The therapeutic potential of targeting the EGFR family in epithelial ovarian cancer

Dual HER/VEGF receptor targeting inhibits in vivo ovarian cancer tumor growth

Ovarian cancer mortality ranks highest among all gynecologic cancers with growth factor pathways playing an integral role in tumorigenesis, metastatic dissemination, and therapeutic resistance. The HER and VEGF receptor (VEGFR) are both overexpressed and/or aberrantly activated in subsets of ovarian tumors. While agents targeting either the HER or VEGF pathways alone have been investigated, the impact of these agents have not led to overall survival benefit in ovarian cancer. We tested the hypothesis that cotargeting HER and VEGFR would maximize antitumor efficacy at tolerable doses. To this end, ovarian cancer xenografts grown intraperitoneally in athymic nude mice were tested in response to AC480 (pan-HER inhibitor, "HERi"), cediranib (pan-VEGFR inhibitor "VEGFRi"), or BMS-690514 (combined HER/VEGFR inhibitor "EVRi"). EVRi was superior to both HERi and VEGFRi in terms of tumor growth, final tumor weight, and progression-free survival. Correlative tumor studies employing phosphoproteomic antibody arrays revealed distinct agent-specific alterations, with EVRi inducing the greatest overall effect on growth factor signaling. These data suggest that simultaneous inhibition of HER and VEGFR may benefit select subsets of ovarian cancer tumors. To this end, we derived a novel HER/VEGF signature that correlated with poor overall survival in high-grade, late stage, serous ovarian cancer patient tumors.

Synergistic Chemoimmunotherapy of Epithelial Ovarian Cancer Using ErbB-Retargeted T Cells Combined with Carboplatin

Epithelial ovarian cancer (EOC) remains the most lethal gynecologic malignancy, underscoring the need for better therapies. Adoptive immunotherapy using genetically targeted T cells represents a promising new treatment for hematologic malignancies. However, solid tumors impose additional obstacles, including the lack of suitable targets for safe systemic therapy and the need to achieve effective T cell homing to sites of disease. Because EOC undergoes transcœlomic metastasis, both of these challenges may be circumvented by T cell administration to the peritoneal cavity. In this study, we describe such an immunotherapeutic approach for EOC, in which human T cells were targeted against the extended ErbB family, using a chimeric Ag receptor named T1E28z. T1E28z was coexpressed with a chimeric cytokine receptor named 4αβ (combination termed T4), enabling the selective ex vivo expansion of engineered T cells using IL-4. Unlike control T cells, T4(+) T cells from healthy donors and patients with EOC were activated by and destroyed ErbB(+) EOC tumor cell lines and autologous tumor cultures. In vivo antitumor activity was demonstrated in mice bearing established luciferase-expressing SKOV-3 EOC xenografts. Tumor regression was accompanied by mild toxicity, manifested by weight loss. Although efficacy was transient, therapeutic response could be prolonged by repeated T cell administration. Furthermore, prior treatment with noncytotoxic doses of carboplatin sensitized SKOV-3 tumors to T4 immunotherapy, promoting enhanced disease regression using lower doses of T4(+) T cells. By combining these approaches, we demonstrate that repeated administration of carboplatin followed by T4(+) T cells achieved optimum therapeutic benefit in the absence of significant toxicity, even in mice with advanced tumor burdens.

Regulation of EGFR trafficking and cell signaling by Sprouty2 and MIG6 in lung cancer cells

The duration and specificity of epidermal growth factor receptor (EGFR) activation and signaling are determinants of cellular decision processes and are tightly regulated by receptor dephosphorylation, internalization and degradation. In addition, regulatory proteins that are upregulated or activated post-transcriptionally upon receptor activation may initiate feedback loops that play crucial roles in spatiotemporal regulation of signaling. We examined the roles of Sprouty2 (SPRY2) and mitogen-inducible gene 6 (MIG6), two feedback regulators of EGFR trafficking and signaling, in lung cancer cells with or without EGFR-activating mutations. These mutations are of interest because they confer unusual cellular sensitivity to EGFR inhibition through a mechanism involving an impairment of EGFR endocytosis. We found that the endocytosis of wild-type and mutant EGFR was promoted by SPRY2 knockdown and antagonized by MIG6 knockdown. SPRY2 knockdown also significantly reduced extracellular signal-regulated kinase (ERK) phosphorylation, EGFR expression, and EGFR recycling. In a cell line expressing mutant EGFR, this effect on ERK led to a marked increase in cell death response to EGFR inhibition. The effects of SPRY2 knockdown on EGFR endocytosis and recycling were primarily the result of the concomitant change in EGFR expression, but this was not true for the observed changes in ERK phosphorylation. Thus, our study demonstrates that SPRY2 and MIG6 are important regulators of wild-type and mutant EGFR trafficking and points to an EGFR expression-independent function of SPRY2 in the regulation of ERK activity that may impact cellular sensitivity to EGFR inhibitors, especially in the context of EGFR mutation.

Targeting tyrosine-kinases in ovarian cancer

INTRODUCTION

Epithelial ovarian cancer (EOC) is the leading cause of gynaecologic cancer death. Although in some cases initial treatment is effective, most of the women diagnosed with EOC will probably need medical treatment for their disease. There is a critical need to develop effective new strategies for the management of patients with advanced or recurrent EOC, and targeted therapy with tyrosine kinase inhibitors (TKIs) has continued to be an area of active research and development in this setting.

AREAS COVERED

This review summarises the available evidence on the use of TKIs in the clinical management of women with EOC. This article consists of material obtained via Medline, PubMed and EMBASE literature searches up to March 2013.

EXPERT OPINION

Several Phase I/II and III trials evaluated TKIs in EOC; however, it is difficult to draw conclusions on the efficacy of TKI regimens in these patients. TKIs seem to be better tolerated than conventional chemotherapy with a different toxicity profile. A better understanding of the signalling pathways, the toxicity profiles, the potential pharmacokinetic interactions as well as the identification of predictive biomarkers are needed to better identify a targeted patient population before these agents become part of routine treatment.

Comprehensive genomic profiling of epithelial ovarian cancer by next generation sequencing-based diagnostic assay reveals new routes to targeted therapies

OBJECTIVE

Targeted next generation sequencing (NGS) was evaluated for its ability to identify unanticipated targetable genomic alterations (GA) for patients with relapsed ovarian epithelial carcinoma (OC).

METHODS

DNA sequencing was performed for 3320 exons of 182 cancer-related genes and 37 introns of 14 genes frequently rearranged in cancer on indexed, adaptor ligated, hybridization-captured libraries using DNA isolated from FFPE sections from 48 histologically verified relapsed OC specimens. The original primary tumor was sequenced in 26 (54%) of the cases and recurrent/metastatic tumor site biopsies were sequenced in 22 (46%) of the cases. Actionability was defined as: GA that predict sensitivity or resistance to approved or standard therapies or are inclusion or exclusion criteria for specific experimental therapies in NCI registered clinical trials.

RESULTS

There were 38 (80%) serous, 5 (10%) endometrioid, 3 (6%) clear cell, 1 mucinous (2%) and 1 (2%) undifferentiated carcinomas. 141 GA were identified with an average of 2.9 GA (range 0-8) per tumor, of which 67 were actionable for an average of 1.4 actionable GA per patient (range 0-5). 33/48 (69%) of OC patient samples harbored at least one actionable GA. Most common GA were TP53 (79%); MYC (25%); BRCA1/2 (23%); KRAS (16.6%) and NF1 (14.5%). One tumor featured an ERBB2 point mutation. One of 3 (33%) of clear cell tumors featured cMET amplification validated by both FISH and IHC.

CONCLUSIONS

NGS assessment of therapy resistant OC identifies an unexpectedly high frequency of GA that could influence targeted therapy selection for the disease.

HER2 mediates epidermal growth factor-induced down-regulation of E-cadherin in human ovarian cancer cells

Overexpression of HER2 is correlated with a poor prognosis in many types of human cancers. Due to the interaction between HER2 and other ErbB receptors, HER2 is implicated in the EGF family of ligands-regulated tumor progression. In ovarian cancer, although the relationships between HER2 amplification and patient prognosis remain controversial, the underlying molecular mechanisms of HER2-mediated tumor progression are not fully understood. Our previous studies demonstrated that EGF induces ovarian cancer cell invasion by down-regulating E-cadherin expression through the up-regulation of its transcriptional repressors, Snail and Slug. It has been shown that overexpression of HER2 down-regulates E-cadherin expression in human mammary epithelial cells. However, whether HER2 mediates EGF-induced down-regulation of E-cadherin remains unknown. In this study, we examined the potential role of HER2 in EGF-induced down-regulation of E-cadherin and increased cell invasion. We show that EGF treatment induces the interaction of EGFR with HER2 and increases the activation of HER2 in human ovarian cancer cells; we also show that these effects are diminished by knockdown of EGFR. Importantly, treatment with HER2-specific tyrosine kinase inhibitor, AG825, and HER2 siRNA diminished the up-regulation of Snail and Slug as well as the down-regulation of E-cadherin by EGF. Finally, we also show that EGF-induced cell invasion was attenuated by treatment with HER2 siRNA. This study demonstrates an important role for HER2 in mediating the effects of EGF on Snail, Slug and E-cadherin expression as well as invasiveness in human ovarian cancer cells.

MicroRNA-138 suppresses ovarian cancer cell invasion and metastasis by targeting SOX4 and HIF-1α

Metastasis is the major factor affecting patient survival in ovarian cancer. However, its molecular mechanisms remain unclear. Our study used isogenic pairs of low- and high-invasive ovarian cancer cell lines to demonstrate the downregulation of miRNA-138 in the highly invasive cells, and its functioning as an inhibitor of cell migration and invasion. An orthotopic xenograft mouse model further demonstrated that the expression of miRNA-138 inhibited ovarian cancer metastasis to other organs. Results indicated that miR-138 directly targeted SRY-related high mobility group box 4 (SOX4) and hypoxia-inducible factor-1α (HIF-1α), and overexpression of SOX4 and HIF-1α effectively reversed the miR-138-mediated suppression of cell invasion. Epidermal growth factor receptor acted as the downstream molecule of SOX4 by way of direct transcriptional control, whereas Slug was the downstream molecule of HIF-1α by way of proteasome-mediated degradation. Analysis of human ovarian tumors further revealed downregulation of miR-138 and upregulation of SOX4 in late-stage tumors. Patients with miR-138(low)/SOX(high) signature are predominant in late stage and tend to have malignant phenotypes including lymph nodes metastasis, larger ascites volume and higher tumor grade. Our study demonstrates the role and clinical relevance of miR-138 in ovarian cancer cell invasion and metastasis, providing a potential therapeutic strategy for suppression of ovarian cancer metastasis by targeting SOX4 and HIF-1α pathways.

Palliative systemic therapy for women with recurrent epithelial ovarian cancer: current options

OBJECTIVES

To review the available systemic treatments for women with recurrent ovarian cancer.

METHODS

A literature review was conducted for recurrent ovarian cancer articles in English, including randomized trials, Phase II trials, or reviews.

RESULTS

We discuss the efficacy and toxicity outcomes associated with systemic therapy for platinum-sensitive and platinum-resistant ovarian cancer. Clearly, platinum-based combination systemic therapy shows a prolonged progression-free interval compared with single-agent chemotherapy with a low toxicity profile. No clear superior management strategy exists for platinum-resistant/refractory disease. Novel targeted antiangiogenic agents (eg, bevacizumab), angiopoeitin inhibitors (eg, AMG 386), and poly ADP ribose polymerase inhibitors (eg, olaparib) are reviewed.

CONCLUSION

Although combination platinum-based chemotherapy has shown benefits for women with platinum-sensitive recurrent ovarian cancer, the optimal treatment strategy for those with platinum-resistant or platinum-refractory disease is not clear. Molecular and genetic targeted therapies may provide opportunities for those women with tumor profiles that show sensitivity for specific agents.

Monoclonal antibodies therapies for ovarian cancer

INTRODUCTION

Despite aggressive debulking surgery, intraperitoneal therapies and the use of new drugs for chemotherapy, patients with ovarian cancer (OC) still have poor prognosis and, therefore, new strategies for its management are needed. Molecular-targeted agents can be considered a new option in drug research. Several antigens related to OC have been isolated and they could be potential target of monoclonal antibodies (mAbs); therefore, different mAbs have been developed and are emerging as new potential OC treatments.

AREAS COVERED

This article aims to review the literature on the use of mAbs in the treatment of OC. The purposes of this manuscript are to offer a brief explanation of the mechanisms of action of mAbs and to help readers in understanding the current role of mAbs in the treatment of OC.

EXPERT OPINION

A deeper knowledge of the molecular biology of OC has brought new developments in targeted therapies. Among these therapies, bevacizumab demonstrated the higher clinical efficacy. Further larger trials are needed to better define the role of the other mAbs in OC treatment. There is a strong need to identify and validate robust biomarkers for a more focused patient selection and for tailoring therapies, optimizing dose and assessing response.

Proteomic analysis of temporally stimulated ovarian cancer cells for biomarker discovery

While ovarian cancer remains the most lethal gynecological malignancy in the United States, there are no biomarkers available that are able to predict therapeutic responses to ovarian malignancies. One major hurdle in the identification of useful biomarkers has been the ability to obtain enough ovarian cancer cells from primary tissues diagnosed in the early stages of serous carcinomas, the most deadly subtype of ovarian tumor. In order to detect ovarian cancer in a state of hyperproliferation, we analyzed the implications of molecular signaling cascades in the ovarian cancer cell line OVCAR3 in a temporal manner, using a mass-spectrometry-based proteomics approach. OVCAR3 cells were treated with EGF(1), and the time course of cell progression was monitored based on Akt phosphorylation and growth dynamics. EGF-stimulated Akt phosphorylation was detected at 12 h post-treatment, but an effect on proliferation was not observed until 48 h post-exposure. Growth-stimulated cellular lysates were analyzed for protein profiles between treatment groups and across time points using iTRAQ labeling and mass spectrometry. The protein response to EGF treatment was identified via iTRAQ analysis in EGF-stimulated lysates relative to vehicle-treated specimens across the treatment time course. Validation studies were performed on one of the differentially regulated proteins, lysosomal-associated membrane protein 1 (LAMP-1), in human tissue lysates and ovarian tumor tissue sections. Further, tissue microarray analysis was performed to demarcate LAMP-1 expression across different stages of epithelial ovarian cancers. These data support the use of this approach for the efficient identification of tissue-based markers in tumor development related to specific signaling pathways. LAMP-1 is a promising biomarker for studies of the progression of EGF-stimulated ovarian cancers and might be useful in predicting treatment responses involving tyrosine kinase inhibitors or EGF receptor monoclonal antibodies.

Molecular cytogenetics as a clinical test for prognostic and predictive biomarkers in newly diagnosed ovarian cancer

BACKGROUND

There is a clinical need for routinely available genomic biomarker testing in newly diagnosed ovarian cancer. In the current study we performed molecular cytogenetics using a validated array based comparative genomic hybridization (array CGH) assay to screen for the presence of predictive and prognostic biomarkers in archival diagnostic tissue from ovarian cancer patients. We hypothesized that biomarkers of high-risk disease would be detectable in tumor samples from patients with treatment refractory, advanced disease, and would be detected less frequently in tumor samples from patients with more favorable outcomes. In addition, we predicted that the use of a genome-wide copy number analysis (CNA) testing platform would enable us to identify novel potentially targetable chromosomal alterations of therapeutic significance in a percentage of cases.

METHODS

Formalin-fixed paraffin-embedded tissue (FFPE) tumor bank specimens were retrieved from the initial surgical resection for 18 ovarian cancer patients. Molecular cytogenetics was performed by array CGH for the detection of somatic chromosomal alterations associated with high-risk disease including amplifications of the CCNE1 and HER2 genes. Genomic risk stratification results were correlated with available clinical data. CGH data from each patient's tumor genome was also surveyed for the presence of potentially targetable aberrations. Relevant therapeutic agents and open studies for investigational drugs were reported for each patient.

RESULTS

High-risk genomic alterations were identified in 12/18 (67%) of cases and all patients with high-risk markers had advanced, treatment refractory disease. Three tumors with minimal genomic changes had no high-risk markers and were from patients with Stage I/II disease that had been completely resected and under surveillance for recurrence. Eleven patients (61%) had at least one potentially targetable genomic alteration including CCNE1, HER2, KRAS gene amplifications, and somatic BRCA1 and/or BRCA2 gene deletions. Bi-allelic PTEN gene deletion was detected in one patient's tumor.

CONCLUSIONS

Clinical genomic profiling of ovarian tumors by array CGH augments pathologic grade and stage to help stratify newly diagnosed ovarian cancer into high and low-risk disease. This personalized genomic information can also help guide treatment planning and disease monitoring by identifying novel potentially targetable genomic alterations that can be used by clinicians to choose rational directed therapies for patients with chemo-resistant disease.

Molecular cytogenetics as a clinical test for prognostic and predictive biomarkers in newly diagnosed ovarian cancer

BACKGROUND

There is a clinical need for routinely available genomic biomarker testing in newly diagnosed ovarian cancer. In the current study we performed molecular cytogenetics using a validated array based comparative genomic hybridization (array CGH) assay to screen for the presence of predictive and prognostic biomarkers in archival diagnostic tissue from ovarian cancer patients. We hypothesized that biomarkers of high-risk disease would be detectable in tumor samples from patients with treatment refractory, advanced disease, and would be detected less frequently in tumor samples from patients with more favorable outcomes. In addition, we predicted that the use of a genome-wide copy number analysis (CNA) testing platform would enable us to identify novel potentially targetable chromosomal alterations of therapeutic significance in a percentage of cases.

METHODS

Formalin-fixed paraffin-embedded tissue (FFPE) tumor bank specimens were retrieved from the initial surgical resection for 18 ovarian cancer patients. Molecular cytogenetics was performed by array CGH for the detection of somatic chromosomal alterations associated with high-risk disease including amplifications of the CCNE1 and HER2 genes. Genomic risk stratification results were correlated with available clinical data. CGH data from each patient's tumor genome was also surveyed for the presence of potentially targetable aberrations. Relevant therapeutic agents and open studies for investigational drugs were reported for each patient.

RESULTS

High-risk genomic alterations were identified in 12/18 (67%) of cases and all patients with high-risk markers had advanced, treatment refractory disease. Three tumors with minimal genomic changes had no high-risk markers and were from patients with Stage I/II disease that had been completely resected and under surveillance for recurrence. Eleven patients (61%) had at least one potentially targetable genomic alteration including CCNE1, HER2, KRAS gene amplifications, and somatic BRCA1 and/or BRCA2 gene deletions. Bi-allelic PTEN gene deletion was detected in one patient's tumor.

CONCLUSIONS

Clinical genomic profiling of ovarian tumors by array CGH augments pathologic grade and stage to help stratify newly diagnosed ovarian cancer into high and low-risk disease. This personalized genomic information can also help guide treatment planning and disease monitoring by identifying novel potentially targetable genomic alterations that can be used by clinicians to choose rational directed therapies for patients with chemo-resistant disease.

Establishment of primary cultures from ovarian tumor tissue and ascites fluid

We have refined the technique for isolating and propagating cultures of primary epithelial ovarian cancer (EOC) cells derived from solid tumors and ascites. Both protocols involve a simple yet rapid method for the growth and propagation of EOC tumor and ascites cells in a basal culture medium without the addition of growth factors. Isolation of tumor EOC cells involves the mechanical disruption of the tumor tissue with the help of a cell scraper, while ascites-derived EOC cells are mixed with growth medium and placed directly into culture with very little manipulation. We further describe a partial trypsinization method to eliminate fibroblast contamination from primary EOC cells derived from solid tumors. These methods allow for the direct application of many molecular, cellular, and functional analyses within a few weeks of initial isolation, with the added potential of retrospective analyses of archived cells and tissues. Thus, we have included steps for long-term cryopreservation of early-passage EOC cells. Initial isolation of EOC cells can be completed within 1 h, and primary cells are further expanded in culture for several weeks.

SnoN/SkiL expression is modulated via arsenic trioxide-induced activation of the PI3K/AKT pathway in ovarian cancer cells

SnoN/SkiL (TGFβ regulator) is dysregulated in ovarian cancer, a disease associated with acquired drug-resistance. Arsenic trioxide (As₂O₃, used in treating APL) induces SnoN to oppose the apoptotic response in ovarian cancer cells. We now report that As₂O₃ increases phosphorylation of EGFR/p66ShcA and EGFR degradation. As₂O₃ activates Src(Y416) whose activity (inhibited by PP2) modulates EGFR activation, its interaction with Shc/Grb2, and p-AKT. Inhibition of PI3K reduces SnoN and cell survival. Although EGFR or MAPK1 siRNA did not alter SnoN expression, As₂O₃-induced cleaved PARP was reduced together with increased XIAP. Collectively, As₂O₃ mediates an initial rise in pY-Src(416) to regulate the PI3K/AKT pathway which increases SnoN and cell survival; these early events may counter the cell death response associated with increased pY-EGFR/MAPK activation.

Utilisation of nanoparticle technology in cancer chemoresistance

The implementation of cytotoxic chemotherapeutic drugs in the fight against cancer has played an invariably essential role for minimizing the extent of tumour progression and/or metastases in the patient and thus allowing for longer event free survival periods following chemotherapy. However, such therapeutics are nonspecific and bring with them dose-dependent cumulative adverse effects which can severely exacerbate patient suffering. In addition, the emergence of innate and/or acquired chemoresistance to the exposed cytotoxic agents undoubtedly serves to thwart effective clinical efficacy of chemotherapy in the cancer patient. The advent of nanotechnology has led to the development of a myriad of nanoparticle-based strategies with the specific goal to overcome such therapeutic hurdles in multiple cancer conditions. This paper aims to provide a brief overview and recollection of all the latest advances in the last few years concerning the application of nanoparticle technology to enhance the safe and effective delivery of chemotherapeutic agents to the tumour site, together with providing possible solutions to circumvent cancer chemoresistance in the clinical setting.

Transforming growth factor alpha (TGFα) regulates granulosa cell tumor (GCT) cell proliferation and migration through activation of multiple pathways

Granulosa cell tumors (GCTs) are the most common ovarian estrogen producing tumors, leading to symptoms of excessive estrogen such as endometrial hyperplasia and endometrial adenocarcinoma. These tumors have malignant potential and often recur. The etiology of GCT is unknown. TGFα is a potent mitogen for many different cells. However, its function in GCT initiation, progression and metastasis has not been determined. The present study aims to determine whether TGFα plays a role in the growth of GCT cells. KGN cells, which are derived from an invasive GCT and have many features of normal granulosa cells, were used as the cellular model. Immunohistochemistry, Western blot and RT-PCR results showed that the ErbB family of receptors is expressed in human GCT tissues and GCT cell lines. RT-PCR results also indicated that TGFα and EGF are expressed in the human granulosa cells and the GCT cell lines, suggesting that TGFα might regulate GCT cell function in an autocrine/paracrine manner. TGFα stimulated KGN cell DNA synthesis, cell proliferation, cell viability, cell cycle progression, and cell migration. TGFα rapidly activated EGFR/PI3K/Akt and mTOR pathways, as indicated by rapid phosphorylation of Akt, TSC2, Rictor, mTOR, P70S6K and S6 proteins following TGFα treatment. TGFα also rapidly activated the EGFR/MEK/ERK pathway, and P38 MAPK pathways, as indicated by the rapid phosphorylation of EGFR, MEK, ERK1/2, P38, and CREB after TGFα treatment. Whereas TGFα triggered a transient activation of Akt, it induced a sustained activation of ERK1/2 in KGN cells. Long-term treatment of KGN cells with TGFα resulted in a significant increase in cyclin D2 and a decrease in p27/Kip1, two critical regulators of granulosa cell proliferation and granulosa cell tumorigenesis. In conclusion, TGFα, via multiple signaling pathways, regulates KGN cell proliferation and migration and may play an important role in the growth and metastasis of GCTs.

EGFR mediates LPA-induced proteolytic enzyme expression and ovarian cancer invasion: inhibition by resveratrol

Lysophosphatidic acid (LPA) augments proliferation and metastasis of various cancer cells. We recently identified a critical role of the Rho/ROCK pathway for LPA-induced proteolytic enzyme expression and cancer cell progression. In the present study, we elucidate the underlying mechanisms by which LPA induces Rho activation and subsequent cellular invasion, and the reversal of these effects by resveratrol. We observed that both Gi and G13 contribute to LPA-induced EGFR activation. The activated EGFR in turn initiates a Ras/Rho/ROCK signaling cascade, leading to proteolytic enzyme secretion. Further we provide evidence that resveratrol inhibits EGFR phosphorylation and subsequent activation of a Ras/Rho/ROCK signaling. Therefore, we demonstrate a mechanistic cascade of LPA activating EGFR through Gi and G13 thus inducing a Ras/Rho/ROCK signaling for proteolytic enzyme expression and ovarian cancer cell invasion, as well as interference of the cascade by resveratrol through blocking EGFR phosphorylation.

Increased DNA methyltransferase activity and DNA methylation following Epidermal Growth Factor stimulation in ovarian cancer cells

Ovarian cancer progression is correlated with accumulation of aberrant CpG island methylation. In ovarian cancer, ascites fluid contains numerous Epidermal-Growth-Factor-Receptor (EGFR) activators, which could result in a tumor microenvironment of constant EGFR activation. Signaling pathways downstream of EGFR, such as Ras, regulate DNA methylation. We hypothesized that chronic EGFR activation could alter DNA methylation. We found that EGFR activation increased DNA methyltransferase (DNMT) activity acutely, as well as after long-term EGF treatment or expression of a mutationally activated EGFR. Furthermore, this increase in DNMT activity was dependent on EGFR catalytic activity and resulted in increased global DNA methylation. Additionally, treatment with the DNMT inhibitor/hypomethylating agent 5-Aza-2'-deoxycytidine (AZA) inhibited the EGF induced increase of both DNMT activity and global methylation. These data support a role for EGFR in the process of accumulated DNA methylation during ovarian cancer progression and suggest that epigenetic therapy may be beneficial for the treatment of ovarian cancer.

Targeting angiogenesis in gynecologic cancers

Gynecologic malignancies carry an estimated incidence of 83,750 cases per year and estimated mortality rate of more than 27,000 women per year. New therapies and therapeutic approaches are needed to improve the outlook for women with gynecologic cancers. Recent insights at the molecular and cellular levels are paving the way for a more directed approach to target mechanisms driving tumorigenesis. This article reviews the roles of new and emerging antiangiogenesis drugs, summarizes the data obtained from clinical trials of antiangiogenic agents, and discusses trials under way to address the role of such strategies in gynecologic cancers.

Strain tunes proteolytic degradation and diffusive transport in fibrin networks

Proteolytic degradation of fibrin, the major structural component in blood clots, is critical both during normal wound healing and in the treatment of ischemic stroke and myocardial infarction. Fibrin-containing clots experience substantial strain due to platelet contraction, fluid shear, and mechanical stress at the wound site. However, little is understood about how mechanical forces may influence fibrin dissolution. We used video microscopy to image strained fibrin clots as they were degraded by plasmin, a major fibrinolytic enzyme. Applied strain causes up to 10-fold reduction in the rate of fibrin degradation. Analysis of our data supports a quantitative model in which the decrease in fibrin proteolysis rates with strain stems from slower transport of plasmin into the clot. We performed fluorescence recovery after photobleaching (FRAP) measurements to further probe the effect of strain on diffusive transport. We find that diffusivity perpendicular to the strain axis decreases with increasing strain, while diffusivity along the strain axis remains unchanged. Our results suggest that the properties of the fibrin network have evolved to protect mechanically loaded fibrin from degradation, consistent with its function in wound healing. The pronounced effect of strain upon diffusivity and proteolytic susceptibility within fibrin networks offers a potentially useful means of guiding cell growth and morphology in fibrin-based biomaterials.

Optimizing molecular-targeted therapies in ovarian cancer: the renewed surge of interest in ovarian cancer biomarkers and cell signaling pathways

The hallmarks of ovarian cancer encompass the development of resistance, disease recurrence and poor prognosis. Ovarian cancer cells express gene signatures which pose significant challenges for cancer drug development, therapeutics, prevention and management. Despite enhancements in contemporary tumor debulking surgery, tentative combination regimens and abdominal radiation which can achieve beneficial response rates, the majority of ovarian cancer patients not only experience adverse effects, but also eventually relapse. Therefore, additional therapeutic possibilities need to be explored to minimize adverse events and prolong progression-free and overall response rates in ovarian cancer patients. Currently, a revival in cancer drug discovery is devoted to identifying diagnostic and prognostic ovarian cancer biomarkers. However, the sensitivity and reliability of such biomarkers may be complicated by mutations in the BRCA1 or BRCA2 genes, diverse genetic risk factors, unidentified initiation and progression elements, molecular tumor heterogeneity and disease staging. There is thus a dire need to expand existing ovarian cancer therapies with broad-spectrum and individualized molecular targeted approaches. The aim of this review is to profile recent developments in our understanding of the interrelationships among selected ovarian tumor biomarkers, heterogeneous expression signatures and related molecular signal transduction pathways, and their translation into more efficacious targeted treatment rationales.

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

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