Angiogenesis in Spontaneous Tumors and Implications for Comparative Tumor Biology

Abstract

Blood supply is essential for development and growth of tumors and angiogenesis is the fundamental process of new blood vessel formation from preexisting ones. Angiogenesis is a prognostic indicator for a variety of tumors, and it coincides with increased shedding of neoplastic cells into the circulation and metastasis. Several molecules such as cell surface receptors, growth factors, and enzymes are involved in this process. While antiangiogenic therapy for cancer has been proposed over 20 years ago, it has garnered much controversy in recent years within the scientific community. The complex relationships between the angiogenic signaling cascade and antiangiogenic substances have indicated the angiogenic pathway as a valid target for anticancer drug development and VEGF has become the primary antiangiogenic drug target. This review discusses the basic and clinical perspectives of angiogenesis highlighting the importance of comparative biology in understanding tumor angiogenesis and the integration of these model systems for future drug development.

Ezh2, endothelin-1, and cd34 as biomarkers of aggressive cervical squamous cell carcinoma: an immunohistochemical study

“…The angiogenic degree of tumor is strongly associated with its aggressiveness and can determine its clinical outcome (22). It was suggested that most tumors microvascular networks have significant abnormalities in morphology and architecture.…”

The use of low‐dose metronomic chemotherapy in dogs—insight into a modern cancer field

“…Angiogenesis consists of the generation of new blood vessels from mature and rapidly dividing endothelial cells present in pre‐existing capillaries . Tumour angiogenesis is a highly complex process involving the participation of several players, including angiogenic molecules and cell types, such as endothelial cells, pericytes and bone marrow‐derived precursor cells . The capacity to activate angiogenesis, also called angiogenic switch, is an essential process for a tumour to move out from the quiescent state .…”

“…The capacity to activate angiogenesis, also called angiogenic switch, is an essential process for a tumour to move out from the quiescent state . Angiogenesis takes place in microscopic pre‐invasive lesions, and not only in the rapid growth phase of the tumour, as it originally was thought . When exposed to MC, endothelial cells in the tumour vasculature are directly affected by the cytotoxic drugs through a selective induction of apoptosis and selective inhibition of proliferation and migration .…”

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“…Similar to normal tissues, vasculature has an important role in tumor growth and progression since it provides the necessary oxygen and nutrients that are present in the blood and allows discarding the toxic waste-products of metabolism [28, 29]. The tumor vasculature, driven by angiogenesis, is thus crucial for growth and survival of tumor cells, but it may also be exploited as a target for cancer therapy [30, 31].…”