Expression of the angopoietin-1, angopoietin-2, Tie2, and vascular endothelial growth factor gene in epithelial ovarian cancer

Clinical Significance of Tie-2-Expressing Monocytes/Macrophages and Angiopoietins in the Progression of Ovarian Cancer-State-of-the-Art

Tumour growth and metastasis are specific to advanced stages of epithelial ovarian cancer (EOC). Tumour angiogenesis is an essential part of these processes. It is responsible for providing tumours with nutrients, metabolites, and cytokines and facilitates tumour and immune cell relocation. Destabilised vasculature, a distinctive feature of tumours, is also responsible for compromising drug delivery into the bulk. Angiogenesis is a complex process that largely depends on how the tumour microenvironment (TME) is composed and how a specific organ is formed. There are contrary reports on whether Tie-2-expressing monocytes/macrophages (TEMs) reported as the proangiogenic population of monocytes have any impact on tumour development. The aim of this paper is to summarise knowledge about ovarian-cancer-specific angiogenesis and the unique role of Tie-2-expressing monocytes/macrophages in this process. The significance of this cell subpopulation for the pathophysiology of EOC remains to be investigated.

A systems biology model of junctional localization and downstream signaling of the Ang-Tie signaling pathway

The Ang–Tie signaling pathway is an important vascular signaling pathway regulating vascular growth and stability. Dysregulation in the pathway is associated with vascular dysfunction and numerous diseases that involve abnormal vascular permeability and endothelial cell inflammation. The understanding of the molecular mechanisms of the Ang–Tie pathway has been limited due to the complex reaction network formed by the ligands, receptors, and molecular regulatory mechanisms. In this study, we developed a mechanistic computational model of the Ang–Tie signaling pathway validated against experimental data. The model captures and reproduces the experimentally observed junctional localization and downstream signaling of the Ang–Tie signaling axis, as well as the time-dependent role of receptor Tie1. The model predicts that Tie1 modulates Tie2’s response to the context-dependent agonist Ang2 by junctional interactions. Furthermore, modulation of Tie1’s junctional localization, inhibition of Tie2 extracellular domain cleavage, and inhibition of VE-PTP are identified as potential molecular strategies for potentiating Ang2’s agonistic activity and rescuing Tie2 signaling in inflammatory endothelial cells.

Gene expression in the Angiopoietin/TIE axis is altered in peripheral tissue of ovarian cancer patients: A prospective observational study

AIMS

Clinical studies suggest altered systemic vascular biology in cancer patients. We assessed expression patterns of endothelial activation- and vascular leakage-related genes in tumor as well as in tumor-free peripheral tissues from patients with and without ovarian cancer (OC).

MAIN METHODS

Patients being scheduled for laparotomy for either gynecologic benign diagnosis (n = 10) or for advanced-stage OC (n = 22) were prospectively recruited to this observational study. Serum samples were taken preoperatively, and tissue samples were taken from peripheral abdominal wall musculature, tumor-free peritoneum and the tumor itself.

KEY FINDINGS

Patients in OC group received significantly more fluid per time intraoperatively (p = 0.01). IL-8 and MCP-1/CCL2, VCAM-1 (CD 106) and ICAM-1 (CD 54) as well as Thrombomodulin were significantly increased in cancer patients' serum at baseline (p = 0.03). Expression of distinct vascular leakage-related genes (Angiopoietin-1 (ANG-1), ANG-2, TIE2, VEGFR1, VEGFR2) was significantly altered in tumor tissue of OC patients (p = 0.003), while in tumor-free peritoneal tissue, ANG-2/1 expression ratio was more than doubled in OC group (p = 0.03). In peripheral musculature, particularly genes from the ANG/TIE axis were significantly changed in OC patients (p = 0.005), suggesting a distinct vascular leakage-related genotype. Gene expression changes in OC patients were significantly associated with the postoperative fluid balance (p = 0.03).

SIGNIFICANCE

Altered expression of barrier dysfunction- and angiogenesis-associated genes from the ANG/TIE axis was detected not only in tumor but also in peripheral tissues of cancer patients. This may contribute to a systemic vascular leakage-related genotype.

Biomarkers of outcome to weekly paclitaxel in epithelial ovarian cancer

OBJECTIVE

We sought to evaluate the role of intrinsic chromosomal aberrations in determining favorable outcome to weekly paclitaxel (WP) in patients with epithelial ovarian cancer (EOC).

METHODS

We evaluated the common genomic aberrations of two patients with EOC and exceptional WP response in the GENIUS study (NCT03740503). We then searched for potential markers of unusual outcomes to WP in a validation cohort. We performed shallow whole genome sequencing (sWGS) in the tumor tissue of women with EOC considered as short-responders (SR; progression with ≤3 cycles) and long-responders (LR; response at ≥8 cycles) to WP monotherapy.

RESULTS

We identified two women with exceptional response to WP, lasting over four years, who shared chromosome 8 gain as a common genomic aberration. In order to validate our findings, we reviewed 188 patients with EOC treated with WP and selected 61 women (39 SR, 22 LR) with unusual responses. By sWGS, there was no differential alterations in the copy number changes in chromosome 8, or in genes related to angiogenesis, tubulin superfamily, cell-cycle, apoptosis and paclitaxel metabolism or transportation pathways. Amongst the LR group, we identified six exceptionally long responders (ExLR), with responses lasting over a year. In an exploratory analysis, there was increased amplification of angiogenesis (VEGFB, MMP9), tubulin superfamily (TSC2) and apoptosis related genes (BCL2L1, BAD) in ExLR compared to SR. We identified one patient with a complete response to WP for over 7 years. Molecular profiling identified unique amplifications in interleukin related genes (CXCR1, CXCR2, IL1A, IL1B), not detected in other patients.

CONCLUSION

Intrinsic tumor pathways may impact outcome with weekly paclitaxel monotherapy and further investigations are required.

The prognostic significance of high/positive expression of tissue VEGF in ovarian cancer

Background & aim

At present, numerous reports have shown that high/positive expression of tissue vascular endothelial growth factor (VEGF) may be associated with the prognosis of patients with ovarian cancer. However, their results still remained controversy. Thus, this meta-analysis was designed to analyze and assess the prognostic value of tissue VEGF expression in patients with ovarian cancer.

Method

We searched PubMed, Embase, Cochrane Library and Web of Science to October, 2017. Hazard Ratio (HR) with its 95% confidence intervals (CIs) was used to evaluate the association between high/positive expression of tissue VEGF and the prognosis of ovarian cancer patients. All statistical analyses were performed using standard statistical procedures provided in RevMan 5.2.

Result

A total of 18 studies (including 1145 patients) were included for this meta-analysis. The positive/high expression of tissue VEGF had an obvious association with overall survival (OS) (HR 2.24, 95% CI 1.36–3.70; P=0.002), progression-free survival (PFS) (HR 1.60, 95% CI 1.11–2.31; P=0.01) and disease-free survival (DFS) (HR 3.49, 95% CI 1.27–9.56; P=0.02) of patients with ovarian cancer respectively.

Conclusion

The present meta-analysis indicated that positive/high expression of tissue VEGF may have a close association with survival of ovarian cancer.

Phase I Study of MEDI3617, a Selective Angiopoietin-2 Inhibitor Alone and Combined with Carboplatin/Paclitaxel, Paclitaxel, or Bevacizumab for Advanced Solid Tumors

Purpose: This first-in-human study aimed to determine the MTD and safety of MEDI3617, a selective anti-angiopoietin-2 (Ang2) mAb, alone and combined with bevacizumab or cytotoxic chemotherapy.Patients and Methods: This phase I/Ib, multicenter, open-label, dose-escalation and dose-expansion study evaluated patients with advanced solid tumors. Patients received intravenous MEDI3617 as monotherapy [5-1,500 mg every 3 weeks (Q3W)] or with bevacizumab every 2 weeks (Q2W) or Q3W, weekly paclitaxel, or carboplatin plus paclitaxel Q3W. Dose expansions included a monotherapy cohort in platinum-resistant ovarian cancer and a bevacizumab combination cohort in bevacizumab-refractory malignant glioma. Safety/tolerability, pharmacokinetics, pharmacodynamics, and clinical activity were assessed.Results: We enrolled 116 patients. No formal MTD was identified (monotherapy or combination therapy). MEDI3617 demonstrated linear pharmacokinetics and maximal accumulation of peripheral Ang2 binding at doses above 300 mg Q3W. MEDI3617 monotherapy safety profile was acceptable, except in advanced ovarian cancer [prolonged grade 3 edema-associated adverse events (AE) occurred]. Otherwise, MEDI3617 combined with chemotherapy or bevacizumab was well tolerated. The AE profiles of MEDI3617 and bevacizumab were largely non-overlapping. Overall response rates in ovarian cancer and glioma monotherapy dose-expansion arms were 6% and 0%, respectively.Conclusions: Recommended MEDI3617 monotherapy dosage is 1,500 mg Q3W or 1,000 mg Q2W, except in ovarian cancer. Although peripheral edema has occurred with other Ang2 inhibitors, the severity and duration seen here in ovarian cancer potentially identifies a new, clinically significant safety signal for this class of agents. On the basis of limited clinical activity, MEDI3617 development was discontinued. Clin Cancer Res; 24(12); 2749-57. ©2018 AACR.

The Selective Tie2 Inhibitor Rebastinib Blocks Recruitment and Function of Tie2Hi Macrophages in Breast Cancer and Pancreatic Neuroendocrine Tumors

Tumor-infiltrating myeloid cells promote tumor progression by mediating angiogenesis, tumor cell intravasation, and metastasis, which can offset the effects of chemotherapy, radiation, and antiangiogenic therapy. Here, we show that the kinase switch control inhibitor rebastinib inhibits Tie2, a tyrosine kinase receptor expressed on endothelial cells and protumoral Tie2-expressing macrophages in mouse models of metastatic cancer. Rebastinib reduces tumor growth and metastasis in an orthotopic mouse model of metastatic mammary carcinoma through reduction of Tie2⁺ myeloid cell infiltration, antiangiogenic effects, and blockade of tumor cell intravasation mediated by perivascular Tie2^Hi/Vegf-A^Hi macrophages in the tumor microenvironment of metastasis (TMEM). The antitumor effects of rebastinib enhance the efficacy of microtubule inhibiting chemotherapeutic agents, either eribulin or paclitaxel, by reducing tumor volume, metastasis, and improving overall survival. Rebastinib inhibition of angiopoietin/Tie2 signaling impairs multiple pathways in tumor progression mediated by protumoral Tie2⁺ macrophages, including TMEM-dependent dissemination and angiopoietin/Tie2-dependent angiogenesis. Rebastinib is a promising therapy for achieving Tie2 inhibition in cancer patients. Mol Cancer Ther; 16(11); 2486-501. ©2017 AACR.

Expression of angiopoietin-TIE system components in angiosarcoma

Angiosarcoma is an aggressive malignancy of endothelial differentiation. Potential roles of the endothelial angiopoietin-tunica interna endothelial cell kinase (ANGPT-TIE) system in angiosarcoma diagnosis, pathogenesis, prognosis and treatment are undefined. To examine the expression and prognostic significance of angiopoietin-1, angiopoietin-2, TIE1 and TEK (TIE2) proteins in angiosarcoma, we immunohistochemically evaluated clinically annotated human angiosarcoma samples. Correlations of protein expression with overall survival and pathological features were explored. The cohort included 51 patients diagnosed with angiosarcoma at the age of 30-86 years (median 67). The 5-year overall survival was 45% with a median of 26 months. Moderate to strong expression of angiopoietin-1, TIE1 and TEK (TIE2) was identified in the majority of angiosarcomas and moderate to strong expression of angiopoietin-2 was observed in 42% of angiosarcomas. Increased angiopoietin-1 expression correlated with improved survival. Non-significant trends toward longer survival were also observed with increased TIE1 and TEK (TIE2) expression. Increased expression of angiopoietin-2, TIE1 and TEK (TIE2) was associated with vasoformative architecture. No differences in expression of these proteins were observed when patients were segregated by age, gender, presence or absence of metastases at diagnosis, primary tumor location, radiation association or the presence of necrosis. We conclude that components of the ANGPT-TIE system are commonly expressed in angiosarcomas. Reduced expression of these proteins is associated with non-vasoformative and clinically more aggressive lesions.

Latest research and treatment of advanced-stage epithelial ovarian cancer

The natural history of ovarian cancer continues to be characterized by late-stage presentation, metastatic bulky disease burden and stagnant mortality statistics, despite prolific drug development. Robust clinical investigation, particularly with modifications to primary treatment surgical goals and adjuvant therapy are increasing median progression-free survival and overall survival, although the cure rates have been affected only modestly. Maintenance therapy holds promise, but studies have yet to identify an agent and/or strategy that can affect survival. Recurrent disease is largely an incurable state; however, current intervention with selected surgery, combination and targeted therapy and investigational protocols are impacting progression-free survival. Ovarian cancer is a diverse and genomically complex disease, which commands global attention. Rational investigation must balance the high rate of discovery with lagging clinical investigation and limited patient resources. Nevertheless, growth in our armamentarium offers unprecedented opportunities for patients suffering with this disease. This Review presents and reviews the contemporary management of the disease spectrum termed epithelial 'ovarian' cancer and describes the direction and early results of clinical investigation.

Synergistic effect of vascular endothelial growth factor and angiopoietin-2 on progression free survival in multiple myeloma

Bone marrow neoangiogenesis plays an important role in multiple myeloma (MM) and depends on the interplay of angiogenic cytokines. We investigated the levels of angiogenic cytokines such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), angiopoietin (Ang)-1, Ang-2 and hypoxia inducible factor-1 alpha (HiF-1α) in MM patients and their association with treatment outcome. Serum levels and mRNA expression of VEGF, Ang-2, Ang-1, bFGF and HiF-1α were evaluated in 71 MM patients using enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction. In multivariate Cox regression analysis, serum levels of VEGF≥756 pg/ml (HR 2.2, 95% CI 1.02-4.91; p=0.045) and relative mRNA expression levels of Ang-2≥0.93 (HR 21.0, 95% CI 6.27-70.45; p<0.001) were predictive of inferior progression free survival (PFS) and patients with concomitant increase in VEGF and Ang-2 had poor outcome compared to the rest of the patients (HR 32.6, 95% CI 7.20-148.36; p<0.001). These results suggest that VEGF and Ang-2 act in synergy and their expression levels at presentation are predictive of PFS in MM.

The prognostic value of vascular endothelial growth factor in ovarian cancer: a systematic review and meta-analysis

OBJECTIVE

The prognostic role of vascular endothelial growth factor (VEGF) in ovarian cancer remains inconclusive. This meta-analysis aimed to explore the association between VEGF overexpression and survival outcomes in ovarian cancer patients.

METHODS

Studies were identified from PubMed and EMBASE searches performed on January 2nd, 2011. After careful review, survival data were extracted from eligible studies. A meta-analysis was performed to generate combined hazard ratio (HR) for progression-free survival (PFS) and overall survival (OS) in serum and tumor tissue studies.

RESULTS

Sixteen studies with 1111 patients were analyzed. Elevated serum VEGF was significantly associated with poor PFS [HR 2.46, 95% CI (1.84, 3.29)] and OS [HR 2.21, 95% CI (1.57, 3.13)]. No significant heterogeneity existed in serum studies. Similarly, tissue VEGF overexpression was associated with poor PFS [HR 1.63, 95% CI (1.09, 2.42)] and OS [HR 1.70, 95% CI (1.01, 2.87)]. However, significant heterogeneity was found in tissue studies, with I(2) of 44% for PFS and 64% for OS. Studies were stratified into subgroups by International Federation of Gynecology and Obstetrics (FIGO) stages. Subgroup analyses showed that high tissue VEGF was significantly associated with shorter PFS [HR 5.34, 95% CI (1.95, 14.59)] and OS [HR 6.13, 95% CI (2.47, 15.26)] in studies where predominantly early-stage patients were included, but not in studies with a majority of advanced-stage patients. Subgroup analysis was not performed in serum studies because all those studies enrolled more patients in advanced stages than early stages.

CONCLUSIONS

Overexpression of VEGF in primary tumor and serum associates with poor PFS and OS for patients with ovarian cancer. The association between high tissue VEGF level and poor prognosis exists in early stage patients, but not in advanced stage patients.

Novel targets for VEGF-independent anti-angiogenic drugs

INTRODUCTION

In the last decades, the active research in the field of tumor angiogenesis led to the development of a class of agents providing an effective inhibition of neovessels formation through the blockade of VEGF-related pathways. More recently, the identification of several non-VEGF factors such as PDGF, FGF, HGF, angiopoietins, ALK1/endoglin, endothelis and ephrins involved in tumor angiogenesis have emphasized the need to develop agents targeting multiple pro-angiogenic pathways.

AREAS COVERED

This review aimed at summarizing the role of non-VEGF molecular pathways in targeting tumor angiogenesis. Preclinical and clinical data for investigational agents against non-VEGF targets have been reviewed emphasizing the role of combined inhibition strategies.

EXPERT OPINION

Besides the successful development of drugs providing a specific VEGF blockade, novel agents targeting alternative angiogenesis-related pathways are being tested. Although it seems that the potential clinical usefulness of these novel compounds have been not yet fully investigated, sunitinib, sorafenib, pazopanib and other multikinase inhibitors have certainly displayed encouraging results. A more in-depth clarification of anti-angiogenic agents is still needed, in order to design the best clinical setting and schedule for target-based agents and possibly anticipate potential tools to overcome the emerging issue of anti-angiogenic drug resistance.

Specifically targeting angiopoietin-2 inhibits angiogenesis, Tie2-expressing monocyte infiltration, and tumor growth

PURPOSE

Angiopoietin-1 (Ang1) plays a key role in maintaining stable vasculature, whereas in a tumor Ang2 antagonizes Ang1's function and promotes the initiation of the angiogenic switch. Specifically targeting Ang2 is a promising anticancer strategy. Here we describe the development and characterization of a new class of biotherapeutics referred to as CovX-Bodies, which are created by chemical fusion of a peptide and a carrier antibody scaffold.

EXPERIMENTAL DESIGN

Various linker tethering sites on peptides were examined for their effect on CovX-Body in vitro potency and pharmacokinetics. Ang2 CovX-Bodies with low nmol/L IC(50)s and significantly improved pharmacokinetics were tested in tumor xenograft studies alone or in combination with standard of care agents. Tumor samples were analyzed for target engagement, via Ang2 protein level, CD31-positive tumor vasculature, and Tie2 expressing monocyte penetration.

RESULTS

Bivalent Ang2 CovX-Bodies selectively block the Ang2-Tie2 interaction (IC(50) < 1 nmol/L) with dramatically improved pharmacokinetics (T(½) > 100 hours). Using a staged Colo-205 xenograft model, significant tumor growth inhibition (TGI) was observed (40%-63%, P < 0.01). Ang2 protein levels were reduced by approximately 50% inside tumors (P < 0.01), whereas tumor microvessel density (P < 0.01) and intratumor proangiogenic Tie2(+)CD11b(+) cells (P < 0.05) were significantly reduced. When combined with sunitinib, sorafenib, bevacizumab, irinotecan, or docetaxel, Ang2 CovX-Bodies produced even greater efficacy (∼80% TGI, P < 0.01).

CONCLUSION

CovX-Bodies provide an elegant solution to overcome the pharmacokinetic-pharmacodynamic problems of peptides. Long-acting Ang2 specific CovX-Bodies will be useful as single agents and in combination with standard-of-care agents.

Chronology and complexities of ovarian tumorigenesis in FORKO mice: age-dependent gene alterations and progressive dysregulation of Major Histocompatibility Complex (MHC) Class I and II profiles

Among gynecologic malignancies ovarian cancer is the deadliest and most difficult to detect at early stages. As ovarian tumors have long latency and are relatively more frequent in postmenopausal women, revealing chronological changes in model systems might help in the discovery of novel molecular targets and diagnostic biomarkers for disease detection and management. Follitropin receptor knockout (FORKO) mice with early and sustained sex steroid hormone disharmony develop various age-dependent ovarian abnormalities including increased incidence ovarian tumors in complete absence of ovulation. These mutants show various tumor cell types including those related to ovarian surface epithelium around 12-15 months of age. To explore why the FORKO mice develop ovarian tumors later in life, we assessed global gene expression changes during the pre-tumor period (at 8 months). Age-matched wild-type and FORKO mice were compared to gain a comprehensive view of genes that are misregulated, even before overt tumors appear in mutants. Applying a conservative 2-fold change to detect changes, our study identified 476 genes (338 upregulated and 138 downregulated) to be altered between 8-month-old FORKO and wild-type ovaries. Using Ingenuity Pathway Analysis (IPA), we found highly significant alterations in five functional networks in pre-tumor stage FORKO ovaries. Notably, the top network to change in 8-month-old FORKO ovaries was associated with functions implicated in immune system development and function. We selected 9 immune related genes that are reportedly altered in Epithelial Ovarian Cancer (EOC) in women and confirmed their expression and chronology of changes in FORKO ovaries before and after tumor development. Our data indicate that immune surveillance mechanisms are compromised with in a 4-month window of tumorigenic alterations. In addition, expression of previously unrecognized genes misregulated in the dysfunctional FORKO ovaries suggests mechanisms not yet appreciated to date. We propose that a better understanding of genes that change before overt tumors develop could provide useful insights into ovarian carcinogenesis and open the door to additional new targets for treating ovarian cancers.

Targeting the ANGPT-TIE2 pathway in malignancy

Angiopoietins (ANGPTs) are ligands of the endothelial cell receptor TIE2 and have crucial roles in the tumour angiogenic switch. Increased expression of ANGPT2 relative to ANGPT1 in tumours correlates with poor prognosis. The biological effects of the ANGPT-TIE system are context dependent, which brings into question what the best strategy is to target this pathway. This Review presents an encompassing picture of what we know about this important axis in tumour biology. The various options for therapeutic intervention are discussed to identify the best path forwards.

The effects of angiopoietin-2 on the growth of tongue carcinoma

We aimed to investigate the effects of angiopoietin-2 (Ang-2) on tumour growth and angiogenesis in human tongue cancer. The pcDNA3.1(-)B/Ang-2 recombined expression plasmid was constructed by subcloning Ang-2 into a pcDNA3.1(-)B vector, and introduced into the Tca8113 cell line by liposome transfection. Then 3x10(6) cells were injected subcutaneously to the back of nude mice. The duration of forming and growing tumours was measured carefully. Formation of vessels was also assessed in harvested tumour tissue. Real-time reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical analyses confirmed the increase of Ang-2 expression in the transfected tumours. Overexpression of Ang-2 in Tca8113 cells prolonged the detectable formation of tumours and inhibited their growth. Tumours derived from Ang-2-transfected cells contained aberrant angiogenic vessels with few associated smooth muscle cells. Transgenic Ang-2 resulted in aberrant tumour angiogenesis in Tca8113 transplanted tumours, and inhibited the growth of Tca8113 tumours.

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.

Quantification of angiogenesis by the Chalkley method and its prognostic significance in epithelial ovarian cancer

AIM

The aim of the present study was to clarify prognostic role of angiogenesis in epithelial ovarian cancer.

METHODS

Quantification of angiogenesis was performed by the Chalkley method after immunostaining of 175 epithelial ovarian cancer specimens with an antibody against CD34.

RESULTS

The Chalkley count was categorised into two groups according to the median value: low <8 or high > or =8. The low Chalkley count correlated significantly with serous and clear cell histological subtype of the tumour (p<0.0005), whereas there existed no association with FIGO (International Federation of Gynecology and Obstetrics) stage, histological grade, presence of primary residual tumour, age at diagnosis, or chemotherapy response. In univariate analysis, the high Chalkley count predicted poor overall survival in the subgroup of patients with FIGO stages III-IV tumours (p=0.007) but not in the entire study cohort. However, in multivariate analysis, the Chalkley count was found to be an independent predictor of death from ovarian cancer in the entire study cohort (p=0.044, RR=1.50, 95% CI 1.01-2.21) as well as in the subgroup of FIGO stages III-IV tumours (p=0.046, RR=1.58, 95% CI 1.01-2.46) together with the presence of primary residual tumour (p<0.0005, RR=5.10, 95% CI 3.02-8.62, and p=0.002, RR=4.28, 95% CI 1.34-13.73, respectively).

CONCLUSIONS

The Chalkley count seems to be suitable for evaluation of angiogenesis and to have prognostic significance in ovarian cancer.

Expression of metastin and a G-protein-coupled receptor (AXOR12) in epithelial ovarian cancer

BACKGROUND

Metastin, a product of the KiSS-1 gene, is a ligand for a G-protein-coupled receptor (AXOR12) and is a strong suppressant of metastasis. The aim of this study was to evaluate whether metastin and AXOR12 gene expressions affect prognosis of patients with epithelial ovarian cancer.

METHODS

The expression levels of metastin, AXOR12 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene expression were analysed by the real-time quantitative reverse transcription-polymerase chain reaction in 76 epithelial ovarian cancer surgical specimens. Their expression (metastin/GAPDH and AXOR12/GAPDH ratios) was correlated with the clinical findings. Furthermore, cellular distribution of metastin and AXOR12 mRNA was examined by in situ hybridisation on tissue sections.

RESULTS

The median and range of mRNA expression for metastin and AXOR12 were 0.047 and 0.01-13.57, and 4.00 and 0.011-135.13, respectively. Patients were dichotomised into two groups having low and high expressions by using the median value as the cutoff. A good agreement was noticed between metastin and AXOR12 gene expression levels (kappa coefficient; 0.74). The presence of residual tumour following resection was negatively associated with metastin (P=0.0084) and AXOR12 (P=0.0148) gene expressions indicating an association of low expression of these genes in more aggressive, and advanced tumours. By univariate Cox regression analysis, the prognosis of the patients with low AXOR12 gene expression was significantly worse than those with high AXOR12 gene expression (P=0.030). The combination of metastin and AXOR12 gene expression level was also significantly associated with the prognosis (P=0.049). Transcripts for both metastin and AXOR12 were detected in the epithelial ovarian carcinoma cells.

CONCLUSIONS

These results present a new insight into the understanding of the biological behaviour of epithelial ovarian cancer. Metastin/AXOR12 signalling may suppress the invasive phenotype of epithelial ovarian cancer.

Angiopoietins lack of prognostic significance in ductal mammary carcinoma

Angiopoietins (Ang) have been shown to regulate the process of vasculature and angiogenesis in tumour. Different angiopoietins have different roles during the angiogenic process. The current study sought to examine the levels of the expression of Ang-1, Ang-2, Ang-3 and their receptor Tie-2 in mammary ductal carcinoma and to assess their relevance to prognosis. Fresh frozen ductal carcinoma tissues (n = 90) and adjacent non-cancerous breast tissues (n = 32) were used. The expression of Ang-1, Ang-2 and Ang-3 transcripts in cancer and normal breast tissues were examined quantitatively using quantitative RT-PCR. The protein expression of Ang-1, Ang-2 and Tie-2 was assessed by immunohistochemistry on frozen sectioned tissues.

Ang-1, Ang-2 and Ang-3 were detected in mammary tissues. Ang-1 was seen in both normal epithelial cells, breast cancer cells as well as in endothelial cells. Ang-2 was seen at a higher level than Ang-1 and it is expressed in epithelial, endothelial as well as stromal cells to certain degree. Ang-1 and Ang-2 transcripts were detected almost equally in cancer and normal breast tissue, and Ang-3 was high in cancer tissue compared to normal breast but not significant (155 ± 123 & 24.1 ± 22.6, P > 0.05). No significant differences were seen between patients with different predicted prognosis (using the Nottingham Prognostic Index as a guide) (Ang-1 p = 0.34, Ang-2 p = 0.26 and Ang-3 p = 0.32, respectively). No significant correlation was seen between Ang-1, Ang-2 and Ang-3 with tumour grade. When the levels of the transcripts were compared against clinical outcome (disease free, developed recurrence and patients who died of breast cancer), levels of Ang-3 transcript was found to be high in breast cancer patient who had bone metastasis 33.8 ± 28.3, although the difference was not significant (p = 0.08). No significant difference was seen with levels of Ang-1 and Ang-2 transcripts and clinical outcomes. Furthermore, no significant trend was observed between Tie-2 receptor and clinical/pathological parameters in the cohort.

These data suggest that angiopoietins (Ang-1, Ang-2 and Ang-3) are expressed in mammary tissues, both in normal and tumour. These molecules have limited value in predicting the prognosis and clinical outcome in patients with mammary ductal carcinoma.

Differential response of lymphatic, venous and arterial endothelial cells to angiopoietin-1 and angiopoietin-2

BACKGROUND

The lymphatic system complements the blood circulatory system in absorption and transport of nutrients, and in the maintenance of homeostasis. Angiopoietins 1 and 2 (Ang1 and Ang2) are regulators of both angiogenesis and lymphangiogenesis through the Tek/Tie-2 receptor tyrosine kinase. The response of endothelial cells to stimulation with either Ang1 or Ang2 is thought to be dependent upon the origin of the endothelial cells. In this study, we examined the effects of the angiopoietins on lymphatic, venous and arterial primary endothelial cells (bmLEC, bmVEC and bmAEC, respectively), which were isolated and cultured from bovine mesenteric vessels.

RESULTS

BmLEC, bmVEC and bmAEC cell populations all express Tie-2 and were shown to express the appropriate cellular markers Prox-1, VEGFR3, and Neuropilin-1 that define the particular origin of each preparation. We showed that while bmLECs responded slightly more readily to angiopoietin-2 (Ang2) stimulation, bmVECs and bmAECs were more sensitive to Ang1 stimulation. Furthermore, exposure of bmLECs to Ang2 induced marginally higher levels of proliferation and survival than did exposure to Ang1. However, exposure to Ang1 resulted in higher levels of migration in bmLECs than did to Ang2.

CONCLUSION

Our results suggest that although both Ang1 and Ang2 can activate the Tie-2 receptor in bmLECs, Ang1 and Ang2 may have distinct roles in mesenteric lymphatic endothelial cells.

Diversity of the angiogenic phenotype in non-small cell lung cancer

Angiogenesis is crucial for tumor biology. There are many mechanisms by which tumors induce angiogenesis. We hypothesize that each individual tumor develops a unique mechanism to induce angiogenesis, and that activation of a particular angiogenic pathway suppresses the evolution of alternative pathways. We characterized 168 human non-small cell lung cancer (NSCLC) specimens for levels of angiogenic factors (angiogenic CXC chemokines, basic fibroblast growth factor, and vascular endothelial growth factor). We also induced lung tumor formation in A/J mice by injecting the tobacco carcinogen NNK. We dissected individual lung tumors and measured expression of angiogenic factors from three distinct families using real-time PCR. Finally, we controlled the angiogenic milieu using in vivo models to determine the resultant phenotype of the angiogenic factors expressed by NSCLC cells. Human tumors displayed marked variation in the expression of angiogenic factors. Individual mouse tumors, even from within the same mouse, displayed variability in their pattern of expression of angiogenic factors. In a sponge model of angiogenesis using murine lung cancer cells, implanting LLC cells with an angiogenic factor suppressed the expression of other angiogenic factors in implanted sponges. This suppressive effect was not seen in vitro. We conclude that lung cancer tumors evolve a unique and dominant angiogenic phenotype. Once an angiogenic pathway is activated, it may allow for tumor growth to proceed in the absence of a selection pressure to activate a second pathway.

The duality of angiogenesis: implications for therapy of human disease

Angiogenesis, the development of a microvasculature to a neoplastic, inflammatory, or infectious disease process, is a promising therapeutic target for disease therapy that has not been fully exploited. To further understand angiogenesis and its potential for therapy of dermatologic disorders, one must understand the many dualities of pathologic angiogenesis. These dualities are direct versus indirect angiogenesis inhibition, the differing origins of endothelial cells, which may arise either locally or through bone marrow stem cells, and regulation of vascular endothelial growth factor (VEGF) by hypoxia-dependent and/or independent pathways. The future development of therapy directed at pathologic angiogenesis is dependent upon an understanding of the factors that regulate angiogenesis. The presence of both direct and indirect inhibition of angiogenesis, the multiple sources of endothelial cells, and the regulation of VEGF by hypoxia-independent and/or-dependent pathways must taken into consideration if the promise of effective therapy of human disease is to be realized.

Prognostic significance of vascular endothelial growth factor expression in ovarian cancer patients: a long-term follow-up

The purpose of the study was to determine vascular endothelial growth factor (VEGF) concentrations in ascites from ovarian cancer and to correlate these data with VEGF expression in ovarian tumors, serum VEGF concentrations, and clinicopathologic characteristics. Ascites, serum, and tumor tissue from 65 ovarian carcinomas and eight borderline tumors were collected. VEGF concentration in peritoneal fluids and sera was determined using enzyme immunoassay. VEGF tumor expression was evaluated immunohistochemically. Significantly higher VEGF concentrations were found in ascites from malignant tumors (median, 2575 pg mL(-1)) compared with borderline tumors (median 181.9 pg mL(-1)) and benign peritoneal fluid (184.5 pg mL(-1)). Both VEGF ascites concentration and tumor expression correlated with advanced tumor stages and ascites volume. Elevated VEGF ascites levels were negatively correlated to patient survival. No differences between VEGF serum levels could be observed between ovarian cancer patients and patients with benign cysts. This study showed for the first time the clinical significance of elevated VEGF ascites level in ovarian carcinomas. VEGF is expressed by ovarian tumor cells and locally released in the malignant peritoneal fluid but is not increased in the serum of preoperative ovarian cancer patients. The enhanced VEGF level support novel therapeutic perspectives by VEGF inhibition.

Expression of angiopoietins, Tie2 and vascular endothelial growth factor in angiogenesis and progression of hepatocellular carcinoma

AIM: To investigate the significance of angiopoietins, Tie2 and vascular endothelial growth factor (VEGF) expression in the angiogenesis and progress of hepatocellular carcinoma (HCC).

METHODS: Fresh surgically resected specimens of HCC and noncancerous liver (NCL) tissue from 38 patients with HCC were obtained, and expression of angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), Tie2, and VEGF messenger RNA (mRNA) was examined by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Expression pattern of each gene in HCC and NCL tissue specimens was compared and the potential role and interaction in angiogenesis of HCC were analyzed. Genes’ expression level and its relationship with tumor’s clinicopathological parameters were also investigated. Immunohistochemical staining of CD34 was performed to determine the microvessel density (MVD) and Ang-2/Ang-1 ratio was calculated. Relationships between Ang-2/Ang-1 ratio, VEGF and MVD and clinicopathological features were also tested so as to evaluate their significance in the progression of HCC.

RESULTS: Ang-2 and VEGF mRNAs in HCC were significantly higher than those in NCL tissue (P < 0.05), whereas the Ang-1 and Tie2 mRNAs showed no statistical significance (P > 0.05), though slightly lower level of Ang-1 mRNA in HCC was observed. Ang-2/Ang-1 ratio and VEGF were both positively correlated to MVD. The Ang-2/ Ang-1 ratio, Ang-2 and VEGF were all associated with tumor’s clinicopathological parameters (P < 0.05) except for histological grades (P > 0.05). Ang-1 and Tie2 levels in different clinicopathological groups were not significantly different (P > 0.05).

CONCLUSION: Dominant Ang-2 expression against Ang-1 through Tie2 receptor in the presence of VEGF plays a critical role in initiating early neovascularization and transformation of noncancerous liver to hepatocellular carcinoma. Its consequently constant operation in formed HCC induces further angiogenesis and progression of HCC.

Angiopoietin 2 expression in invasive ductal carcinoma of the breast: its relationship to the VEGF expression and microvessel density

Angiopoietin (Ang) is a ligand for the endothelium-specific tyrosine kinase receptor Tie-2, while a shift in the Ang-1:Ang-2 expression ratio in favor of Ang-2 was found to be associated with tumor angiogenesis. In the present study, we analyzed the immunohistochemical expression of Ang-2 in a series of 198 breast cancers, in which VEGF expression and microvessel density (MVD) were previously determined. Ang-2 expression was negative in 24 (12%), positive in 50 (25%) and strongly positive in 124 (63%) of 198 cases. A significant correlation was found between Ang-2 and VEGF expressions (p=0.0004) and between Ang-2 expression and MVD (p=0.0006), while a high MVD was found in 10 (77%) of 13 tumors with a strongly positive VEGF and positive Ang-2 expression and in 40 (71%) of 56 tumors with a strongly positive VEGF and strongly positive Ang-2 expression. Although there was no difference in the disease free survival (DFS) stratified according to Ang-2 expression alone, the 69 patients with a strongly positive VEGF and a strongly positive or positive Ang-2 expression had a significantly (p=0.0316) worse DFS than those with other combinations of VEGF and Ang-2 expressions. A multivariate analysis indicated lymph node metastasis and MVD to be independently significant prognostic factors for DFS, while the combination of VEGF and Ang-2 expressions was not a significant factor for DFS. In conclusion, the Ang-2 expression was found to be closely correlated with VEGF expression and MVD in breast cancer, while a high MVD was frequently found in tumors with a high expression of both VEGF and Ang-2. The survival analysis demonstrated a high MVD, which was induced by a high expression of both VEGF and Ang-2, to therefore have a strong prognostic significance in breast cancer.

Angiogenesis in normal and neoplastic ovaries

Ovarian physiology is intricately connected to hormonally regulated angiogenic response. Recent advances in the post genomic revolution have significantly impacted our understanding of ovarian function. In an angiogenesis perspective, the ovary offers a unique opportunity to unravel the molecular orchestration of blood vessel development and regression under normal conditions. A majority of ovarian cancers develop from the single layer of epithelium surrounding the ovaries. Angiogenesis is critical for the development of ovarian cancer and its peritoneal dissemination. The present review summarizes recent findings on the angiogenic response in neoplastic ovaries and discusses the prospects of using anti-angiogenic approaches to treat ovarian cancer.

Modulation of gene expression by tumor-derived p53 mutants

p53 mutants with a single amino acid substitution are overexpressed in a majority of human cancers containing a p53 mutation. Overexpression of the mutant protein suggests that there is a selection pressure on the cell indicative of an active functional role for mutant p53. Indeed, H1299 cells expressing mutant p53-R175H, p53-R273H or p53-D281G grow at a faster rate compared with a control cell line. Using p53-specific small interfering RNA, we show that the growth rate of mutant p53-expressing cells decreases as mutant p53 level decreases, demonstrating that the increased cellular growth is dependent on p53 expression. Increased growth rate is not observed for H1299 cell clones expressing mutant p53-D281G (L22Q/W23S), which has been shown to be defective in transactivation in transient transcriptional assays. This shows that the increased growth rate imparted by mutant p53 in H1299 cells requires the transactivation function of mutant p53. By performing microarray hybridization analyses, we show that constitutive expression of three common p53 mutants (p53-R175H, p53-R273H, and p53-D281G) in H1299 human lung carcinoma cells evokes regulation of a common set of genes, a significant number of which are involved in cell growth regulation. Predictably, H1299 cells expressing p53-D281G (L22Q/W23S) are defective in up-regulating a number of these genes. The differences in expression profiles induced by individual p53 mutants in the cells may be representative of the p53 mutants and how they can affect gene expression resulting in the observed "gain of function" phenotypes (i.e., increased growth rate, decreased sensitivity to chemotherapeutic agents, and so forth).

Angiogenesis and organ transplantation

Angiogenesis is a vessel development process that maintains the vascular supply for organ function. Regulation of angiogenesis is provided by positive factors, such as vascular endothelial or basic fibroblast growth factors, and negative factors, such as thrombospondin and macrophage-derived inflammatory cytokines. While the role of angiogenesis in the wound healing, embryogenesis, tumor growth and proliferative diseases is clear, in organ transplantation it is not yet well established. Herein we discuss the potential role of angiogenesis in chronic renal disease and in transplant settings.