Angiogenesis at the Interface between Basic and Clinical Research

Angiogenesis in gliomas

Angiogenesis, the sprouting of new blood vessels from preexisting blood vessels, is a hallmark of glioma progression. Malignant gliomas are among the most lethal tumors with a very dismal prognosis, despite advances in standard therapy, including surgery, radiation, and chemotherapy. The median survival of patients with malignant gliomas has changed little in the last few years and is still measured in months. In an attempt to develop new therapeutic strategies and identify the molecular mechanism involved in glioma growth and progression, there has been extraordinary scientific interest in the past 2 decades in angiogenic responses associated with gliomas. This chapter focuses on the molecular mechanism of glioma angiogenesis and summarizes some of the therapeutic approaches based on antiangiogenesis.

Targeted therapies: focus on a new strategy for gastrointestinal tumors

In the last few years the knowledge of molecular oncology has led to the development of many new biological agents whose targets are extracellular or intracellular molecules involved in the main signalling pathways that play major roles in cancer development. These agents represent a new approach to gastrointestinal malignancies, as for many other types of tumors; preliminary data show that targeted therapy may enhance activity of chemotherapeutic agents (i.e. cetuximab in metastatic colorectal cancer (CRC)) or be active as monotherapy (i.e. imatinib in gastro-intestinal stromal tumors). Despite the encouraging preclinical results, the majority of these compounds have not yet produced convincing clinical results. However, these new agents raise a new challenge in the treatment of gastrointestinal cancers, especially for CRC.

alphav Vitronectin receptors in vascular-mediated disorders

Various integrin antagonist candidates including antibodies, cyclic peptides, peptidomimetics, and non-peptides have been clinically evaluated and shown to successfully modulate certain disease processes. This review will focus on the key role of the alphav integrin (alphavbeta3 and alphavbeta5) in vascular disorders such as restenosis and angiogenesis-mediated disorders.

Multiple points of intervention in the prevention of cancer and other mutation-related diseases

Multiple points of intervention are the target for dietary and pharmacological interventions aimed at preventing cancer and other diseases in which mutations in somatic cells play a pathogenetic role. For instance, our studies showed that DNA adducts can be consistently detected in arterial smooth muscle cells from human atherosclerotic lesions. Their levels were significantly correlated with the occurrence of atherogenic risk factors known from traditional epidemiology and were strikingly enhanced in atherosclerotic patients lacking the GSTM1 genotype. Cancer chemoprevention has a dual goal, i.e. prevention of occurrence of the disease (primary prevention) and early detection and reversion of tumors at a premalignant stage (secondary prevention). At a later stage, attempts can be made to prevent local recurrences as well as invasion and metastasis of malignant cells (tertiary prevention). For a rational use of chemopreventive agents it is essential not only to evaluate their efficacy and safety but also to understand the mechanisms involved. Sometimes it is difficult to discriminate whether modulation of a given end-point is actually a specific mechanism or rather the epiphenomenon of other events. For instance, we recently found that apoptosis is considerably stimulated in the respiratory tract of smoke-exposed rats; whereas certain chemopreventive agents work by further enhancing smoke-related apoptosis, other agents appear to downregulate apoptosis simply because they inhibit the genotoxic events signaling this process. We propose here a detailed, updated classification of the points of intervention exploitable in the prevention of mutation and cancer. The general outline includes a variety of extracellular and cellular mechanisms modulating the genotoxic response and tumor initiation as well as tumor promotion, progression, angiogenesis, invasion, and metastasis. This classification is not intended to provide a rigid scheme, since several intervention points are reiterated several times over different phases of the process. Moreover, some mechanisms are strictly interconnected or partially overlapping. Interestingly, a number of chemopreventive agents work through multiple mechanisms, which warrants a higher efficacy and a broader spectrum of action. It is also convenient to combine chemopreventive agents working through complementary mechanisms. In recent preclinical studies, we observed that combination of N-acetylcysteine with either oltipraz or ascorbic acid produces additive or more than additive protective effects towards early biomarkers and/or experimentally-induced tumors.

Fibrosis and angiogenesis

Research during the past few years has contributed vastly to a better understanding of fibrosis and angiogenesis. Although studies to understand the molecular processes associated with fibrosis and angiogenesis were performed independently of each other, some common parallels have emerged. Translation of these observations into potential therapeutic possibilities needs further exploration.

Small molecule alpha(v) integrin antagonists: novel anticancer agents

The members of the integrin family are targets that potentially provide both therapeutic and diagnostic opportunities. Advances in the understanding of the signalling pathways, transcriptional regulation and the structure/function relationships of the adhesion molecules to extracellular matrix proteins have all contributed to these opportunities. The role of the integrins in pathological processes in both acute and chronic diseases, include ocular, cancer (solid tumours and metastasis), cardiovascular (stroke and heart failure) and inflammatory (rheumatoid arthritis) conditions. Various therapeutic candidates, including antibodies, cyclic peptides and peptidomimetics, have been identified. This review will focus on the key role of the alpha(v) integrin (alpha(v)beta(3) and alpha(v)beta(5)) in angiogenic processes in tumours, including its potential use in cancer diagnostics and therapy.