Circulating plasma vascular endothelial growth factor in mice bearing human ovarian carcinoma xenograft correlates with tumor progression and response to therapy

Vascular endothelial growth factor polymorphisms and a synchronized examination of plasma and tissue expression in epithelial ovarian cancers

In this study, we have analyzed six genetic polymorphisms of the VEGF-A gene and correlated the genetic data with plasma and tissue expression of VEGF-A in epithelial ovarian carcinomas. A total of 130 cases including 95 malignant carcinomas, 17 low malignant potential and 18 benign tumours were studied. rs699947, rs833061, rs1570360, rs2010963, rs1413711 and rs3025039 were studied by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Plasma levels of VEGF-A were estimated by enzyme-linked immunosorbent assay (ELISA) and tissue expression of VEGF-A by immunohistochemistry (IHC). Four polymorphisms of the above excluding rs699947 and rs3025039 showed significant association with malignancy, and we observed the presence of positive correlation between haplotype CCGGCC and increased expression of VEGF-A in both plasma and tissues which also correlated with poor prognosis and recurrence suggesting a probable increase in resistance to treatment in such carriers. Highly upregulated tissue expression of VEGF-A was seen in all epithelial ovarian carcinomas with intensity of expression increasing from benign to malignant cases. ELISA data from our study showed an increase in circulating levels of VEGF-A in malignancies. VEGF-A plasma levels can be employed as a biomarker for high-grade malignancy in epithelial ovarian cancers alongside tissue expression and CA-125 levels. This study is unique due to the fact that a simultaneous analysis of plasma and tissue expression has been demonstrated and is a first such study in epithelial ovarian cancers and representing the Indian population (South-east Asian) synchronized with genetic polymorphism data as well.

Intraperitoneal administration of cisplatin plus bevacizumab for the management of malignant ascites in ovarian epithelial cancer: results of a phase III clinical trial

Bevacizumab is a humanized antihuman VEGF-A monoclonal antibody. This study aims to evaluate the efficacy and safety of intraperitoneal administration of cisplatin plus bevacizumab (Avastin) in the management of malignant ascites in ovarian epithelial cancer. Fifty-eight ovarian epithelial cancer patients with malignant ascites were randomly assigned to receive either intraperitoneal administration of cisplatin only (control group, n = 27, cisplatin: 40 mg/m(2) every 2 weeks, for 6 weeks) or cisplatin plus bevacizumab (study group, n = 31, cisplatin: 40 mg/m(2), bevacizumab: 300 mg, every 2 weeks for 6 weeks). All patients regularly received TC regimen (paclitaxel 135 mg/m(2) d1 + carboplatin AUC 5 d1) every 3 weeks. The outcome, quality of life (QoL) and adverse effect of the treatment were analyzed, and VEGF and CA-125 level in ascites were detected by ELISA. After treatment with cisplatin plus bevacizumab, VEGF level in ascites was significantly decreased compared to baseline (P < 0.05). Meanwhile, ascites VEGF level of study group was significantly lower than that of control group (P < 0.05). The overall response rate (ORR) of study group was significantly higher than that of control group (ORR 90.32 vs. 59.26 %, P < 0.05). QoL improvement rate of study group was also significantly higher than that of control group (93.55 vs. 48.15 %, P < 0.05). All patients were well tolerated, and no serious adverse effect occurred. Intraperitoneal administration of cisplatin plus bevacizumab is effective and safe for the management of malignant ascites in ovarian epithelial cancer.

Quantitative insight in utilizing circulating angiogenic factors as biomarkers for antiangiogenic therapy: systems pharmacology approach

Circulating angiogenic factors (CAF) like vascular endothelial growth factor (VEGF), placental growth factor (PlGF), and sVEGFR2 have potential as biomarkers for antiangiogenic therapy. The interpretation of changes in CAF is complicated by the dynamic nature of the tumor and host cells emanating CAF in response to VEGF pathway inhibition. We developed a systems pharmacology model of anti-VEGF agents to investigate CAF modulation by tumor and host cells, and the relationship between overall CAF changes in response to sunitinib and antitumor efficacy. This model distinguishes between the tumor cells' contributions from tumor-independent response to therapy and total plasma CAF correlating with antitumor activity. Altered VEGF is more likely to serve as a useful biomarker reflecting tumor responses in cancer patients whose pretreatment VEGF is higher than baseline VEGF in healthy subjects. Our findings provide a mechanistic insight into tumor modulation of angiogenic molecules, and may explain the inconsistent results found in previous biomarker studies.

Risk factors for GI adverse events in a phase III randomized trial of bevacizumab in first-line therapy of advanced ovarian cancer: A Gynecologic Oncology Group Study

PURPOSE

To evaluate risk factors for GI adverse events (AEs) within a phase III trial of bevacizumab in first-line ovarian cancer therapy.

PATIENTS AND METHODS

Women with previously untreated advanced disease after surgery were randomly allocated to six cycles of platinum-taxane chemotherapy plus placebo cycles (C)2 to C22 (R1); chemotherapy plus bevacizumab C2 to C6 plus placebo C7 to C22 (R2); or chemotherapy plus bevacizumab C2 to C22 (R3). Patients were evaluated for history or on-study development of potential risk factors for GI AEs defined as grade ≥ 2 perforation, fistula, necrosis, or hemorrhage.

RESULTS

Of 1,873 patients enrolled, 1,759 (94%) were evaluable, and 2.8% (50 of 1,759) experienced a GI AE: 10 of 587 (1.7%, R1), 20 of 587 (3.4%, R2), and 20 of 585 (3.4%, R3). Univariable analyses indicated that previous treatment of inflammatory bowel disease (IBD; P = .005) and small bowel resection (SBR; P = .032) or large bowel resection (LBR; P = .012) at primary surgery were significantly associated with a GI AE. The multivariable estimated relative odds of a GI AE were 13.4 (95% CI, 3.44 to 52.3; P < .001) for IBD; 2.05 (95% CI, 1.09 to 3.88; P = .026) for LBR; 1.95 (95% CI, 0.894 to 4.25; P = .093) for SBR; and 2.15 for bevacizumab exposure (aggregated 95% CI, 1.05 to 4.40; P = .036).

CONCLUSION

History of treatment for IBD, and bowel resection at primary surgery, increase the odds of GI AEs in patients receiving first-line platinum-taxane chemotherapy for advanced ovarian cancer. After accounting for these risk factors, concurrent bevacizumab doubles the odds of a GI AE, but is not appreciably increased by continuation beyond chemotherapy.

Ascitic Fluid Analysis in the Differential Diagnosis of Ascites: Focus on Cirrhotic Ascites

Ascites is the pathologic accumulation of fluid within the peritoneal cavity. Because many diseases can cause ascites, in particular cirrhosis, samples of ascitic fluid are commonly analyzed in order to develop a differential diagnosis. The concept of transudate versus exudate, as determined by total protein measurements, is outdated and the use of serum-ascites albumin gradient as an indicator of portal hypertension is more accurate. Lactate dehydrogenase (LDH), vascular endothelial growth factor (VEGF), and other tumor markers can be helpful in distinguishing between malignant and benign conditions. Glucose and adenosine deaminase levels may support a diagnosis of tuberculous disease, and amylase level may indicate a diagnosis of pancreatitis. Given the specificity and sensitivity of laboratory results, accurate diagnosis should be based on both laboratory data and clinical judgment.

Distribution of selenium and oxidative stress in breast tumor-bearing mice

The present study investigated the effects of breast tumors on the blood and tissue distribution of essential trace mineral selenium (Se), and oxidative stress status of mice. Female 10-week-old BALB/cByJNarl mice were randomly assigned into control (CNL) and breast tumor-bearing (TB) groups. TB mice were injected subcutaneously into the right hind thigh with 5 × 10(6) EMT6 mouse mammary tumor cells. After 22 days, we measured Se concentrations, Se-dependent glutathione peroxidase (GPx) activities, and malondialdehyde (MDA) products (indicator of oxidative stress) in plasma, various tissues, and plasma vascular endothelial growth factor (VEGF) concentrations. There were no significant differences in body weights and daily intake between both groups. Compared with the CNL group, TB mice have decreases in plasma Se concentrations and GPx activities, as well as higher plasma VEGF and MDA concentrations. Plasma Se concentrations were also negatively correlated with plasma MDA and VEGF concentrations. Furthermore, tissue Se concentrations and GPx activities in TB animals were lower; whereas the MDA concentrations higher in various tissues including liver, kidney, brain, lung, spleen, and thymic tissues. In conclusion, disruption of Se homeostasis critically reflects oxidative stress in target tissues, thus may increase the risk for progression of breast cancer and metastasis.

Chick chorioallantoic membrane (CAM) assay as an in vivo model to study the effect of newly identified molecules on ovarian cancer invasion and metastasis

The majority of ovarian cancer patients present with advanced disease and despite aggressive treatment, prognosis remains poor. Significant improvement in ovarian cancer survival will require the development of more effective molecularly targeted therapeutics. Commonly, mouse models are used for the in vivo assessment of potential new therapeutic targets in ovarian cancer. However, animal models are costly and time consuming. Other models, such as the chick embryo chorioallantoic membrane (CAM) assay, are therefore an attractive alternative. CAM assays have been widely used to study angiogenesis and tumor invasion of colorectal, prostate and brain cancers. However, there have been limited studies that have used CAM assays to assess ovarian cancer invasion and metastasis. We have therefore developed a CAM assay protocol to monitor the metastatic properties of ovarian cancer cells (OVCAR-3, SKOV-3 and OV-90) and to study the effect of potential therapeutic molecules in vivo. The results from the CAM assay are consistent with cancer cell motility and invasion observed in in vitro assays. Our results demonstrate that the CAM assay is a robust and cost effective model to study ovarian cancer cell metastasis. It is therefore a very useful in vivo model for screening of potential novel therapeutics.

Cisplatin plus paclitaxel and maintenance of bevacizumab on tumour progression, dissemination, and survival of ovarian carcinoma xenograft models

Background:

Bevacizumab is being incorporated as first-line therapy with standard-of-care chemotherapy on epithelial ovarian carcinoma (EOC). We investigated bevacizumab combined with chemotherapy on tumour progression and mouse survival in EOC xenograft models.

Methods:

Bevacizumab was administered concomitantly with cisplatin plus paclitaxel (DDP+PTX), continued after induction (maintenance) or started after chemotherapy. The effect on tumour progression was monitored by bioluminescence imaging (BLI) (1A9-luc xenograft). Tumour dissemination into the peritoneal organs and ascites formation (HOC22 xenograft) was evaluated by histological analysis at the end of treatment (interim) and at euthanasia (survival). The effects on overall survival (OS) were investigated in both EOC models.

Results:

Bevacizumab with PTX+DDP delayed tumour progression in mice bearing EOC xenografts. OS was significantly extended, with complete responses, by bevacizumab continued after stopping chemotherapy in the HOC22 xenograft. Bevacizumab alone inhibited ascites formation, with only limited effect on tumour burden, but combined with PTX+DDP reduced ascites and metastases. Bevacizumab started after induction with PTX+DDP and maintained was equally effective on tumour progression and survival on 1A9-luc xenograft.

Conclusion:

Bevacizumab combined with chemotherapy not only affected tumour progression, but when administered as maintenance regimen significantly prolonged survival, reducing ascites, and tumour dissemination. We believe our findings are consistent with the clinical results and shed light on the potential effects of this kind of treatment on tumour progression.

Biologic rationale and clinical activity of mTOR inhibitors in gynecological cancer

Advanced recurrent gynecological malignancies have a poor prognosis despite systemic treatment, which is usually cytotoxic chemotherapy. Responses are generally short-lived and more effective treatments are needed. Rationally designed molecularly targeted therapy is an emerging and important option in this setting. The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase of the phosphatidylinositol-3-kinase (PI3K)/AKT signaling pathway with a critical role in controlling cancer cellular growth, metabolism and cell cycle progression. Aberrant PI3K-dependent signaling occurs frequently in a wide range of tumor types, including ovarian, endometrial and cervical cancer. Early clinical studies of first-generation mTOR inhibitors have shown promising clinical activity in endometrial cancer. However, the molecular basis of sensitivity and resistance to these agents remains largely unknown. In this review, we will update the clinical and biological data underlying the development of first generation mTOR inhibitors in the treatment of gynecological tumors. The role of potential new combination regimens with mTOR inhibitors in gynecological cancers will also be discussed.

Incorporation of bevacizumab in the primary treatment of ovarian cancer

BACKGROUND

Vascular endothelial growth factor is a key promoter of angiogenesis and disease progression in epithelial ovarian cancer. Bevacizumab, a humanized anti-vascular endothelial growth factor monoclonal antibody, has shown single-agent activity in women with recurrent tumors. Thus, we aimed to evaluate the addition of bevacizumab to standard front-line therapy.

METHODS

In our double-blind, placebo-controlled, phase 3 trial, we randomly assigned eligible patients with newly diagnosed stage III (incompletely resectable) or stage IV epithelial ovarian cancer who had undergone debulking surgery to receive one of three treatments. All three included chemotherapy consisting of intravenous paclitaxel at a dose of 175 mg per square meter of body-surface area, plus carboplatin at an area under the curve of 6, for cycles 1 through 6, plus a study treatment for cycles 2 through 22, each cycle of 3 weeks' duration. The control treatment was chemotherapy with placebo added in cycles 2 through 22; bevacizumab-initiation treatment was chemotherapy with bevacizumab (15 mg per kilogram of body weight) added in cycles 2 through 6 and placebo added in cycles 7 through 22. Bevacizumab-throughout treatment was chemotherapy with bevacizumab added in cycles 2 through 22. The primary end point was progression-free survival.

RESULTS

Overall, 1873 women were enrolled. The median progression-free survival was 10.3 months in the control group, 11.2 in the bevacizumab-initiation group, and 14.1 in the bevacizumab-throughout group. Relative to control treatment, the hazard ratio for progression or death was 0.908 (95% confidence interval [CI], 0.795 to 1.040; P=0.16) with bevacizumab initiation and 0.717 (95% CI, 0.625 to 0.824; P<0.001) with bevacizumab throughout. At the time of analysis, 76.3% of patients were alive, with no significant differences in overall survival among the three groups. The rate of hypertension requiring medical therapy was higher in the bevacizumab-initiation group (16.5%) and the bevacizumab-throughout group (22.9%) than in the control group (7.2%). Gastrointestinal-wall disruption requiring medical intervention occurred in 1.2%, 2.8%, and 2.6% of patients in the control group, the bevacizumab-initiation group, and the bevacizumab-throughout group, respectively.

CONCLUSIONS

The use of bevacizumab during and up to 10 months after carboplatin and paclitaxel chemotherapy prolongs the median progression-free survival by about 4 months in patients with advanced epithelial ovarian cancer. (Funded by the National Cancer Institute and Genentech; ClinicalTrials.gov number, NCT00262847.).

Regulator of G-protein signaling 5 (RGS5) protein: a novel marker of cancer vasculature elicited and sustained by the tumor's proangiogenic microenvironment

We previously identified regulator of G-protein signaling 5 (RGS5) among several genes expressed by tumor-derived endothelial cells (EC). In this study, we provide the first in vivo/ex vivo evidence of RGS5 protein in the vasculature of ovarian carcinoma clinical specimens and its absence in human ovaries. Consistent with this, we show higher amounts of Rgs5 transcript in EC isolated from human cancers (as opposed to normal tissues) and demonstrate that expression is sustained by a milieu of factors typical of the proangiogenic tumor environment, including vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF-2). Supporting these findings, we show elevated levels of Rgs5 mRNA in the stroma from strongly (as opposed to weakly) angiogenic ovarian carcinoma xenografts and accordingly, we also show more of the protein associated to the abnormal vasculature. RGS5 protein predominantly colocalizes with the endothelium expressing platelet/endothelial cell adhesion molecule-1 (PECAM-1/CD31) and to a much lesser extent with perivascular/mural cells expressing platelet-derived growth factor receptor-beta (PDGFR-β) or alpha smooth muscle actin (αSMA). To toughen the relevance of the findings, we demonstrate RGS5 in the blood vessels of other cancer models endowed with a proangiogenic environment, such as human melanoma and renal carcinoma xenografts; to the contrary, it was undetectable in the vasculature of normal mouse tissues. RGS5 expression by the cancer vasculature triggered and retained by the proangiogenic microenvironment supports its exploitation as a novel biomarker and opens the path to explore new possibilities of therapeutic intervention aimed at targeting tumor blood vessels.

The effects of vandetanib on paclitaxel tumor distribution and antitumor activity in a xenograft model of human ovarian carcinoma

This study was designed to determine the effects of vandetanib, a small-molecule receptor tyrosine kinase inhibitor of vascular endothelial growth factor and epidermal growth factor receptor, on paclitaxel (PTX) tumor distribution and antitumor activity in xenograft models of human ovarian carcinoma. Nude mice bearing A2780-1A9 xenografts received daily (5, 10, or 15 days) doses of vandetanib (50 mg/kg per os), combined with PTX (20 mg/kg intravenously). Morphologic and functional modifications associated with the tumor vasculature (CD31 and alpha-smooth muscle actin staining and Hoechst 33342 perfusion) and PTX concentrations in plasma and tumor tissues were analyzed. Activity was evaluated as inhibition of tumor growth subcutaneously and spreading into the peritoneal cavity. Vandetanib treatment produced no significant change in tumor vessel density, although a reduced number of large vessels, an increased percentage of mature vessels, and diminished tumor perfusion were evident. Pretreatment with vandetanib led to decreased tumor PTX levels within 1 hour of PTX injection, although 24 hours later, tumor PTX levels were comparable with controls. In efficacy studies, the combination of vandetanib plus PTX improved antitumor activity compared with vandetanib or PTX alone, with greater effects being obtained when PTX was administered before vandetanib. The combination of PTX plus vandetanib reduced tumor burden in the peritoneal cavity of mice and significantly increased their survival. Analysis of vascular changes and PTX tumor uptake in vandetanib-treated tumors may help to guide the scheduling of vandetanib plus PTX combinations and may have implications for the design of clinical trials with these drugs.

Intraperitoneal VEGF inhibition using bevacizumab: a potential approach for the symptomatic treatment of malignant ascites?

Despite overall improvements in oncological care in the palliative setting, symptomatic malignant ascites remains a severe clinical problem. This form of effusion is known to be widely resistant to established modes of systemic therapy. Accordingly, frequent paracentesis often represents the only effective way for symptom relief in patients with advanced cancer. This invasive mode of therapy, however, is often very burdensome for the patient who is already severely distressed by the underlying malignancy. Recently, the trifunctional monoclonal antibody catumaxomab given i.p. has shown symptom relief in patients with ovarian cancer and malignant ascites. On another front, the release of vascular endothelial growth factor (VEGF) by tumor cells has been identified as a main factor promoting the i.p. secretion of fluid. Accordingly, recent evidence suggests that targeting VEGF may have the potential to suspend the ascites production resulting from peritoneal metastasis. Here, we review preclinical and clinical data supporting this hypothesis. We show current evidence suggesting that the i.p. application of the anti-VEGF antibody bevacizumab, which is already in use as an i.v. therapeutic drug for a variety of tumors, might represent an effective way to prevent local fluid accumulation. Because such an effect would result in significant relief for patients, future clinical studies should stringently assess the effectiveness of this targeted therapy for the treatment of malignant i.p. effusions.

Vascular endothelial growth factor stimulates organ-specific host matrix metalloproteinase-9 expression and ovarian cancer invasion

Vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP) regulate each other, contributing to tumor progression. We have previously reported that MMP9 induces the release of tumor VEGF, promoting ascites formation in human ovarian carcinoma xenografts. The aim of this study was to investigate whether tumor-derived VEGF regulated the expression of gelatinase by the stroma, influencing the invasive properties of ovarian tumors. Tumor variants derived from 1A9 human ovarian carcinoma, stably expressing VEGF(121) in the sense (1A9-VS-1) and antisense orientations (1A9-VAS-3), were used. In vivo, zymographic analysis of tumors from 1A9-VS-1 implanted in the peritoneal cavity of nude mice showed higher levels of gelatinases, particularly murine MMP9, indicating that VEGF stimulates host expression of the matrix-degrading enzyme. Murine MMP9 expression was also high in the ovaries of mice bearing 1A9-VS-1 tumors. The effect on host MMP9 activity was organ-specific. The levels of host pro-MMP9 in ovaries correlated with the plasma levels of tumor VEGF and with the selective invasion of the ovaries. Induction of host MMP9 expression in tumors and ovaries was independent of the site of tumor growth as it was seen in mice carrying both intraperitoneal and subcutaneous tumors. The anti-VEGF antibody bevacizumab (Avastin) inhibited MMP9 expression and tumor invasion in the ovaries of mice bearing 1A9-VS-1 tumors. These findings point to a complex cross-talk between VEGF and MMPs in the progression of ovarian tumor and suggest the possibility of using VEGF inhibitors to affect MMP-dependent tumor invasion.

Vascular endothelial growth factor levels in ascites between chemonaive and chemotreated patients

PURPOSE

Vascular endothelial growth factor (VEGF) levels in malignant ascites have high diagnostic value for their discrimination from ascites of non-malignant origin. However, there have been no reports on the comparison of VEGF levels between malignant ascites of chemonaive and chemotreated patients.

MATERIALS AND METHODS

VEGF levels were measured in 44 ascites patients (cirrhosis ascites, 10; chemonaive patients, 21; chemotreated patients, 13) and compared to the level of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9). The diagnostic parameters of sensitivity, specificity, and correlation among 3 markers were evaluated.

RESULTS

VEGF levels in malignant ascites of chemonaive and chemotreated patients were significantly higher than those in cirrhotic ascites (p<0.05). VEGF levels in ascites of chemonaive patients were significantly higher than those in chemotreated patients (p<0.05). A cutoff value of 10.4 pg/mL was calculated using receiver operating characteristic curves (ROCs) for VEGF in chemotreated and chemonaive patients, which gave sensitivities of 75.0% and 53.8% and specificities of 69.6% and 47.1%, respectively. Positive correlations were observed between VEGF and CEA (r=0.353, p<0.05) as well as between VEGF and CA19-9 (r=0.367, p<0.05) in ascites.

CONCLUSION

VEGF levels could be a useful tumor marker for malignant ascites, but its value should carefully be interpreted because of lesser reliability in chemotreated ones.

Tumor engineering: orthotopic cancer models in mice using cell-loaded, injectable, cross-linked hyaluronan-derived hydrogels

Current cancer xenograft models used to evaluate new anticancer therapies are limited to "good take" cell lines, fail to mimic normal human disease, and poorly predict clinical outcomes. We now describe the use of an injectable, in situ cross-linkable synthetic extracellular matrix (sECM) to deliver and grow cancer cells in vivo. The hyaluronan (HA)-derived sECMs were seeded with breast, colon, and ovarian cancer cells prior to gelation, and then injected subcutaneously into mammary fat pads, subserosally in colons, and intracapsularly in ovaries, respectively. Two cell lines were used for each type of cancer, and results were compared with orthotopic injection of cells in serum-free medium. At 4 weeks postinjection, four parameters were measured: (i) incidence and size of cancer at the injection site, (ii) vascularization or necrosis of new cancer tissue, (iii) cancer seeding in adjacent tissues, and (iv) metastasis to lymph nodes and other vital organs. In addition, the activation of the phosphoinositide 3-kinase (PI 3-K) signaling pathway was analyzed immunohistochemically. Overall, orthotopic delivery of cancer cells in sECM hydrogels showed clear advantages: (i) increased incidence of cancer formation and reduced variability in tumor size, (ii) enhanced growth of organ-specific cancers with good tumor-tissue integration, (iii) improved vascularization and reduced necrosis within the tumor, (iv) reduced cancer seeding on adjacent tissues, and (v) better general health of animals. Thus, engineered tumors represent an improved approach to traditional tumor xenografts, and facilitate studies in cancer biology, invasion and metastasis, as well as the investigation of new therapeutic and diagnostic protocols.

A homeobox gene related to Drosophila distal-less promotes ovarian tumorigenicity by inducing expression of vascular endothelial growth factor and fibroblast growth factor-2

Homeobox genes control developmental patterning and are increasingly being found to be deregulated in tumors. The DLX4 homeobox gene maps to the 17q21.3-q22 region that is amplified in some epithelial ovarian cancers. Because amplification of this region correlates with poor prognosis, we investigated whether DLX4 overexpression contributes to aggressive behavior of this disease. DLX4 was not detected in normal ovary and cystadenomas, whereas its expression in ovarian carcinomas was strongly associated with high tumor grade and advanced disease stage. Overexpression of DLX4 in ovarian cancer cells promoted growth in low serum and colony formation. Imaging of mice bearing intraperitoneal tumors revealed that DLX4 overexpression substantially increased tumor burden. Tumors that overexpressed DLX4 were more vascularized than vector-control tumors. Conditioned medium of DLX4-overexpressing tumor cells was more effective than medium conditioned by vector-control cells in stimulating endothelial cell growth. These observations were associated with the ability of DLX4 to induce expression of vascular endothelial growth factor as well as intracellular and secreted isoforms of fibroblast growth factor-2. Moreover, increased levels of these fibroblast growth factor-2 isoforms induced vascular endothelial growth factor expression in tumor cells. This study reveals a novel role for a homeobox gene in ovarian tumorigenicity by its induction of a proangiogenic, growth-stimulatory molecular program.

Bioavailability of VEGF in tumor-shed vesicles depends on vesicle burst induced by acidic pH

Tumor angiogenesis is regulated by a dynamic cross-talk between tumor cells and the host microenvironment. Because membrane vesicles shed by tumor cells are known to mediate several tumor-host interactions, we determined whether vesicles might also stimulate angiogenesis. Vesicles shed by human ovarian carcinoma cell lines CABA I and A2780 stimulated the motility and invasiveness of endothelial cells in vitro. Enzyme-linked immunosorbent assay and Western blot analysis revealed relevant amounts of vascular endothelial growth factor (VEGF) and the two matrix metalloproteinases MMP-2 and MMP-9, but not fibroblast growth factor-2, contained in shed vesicles. An A2780 cell-derived clone transfected to overexpress VEGF shed the same amount of vesicles as did a control clone, but contained significantly more VEGF within the vesicles. Despite a greater amount of VEGF in vesicles of the overexpressing clone, vesicles of both clones stimulated endothelial cell motility to comparable levels, suggesting that VEGF was stored within the vesicle and was unavailable. Only following vesicle burst induced by acidic pH (a characteristic of the tumor microenvironment) was VEGF released, leading to significantly higher stimulation of cell motility. Thus, tumor-shed membrane vesicles carry VEGF and release it in a bioactive form in conditions typical of the tumor microenvironment.

Molecular predictors of response and outcome in ovarian cancer

A major problem in clinical management of patients with epithelial ovarian cancer (EOC) is the largely unpredictable response to first-line treatment and the occurrence of relapse after complete initial response, associated with broad cross-resistance to even structurally dissimilar drugs. During tumor development and progression, multiple genic alterations take place that might contribute specifically to the treatment response and eventually impact on disease outcome. One area of intense research is the identification of molecular markers to accurately assess the prognosis of EOC patients and to define innovative therapeutic strategies. A large survey of recent published data indicates the need to revisit traditional molecular markers with respect to their contribution to the assessment of overall survival in selected populations. Furthermore, recent technological developments that enable simultaneous measurement of many parameters ("omic" approaches) hold the promise of identifying new molecular prognostic and predictive markers.

Prediction of individual response to platinum/paclitaxel combination using novel marker genes in ovarian cancers

We attempted to identify potent marker genes using a new statistical analysis and developed a prediction system for individual response to platinum/paclitaxel combination chemotherapy in ovarian cancer patients based on the hypothesis that expression analysis of a set of the key drug sensitivity genes for platinum and paclitaxel could allow us to predict therapeutic response to the combination. From 10 human ovarian cancer cell lines, genes correlative in the expression levels with cytotoxicities of cisplatin (CDDP) and paclitaxel were chosen. We first selected five reliable prediction markers for the two drugs from 22 genes already known as sensitivity determinants and then identified another 8 novel genes through a two-dimensional mixed normal model using oligomicroarray expression data. Using expression data of genes quantified by real-time reverse transcription-PCR, we fixed the best linear model, which converted the quantified expression data into an IC(50) of each drug. Multiple regression analysis of the selected genes yielded three prediction formulae for in vitro activity of CDDP and paclitaxel. In the same way, using the same genes selected in vitro, we then attempted to develop prediction formulae for progression-free survival to the platinum/paclitaxel combination. We therefore constructed possible formulae using different sets of 13 selected marker genes (5 known and 8 novel genes): Utility confirmation analyses using another nine test samples seemed to show that the formulae using a set of 8 novel marker genes alone could accurately predict progression-free survival (r = 0.683; P = 0.042).