockdown in ovarian adenocarcinoma SKOV3 cells resulted in an increase in CDH1 expression. Multivariate analysis showed that high ZEB2 expression was independently associated with poor prognosis. Furthermore, the prognostic effect of E-cadherin encoded by CDH1 was verified using immunohistochemical analysis of an independent advanced stage cancer samples set (n = 74). These findings suggest that the expression of epithelial-mesenchymal transition-related genes such as ZEB2 and CDH1 may play important roles in the invasion process of advanced stage serous ovarian cancer.

Ovarian adenocarcinomas in the laying hen and women share similar alterations in p53, ras, and HER-2/neu

We examined alterations in the p53 tumor suppressor gene and the ras and HER-2/neu oncogenes in chicken ovarian cancers to determine if these tumors have genetic alterations similar to those in human ovarian adenocarcinomas. Mutations in the p53 tumor suppressor gene and the H-ras and K-ras oncogenes were assessed by direct sequencing in 172 ovarian cancers obtained from 4-year-old birds enrolled at age 2 in two separate 2-year chemoprevention trials. Birds in trial B had approximately twice as many lifetime ovulations as those in trial A. Immunohistochemical staining for the HER-2/neu oncogene was done on a subset of avian ovarian and oviductal adenocarcinomas. Alterations in p53 were detected in 48% of chicken ovarian cancers. Incidence of p53 alterations varied according to the number of lifetime ovulations, ranging from 14% in trial A to 96% in trial B (P < 0.01). No mutations were seen in H-ras, and only 2 of 172 (1.2%) tumors had K-ras mutations. Significant HER-2/neu staining was noted in 10 of 19 ovarian adenocarcinomas but in only 1 of 17 oviductal adenocarcinomas. Similar to human ovarian cancers, p53 alterations are common in chicken ovarian adenocarcinomas and correlate with the number of lifetime ovulations. Ras mutations are rare, similar to high-grade human ovarian cancers. HER-2/neu overexpression is common and may represent a marker to exclude an oviductal origin in cancers involving both the ovary and oviduct.

Stage IV ovarian cancer: disease site-specific rationale for postoperative treatment

OBJECTIVES

We aimed to define the site-specific patterns of treatment failure in stage IV ovarian cancer.

METHODS

Data from all consecutive Mayo Clinic patients with stage IV epithelial ovarian cancer, from 1994 through 2003, were collected and analyzed. Statistical analyses included the chi(2) test and Kaplan-Meier curves with log-rank tests.

RESULTS

Review of our patient database identified 109 patients with stage IV ovarian cancer: mean age, 62 years (range, 36-83 years); 5-year overall survival, 15%. Most patients (74%) had intraperitoneal disease at the time of relapse, 36% had pleural effusion, and 49% had extraperitoneal metastases. At the time of death 75% had intraperitoneal localizations, 51% had pleural effusion, and 46% had extraperitoneal metastases. Patients with pleural effusion were more likely to have pleural disease at relapse and at last follow-up. Extrapleural disease at the time of diagnosis predicted extrapleural disease at relapse and at last follow-up. Most patients classified as having stage IV disease by pleural cytology only, as opposed to all other patients, had intraperitoneal disease at relapse (88% vs 58.7%, P=.001) and last follow-up (88.5% vs 59.6%, P=.001). Patients having stage IV disease by pleural cytology only had survival benefit when disease was optimally debulked in the abdomen and pelvis (median survival, 3.1 years vs 1.3 years; P=.001). Patients with multiple unresectable liver metastases had poor prognosis (median survival, 1.2 years) owing to progression of liver disease.

CONCLUSIONS

Clinical trials for stage IV ovarian cancer should reflect the site-specific risks for recurrence according to disease location at diagnosis.

A snapshot of microarray-generated gene expression signatures associated with ovarian carcinoma

It was hypothesized that analysis of global gene expression in ovarian carcinoma can identify dysregulated genes that can serve as molecular markers and provide further insight into carcinogenesis and provide the basis for development of new diagnostic tools as well as new targeted therapy protocols. By applying bioinformatics tools for screening of biomedical databases, a gene expression profile databank, specific for ovarian carcinoma, was constructed with utilizable data sets published in 28 studies that applied different array technology platforms. The data sets were divided into four compartments: (i) genes associated with carcinogenesis: in 14 studies, 1881 genes were extracted, 75 genes were identified in more than one study, and only 4 genes (PRKCBP1, SPON1, TACSTD1, and PTPRM) were identified in three studies. (ii) Genes associated with histologic subtypes: in four studies, 463 genes could be identified, but none of them was identified in more than a single study. (iii) Genes associated with therapy response: in seven studies, 606 genes were identified from which 38 were differentially regulated in at least two studies, 3 genes (TMSB4X, GRN, and TJP1) in three studies, and 1 gene (IFITM1) in four studies. (iv) Genes associated with prognosis and progression: 254 genes were found in seven studies. From these genes, merely three were identified in at least two different studies. This snapshot of available gene expression data not only provides independently described potential diagnostic and therapeutic targets for ovarian carcinoma but also emphasizes the drawbacks of the current state of global gene expression analyses in ovarian cancer.

Early detection of ovarian cancer

Ovarian cancer is associated with an overall mortality of 75%, but can be cured in up to 90% of cases if diagnosed while still limited to the ovaries. Given the low prevalence of ovarian cancer in the general population, an effective screening strategy must not only have a high sensitivity for early-stage disease (>75%), but must also have a very high specificity (99.6%) to prompt no more than ten operations for each case of ovarian cancer diagnosed (positive predictive value [PPV] of 10%). Attempts to develop an effective screening strategy for ovarian cancer have utilized ultrasonography and serum tumor markers. Transvaginal sonography (TVS) and the serum marker CA125 have received the most attention to date. Used individually on a single occasion, neither of these approaches provides an adequate PPV and the cost of annual TVS is significant. Recent clinical trials have focused on serial monitoring of CA125 and the sequential use of a rising CA125 to prompt TVS in a limited number of women screened. Sequential monitoring of CA125 has significantly improved specificity of the assay in women over 50 years of age. The limited sensitivity of CA125 has, however, prompted a search for multiple serum markers that, in combination, would detect more than 90% of early-stage disease. Recent developments in genomic and proteomic research have identified a number of candidate biomarkers. Platforms have been developed that can assay more than 50 analytes in a few hundred microliters of serum. Panels of biomarkers have been discovered with high sensitivity and specificity for early-stage disease, but these require prospective validation. Several biomarkers have also been detected in urine, raising the possibility of a less expensive, more convenient screening test. Imaging techniques have been improved and mathematical methods developed that, in aggregate, promise to provide an effective screening strategy for ovarian cancer. In this review, we will assess the current status and describe future directions in ovarian cancer screening.