INTRODUCTION: Translational Research: The Role of VEGF in Tumor Angiogenesis

Inhibiting angiogenesis with human single-chain variable fragment antibody targeting VEGF

Vascular endothelial growth factor (VEGF) is a highly specific angiogenesis factor which has crucial roles in the angiogenesis of tumors. Anti-angiogenesis agents can inhibit growth and metastasis of tumor cells. Single-chain variable fragments (scFv) have the same affinity as whole antibodies and smaller size, thus result in more tissue permeability and higher production yield. In this research we aim to isolate a human scFv antibody against VEGF that inhibits angiogenesis. For that, we have used human scFv phage library to isolate a specific scFv antibody against binding site of VEGF. The human scFv phage library was amplified according to the manufacture protocol and panned against recombinant VEGF. ScFv antibody was isolated after five rounds of panning. Phage ELISA was used for detection of the highest affinity binder (HR6). Soluble HR6 scFv was expressed in non-suppressor strain of Escherichia coli HB2151 and purified using Ni-NTA chromatography. In vivo and in vitro function of the HR6 scFv was analyzed by chorioallantoic membrane assay and endothelial cell proliferation assay on VEGF stimulated HUVECs. Result of the cross reactivity showed that HR6 scFv specifically bounds to VEGF. The affinity was calculated to be 1.8×10(-7)M. HR6 could stop HUVEC proliferation in a dose dependent manner and anti-angiogenesis activity was observed using 10μg of HR6 in chorioallantoic membrane assay. In this work, we demonstrate that a HR6 scFv selected from human library phage display specifically blocks VEGF signaling, furthermore, this scFv has an anti-angiogenesis effect and because of its small size has more tissue diffusion. The HR6 antibody was isolated form a human library thus, it is not immunogenic for humans and could serve as a potential therapeutic agent in cancer.

Tyrosine kinase inhibitors (TKIs) in human and pet tumours with special reference to breast cancer: a comparative review

Tyrosine kinase receptors (TKRs) play a key role in tumour cell proliferation and survival since they are involved in endothelial cell activation leading to tumour neoangiogenesis. In particular, vascular endothelial growth factor receptors (VEGFRs), platelet-derived growth factor receptor (PDGFR), stem cell factor receptor (c-KitR), and colony-stimulating factor 1 (CSF-1) are overexpressed or constitutively activated in human and pet malignancies. A variety of small molecule inhibitors targeting specific tyrosine kinases (known as tyrosine kinase inhibitors or TKIs) have recently been approved, or are under investigation, for the treatment of human cancer. TKI application in animal cancer is however relatively recent. This review aims to illustrate the major aspects of tyrosine kinase dysfunctions, with special regard to human and animal cancer of the mammary gland, providing an update on the background of the anti-angiogenic and anti-neoplastic properties of TKIs in human and veterinary cancer.

Mesh-loosening quantification of inhibition of angiogenic tube formation through image analysis

Angiogenesis is a key step in tumor development, and anti-angiogenesis processes are important for drug discovery and development. The dose-response relationship for an inhibitor is studied using images of endothelial cells captured in vitro by Matrigel assay. In order to improve the quantification of anti-angiogenic processes for faithful synchronization with continuous variation of an inhibitor dose, we have developed an automated image analysis method-mesh-loosening analysis-to evaluate the disruption of tube formation from endothelial cells. The method is based on numerical and morphological changes of mesh regions surrounded by tubes and perceived by considering the spaces between the tubes rather than the tubes themselves. The anti-angiogenic effect of suramin is analyzed comprehensively using four attributes obtained from the mesh regions. The relation between the dose of suramin and response shows an exponential curve that can be approximated as a sigmoid function, even though human assessments yield strong inhibition at moderate doses. The calculated half-minimal inhibitory concentration was in agreement with prior published reports. The results show that mesh-loosening analysis is useful and appropriate for screening applications that need precise and comprehensive quantification of the anti-angiogenic process to compensate for the inadequacy of human assessment. Feasibility study with shikonin shows the robustness of the mesh-loosening analysis.

High expression of proline-rich tyrosine kinase 2 is associated with poor survival of hepatocellular carcinoma via regulating phosphatidylinositol 3-kinase/AKT pathway

BACKGROUND

The peritumoral environment has been implicated to be important in the process of metastasis and recurrence in hepatocellular carcinoma (HCC). Our aims were to assess the prognostic value of proline-rich tyrosine kinase 2 (Pyk2) in HCC and investigate related molecular mechanism.

METHODS

Expression of Pyk2 was tested by immunohistochemistry in tissue microarrays containing 141 paired HCC samples. Correlation between Pyk2 and vascular endothelial growth factor (VEGF) expression in clinical samples was analyzed by Spearman rank correlation. Matrigel invasion, anchorage-independent growth assay and immunoblotting were performed to study the effect of Pyk2 on the invasion and progression of HCC cells and phosphoinositide 3-kinase (PI3K)/AKT pathway activation.

RESULTS

Higher Pyk2 density in both tumor and peritumor was associated with lower overall survival (P = 0.044; P = 0.041, respectively), serum AFP levels > 1,000 ng/ml (P = 0.013; P = 0.032, respectively) and postoperative distant metastasis (both P < 0.001). However, only higher peritumoral Pyk2 density was related to lower disease-free survival (P = 0.014) and vascular invasion (P = 0.035). A significant correlation between Pyk2 and VEGF density in tumor or peritumoral liver tissue was observed (r = 0. 3133, P = 0.0002; r = 0.5176, P < 0.0001, respectively). Immunoblotting showed that Pyk2 activated PI3K-AKT pathway to upregulate VEGF expression in HL-7702, SMMC-7721 and HepG2 cells.

CONCLUSIONS

High Pyk2, especially peritumoral Pyk2 was associated with poor survival, disease recurrence, and metastasis in HCC. PI3K-AKT pathway was involved in Pyk2-mediated VEGF expression during HCC progression and invasion.

Integration of novel agents into treatment of myeloma

More than 150 years have passed since the first treatments of multiple myeloma were initiated. The past decade has seen a renaissance in the generation of therapies for myeloma as a result of heightened understanding of the molecular pathogenesis of the disease. This review article highlights the development and incorporation of the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide into standard myeloma treatment regimens. We also discuss the creation of multiple other myeloma agents currently in phase I/II testing and designed to target specific pathways in myeloma physiology.

Distribution, metabolism, and excretion of the anti-angiogenic compound SU5416

SU5416, 3-(3,5-dimethyl-1H-pyrrol-2-ylmethylene)-1,3-dihydro-indol-2-one, is a potent inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinase, Flk-1/KDR (fetal liver kinase 1/kinase insert domain-containing receptor), also known as VEGF receptor 2 (VEGFR2). It was the first VEGFR2 inhibitor to enter clinical trials for the treatment of colorectal and non-small cell lung cancers. Pre-clinical evaluation of SU5416 included studies related to the distribution, metabolism and excretion of this compound. These studies have provided information useful in understanding the disposition and metabolism of the indolinone class of chemicals, which has not been studied previously with therapeutic intent. The lessons we learned from SU5416 have been successfully applied in developing next generation indolinone compounds targeting tumor angiogenesis.

A phase I Study with oral SU5416 in patients with advanced solid tumors: A drug inducing its clearance

Vascular endothelial growth factor (VEGF) is a potent stimulant of angiogenesis. SU5416, is a small molecule tyrosine kinase inhibitor, and a potent inhibitor of VEGF-mediated Flk-1 receptor signaling. Intravenous agent SU5416 has shown evidence of biological activity against a variety of tumor types. The current intravenous dosing regimen is not optimal for long-term administration, which is needed for optimal efficacy. The aim of this study was to evaluate the safety profile and pharmacokinetics of a Nanocrystal Colloidal Dispersion (NCD) SU5416 formulation in humans. Patients with advanced and/or metastatic solid organ tumors were included in the trial; various SU5416 regimens were tested for tolerability, safety and were evaluated concerning pharmacokinetics. The results of this study indicate that induction of clearance after oral dosing of NCD SU5416 in humans occurs and is greater than following i.v. administration. It has been confirmed that SU5416 is a high clearance compound, also as an oral NCD formulation. The NCD formulation was well tolerated, but no effective drug serum levels could be achieved. These data help to understand the ADME (Absorption, Distribution, Metabolism, Excretion) properties of indoline chemical class compounds. The lessons learned should be applied in the development of next generation indoline anti-angiogenic and anti-tumor compounds.

Preoperative serum vascular endothelial growth factor is not a marker for subsequent recurrence during long-term follow-up of colorectal cancer patients

BACKGROUND

Serum vascular endothelial growth factor has been associated with stage of disease in colorectal cancer patients. We investigated whether preoperative serum vascular endothelial growth factor can provide any relevant clinical prognostic information during long-term follow-up of colorectal cancer patients.

METHODS

Preoperative serum samples of 79 colorectal cancer patients and serum of 28 healthy controls were stored at -80 degrees C until later vascular endothelial growth factor analysis by enzyme-linked immunosorbent assay technique and carcinoembryogenic antigen concentration measurement were performed. There were three patient groups for comparison: 21 patients with overt liver metastases, 18 patients who developed recurrent disease after initial curative surgery, and 40 patients who remained disease-free for at least five years.

RESULTS

We could not demonstrate any significant difference in serum vascular endothelial growth factor values between the patient groups and controls, nor between the three patient groups (Mann-Whitney U test). There was no relevant correlation between serum vascular endothelial growth factor and carcinoembryogenic antigen concentrations (Pearson r = 0.2; P = 0.07).

CONCLUSION

Although vascular endothelial growth factor has been shown in previous studies to be a potent inducer of angiogenesis and metastases formation, the present data demonstrate that preoperative serum vascular endothelial growth factor concentration does not provide any relevant individual prognostic information in patients with colorectal cancer.

Platelet--cancer interactions: mechanisms and pharmacology of tumour cell-induced platelet aggregation

During haematogenous metastasis, cancer cells migrate to the vasculature and interact with platelets resulting in tumour cell-induced platelet aggregation (TCIPA). We review: 1. The biological and clinical significance of TCIPA; 2. Molecular mechanisms involved in platelet aggregation by cancer cells; 3. Strategies for pharmacological regulation of these interactions. We conclude that pharmacological regulation of platelet-cancer cell interactions may reduce the impact of TCIPA on cancer biology.

Thymidine phosphorylase expression in normal, hyperplastic and neoplastic prostates: correlation with tumour associated macrophages, infiltrating lymphocytes, and angiogenesis

Thymidine phosphorylase is an angiogenic factor primarily expressed by cancer cells, stromal cells and tumour-associated macrophages in many human malignancies. These different types of thymidine phosphorylase-expressing cells, however, may have a distinct place in the angiogenic process, and this question was addressed in the present study. A series of 20 normal/hyperplastic prostate glands and 60 prostate carcinomas was investigated by immunohistochemistry, using specific antibodies for thymidine phosphorylase (P-GF.44C), tumour-associated macrophages (CD68), endothelium (CD31) and prostate specific antigen (ER-PR8). Thymidine phosphorylase expression by normal and hyperplastic epithelial or stromal cells occurred almost exclusively in the context of an intense lymphocytic infiltrate. High thymidine phosphorylase cancer cells and thymidine phosphorylase stromal cells expression was associated with high angiogenesis in prostate carcinomas, and this significant association was extended to include both tumour-associated macrophages and tumour-infiltrating lymphocytes. Thymidine phosphorylase expression and tumour-infiltrating lymphocytes were related inversely with prostate specific antigen reactivity. In conclusion, thymidine phosphorylase is a major angiogenic factor in prostate carcinomas and its up-regulation is likely to occur in the context of a host immune response.

Smart drugs: tyrosine kinase inhibitors in cancer therapy

Cancer therapy directed at specific, frequently occurring molecular alterations in signaling pathways of cancer cells has been validated through the clinical development and regulatory approval of agents such as Herceptin for the treatment of advanced breast cancer and Gleevec for chronic myelogenous leukemia and gastrointestinal stromal tumors. While most novel, target-directed cancer drugs have pregenomic origins, one can anticipate a postgenomic wave of sophisticated "smart drugs" to fundamentally change the treatment of all cancers. With these prospects, interest in this new class of therapeutics extends from basic research scientists to practicing oncologists and their patients. An extension of the initial successes in molecular oncology will occur more quickly and successfully through an appreciation of lessons learned with the first group of agents in their progress through clinical development.