Molecular determinants of tumor differentiation in papillary serous ovarian carcinoma

Ubiquitin Proteasome Pathway Transcriptome in Epithelial Ovarian Cancer

In this article, we reviewed the transcription of genes coding for components of the ubiquitin proteasome pathway in publicly available datasets of epithelial ovarian cancer (EOC). KEGG analysis was used to identify the major pathways distinguishing EOC of low malignant potential (LMP) from invasive high-grade serous ovarian carcinomas (HGSOC), and to identify the components of the ubiquitin proteasome system that contributed to these pathways. We identified elevated transcription of several genes encoding ubiquitin conjugases associated with HGSOC. Fifty-eight genes coding for ubiquitin ligases and more than 100 genes encoding ubiquitin ligase adaptors that were differentially expressed between LMP and HGSOC were also identified. Many differentially expressed genes encoding E3 ligase adaptors were Cullin Ring Ligase (CRL) adaptors, and 64 of them belonged to the Cullin 4 DCX/DWD family of CRLs. The data suggest that CRLs play a role in HGSOC and that some of these proteins may be novel therapeutic targets. Differential expression of genes encoding deubiquitinases and proteasome subunits was also noted.

Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic focus primarily on assessment of pathogenic or likely pathogenic variants associated with increased risk of breast, ovarian, and pancreatic cancer and recommended approaches to genetic testing/counseling and management strategies in individuals with these pathogenic or likely pathogenic variants. This manuscript focuses on cancer risk and risk management for BRCA-related breast/ovarian cancer syndrome and Li-Fraumeni syndrome. Carriers of a BRCA1/2 pathogenic or likely pathogenic variant have an excessive risk for both breast and ovarian cancer that warrants consideration of more intensive screening and preventive strategies. There is also evidence that risks of prostate cancer and pancreatic cancer are elevated in these carriers. Li-Fraumeni syndrome is a highly penetrant cancer syndrome associated with a high lifetime risk for cancer, including soft tissue sarcomas, osteosarcomas, premenopausal breast cancer, colon cancer, gastric cancer, adrenocortical carcinoma, and brain tumors.

Management of Gynecologic Cancers In Relation to Genetic Predisposition

OBJECTIVE

To review hereditary gynecologic cancer syndromes and outline current clinical management considerations.

DATA SOURCES

Retrieved articles and guidelines dated 2013-2018 from PubMed, National Comprehensive Cancer Network, American College of Medical Genetics and Genomics, American College of Obstetricians and Gynecologists, American Cancer Society, National Cancer Institute, Centers for Disease Control and Prevention, and National Institutes of Health databases.

CONCLUSION

Advances in genetic testing technology have allowed for the identification of a growing number of patients with genetic mutations associated with hereditary cancer. Individuals with a hereditary predisposition to cancer may qualify for targeted drug therapies, risk-reducing surgeries, and/or high-risk cancer surveillance depending on the specific gene mutation(s) they harbor. Furthermore, there are clinical implications for relatives.

IMPLICATIONS FOR NURSING PRACTICE

This article is an educational guide for oncology nurses who often play a key role in identifying patients at risk for hereditary cancer, prompting referrals for genetic evaluation, and providing follow-up care for these patients.

Strengthening the AntiTumor NK Cell Function for the Treatment of Ovarian Cancer

The crosstalk between cancer cells and host cells is a crucial prerequisite for tumor growth and progression. The cells from both the innate and adaptive immune systems enter into a perverse relationship with tumor cells to create a tumor-promoting and immunosuppressive tumor microenvironment (TME). Epithelial ovarian cancer (EOC), the most lethal of all gynecological malignancies, is characterized by a unique TME that paves the way to the formation of metastasis and mediates therapy resistance through the deregulation of immune surveillance. A characteristic feature of the ovarian cancer TME is the ascites/peritoneal fluid, a malignancy-associated effusion occurring at more advanced stages, which enables the peritoneal dissemination of tumor cells and the formation of metastasis. The standard therapy for EOC involves a combination of debulking surgery and platinum-based chemotherapy. However, most patients experience disease recurrence. New therapeutic strategies are needed to improve the prognosis of patients with advanced EOC. Harnessing the body’s natural immune defenses against cancer in the form of immunotherapy is emerging as an innovative treatment strategy. NK cells have attracted attention as a promising cancer immunotherapeutic target due to their ability to kill malignant cells and avoid healthy cells. Here, we will discuss the recent advances in the clinical application of NK cell immunotherapy in EOC.

B-Myb Mediates Proliferation and Migration of Non-Small-Cell Lung Cancer via Suppressing IGFBP3

B-Myb has been shown to play an important oncogenic role in several types of human cancers, including non-small-cell lung cancer (NSCLC). We previously found that B-Myb is aberrantly upregulated in NSCLC, and overexpression of B-Myb can significantly promote NSCLC cell growth and motility. In the present study, we have further investigated the therapeutic potential of B-Myb in NSCLC. Kaplan–Meier and Cox proportional hazards analysis indicated that high expression of B-Myb is significantly associated with poor prognosis in NSCLC patients. A loss-of-function study demonstrated that depletion of B-Myb resulted in significant inhibition of cell growth and delayed cell cycle progression in NSCLC cells. Notably, B-Myb depletion also decreased NSCLC cell migration and invasion ability as well as colony-forming ability. Moreover, an in vivo study demonstrated that B-Myb depletion caused significant inhibition of tumor growth in a NSCLC xenograft nude mouse model. A molecular mechanistic study by RNA-seq analysis revealed that B-Myb depletion led to deregulation of various downstream genes, including insulin-like growth factor binding protein 3 (IGFBP3). Overexpression of IGFBP3 suppressed the B-Myb-induced proliferation and migration, whereas knockdown of IGFBP3 significantly rescued the inhibited cell proliferation and motility caused by B-Myb siRNA (small interfering RNA). Expression and luciferase reporter assays revealed that B-Myb could directly suppress the expression of IGFBP3. Taken together, our results suggest that B-Myb functions as a tumor-promoting gene via suppressing IGFBP3 and could serve as a novel therapeutic target in NSCLC.

Primary cytoreductive surgery and adjuvant hormonal monotherapy in women with advanced low-grade serous ovarian carcinoma: Reducing overtreatment without compromising survival?

OBJECTIVES

Women with advanced-stage, low-grade serous ovarian carcinoma (LGSC) have low chemotherapy response rates and poor overall survival. Most LGSC tumors overexpress hormone receptors, which represent a potential treatment target. Our study objective was to determine the outcomes of patients with advanced-stage LGSC treated with primary cytoreductive surgery (CRS) and hormone therapy (HT).

METHODS

A retrospective study was performed at two academic cancer centers. Patients with Stage II-IV LGSC underwent either primary or interval CRS followed by adjuvant HT between 2004 and 2016. Gynecologic pathologists reviewed all cases. Two-year progression-free (PFS) and overall survival (OS) were calculated.

RESULTS

Twenty-seven patients were studied; primary CRS followed by HT were administered in 26, while 1 patient had neoadjuvant chemotherapy followed by CRS and HT. The median patient age was 47.5, and patients had Stage II (n=2), Stage IIIA (n=6), Stage IIIC (n=18), and Stage IV (n=1) disease. Optimal cytoreduction to no gross residual was achieved in 85.2%. Ninety six percent of tumors expressed estrogen receptors, while only 32% expressed progesterone receptors. Letrozole was administered post operatively in 55.5% cases, anastrozole in 37.1% and tamoxifen in 7.4%. After a median follow up of 41months, only 6 patients (22.2%) have developed a tumor recurrence and two patients have died of disease. Median PFS and OS have not yet been reached, but 2-year PFS and OS were 82.8% and 96.3%, respectively, and 3-year PFS and OS were 79.0% and 92.6%, respectively.

CONCLUSIONS

Our series describes the initial experience with cytoreductive surgery and hormonal monotherapy for women with Stage II-IV primary ovarian LGSC. While surgery remains the mainstay of treatment, chemotherapy may not be necessary in patients with advanced-stage disease who receive adjuvant hormonal therapy. A cooperative group, Phase III trial is planned to define the optimal therapy for women with this ovarian carcinoma subtype.

Activity of Bevacizumab in Patients With Low-Grade Serous Ovarian Carcinoma

Objectives

The aim of this study was to evaluate the antitumor activity of bevacizumab in low-grade serous ovarian carcinoma (LGSOC).

Methods

We retrospectively identified patients with LGSOC treated with bevacizumab.

Results

Twelve patients with LGSOC who received bevacizumab were identified. Eleven patients received bevacizumab alone. Only 1 (8.3%) of 12 patients had evidence of a partial response. Ten (90.9%) of the 11 patients were progression free at 6 months. All but 1 patient who received only 2 courses before treatment interruption had a progression-free survival (PFS) of greater than 6 months. The median PFS was 48 months (range, 5–123+ months). Three of the patients reported in this series had extended disease stabilization that lasted for 123+, 48, and 15+ months after progression-free intervals on prior chemotherapy regimens of 2.5, 4, and 7 months, respectively. The median overall survival was not reached at a median follow-up of 32 months, with only 1 of the 12 patients dying of disease.

Conclusions

In our series, in patients with LGSOC treated primarily with bevacizumab, primarily as a single agent, a low response rate but very long PFS is observed. In addition, patients have had secondary PFS durations that exceeded their prior PFS, which is a sign of anticancer activity.

Survival in women with grade 1 serous ovarian carcinoma

OBJECTIVE

To examine clinicopathologic variables associated with survival among women with low-grade (grade 1) serous ovarian carcinoma enrolled in a phase III study.

METHODS

This was an ancillary data analysis of Gynecologic Oncology Group protocol 182, a phase III study of women with stage III-IV epithelial ovarian carcinoma treated with carboplatin and paclitaxel compared with triplet or sequential doublet regimens. Women with grade 1 serous carcinoma (a surrogate for low-grade serous disease) were included in the analysis.

RESULTS

Among the 3,686 enrolled participants, 189 had grade 1 disease. The median age was 56.5 years and 87.3% had stage III disease. The median follow-up time was 47.1 months. Stratification according to residual disease after primary surgery was microscopic residual in 24.9%, 0.1-1.0 cm of residual in 51.3%, and more than 1.0 cm of residual in 23.8%. On multivariate analysis, only residual disease status (P=.006) was significantly associated with survival. Patients with microscopic residual had a significantly longer median progression-free (33.2 months) and overall survival (96.9 months) compared with those with residual 0.1-1.0 cm (14.7 months and 44.5 months, respectively) and more than 1.0 cm of residual disease (14.1 months and 42.0 months, respectively; progression-free and overall survival, P<.001). After adjustment for other variables, patients with low-grade serous carcinoma with measurable residual disease had a similar adjusted hazard ratio for death (2.12; P=.002) as their high-grade serous carcinoma counterparts with measurable disease (2.31; P<.001).

CONCLUSIONS

Surgical cytoreduction to microscopic residual was associated with improved progression-free and overall survival in women with advanced-stage low-grade serous ovarian carcinoma.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00011986.

LEVEL OF EVIDENCE

II.

Overexpression of WDR62 is associated with centrosome amplification in human ovarian cancer

PURPOSE

To assess the clinical significance of WD40 repeat containing 62 (WDR62), a novel centrosome abnormalities-associated gene, in ovarian cancer.

MATERIALS AND METHODS

In this study, WDR62 expression was assessed by western blot (6 ovarian cancer cell lines) and immunohistochemistry (primary epithelial ovarian cancer clinical specimens), and clinical variables were collected by retrospective chart review. Centrosome amplification was assessed by immunofluorescence staining in ovarian cancer cell lines, and by immunohistochemistry staining in ovarian cancer samples.

RESULTS

Six ovarian cancer cell lines exhibited significant WDR62 protein overexpression, and amplification of centrosome. High-grade ovarian cancer specimens exhibited significantly stronger nuclear staining of WDR62 than low-grade ovarian carcinoma specimens (80.4% vs 41.3%; P<0.012). High WDR62 expression was strongly associated with supernumerary centrosome count in tumor cells (P < 0.001).

CONCLUSION

Our findings suggest that WDR62 overexpression is related to centrosome amplification in ovarian cancer. It may be a novel useful differentiation biomarker and a potential therapy target for OC. Further assessment of WDR62 expression is highly warranted in large, prospective studies.

Claudins overexpression in ovarian cancer: potential targets for Clostridium Perfringens Enterotoxin (CPE) based diagnosis and therapy

Claudins are a family of tight junction proteins regulating paracellular permeability and cell polarity with different patterns of expression in benign and malignant human tissues. There are approximately 27 members of the claudin family identified to date with varying cell and tissue-specific expression. Claudins-3, -4 and -7 represent the most highly differentially expressed claudins in ovarian cancer. While their exact role in ovarian tumors is still being elucidated, these proteins are thought to be critical for ovarian cancer cell invasion/dissemination and resistance to chemotherapy. Claudin-3 and claudin-4 are the natural receptors for the Clostridium perfringens enterotoxin (CPE), a potent cytolytic toxin. These surface proteins may therefore represent attractive targets for the detection and treatment of chemotherapy-resistant ovarian cancer and other aggressive solid tumors overexpressing claudin-3 and -4 using CPE-based theranostic agents.

The life and times of low-grade serous carcinoma of the ovary

For the past several years, all women with epithelial ovarian cancer have been treated identically, whether in a clinical trial or off protocol. Over the past decade, we have come to appreciate the magnitude of the heterogeneity of ovarian cancer. The development of the binary grading system for serous carcinoma was a major advance, leading to separate clinical trials for patients with this subtype, originating from the Gynecologic Oncology Group's Rare Tumor Committee. The mitogen-activated protein kinase (MAPK) pathway appears to play a prominent role in the pathogenesis of this subtype. Approximately 20% to 40% of low-grade serous carcinomas have a KRAS mutation, while BRAF mutations are rare-approximately 5%. In genomic profiling studies, these tumors appear to cluster with serous tumors of low malignant potential. Compared with high-grade serous carcinomas, low-grade serous carcinomas are also characterized by a low frequency of p53 mutations, greater expression of ER and PR, and greater expression of PAX2 and IGF-1. Primary treatment of low-grade serous carcinoma includes surgery plus platinum-based chemotherapy (either adjuvant or neoadjuvant). Clinical behavior is characterized by young age at diagnosis, relative chemoresistance, and prolonged overall survival. Current options for treatment of relapsed disease include secondary cytoreduction in selected patients, salvage chemotherapy, or hormone therapy. A recently completed trial of a MEK inhibitor for women with recurrent disease demonstrated promising activity. Future directions will include further investigations of the molecular biology and biomarker-driven clinical trials with targeted agent monotherapy and combinations.

Low-grade and high-grade serous Mullerian carcinoma: review and analysis of publicly available gene expression profiles

OBJECTIVE

Mullerian low grade serous carcinoma (LGSC) and high grade serous carcinoma (HGSC) have distinct molecular profiles, clinical behavior and treatment response. Our objective was to study the biological profiles of these carcinomas.

METHODS

This study examines publicly available gene expression profiles of LGSC and HGSC to identify differentially expressed genes and key pathways involved in carcinogenesis and chemotherapy response.

RESULTS

Our analysis supports the hypothesis that serous mullerian carcinoma develop through two different pathways yielding two distinct malignancies, namely LGSC and HGSC. Furthermore, genes potentially involved in chemotherapeutic resistance of LGSC were identified. Suppressing the levels of these genes/proteins may increase clinical response to standard chemotherapy in patients with LGSC.

CONCLUSION

In summary, this review shows the molecular profile of LGSC and HGSC through multi-center analysis of gene expression profiles of these tumors. The gene signatures of these neoplasms may potentially be used to develop disease-specific, targeted therapy for LGSC and HGSC.

Cellular apoptosis susceptibility (chromosome segregation 1-like, CSE1L) gene is a key regulator of apoptosis, migration and invasion in colorectal cancer

Cellular apoptosis susceptibility (chromosome segregation 1-like, CSE1L) gene maps to chromosomal region 20q13.13, a region frequently amplified in solid tumours. In this study, we investigated the roles played by CSE1L in colorectal cancer by examining CSE1L expression and clinico-pathological parameters in colorectal cancer and investigating the effect of CSE1L on the viability, adhesion and migration of colorectal cancer cells. RT-PCR showed that CSE1L mRNA was over-expressed in colorectal cancer. CSE1L depletion by knock-down with CSE1L-specific siRNA significantly reduced viability in HCT116 cells (p = 0.004) and SW480 cells (p = 0.003) whilst significantly increasing the proportion of apoptotic HCT116 cells (p < 0.001) and SW480 cells (p < 0.001). Furthermore, CSE1L depletion significantly reduced the adhesive capacity of HCT116 (p = 0.003) and SW480 cells (p = 0.004). Analysis by qRT-PCR following CSE1L siRNA treatment of HCT116 and SW480 cells showed significant modulation of key apoptotic (p53, p73 and BAK) and adhesive (E-cadherin, Ep-CAM and ICAM-1) molecules. Immunohistochemistry of a colorectal cancer tissue microarray showed that CSE1L had a significantly increased level in colorectal cancer compared to normal colorectal epithelium (p < 0.001). There were significant decreases in both nuclear (p = 0.006) and cytoplasmic (p = 0.003) staining of CSE1L in tumours with lymph node metastasis (stage 3 tumours) compared with lymph node-negative tumours (stage 1 and 2 tumours). In lymph node-negative patients, poor survival was associated with increased CSE1L cytoplasmic expression (p = 0.042). These results indicate that CSE1L is associated with viability and apoptosis, cellular adhesion and invasion, thus implicating CSE1L in the progression of colorectal cancer.

Addiction of MYCN amplified tumours to B-MYB underscores a reciprocal regulatory loop

MYCN is a member of the MYC family of oncoproteins frequently amplified or overexpressed in aggressive, paediatric tumours of the nervous system. In this study we have identified the gene B-MYB, encoding the transcription factor also known as MYBL2, as a downstream target of MYCN. Using multiple in silico databases we show that expression of B-MYB significantly correlates with that of MYCN in neuroblastoma patients. MYCN binds to and activates the B-MYB gene in vivo and in vitro. Blunting B-MYB expression by RNA interference causes reduced proliferation of MYCN amplified, but not MYCN-non amplified, neuroblastoma cell lines, indicating that tumour cells are addicted to B-MYB in a MYCN dependent manner. Notably, B-MYB binds in vivo to the MYCN amplicon and is required for its expression. We conclude that MYCN and B-MYB are engaged in a reciprocal regulatory loop whose pharmacological targeting could be beneficial to patients with the aggressive forms of cancer in which MYCN is amplified.

Modelling genetic and clinical heterogeneity in epithelial ovarian cancers

The biology underlying early-stage epithelial ovarian cancer (EOC) development is poorly understood. Identifying biomarkers associated with early-stage disease could have a significant impact on reducing mortality. Here, we describe establishment of a three-dimensional (3D) in vitro genetic model of EOC initiation and early-stage neoplastic progression. Normal primary ovarian epithelial (POE) cells, immortalized using hTERT (immortalised ovarian epithelial [IOE] cells), were partially transformed by overexpressing the CMYC oncogene (IOE(CMYC) cells). Subsequent expression of mutant alleles of KRAS (KRAS(G12V)) or BRAF (BRAF(V600E)) created double-mutant lines (IOE(CMYC.KRAS) and IOE(CMYC.BRAF)). The transformed phenotype of IOE(CMYC) cells was further enhanced in concert with KRAS(G12V)/BRAF(V600E) expression, as in vitro analyses indicated that IOE(CMYC) cells had undergone morphological and phenotypic changes characteristic of neoplastic progression. When cultured as 3D spheroids, IOE cells underwent growth arrest, reminiscent of nonproliferative, unstimulated POE in vivo. In contrast, IOSE(CMYC+BRAF/KRAS) cells formed highly proliferative, poly-aggregate spheroid structures, showing increased expression of the Wilms tumour 1 tumourigenic marker and MIB1 proliferation marker. Transcriptomic analyses identified different gene expression profiles between the different cell lines and novel candidate genes (e.g. RGS4, CTGF and THBS1) that are somatically altered in EOCs. Gene expression signatures were compared with signatures from primary EOCs; tumours with IOE(CMYC) 'like' signatures were more likely to be high grade (P = 0.018); tumours with BRAF signatures were associated with improved relapse-free survival (P = 0.003). In conclusion, we have established in vitro 3D models of early-stage EOCs, which reflect genetic and phenotypic heterogeneity of the disease. Molecular genetic characteristics of these models correlated with molecular and clinical features of primary EOCs.

Suppression of Aurora-A oncogenic potential by c-Myc downregulation

The abnormality of serine/threonine kinase Aurora-A is seen in many types of cancers. Although in physiological context it has been shown to play a vital role in cellular mitosis, how this oncogene contributes to tumorigenesis remains unclear. Here we demonstrate that Aurora-A overexpression enhances both the expression level and transcriptional activity of c-Myc. The inhibition of c-Myc expression by RNA interference significantly impaired the oncogenic potential of Aurora-A, resulting in attenuated cellular proliferation and transformation rates as well as fewer centrosomal aberrations. Furthermore, downregulation of c-Myc effectively overcame Aurora-A-induced resistance to cisplatin in esophageal cancer cells. Taken together, our results suggest an important role for c-Myc in mediating the oncogenic activity of Aurora-A, which may in turn allow for future targeting of c-Myc as a potential therapeutic strategy for tumors with Aurora-A overexpression.

BRAF mutation is rare in advanced-stage low-grade ovarian serous carcinomas

Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed.

BRAF mutation is rare in advanced-stage low-grade ovarian serous carcinomas

Low-grade ovarian serous carcinomas are believed to arise via an adenoma-serous borderline tumor-serous carcinoma sequence. In this study, we found that advanced-stage, low-grade ovarian serous carcinomas both with and without adjacent serous borderline tumor shared similar regions of loss of heterozygosity. We then analyzed 91 ovarian tumor samples for mutations in TP53, BRAF, and KRAS. TP53 mutations were not detected in any serous borderline tumors (n = 30) or low-grade serous carcinomas (n = 43) but were found in 73% of high-grade serous carcinomas (n = 18). BRAF (n = 9) or KRAS (n = 5) mutation was detected in 47% of serous borderline tumors, but among the low-grade serous carcinomas (39 stage III, 2 stage II, and 2 stage I), only one (2%) had a BRAF mutation and eight (19%) had a KRAS mutation. The low frequency of BRAF mutations in advanced-stage, low-grade serous carcinomas, which contrasts with previous findings, suggests that aggressive, low-grade serous carcinomas are more likely derived from serous borderline tumors without BRAF mutation. In addition, advanced-stage, low-grade carcinoma patients with BRAF or KRAS mutation have a better apparent clinical outcome. However, further investigation is needed.

Addiction of MYCN amplified tumours to B-MYB underscores a reciprocal regulatory loop

MYCN is a member of the MYC family of oncoproteins frequently amplified or overexpressed in aggressive, paediatric tumours of the nervous system. In this study we have identified the gene B-MYB, encoding the transcription factor also known as MYBL2, as a downstream target of MYCN. Using multiple in silico databases we show that expression of B-MYB significantly correlates with that of MYCN in neuroblastoma patients. MYCN binds to and activates the B-MYB gene in vivo and in vitro. Blunting B-MYB expression by RNA interference causes reduced proliferation of MYCN amplified, but not MYCN-non amplified, neuroblastoma cell lines, indicating that tumour cells are addicted to B-MYB in a MYCN dependent manner. Notably, B-MYB binds in vivo to the MYCN amplicon and is required for its expression. We conclude that MYCN and B-MYB are engaged in a reciprocal regulatory loop whose pharmacological targeting could be beneficial to patients with the aggressive forms of cancer in which MYCN is amplified.

Clostridium perfringens enterotoxin carboxy-terminal fragment is a novel tumor-homing peptide for human ovarian cancer

Background

Development of innovative, effective therapies against recurrent/chemotherapy-resistant ovarian cancer remains a high priority. Using high-throughput technologies to analyze genetic fingerprints of ovarian cancer, we have discovered extremely high expression of the genes encoding the proteins claudin-3 and claudin-4.

Methods

Because claudin-3 and -4 are the epithelial receptors for Clostridium perfringens enterotoxin (CPE), and are sufficient to mediate CPE binding, in this study we evaluated the in vitro and in vivo bioactivity of the carboxy-terminal fragment of CPE (i.e., CPE_290-319 binding peptide) as a carrier for tumor imaging agents and intracellular delivery of therapeutic drugs. Claudin-3 and -4 expression was examined with rt-PCR and flow cytometry in multiple primary ovarian carcinoma cell lines. Cell binding assays were used to assess the accuracy and specificity of the CPE peptide in vitro against primary chemotherapy-resistant ovarian carcinoma cell lines. Confocal microscopy and biodistribution assays were performed to evaluate the localization and uptake of the FITC-conjugated CPE peptide in established tumor tissue.

Results

Using a FITC-conjugated CPE peptide we show specific in vitro and in vivo binding to multiple primary chemotherapy resistant ovarian cancer cell lines. Bio-distribution studies in SCID mice harboring clinically relevant animal models of chemotherapy resistant ovarian carcinoma showed higher uptake of the peptide in tumor cells than in normal organs. Imunofluorescence was detectable within discrete accumulations (i.e., tumor spheroids) or even single chemotherapy resistant ovarian cancer cells floating in the ascites of xenografted animals while a time-dependent internalization of the FITC-conjugated CPE peptide was consistently noted in chemotherapy-resistant ovarian tumor cells by confocal microscopy.

Conclusions

Based on the high levels of claudin-3 and -4 expression in chemotherapy-resistant ovarian cancer and other highly aggressive human epithelial tumors including breast, prostate and pancreatic cancers, CPE peptide holds promise as a lead peptide for the development of new diagnostic tracers or alternative anticancer agents.

Molecular characterization of ovarian cancer by gene-expression profiling

Ovarian cancer is the second most common gynecologic malignancy, and represents the fifth most common cause of cancer death in women in the United States. The age at diagnosis, extent of disease, success of primary surgery, and the histopathological features of the tumor are important prognostic markers. Epithelial ovarian carcinomas are classified into four major categories: serous, mucinous, endometrioid, and clear cell. Each subtypes of ovarian carcinoma are known to have different clinical characteristics and biological behaviour and response to chemotherapy. Molecular studies have supported for the notion that the different histological types of ovarian cancer likely represent histopathologically, genetically, and biologically distinct diseases. Microarray-based profiling technologies have provided an opportunity to simultaneously examine the relationship between thousands of genes and clinical phenotypes. In this review, we will summarise the current gene-expression profiles that address the classification of ovarian cancer into molecular subtypes with different outcomes.

Translocation t(11;18)(q21;q21) in gastric B-cell lymphomas

Translocation t(11;18)(q21;q21) is the most frequent chromosomal aberration reported in gastric mucosa-associated lymphoid tissue (MALT) lymphomas. Intriguingly, this translocation has been reported only rarely in diffuse large B-cell lymphomas; it has been proposed that t(11;18)-positive tumors rarely progress to diffuse large B-cell lymphomas. We examined the frequency of chromosomal translocation t(11;18)(q21;q21) in mucosa-associated lymphoid tissue lymphoma and diffuse large B-cell lymphoma of the stomach. Paraffin-embedded tissues from patients with gastric B-cell lymphomas were selected retrospectively. The presence of the t(11;18)(q21;q21) was determined using reverse transcriptase-polymerase chain reaction and/or fluorescence in situ hybridization. beta-Actin transcript was also determined to evaluate the integrity and efficiency of RNA (cDNA) recovery from paraffin-embedded tissues. We analyzed 53 gastric B-cell lymphomas (33 diffuse large B-cell and 20 mucosa-associated lymphoid tissue) obtained from Italy, the USA, or Japan. Beta-actin transcript was amplified in 50 cases (94%), including 19 mucosa-associated lymphoid tissue and 31 diffuse large B-cell lymphomas (five with mucosa-associated lymphoid tissue components). The t(11;18) translocation was detected in 19% (6 of 31) cases with diffuse large B-cell lymphoma versus 26% (five of 19) with mucosa-associated lymphoid tissue lymphoma (P = 0.72). One of five diffuse large B-cell lymphomas with a mucosa-associated lymphoid tissue component showed the t(11;18)(q21;q21). In conclusion, translocation t(11;18)(q21;q21) was found in both mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the stomach at approximately equivalent frequencies; its presence does not exclude progression to diffuse large B-cell lymphoma.

Recurrent low-grade serous ovarian carcinoma is relatively chemoresistant

PURPOSE

Previous studies have suggested that low-grade serous ovarian carcinoma is more chemoresistant to first-line or neoadjuvant chemotherapy than high-grade serous carcinoma. The purpose of this study was to further characterize this chemoresistance in recurrent low-grade serous ovarian carcinoma.

METHODS

From a 1990-2007 search of the departmental databases at our institution, we identified recurrent low-grade serous ovarian carcinoma patients; abstracted chemotherapy response information from the medical records of those whose disease was: 1) histologically-confirmed, 2) measurable or evaluable, and 3) treated with chemotherapy; and retrospectively reviewed these data. Response was determined based on modified RECIST. Time to progression and overall survival were also calculated.

RESULTS

We identified 58 evaluable patients with recurrent low-grade serous ovarian carcinoma who received 108 separate chemotherapy regimens ("patient-regimens"), which produced 4 responses-(1 complete and 3 partial; overall response rate, 3.7%). The overall response rate for the platinum-sensitive cohort was 4.9%, and for the platinum-resistant cohort, 2.1%. Stable disease was observed in 65 (60.2%) of 108 patient-regimens. Median overall survival was 87.1 months. The median time to progression was 29.0 weeks (34.7, platinum-sensitive cohort; 26.4, platinum-resistant cohort) (P=0.32).

CONCLUSIONS

Compared with high-grade ovarian cancers, recurrent low-grade serous ovarian carcinoma appears relatively chemoresistant. Whether the latter's high rate of stable disease owes more to the tumor's biology or the influence of chemotherapy remains unclear. Based on these findings, phase II trials of novel targeted agents in recurrent low-grade serous ovarian carcinoma are warranted.

Low-grade serous ovarian cancer: a unique disease

Low-grade serous carcinomas represent approximately 10% of all serous ovarian carcinomas. A growing body of research has demonstrated several important differences between the clinical and molecular characteristics of these tumors and those of high-grade serous ovarian carcinomas. Patients with low-grade serous ovarian tumors are diagnosed at a younger age, have a longer overall survival, and have lower response rates to conventional chemotherapy. In addition, low-grade serous ovarian carcinomas have pathologic and molecular characteristics distinct from high-grade serous carcinomas, yet similar to serous tumors of low malignant potential. This suggests a common pathogenesis and a continuum of disease from serous tumors of low malignant potential to low-grade serous carcinomas. Further study, focusing specifically on low-grade serous carcinomas, is needed to determine the role of other chemotherapeutic agents, hormonal therapy, or targeted biologic agents in the treatment of this disease.

Genomic analysis of epithelial ovarian cancer

Ovarian cancer is a major health problem for women in the United States. Despite evidence of considerable heterogeneity, most cases of ovarian cancer are treated in a similar fashion. The molecular basis for the clinicopathologic characteristics of these tumors remains poorly defined. Whole genome expression profiling is a genomic tool, which can identify dysregulated genes and uncover unique sub-classes of tumors. The application of this technology to ovarian cancer has provided a solid molecular basis for differences in histology and grade of ovarian tumors. Differentially expressed genes identified pathways implicated in cell proliferation, invasion, motility, chromosomal instability, and gene silencing and provided new insights into the origin and potential treatment of these cancers. The added knowledge provided by global gene expression profiling should allow for a more rational treatment of ovarian cancers. These techniques are leading to a paradigm shift from empirical treatment to an individually tailored approach. This review summarizes the new genomic data on epithelial ovarian cancers of different histology and grade and the impact it will have on our understanding and treatment of this disease.

Epidemiology of low-grade serous ovarian cancer

OBJECTIVE

The objective of the study was to determine whether the epidemiology of low-grade ovarian serous cancers is distinct from that of high-grade ovarian serous cancers.

STUDY DESIGN

The National Cancer Institute's Surveillance Epidemiology and End Results (SEER) program reports incidence, and survival, data from representative population based cancer registries. The SEER data are analyzed to compare the descriptive epidemiologies of low- and high-grade lesions.

RESULTS

Mean survival (99 vs 57 months) and age (55.5 vs 62.6 years) trends in annual incidence rate (-3.8% vs 1.4%), rate ratio of advanced to early disease (1.9 vs 10.2), rate ratio of post- to premenopausal incidence (5.0 vs 13.0). and difference in average age between advanced and early stage (none vs 2.5 years) are significantly different for patients with low-grade, compared with high-grade, disease.

CONCLUSION

Epidemiology of low-grade tumors appears sufficiently different from that of high-grade lesions to support the concept that low-grade ovarian serous cancers constitute a distinct clinical, and perhaps biologic, entity.

Neoadjuvant chemotherapy for low-grade serous carcinoma of the ovary or peritoneum

OBJECTIVE

To evaluate the response of women with low-grade serous carcinoma of the ovary or peritoneum to platinum-based neoadjuvant chemotherapy.

METHODS

Using institutional databases, we identified 25 women with advanced low-grade serous carcinoma of the ovary or peritoneum treated with neoadjuvant platinum-based chemotherapy between 1989 and 2006. Demographic and clinical variables were abstracted from the medical records. Progression-free survival (PFS) and overall survival (OS) were estimated using the method of Kaplan and Meier.

RESULTS

Median patient age at diagnosis was 45 years (range 29-81). The majority of patients (n=19, 76%) received a combination of a taxane and platinum drug. A median of six cycles of chemotherapy was administered (range 2-16). Of the 20 patients for whom pre- and post-neoadjuvant chemotherapy CA-125 levels were available, 50% had a >50% reduction after neoadjuvant chemotherapy. However, radiographic survey of the 24 patients evaluable at the completion of neoadjuvant chemotherapy demonstrated one patient (4%) with a complete response, 21 (88%) with stable disease and 2 (8%) with progression following neoadjuvant chemotherapy. Median PFS and OS for all patients were 21.4 and 56.1 months, respectively.

CONCLUSIONS

The low response rate to platinum-based neoadjuvant chemotherapy observed indicates that low-grade serous carcinoma is not as responsive to conventional chemotherapy as high-grade serous carcinoma. Prospective clinical trials focused specifically on low-grade serous carcinoma are needed to make meaningful advances in the treatment of this disease.

Simultaneous Aurora-A/STK15 overexpression and centrosome amplification induce chromosomal instability in tumour cells with a MIN phenotype

Background

Genetic instability is a hallmark of tumours and preneoplastic lesions. The predominant form of genome instability in human cancer is chromosome instability (CIN). CIN is characterized by chromosomal aberrations, gains or losses of whole chromosomes (aneuploidy), and it is often associated with centrosome amplification. Centrosomes control cell division by forming a bipolar mitotic spindle and play an essential role in the maintenance of chromosomal stability.

However, whether centrosome amplification could directly cause aneuploidy is not fully established. Also, alterations in genes required for mitotic progression could be involved in CIN.

A major candidate is represented by Aurora-A/STK15 that associates with centrosomes and is overexpressed in several types of human tumour.

Methods

Centrosome amplification were induced by hydroxyurea treatment and visualized by immunofluorescence microscopy. Aurora-A/STK15 ectopic expression was achieved by retroviral infection and puromycin selection in HCT116 tumour cells. Effects of Aurora-A/STK15 depletion on centrosome status and ploidy were determined by Aurora-A/STK15 transcriptional silencing by RNA interference. Changes in the expression levels of some mitotic genes were determined by Real time RT-PCR.

Results

We investigated whether amplification of centrosomes and overexpression of Aurora-A/STK15 induce CIN using as a model system a colon carcinoma cell line (HCT116). We found that in HCT116 cells, chromosomally stable and near diploid cells harbouring a MIN phenotype, centrosome amplification induced by hydroxyurea treatment is neither maintained nor induces aneuploidy. On the contrary, ectopic overexpression of Aurora-A/STK15 induced supernumerary centrosomes and aneuploidy. Aurora-A/STK15 transcriptional silencing by RNA interference in cells ectopically overexpressing this kinase promptly decreased cell numbers with supernumerary centrosomes and aneuploidy.

Conclusion

Our results show that centrosome amplification alone is not sufficient to induce chromosomal instability in colon cancer cells with a MIN phenotype. Alternatively, centrosome amplification has to be associated with alterations in genes regulating mitosis progression such as Aurora-A/STK15 to trigger CIN.

Comparison of the clinical behavior of newly diagnosed stages II–IV low-grade serous carcinoma of the ovary with that of serous ovarian tumors of low malignant potential that recur as low-grade serous carcinoma

BACKGROUND

Serous ovarian tumors of low malignant potential (STLMP) frequently coexist with low-grade serous carcinoma of the ovary (LGSC) and, when they recur, frequently do so as LGSC. The purpose of this study was to compare the outcomes of patients with these two tumor types.

METHODS

All patients with stages II-IV LGSC (group 1) or with STLMP that recurred as LGSC (group 2) seen at our institution from 1973 to 2003 were identified, and demographic data were obtained. For group 1, progression-free and overall survival times were calculated from the date of primary diagnosis to the date of disease progression/recurrence or the date of last contact/death, respectively. For group 2, progression-free and overall survival times were calculated from the date of first relapse as a LGSC to the date of progression or the date of last contact/death, respectively. The method of Kaplan and Meier was used to estimate survival, and the log-rank test was used to compare differences between survival curves.

RESULTS

We identified 112 patients in group 1 and 41 in group 2. There were no statistically significant differences between the two groups in median age (42.7 vs. 45.4 years [at relapse]; P=0.37), progression-free survival time (19.5 vs. 25 months; P=0.92), or overall survival time (81.8 vs. 82.8 months; P=0.84).

CONCLUSIONS

The age at diagnosis, progression-free survival time, and overall survival time associated with newly diagnosed stages II-IV LGSC of the ovary are similar to those of STLMP that recur as LGSC, providing further evidence of an association between these two tumor types.

Genetic intra-tumour heterogeneity in epithelial ovarian cancer and its implications for molecular diagnosis of tumours

Genetic analysis of solid tumours using DNA or cDNA expression microarrays may enable individualized treatment based on the profiles of genetic changes that are identified from each patient. This could result in better response to adjuvant chemotherapy and, consequently, improved clinical outcome. So far, most research studies that have tested the efficacy of such an approach have sampled only single areas of neoplastic tissue from tumours; this assumes that the genetic profile within solid tumours is homogeneous throughout. The aim of this study was to evaluate the extent of genetic intra-tumour heterogeneity (ITH) within a series of epithelial ovarian cancers. Several different regions (five to eight regions) of tumour tissue from 16 grade 3, serous epithelial ovarian cancers were analysed for genetic alterations using a combination of microsatellite analysis and single nucleotide polymorphism (SNP) analysis, in order to establish the extent of ITH. Maximum parsimony tree analysis was applied to the genetic data from each tumour to evaluate the clonal relationship between different regions within tumours. Extensive ITH was identified within all ovarian cancers using both microsatellite and SNP analysis. Evolutionary analysis of microsatellite data suggested that the origin of all tumours was monoclonal, but that subsequent clonal divergence created mixed populations of genetically distinct cells within the tumour. SNP analysis suggested that ITH was not restricted to random genetic changes, but affected genes that have an important functional role in ovarian cancer development. The frequent occurrence of ITH within epithelial ovarian cancers may have implications for the interpretation of genetic data generated from emerging technologies such as DNA and mRNA expression microarrays, and their use in the clinical management of patients with ovarian cancer. The basis of genetic ITH and the possible implications for molecular approaches to clinical diagnosis of ovarian cancers may apply to other tumour types.

Emerging roles for PAX8 in ovarian cancer and endosalpingeal development

OBJECTIVES

Epithelial ovarian carcinomas develop from ovarian surface epithelia that undergo complex differentiation to form distinguishable phenotypes resembling those of the epithelia of the female urogenital regions. While previous studies have implicated regulatory developmental homeobox (HOX) genes in this process, other factors responsible for this differentiation are largely unknown. Aberrant transcriptional expression of PAX8 has been reported in epithelial ovarian cancer, prompting us to initiate the molecular characterization of this master regulatory gene in ovarian cancer development.

METHODS

Immunohistochemistry, immunoblotting and RT-PCR were used to investigate the presence of PAX8 and its protein products in epithelial ovarian cancer subtypes, normal ovarian surface epithelia, ovarian inclusion cysts and normal endosalpingeal epithelia.

RESULTS

In this report, we confirm microarray results indicating that the transcription factor, PAX8, is highly expressed in epithelial ovarian cancer but absent from the precursor ovarian surface epithelia of healthy individuals. Furthermore, we report that PAX8 is localized to the nucleus of non-ciliated epithelia in simple ovarian epithelial inclusion cysts and in three epithelial ovarian cancer subtypes (serous, endometrioid and clear cell). We also determined that PAX8 is expressed in the non-ciliated, secretory cells of healthy fallopian tube mucosal linings but not in the adjacent ciliated epithelia.

CONCLUSION

These findings support the hypothesis that PAX8 plays parallel roles in the development of epithelial ovarian cancer and in the developmental differentiation of coelomic epithelia into endosalpingeal epithelia.

Differential gene expression profiles between tumor biopsies and short-term primary cultures of ovarian serous carcinomas: Identification of novel molecular biomarkers for early diagnosis and therapy

OBJECTIVE

To identify novel molecular biomarkers useful for the early diagnosis and therapy of ovarian cancer by gene expression profiling. To compare the genetic fingerprints of flash-frozen ovarian serous carcinomas to those of matched highly purified primary tumor cell cultures.

METHODS

Gene expression profiles of 19 flash-frozen ovarian serous papillary carcinoma (OSPC) were analyzed and compared to 15 controls (highly purified human ovarian surface epithelium short-term cultures, HOSE) using oligonucleotide microarrays complementary to >14,500 human genes. In addition, gene expression profiling of 5 highly purified primary OSPC cultured in vitro for less than 2 weeks was compared to flash-frozen ovarian carcinoma biopsies obtained from matched samples. Quantitative RT-PCR and IHC staining techniques were used to validate microarray data at RNA and protein levels for some of the differentially expressed genes.

RESULTS

Unsupervised analysis of gene expression data readily distinguished normal tissue from flash-frozen OSPC and identified 901 and 557 genes that exhibited >3-fold up-regulation or down-regulation, respectively, in OSPC when compared to HOSE. Mammaglobin 2, an ovarian secreted protein, was identified as the top differentially expressed gene in OSPC (19 out 19 OSPC versus 0 out of 15 HOSE) with over 827-fold up-regulation relative to HOSE. The claudin and kallikrein family of proteins including the clostridium perfringens enterotoxin receptors claudin 3 and 4, kallikreins 6, 7, 8, 10, 11 and the immunomodulatory molecule B7-H4 were found among the most highly overexpressed genes in OSPC when compared to HOSE. Genetic fingerprints of flash-frozen OSPC were found to have high correlation with those of purified primary OSPC short-term in vitro cultures with only 31 out of 8,637 genes (0.35%) differentially expressed between the two groups.

CONCLUSIONS

Short-term in vitro culture of primary ovarian carcinomas may greatly increase the purity of ovarian tumor RNA available for gene expression profiling without causing major alteration in OSPC fingerprints. Mammaglobin 2, kallikreins 6, 7, 8, 10, 11, claudin 3 and 4 and B7-H4 gene expression products represent candidate biomarkers endowed with great potential for early screening and therapy of OSPC patients.

Clinical Behavior of Stage II-IV Low-Grade Serous Carcinoma of the Ovary

OBJECTIVE

To analyze the clinical behavior of patients with stage II-IV low-grade serous carcinoma of the ovary seen at our institution who underwent primary surgery followed by platinum-based chemotherapy.

METHODS

Patients with stage II-IV low-grade serous carcinoma of the ovary from 1978 to 2003 were identified using existing databases. Clinicopathologic information was obtained from medical records. Progression-free survival and overall survival were estimated by the method of Kaplan and Meier. The log-rank test was used to compare differences between survival curves. Univariable and multivariable analyses were performed using Cox proportional hazards regression.

RESULTS

We identified 112 eligible patients. Median age was 43 years.; 90% had stage III disease. Preoperative serum CA 125 was elevated in 86% of patients. The most common sites of extraovarian disease were omentum, fallopian tubes, pelvic peritoneum, and uterus. Response rate to platinum-based chemotherapy in 10 evaluable patients (15% of patients with gross residual disease) was 80%, and 42 patients underwent second-look surgery: microscopically negative findings, 2 (5%); microscopically positive disease, 13 (33%); macroscopically positive disease, 24 (62%); and insufficient information, 3 (7%). Median progression-free survival and overall survival times were 19.5 and 81.8 months. Persistent disease after primary chemotherapy was the only factor associated with shorter overall survival time (hazard ratio 3.46, 95% confidence interval 2.00-5.97, P<.001).

CONCLUSION

Metastatic low-grade serous carcinoma of the ovary is characterized by young age at diagnosis and prolonged overall survival. Segregating women with this diagnosis in future clinical trials is warranted.

Molecular prognostic markers in ovarian cancer: toward patient-tailored therapy

In ovarian cancer the ceiling seems to be reached with chemotherapeutic drugs. Therefore a paradigm shift is needed. Instead of treating all patients according to standard guidelines, individualized molecular targeted treatment should be aimed for. This means that molecular profiles of the distinct ovarian cancer subtypes should be established. Until recently, most studies trying to identify molecular targets were single-marker studies. The prognostic role of key components of apoptotic and prosurvival pathways such as p53, EGFR, and HER2 has been extensively studied because resistance to chemotherapy is often caused by failure of tumor cells to go into apoptosis. However, it is more than likely that different ovarian cancer subtypes with extensive molecular heterogeneity exist. Therefore, exploration of the potential of specific tumor-targeted therapy, based on expression of a prognostic tumor profile, may be of interest. Recently, new profiling techniques, such as DNA and protein microarrays, have enabled high-throughput screening of tumors. In this review an overview of the current status of prognostic marker and molecular targeting research in ovarian cancer, including microarray studies, is presented.

Expression profiling correlates with treatment response in women with advanced serous epithelial ovarian cancer

The majority of epithelial ovarian carcinomas are of serous subtype, with most women presenting at an advanced stage. Approximately 70% respond to initial chemotherapy but eventually relapse. We aimed to find markers of treatment response that might be suitable for routine use, using the gene expression profile of tumor tissue. Thirty one women with histologically-confirmed late-stage serous ovarian cancer were classified into 3 groups based on response to treatment (nonresponders, responders with relapse less than 12 months and responders with no relapse within 12 months). Gene expression profiles of these specimens were analyzed with respect to treatment response and survival (minimum 36 months follow-up). Patients' clinical features did not correlate with prognosis, or with specific gene expression patterns of their tumors. However women who did not respond to treatment could be distinguished from those who responded with no relapse within 12 months based on 34 gene transcripts (p < 0.02). Poor prognosis was associated with high expression of inhibitor of differentiation-2 (ID2) (p = 0.001). High expression of decorin (DCN) and ID2 together was strongly associated with reduced survival (p = 0.003), with an estimated 7-fold increased risk of dying (95% CI 1.9-29.6; 14 months survival) compared with low expression (44 months). Immunohistochemical analysis revealed both nuclear and cytoplasmic distribution of ID2 in ovarian tumors. High percentage of nuclear staining was associated with poor survival, although not statistically significantly. In conclusion, elevated expression of ID2 and DCN was significantly associated with poor prognosis in a homogeneous group of ovarian cancer patients for whom survival could not be predicted from clinical factors.

Expression profiling of serous low malignant potential, low-grade, and high-grade tumors of the ovary

Papillary serous low malignant potential (LMP) tumors are characterized by malignant features and metastatic potential yet display a benign clinical course. The role of LMP tumors in the development of invasive epithelial cancer of the ovary is not clearly defined. The aim of this study is to determine the relationships among LMP tumors and invasive ovarian cancers and identify genes contributing to their phenotypes. Affymetrix U133 Plus 2.0 microarrays (Santa Clara, CA) were used to interrogate 80 microdissected serous LMP tumors and invasive ovarian malignancies along with 10 ovarian surface epithelium (OSE) brushings. Gene expression profiles for each tumor class were used to complete unsupervised hierarchical clustering analyses and identify differentially expressed genes contributing to these associations. Unsupervised hierarchical clustering analysis revealed a distinct separation between clusters containing borderline and high-grade lesions. The majority of low-grade tumors clustered with LMP tumors. Comparing OSE with high-grade and LMP expression profiles revealed enhanced expression of genes linked to cell proliferation, chromosomal instability, and epigenetic silencing in high-grade cancers, whereas LMP tumors displayed activated p53 signaling. The expression profiles of LMP, low-grade, and high-grade papillary serous ovarian carcinomas suggest that LMP tumors are distinct from high-grade cancers; however, they are remarkably similar to low-grade cancers. Prominent expression of p53 pathway members may play an important role in the LMP tumor phenotype.

Quantitative biochemical analysis of lactate dehydrogenase in human ovarian tissues: correlation with tumor grade

In an attempt to identify glycolytic capacity of normal and neoplastic human ovary, total lactate dehydrogenase (LDH) activity was measured in tissue cytosol originating from 69 patients (18 with benign ovarian tumor, 34 with ovarian carcinoma, six with nonepithelial ovarian malignant tumors, and 11 with tumor metastatic to ovary) and compared to the LDH activity of normal ovarian tissues (n = 19). Median value of total LDH-specific activity expressed as U/mg protein was 0.546 in normal tissues, 0.584 in benign tumors, 1.071 in malignancies metastatic to ovaries, 0.872 in nonepithelial primary ovarian tumors, and 0.818 in primary carcinomas. A significant rise in LDH-specific activity was found in malignant primary and secondary tumors of epithelial and nonepithelial origin, but not in benign neoplasms, compared to the activity in normal tissue. Ovarian carcinomas of serous histologic type did not differ in LDH activity from mucinous tumors. However, poorly differentiated carcinomas (grade 3) showed significantly enhanced activity of this glycolytic enzyme when compared to its grade 1 counterpart. The subgroup of grade 1 tumors did not differ in LDH activity from normal and benign ovarian tissue. Obtained results suggest that direct correlation might exist between ovarian epithelial tumor grade and lactate dehydrogenase activity.

In silico chromosomal clustering of genes displaying altered expression patterns in ovarian cancer

Ovarian cancer, the leading cause of death due to gynecological malignancy, is diagnosed in most cases at an advanced stage. Combined with the paucity of symptoms of early-stage disease, the need to develop novel effective markers for the detection of potentially curable, early-stage disease is self-evident. Comprehensive analyses of somatic gene expression patterns in ovarian cancer were reported previously (n=17) and yielded substantial information on somatically altered genes, information that can potentially be useful in developing early detection markers. To further substantiate the role that these genes play in ovarian cancer tumorogenesis, we surveyed these reports and arranged the significantly altered genes from all reported studies by their chromosomal location (in silico chromosomal clustering). Subsequent comparison of this clustering to known genomic somatic alterations at the DNA level from data obtained using comparative genomic hybridization (CGH) was carried out. The major chromosomal regions that displayed overexpressed genes were correlated with the major CGH-detectable DNA amplification areas at 20q (harboring HE4, SLPI, MYBL2, UBE2C, and SDC4) and 1q (harboring MUC1). These genes may provide insights into ovarian cancer pathogenesis and may also prove to be useful as early detection tools.

Treatment of chemotherapy-resistant human ovarian cancer xenografts in C.B-17/SCID mice by intraperitoneal administration of Clostridium perfringens enterotoxin

Ovarian cancer remains the most lethal gynecologic malignancy in the United States. Although many patients with advanced-stage disease initially respond to standard combinations of surgical and cytotoxic therapy, nearly 90% develop recurrence and inevitably die from the development of chemotherapy-resistant disease. The discovery of novel and effective therapy against chemotherapy-resistant/recurrent ovarian cancer remains a high priority. Using expression profiling, we and others have recently found claudin-3 and claudin-4 genes to be highly expressed in ovarian cancer. Because these tight junction proteins have been described as the low- and high-affinity receptors, respectively, for the cytotoxic Clostridium perfringens enterotoxin (CPE), in this study we investigated the level of expression of claudin-3 and/or claudin-4 in chemotherapy-naive and chemotherapy-resistant primary human ovarian cancers as well as their sensitivity to CPE treatment in vitro. We report that 100% (17 of 17) of the primary ovarian tumors tested overexpress one or both CPE receptors by quantitative reverse transcription-PCR. All ovarian tumors showed a dose-dependent cytotoxic effect to CPE in vitro. Importantly, chemotherapy-resistant/recurrent ovarian tumors were found to express claudin-3 and claudin-4 genes at significantly higher levels when compared with chemotherapy-naive ovarian cancers. All primary ovarian tumors tested, regardless of their resistance to chemotherapeutic agents, died within 24 hours to the exposure to 3.3 microg/mL CPE in vitro. In addition, we have studied the in vivo efficacy of i.p. CPE therapy in SCID mouse xenografts in a highly relevant clinical model of chemotherapy-resistant freshly explanted human ovarian cancer (i.e., OVA-1). Multiple i.p. administration of sublethal doses of CPE every 3 days significantly inhibited tumor growth in 100% of mice harboring 1 week established OVA-1. Repeated i.p. doses of CPE also had a significant inhibitory effect on tumor progression with extended survival of animals harboring large ovarian tumor burdens (i.e., 4-week established OVA-1). Our findings suggest that CPE may have potential as a novel treatment for chemotherapy-resistant/recurrent ovarian cancer.

Distinction between serous tumors of low malignant potential and serous carcinomas based on global mRNA expression profiling

OBJECTIVES

The molecular pathogenesis of ovarian serous tumors of low malignant potential (S-LMP) is not well understood, although the collective data suggest that they arise through molecular mechanisms distinct from those leading to conventional serous carcinomas (S-Ca). To further examine the molecular differences between these two diseases, we studied the gene expression pattern of ovarian S-LMP and S-Ca using high-density spotted cDNA and tissue microarrays.

METHODS

Total RNA from 23 ovarian S-LMP and S-Ca was analyzed on 43,200 spot cDNA microarrays and the differential expression of proteins encoded by differentially expressed genes was validated using tissue microarrays.

RESULTS

Unsupervised hierarchical clustering analysis of filtered data showed a complete separation between S-LMP and S-Ca, based predominantly on a small set of genes expressed at higher levels in S-LMP than in S-Ca. Many genes previously identified as up-regulated in ovarian carcinoma relative to normal ovarian tissue were expressed at even higher levels in S-LMP. These genes included mucin-1, mesothelin, HE4, PAX 8, and apolipoprotein J/clusterin. Immunohistochemical staining of tissue microarrays confirmed higher expression of selected proteins encoded by these genes in the S-LMP. Few genes were expressed at a higher level in S-Ca; these included E2F1, topoisomerase IIalpha, and cyclin E, with higher levels of cyclin E protein confirmed by immunohistochemistry.

CONCLUSIONS

S-LMP and S-Ca are distinguished at the molecular level by a relatively small gene set, suggesting the pathogenesis of S-LMP as well as S-Ca may involve molecular pathways that escape detection by global gene expression profiling. In order to obtain biologically and clinically relevant information about the mechanisms involved in ovarian carcinogenesis, future studies based on molecular profiles of ovarian cancer should include analyses of low malignant potential tumors. Inclusion of such tumors is also critical to the evaluation of the efficacy of potential new diagnostic and/or therapeutic biomarkers.

Molecular and prognostic distinction between serous ovarian carcinomas of varying grade and malignant potential

Profiles of gene transcription have begun to delineate the molecular basis of ovarian cancer, including distinctions between carcinomas of differing histology, tumor progression and patient outcome. However, the similarities and differences among the most commonly diagnosed noninvasive borderline (low malignant potential, LMP) lesions and invasive serous carcinomas of varying grade (G1, G2 and G3) have not yet been explored. Here, we used oligonucleotide arrays to profile the expression of 12,500 genes in a series of 57 predominantly stage III serous ovarian adenocarcinomas from 52 patients, eight with borderline tumors and 44 with adenocarcinomas of varying grade. Unsupervised and supervised analyses showed that LMP lesions were distinct from high-grade serous adenocarcinomas, as might be expected; however, well-differentiated (G1) invasive adenocarcinomas showed a strikingly similar profile to LMP tumors as compared to cancers with moderate (G2) or poor (G3) cellular differentiation, which were also highly similar. Comparative genomic hybridization of an independent cohort of five LMP and 63 invasive carcinomas of varying grade demonstrated LMP and G1 were again similar, exhibiting significantly less chromosomal aberration than G2/G3 carcinomas. A majority of LMP and G1 tumors were characterized by high levels of p21/WAF1, with concomitant expression of cell growth suppressors, gadd34 and BTG-2. In contrast, G2/G3 cancers were characterized by the expression of genes associated with the cell cycle and by STAT-1-, STAT-3/JAK-1/2-induced gene expression. The distinction between the LMP-G1 and G2-G3 groups of tumors was highly correlated to patient outcome (chi(2) for equivalence of death rates=7.681189; P=0.0056, log-rank test). Our results are consistent with the recent demonstration of a poor differentiation molecular 'meta-signature' in human cancer, and underscore a number of cell-cycle- and STAT-associated targets that may prove useful as points of therapeutic intervention for those patients with aggressive disease.

Genomic and proteomic technologies for individualisation and improvement of cancer treatment

The development of microarray-based technologies for characterising tumours, both at the genomic and proteomic levels, has had a significant impact on the field of oncology. Gene expression profiling of various human tumour tissues has led to the identification of expression patterns related to disease outcome and drug resistance, as well as to the discovery of new therapeutic targets and insights into disease pathogenesis. Protein microarray technologies, such as reverse-phase protein arrays, provide the unique opportunity to profile tissues and assess the activity of signalling pathways within isolated cell populations. This technology can be used to identify patients likely to benefit from specific treatment modalities and also to monitor therapeutic response in samples obtained during and after treatment. Routine application of genomic and proteomic microarray technologies in clinical practice will require significant efforts to standardise the techniques, controls and reference standards, and analytical tools used. Extensive, independent validation using large, statistically-powered datasets will also be necessary. Inclusion of concomitant genomic and proteomic-based molecular profiling techniques into clinical trial protocols will bring us closer to the reality of patient-tailored therapy.