Angiogenesis in normal and neoplastic ovaries

Inhibition of tumor growth and metastasis by a self-therapeutic nanoparticle

Although biomedical applications of nanotechnology, which typically involve functionalized nanoparticles, have taken significant strides, biological characterization of unmodified nanoparticles remains underinvestigated. Herein we demonstrate that unmodified gold nanoparticles (AuNPs) inhibit the proliferation of cancer cells in a size- and concentration-dependent manner by abrogating MAPK-signaling. In addition, these AuNPs reverse epithelial-mesenchymal transition (EMT) in cancer cells by reducing secretion of a number of proteins involved in EMT, up-regulating E-Cadherin, and down-regulating Snail, N-Cadherin, and Vimentin. Inhibition of MAPK signaling and reversal of EMT upon AuNP treatment inhibits tumor growth and metastasis in two separate orthotopic models of ovarian cancer. Western blot analyses of tumor tissues reveal up-regulation of E-Cadherin and down-regulation of Snail and phospho-MAPK, confirming the reversal of EMT and inhibition of MAPK signaling upon AuNP treatment. The ability of a single self-therapeutic nanoparticle to abrogate signaling cascades of multiple growth factors is distinctive and purports possible medical applications as potential antitumor and antimetastatic agent.

Enhancement of ovarian malignancy on clinical contrast enhanced MRI studies

Purpose. To assess if there is a significant difference in enhancement of high grade serous carcinoma of the ovary compared with other ovarian malignancies on clinically performed contrast enhanced MRI studies. Methods. In this institutional-review–board-approved study, two radiologists reviewed contrast enhanced MRI scans in 37 patients with ovarian cancer. Readers measured the signal intensity (SI) of ovarian mass and gluteal fat pre- and postcontrast administration. Percentage enhancement (PE) was calculated as [(post-pre)/precontrast SI] × 100. Results. Pathology revealed 19 patients with unilateral and 18 patients with bilateral malignancies for a total of 55 malignant ovaries-high grade serous carcinoma in 25/55 ovaries (45%), other epithelial carcinomas in 12 ovaries (22%), nonepithelial cancers in 8 ovaries (14%), and borderline tumors in 10 ovaries (18%). Enhancement of high grade serous carcinoma was not significantly different from other invasive ovarian malignancies (Reader 1 P = 0.865; Reader 2 P = 0.353). Enhancement of invasive ovarian malignancies was more than borderline tumors but did not reach statistical significance (Reader 1P = 0.102; Reader 2 P = 0.072). Conclusion. On clinically performed contrast enhanced MRI studies, enhancement of high grade serous ovarian carcinoma is not significantly different from other ovarian malignancies.

Investigational agents in development for the treatment of ovarian cancer

Although significant success has been achieved in the treatment of advanced and recurrent ovarian cancer, there is clearly room for improvement. The use of targeted agents in this patient population has the promise to provide improved survival and quality of life. There are a myriad of relevant pathways under exploration in all settings of ovarian cancer. Clinical trial data are accumulating for antiangiogenic therapy, including vascular endothelial growth factor (VEGF)-specific inhibitors and multiple angiogenic signaling target inhibitors, as well as poly-ADP-ribose polymerase (PARP) inhibitors. Other types of tumorigenic pathway inhibitors, including those that target phosphatidylinositol-3-kinase (PI3K), mammalian target of rapamycin (mTOR), protein kinase B (AKT), Src, folate receptor alpha, and insulin-like growth factor-1 receptor (IGF-1R) pathways are in earlier phases of development for ovarian cancer. Attempts to target the epidermal growth factor receptor (EGFR) of ovarian tumors have been met with limited success; however, newer agents that inhibit this pathway show promise. Finally, with recognition of the role of Wee-1 in p53-deficient tumors, an inhibitor of this tyrosine kinase is being evaluated in recurrent ovarian cancer. The logistical challenge is to determine the optimal timing and proper combinations of novel agents independently as well as concomitantly with conventional chemotherapeutics. Reported results have been modest; however, our growing understanding of these pathways will be potentially reflected in greater impact on response and survival.

Antiangiogenic agents as a maintenance strategy for advanced epithelial ovarian cancer

Bevacizumab is the first antiangiogenic agent to have demonstrated benefit as first-line and maintenance therapy in epithelial ovarian cancer (EOC), with the Gynecologic Oncology Group 218 and ICON 7 phase III trials revealing significantly prolonged progression-free survival (PFS) for carboplatin/paclitaxel plus bevacizumab followed by bevacizumab maintenance versus carboplatin/paclitaxel alone. Results are forthcoming from several phase III maintenance trials of investigational antiangiogenic agents, each evaluating PFS as the primary endpoint: AGO-OVAR12/LUME-Ovar1 (nintedanib [BIBF 1120]), AGO-OVAR16 (pazopanib), and TRINOVA-1, -2, and -3 (AMG 386). Here we review available data and ongoing clinical trials of investigational antiangiogenic agents as maintenance therapy for EOC. Current controversies, including uncertainties regarding the (1) most appropriate clinical trial endpoints, (2) optimal dosing, duration, and timing of therapy (e.g., with first-line chemotherapy and/or as maintenance monotherapy), and (3) feasibility, tolerability, and cost of adding these agents to platinum/taxane regimens are also highlighted.

Novel Antiangiogenic Therapies in Ovarian Cancer

Epithelial ovarian cancer is the leading cause of death in the developed world for women with gynecologic carcinomas. Despite the effectiveness of platinum salts and taxanes as primary treatments, approximately 80% of women will recur and for them prognosis with available treatments is poor. Of the novel mechanisms under active investigation, there is ample evidence to indicate that angiogenesis is important to the development, progression and poor prognosis of ovarian cancer. Novel treatments are therefore required. A number of agents are undergoing evaluation, including vascular disrupting agents, angiogenesis inhibitors, tyrosine kinase inhibitors and agents targeting the folate receptor. At present, Phase III data are only available for the VEGF-targeted monoclonal antibody, bevacizumab, and that has demonstrated a progression-free survival benefit when used in combination with first-line paclitaxel/carboplatin and continued as maintenance therapy. The strategy of inhibiting angiogenesis in ovarian cancer remains promising. However, other agents in development may point to other important targets in ovarian cancer.

Significance of vascular endothelial growth factor in growth and peritoneal dissemination of ovarian cancer

Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis which drives endothelial cell survival, proliferation, and migration while increasing vascular permeability. Playing an important role in the physiology of normal ovaries, VEGF has also been implicated in the pathogenesis of ovarian cancer. Essentially by promoting tumor angiogenesis and enhancing vascular permeability, VEGF contributes to the development of peritoneal carcinomatosis associated with malignant ascites formation, the characteristic feature of advanced ovarian cancer at diagnosis. In both experimental and clinical studies, VEGF levels have been inversely correlated with survival. Moreover, VEGF inhibition has been shown to inhibit tumor growth and ascites production and to suppress tumor invasion and metastasis. These findings have laid the basis for the clinical evaluation of agents targeting VEGF signaling pathway in patients with ovarian cancer. In this review, we will focus on VEGF involvement in the pathophysiology of ovarian cancer and its contribution to the disease progression and dissemination.

Turning promise into progress for antiangiogenic agents in epithelial ovarian cancer

Despite efforts to improve chemotherapeutic efficacy in epithelial ovarian cancer, outcome for patients with advanced disease has remained unchanged since the introduction of standard carboplatin and paclitaxel. Interest has therefore shifted toward molecularly targeted therapies that interfere with important features of ovarian carcinogenesis, such as angiogenesis. Several angiogenesis inhibitors, targeting vascular endothelial growth factor (VEGF) ligands (bevacizumab, VEGF-Trap) or their receptors (VEGFR-targeted tyrosine kinase inhibitors) have been clinically evaluated. These agents demonstrated efficacy in phase II clinical trials. Results from phase III trials, in which bevacizumab was added to standard frontline chemotherapy, show a modest effect. Although the initial expectations for angiogenesis inhibitors have been tempered, further research is warranted to define their precise place in the treatment of ovarian cancer. This review summarizes the performed and ongoing studies with regard to angiogenesis inhibitors in ovarian cancer, and the available data on biomarkers for response prediction. Preclinical studies evaluating alternative angiogenesis inhibitors will also be discussed.

Association of interleukin 16 with the development of ovarian tumor and tumor-associated neoangiogenesis in laying hen model of spontaneous ovarian cancer

OBJECTIVE

Tumor-associated neoangiogenesis (TAN) is an early event in ovarian tumor development. Interleukin 16 (IL-16) is a proangiogenic cytokine that stimulates production of neoangiogenic factors. The goal of this study was to determine the association of IL-16 with tumor development and ovarian TAN in laying hens, an animal model of spontaneous ovarian cancer (OVCA).

METHODS

Sera and ovarian tissues from 3-year-old laying hens were collected and processed for histopathologic, immunoassay, immunohistochemistry, immunoblotting, and molecular biological studies to determine the tissue expression and serum levels of IL-16. Samples were divided into 3 groups based on the diagnosis of the histopathologic ovarian tissue examination, namely, normal (healthy control, n = 81), early (n = 23 including 11 with microscopic OVCA), and late stages (n = 16) of OVCA.

RESULTS

Serum levels of IL-16 were significantly higher in hens with microscopic, early, and late stages of OVCA than normal hens (P < 0.0001). The frequencies of IL-16 cells in tumor-bearing ovaries were significantly higher than normal hens (P < 0.05). The expression of IL-16 protein and mRNA were stronger in tumor-bearing ovaries than normal ovaries. In addition to ovarian stroma, IL-16 was also expressed by the epithelial cells of the tumor in OVCA hens. Differences in serum levels and ovarian IL-16 expression were not significant among different histological subtypes of OVCA including serous, endometrioid, and mucinous. Similar to the serum levels and ovarian expression of IL-16, the densities of neoangiogenic microvessels were significantly higher in hens with tumor-bearing ovaries than normal hens.

CONCLUSIONS

The results of the study suggest that changes in serum levels of IL-16 are associated with tumor development and TAN. Thus, serum IL-16 levels may be an indicator of ovarian TAN at the early stage of OVCA.

Anti-angiogenic agents in ovarian cancer: dawn of a new era?

Epithelial ovarian cancer is a leading cause of cancer-related death for women both in the United States and worldwide, and the effectiveness of cytotoxic chemotherapy has plateaued. Angiogenesis plays an important role in ovarian cancer biology, and exploration of anti-angiogenic agents in this disease has demonstrated anti-tumor activity both as monotherapy and in combination with cytotoxic chemotherapy. However, key questions remain regarding the use of these drugs in ovarian cancer, such as where in treatment should they be used, should these drugs be used as single agents or combined with chemotherapy, can and which biomarkers predict efficacy, are there efficacy and toxicity differences amongst the various agents, what are the cost-benefit ratios of these therapies, and are the patient outcome improvements observed in completed studies significant enough to warrant widespread use of these drugs? Here, we review recent progress and discuss ongoing controversies regarding the use of anti-angiogenic therapies in ovarian cancer.

Inhibition of ovarian cancer by RGD-P125A-endostatin-Fc fusion proteins

Previous studies have shown that a single point mutation in endostatin at position 125 (P125A) can improve the biological activity of endostatin. Addition of an integrin-targeting moiety, R-G-D, resulted in better localization to tumor vasculature and improved the antiangiogenic activity of endostatin. Because endostatin has relatively shorter serum half-life, frequent dosing was required for inhibiting tumor growth. In our study, we have genetically fused RGD-P125A-endostatin to Fc of IgG4 isotype and evaluated its antiangiogenic and antitumor effects in athymic mice. Two genetic constructs were made, RGD-P125A-endostatin-Fc (RE-Fc) and P125A-endostatin-RGD-Fc (ER-Fc). Both constructs were cloned and expressed in mammalian cells. Purified fusion proteins inhibited endothelial cell migration and proliferation better than yeast-derived P125A-endostatin. Both RE-Fc and ER-Fc inhibited ovarian cancer growth and were found to be as effective as Bevacizumab treatment. Fusion protein showed marked increased half-life. Combination treatment with Bevacizumab and ER-Fc showed additive inhibition of ovarian cancer growth. These studies demonstrate that genetic fusion with human IgG4-Fc increases the half-life of P125A-endostatin and can be used along with Bevacizumab to improve antiangiogenic and antitumor activities.

Contrast-enhanced sonography depicts spontaneous ovarian cancer at early stages in a preclinical animal model

OBJECTIVE

Our goal was to examine the feasibility of using laying hens, a preclinical model of human spontaneous ovarian cancer, in determining the kinetics of an ultrasound contrast agent indicative of ovarian tumor-associated neoangiogenesis in early-stage ovarian cancer.

METHODS

Three-year-old White Leghorn laying hens with decreased ovarian function were scanned before and after intravenous injection of a human serum albumin-perflutren contrast agent at a dose of 5 μL/kg body weight. Gray scale morphologic characteristics, Doppler indices, the arrival time, peak intensity, and wash-out of the contrast agent were recorded and archived on still images and video clips. Hens were euthanized thereafter; sonographic predictions were compared at gross examination; and ovarian tissues were collected. Archived clips were analyzed to determine contrast parameters and Doppler intensities of vessels. A time-intensity curve per hen was drawn, and the area under the curve was derived. Tumor types and the density of ovarian microvessels were determined by histologic examination and immunohistochemistry and compared to sonographic predictions.

RESULTS

The contrast agent significantly (P < .05) enhanced the visualization of microvessels, which was confirmed by immunohistochemistry. Contrast parameters, including the time of wash-out and area under the curve, were significantly different (P < .05) between ovaries of normal hens and hens with ovarian cancer and correctly detected cancer at earlier stages than the time of peak intensity.

CONCLUSIONS

The laying hen may be a useful animal model for determining ovarian tumor-associated vascular kinetics diagnostic of early-stage ovarian cancer using a contrast agent. This model may also be useful for testing the efficacy of different contrast agents in a preclinical setting.

Overview of anti-angiogenic agents in development for ovarian cancer

OBJECTIVE

To review the rationale for targeting the vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and fibroblast growth factor (FGF) pathways for anti-angiogenic therapy in patients with ovarian cancer and to summarize the currently available data with agents that block these pathways.

METHODS

Relevant papers and studies were identified by searches conducted on Medline using the terms angiogenesis, ovarian cancer, VEGF, PDGF, FGF, receptor, kinase, and inhibitor alone or in combination as well as by searches by drug name and by review of abstracts presented at recent oncology meetings.

RESULTS

The VEGF pathway is considered to be the key driver of angiogenesis, but the PDGF and FGF pathways also play important roles and may contribute to resistance to VEGF-specific blockade. Each pathway may also promote tumorigenesis; tumor cell overexpression of these growth factors and their receptors have been detected in ovarian tumor specimens, suggesting that autocrine loops may lead to tumor growth and progression. Selective inhibitors of the VEGF pathway (e.g., bevacizumab and VEGF Trap) as well as VEGF/PDGF pathway inhibitors (e.g., sorafenib and sunitinib) and VEGF/PDGF/FGF pathway inhibitors (e.g., cediranib, pazopanib, and BIBF 1120) have shown single-agent activity in women with ovarian cancer in phase II trials. Response rates of up to 21% have been reported with several agents in patients with recurrent ovarian cancer. Phase III trials with many anti-angiogenic agents in the treatment of ovarian cancer are currently ongoing.

CONCLUSIONS

Anti-angiogenic agents may provide an improvement in the treatment of patients with recurrent ovarian cancer and may be useful when incorporated into first-line platinum/taxane therapy. It remains to be determined whether multitargeted agents will offer greater clinical benefit than specific VEGF pathway inhibitors.

Antiangiogenic Therapies in Epithelial Ovarian Cancer

Background

Angiogenesis is a critical component of tumor development and proliferation, and increased angiogenesis has been associated with a worse clinical outcome in a number of solid tumors, including ovarian cancer. Therefore, agents that target the angiogenic process are of considerable interest in the treatment of ovarian cancer.

Methods

Studies evaluating the efficacy of antiangiogenic agents in ovarian cancer are reported. Antiangiogenic agents examined include vascular endothelial growth factor (VEGF) pathway inhibitors, including monoclonal antibodies, tyrosine kinase inhibitors (TKIs), and a soluble receptor decoy, as well as inhibitors of other angiogenic factors and vascular disrupting agents.

Results

The VEGF inhibitor bevacizumab has been shown to have efficacy in ovarian cancer in phase II trials and a progression-free survival advantage in one phase III trial. TKIs block the VEGF receptors and secondary angiogenic pathways and have shown activity in phase I and II trials. Alternative angiogenesis inhibitors include EphA2 inhibitors and a selective angiopoietin 1/2-neutralizing peptibody. Another strategy is to destroy the existing tumor vasculature, and a number of vascular disrupting agents are being studied in preclinical and phase I trials. Antiangiogenic agents have a unique side effect profile, likely due to inhibition of normal physiologic angiogenesis.

Conclusions

Phase II and early phase III trials have demonstrated that antiangiogenic therapies have significant activity in ovarian cancer. The results of phase III trials in the front-line and recurrent settings will determine the extent of clinical benefit of antiangiogenic therapies in combination with chemotherapy. Antiangiogenic agents have a distinct side effect profile, and further studies are necessary to evaluate how to minimize the incidence of these events and to identify women most likely to benefit from these therapies.

Evaluation of vascular endothelial growth factor as a prognostic marker for local relapse in early-stage breast cancer patients treated with breast-conserving therapy

PURPOSE

Vascular endothelial growth factor (VEGF) is an important protein involved in the process of angiogenesis that has been found to correlate with relapse-free and overall survival in breast cancer, predominantly in locally advanced and metastatic disease. A paucity of data is available on the prognostic implications of VEGF in early-stage breast cancer; specifically, its prognostic value for local relapse after breast-conserving therapy (BCT) is largely unknown. The purpose of our study was to assess VEGF expression in a cohort of early-stage breast cancer patients treated with BCT and to correlate the clinical and pathologic features and outcomes with overexpression of VEGF.

METHODS AND MATERIALS

After obtaining institutional review board approval, the paraffin specimens of 368 patients with early-stage breast cancer treated with BCT between 1975 and 2005 were constructed into tissue microarrays with twofold redundancy. The tissue microarrays were stained for VEGF and read by a trained pathologist, who was unaware of the clinical details, as positive or negative according the standard guidelines. The clinical and pathologic data, long-term outcomes, and results of VEGF staining were analyzed.

RESULTS

The median follow-up for the entire cohort was 6.5 years. VEGF expression was positive in 56 (15%) of the 368 patients. Although VEGF expression did not correlate with age at diagnosis, tumor size, nodal status, histologic type, family history, estrogen receptor/progesterone receptor status, or HER-2 status, a trend was seen toward increased VEGF expression in the black cohort (26% black vs. 13% white, p=.068). Within the margin-negative cohort, VEGF did not predict for local relapse-free survival (RFS) (96% vs. 95%), nodal RFS (100% vs. 100%), distant metastasis-free survival (91% vs. 92%), overall survival (92% vs. 97%), respectively (all p>.05). Subset analysis revealed that VEGF was highly predictive of local RFS in node-positive, margin-negative patients (86% vs. 100%, p=.029) on univariate analysis, but it did not retain its significance on multivariate analysis (hazard ratio, 2.52; 95% confidence interval, 0.804-7.920, p=.113). No other subgroups were identified in which a correlation was found between VEGF expression and local relapse.

CONCLUSION

To our knowledge, our study is the first to assess the prognostic value of VEGF with the endpoint of local relapse in early-stage breast cancer treated with BCT, an important question given the recent increased use of targeted antiangiogenic agents in early-stage breast cancer. Our study results suggest that VEGF is not an independent predictor of local RFS after BCT, but additional, larger studies specifically analyzing the endpoint of VEGF and local relapse are warranted.

Epithelial ovarian cancer: focus on targeted therapy

Ovarian cancer remains the leading cause of gynecological cancer-related mortality in the Western World despite the advances in surgical techniques and chemotherapy regimens over the past three decades. Although response rates and complete responses in advanced disease are >80% and 40-60%, respectively, after first-line treatment with carboplatin and paclitaxel, most of the patients will eventually relapse with a median progression-free survival of 18 months. Currently, research efforts have improved our understanding on the molecular biology of ovarian cancer and novel targeted treatment strategies are likely to contribute to the management of the disease and give the chance to an individualized therapeutic approach.

Detection of tumor-associated neoangiogenesis by Doppler ultrasonography during early-stage ovarian cancer in laying hens: a preclinical model of human spontaneous ovarian cancer

OBJECTIVE

Tumor-associated neoangiogenesis (TAN) is one of the earliest events in ovarian tumor growth and represents a potential target for early detection of ovarian cancer (OVCA). Because it is difficult to identify patients with early-stage OVCA, the goal of this study was to explore a spontaneous animal model of in vivo ovarian TAN associated with early-stage OVCA detectable by Doppler ultrasonography (DUS).

METHODS

White Leghorn laying hens were scanned transvaginally at 15-week intervals up to 45 weeks. Gray scale ovarian morphologic characteristics and Doppler indices were recorded. Hens were euthanized at diagnosis for ultrasonographic morphologic/vascular abnormalities or at the end of the study (those that remained normal). Ovarian morphologic and histologic characteristics were evaluated. Vascular endothelial growth factor (VEGF) and alpha(v)beta(3)-integrin expression was assessed by immunohistochemical analysis. Doppler ultrasonographic observations were compared with histologic and immunohisto-chemical findings to determine the ability of DUS to detect ovarian TAN.

RESULTS

Significant changes in ovarian blood flow parameters were observed during transformation from normal to tumor development in the ovary (P < .05). Tumor-related changes in ovarian vascularity were identified by DUS before the tumor became detectable by gray scale imaging. Increased expression of VEGF and alpha(v)beta(3)-integrins was associated with tumor development. Ovarian TAN preceded tumor progression in hens.

CONCLUSIONS

The results suggest that ovarian TAN may be an effective target for the detection of early-stage OVCA. The laying hen may also be useful for studying the detection and inhibition of ovarian TAN using various means, including the efficacy of contrast agents, targeted molecular imaging, and antiangiogenic therapies.

Angiogenesis and ovarian cancer

Ovarian carcinoma is the most important cause of gynaecological cancer-related mortality in Western societies. The age at diagnosis, extent of disease (as expressed by FIGO state), success of primary surgery and the histopathological features of the tumour are important prognostic markers. The majority of patients with ovarian cancer present with advanced disease (FIGO stage III/IV) and in this group of patients the median survival is only three years. New treatment approaches are therefore required to improve outcome in this disease. Angiogenesis, the development of a neovascular blood supply, is a critical step in the propagation of malignant tumour growth and metastasis and represents a promising target. This review will focus on angiogenesis, VEGF biology and the potential value of angiogenic factors with prognostic value in ovarian cancer.

Antiangiogenic drugs in ovarian cancer

BACKGROUND

There is a critical need to develop effective new strategies for the management of patients with advanced epithelial ovarian cancer.

OBJECTIVE

The purpose of this manuscript is to discuss the rationale for, and initial clinical results of, attempts to interfere with the process of tumor angiogenesis as a novel treatment paradigm in ovarian cancer.

RESULTS/CONCLUSION

Phase II clinical trial data provide strong support for the suggestion that antiangiogenic agents have the potential to play a major therapeutic role in this difficult malignancy. It is reasonable to acknowledge that the pending results of several ongoing evidence-based randomized Phase III trials that directly explore the clinical utility of this strategy may substantially alter the current standard management approaches in advanced ovarian cancer.

Stanniocalcin, a potential ovarian angiogenesis regulator, does not affect endothelial cell apoptosis

The ovarian follicle represents an outstanding model for the investigation of the angiogenic process. In fact, follicular development is associated with an extensive neovascularization, and physiological angiogenesis is necessary for folliculogenesis. However, although the major factors triggering the angiogenic events have been thoroughly investigated and are now relatively well defined, information about the molecular events involved in the modulation and/or arrest of neovascularization is still scarce. Therefore, this research focused on the potential involvement of stanniocalcin (STC), a protein whose biological function is still unclear, in the control mechanisms of follicular angiogenesis. We evaluated the effect of 5 and 50 ng/mL STC on the production of the main proangiogenic factor, vascular endothelial growth factor (VEGF), by swine granulosa cells. Moreover, STC's effect on cell viability and the modulation of caspase-3 and -7 activities in swine aortic endothelial cells were also examined. Granulosa cell VEGF production was significantly (P < 0.001) inhibited by STC. Endothelial cell viability was significantly (P < 0.001) increased, whereas caspase activities were reduced (P < 0.01) by STC. These data indicate that STC is not angiosuppressive for endothelial cells, although it could potentially modulate local angiogenesis acting at the granulosa cell level.

Nuclear expression of Snail1 in borderline and malignant epithelial ovarian tumours is associated with tumour progression

Background

Transcription factor Snail1 has a central role in induction of epithelial-mesenchymal transition (EMT). The aim of the present study was to elucidate the expression of Snail1 protein during epithelial ovarian tumourigenesis and to study the association of Snail1 expression with clinicopathological factors and prognosis.

Methods

Epithelial and stromal fibroblast-like fusiform cells of 14 normal ovarian samples, 21 benign, 24 borderline and 74 malignant epithelial ovarian tumours were studied for Snail1 protein using immunohistochemistry.

Results

Nuclei of surface peritoneal cells of normal ovaries (n = 14) were regarded as negative for Snail1. Nuclear expression of Snail1 protein in epithelial ovarian tumours was increased during tumour progression from precursor lesions into carcinomas both in epithelial (p = 0.006) and stromal cells (p = 0.007). Nuclei of benign tumours (n = 21) were negative for Snail1. In borderline tumours (n = 24) occasional positive epithelial cells were found in 2 (8%) samples and in 3 (13%) samples stromal cells were focally positive for Snail1. In carcinomas (n = 74) focal Snail1 staining in epithelial cells was present in 17 (23%) tumours, and in stromal cells in 18 (24%) tumours. Nuclear expression of Snail1 in epithelial or stromal cells was not associated with clinicopathological factors or prognosis.

Conclusion

Nuclear Snail1 expression seems to be related to tumour progression, and expression in borderline tumours indicates a role for Snail1 in early epithelial ovarian tumour development. Snail1 also appears to function more generally in tissue remodelling as positive staining was demonstrated in stromal cells.

The level of RCAS1 expression is inversely correlated with the number of vimentin-positive stromal cells in epithelial ovarian cancer

Expression of RCAS1 is significantly associated with clinical prognosis in 15 different types of human cancer. We have previously reported that RCAS1 expression is correlated with a decreasing number of vimentin-positive stromal cells in cervical cancer. Moreover, RCAS1 expression is related to the expression of matrix metalloprotease 1 and laminin 5 and angiogenesis. We examined whether RCAS1 contributes to connective tissue remodeling in epithelial ovarian cancer. RCAS1 expression was studied retrospectively via immunohistochemistry. Samples were obtained from resected tumor tissues from 65 patients with epithelial ovarian cancer. Statistical analysis was done to correlate RCAS1 expression and clinicopathologic variables. The associations between RCAS1 expression and the number of vimentin-positive cells or microvessel density were evaluated. Western blot analysis was also performed to verify the perturbation of vimentin expression in fibroblast L cells, following stimulation by soluble RCAS1. RCAS1 expression was detected in 72.3% (47/65 total cases) and significantly correlated with age and histological subtype. Patients with advanced stage, positive lymph node metastasis, or positive peritoneal cytological results had significantly shorter overall survival rates; however, no significant relationship was detected between RCAS1 immunoreactivity and overall survival. In the connective tissue surrounding tumor cells, the number of cells expressing vimentin significantly decreased in relation to the RCAS1 expression level. The growth of L cells was suppressed after stimulation by soluble RCAS1, and the expression of vimentin was markedly diminished. RCAS1 may contribute to connective tissue remodeling by altering the number of vimentin-positive cells in epithelial ovarian cancer.

Beyond chemotherapy: targeted therapies in ovarian cancer

Ovarian cancer is the leading cause of death from gynaecological malignancies in the Western world. Despite the evolution of surgical techniques and meticulously designed chemotherapy regimens, relapse remains almost inevitable in patients with advanced disease. In an age when great advances have been made in understanding the genetics and molecular biology of this heterogeneous disease, it is likely that the introduction of novel targeted therapies will have a major impact on the management of ovarian cancer. Importantly, such strategies might allow selection of treatments based on the molecular characteristics of tumours and bring us closer to an era of personalized medicine.

Antiangiogenic drugs in ovarian cancer

Ovarian cancer continues to be a major cause of morbidity and mortality in women. Antiangiogenic treatments have emerged as a promising strategy to treat ovarian cancer. This article reviews the rationale supporting the use of antiangiogenic treatments in ovarian cancer, the clinical development of this group of drugs and the toxicities specific to this modality of treatment.

Development of antiangiogenic agents for ovarian cancer

Epithelial ovarian cancer (EOC) remains a major source of cancer morbidity and mortality, despite advances in surgical and chemotherapeutic management. The molecular pathways that control angiogenesis have been demonstrated to be key to the pathogenesis of EOC, and have been shown to have prognostic significance. Increased understanding of the pathways and molecules involved in angiogenesis has allowed the identification of a number of targets for antiangiogenic therapies and the development of a variety of antiangiogenic drugs. There is now significant preclinical evidence, and a growing body of clinical data, demonstrating promising results with antiangiogenic drugs in the treatment of EOC. Single-agent VEGF inhibitor response rates in pretreated patients of between 15 and 20% have been reported, with much higher response rates when used in combination with chemotherapeutic agents. These benefits, however, must be balanced with the toxicities associated with these drugs, particularly the more serious ones, such as gastrointestinal perforation. The results of ongoing and future randomized clinical trials will confirm if, and how, antiangiogenic therapies should be integrated into the routine management of EOC. However, critical issues, such as the relative importance of combination remission induction regimens and maintenance therapy, remain poorly defined.

Novel Approaches in Advancing the Treatment of Epithelial Ovarian Cancer: The Role of Angiogenesis Inhibition

Despite an aggressive approach of surgical cytoreduction and adjuvant combination chemotherapy, ovarian cancer mortality remains a significant problem. We are entering a new era of cancer therapeutics in which targeted therapies offer the potential for improvement in long-term disease control with fewer toxicities. The greatest success of targeted therapy to date in the setting of epithelial ovarian carcinoma has come from angiogenesis inhibition. This review will focus on the role of angiogenesis in normal ovarian function as well as in ovarian carcinoma development and disease progression. Current knowledge about the molecular pathways involved in angiogenesis and various approaches to angiogenesis inhibition in the treatment of ovarian cancer are discussed. Current data regarding the role of bevacizumab and other novel agents in the treatment of ovarian carcinoma are summarized.

Modulation of angiogenic phenotype alters tumorigenicity in rat ovarian epithelial cells

Vascular endothelial growth factor (VEGF) expression correlates with microvessel density, stage, malignant ascites, metastasis, and survival in ovarian cancer. By transducing VEGF165 into a nontumorigenic rat ovarian surface epithelial cell line (ROSE199), we investigated the direct effect of an angiogenic phenotype on tumor development. The neu oncogene, which is overexpressed in >30% of ovarian cancers, was used in comparison. Neu-transfected ROSE199 cells showed phenotypic characteristics of transformation in vitro with an abundance of focus-forming units in monolayer cultures and anchorage-independent growth in soft agar. In contrast, VEGF-secreting ROSE199 cells (VR) retained normal morphology and in vitro growth characteristics (e.g., proliferation rate) compared with parental ROSE199 cells. Interestingly, injection of VR cells into athymic mice formed malignant ascites in 100% of the animals when injected into the peritoneum and developed vascularized tumors in 85% of the mice when injected s.c. Furthermore, blocking VEGF-mediated signaling by the Flk-1/KDR receptor kinase inhibitor SU5416 significantly inhibited the growth of VR tumors. To validate that the proangiogenic switch is responsible for tumor development, the angiogenic phenotype was balanced by the inducible coexpression of endostatin under the control of Tet-activated promoter. Coexpression of endostatin along with VEGF reversed the tumorigenic phenotype of VR cells. These studies show that alterations in the angiogenic characteristics of ovarian surface epithelium may play an important role in the etiology of ovarian cancer, and that inhibition of angiogenesis can be effective in the treatment of epithelial ovarian cancer.