Role and Mechanisms of Angiogenesis in Tumours

Abstract

This article presents the accurate and current state of knowledge regarding the process of angiogenesis in neoplastic cells and its importance for tumour development. It provides a detailed review of the different types of angiogenesis with a brief discussion of individual angiogenic factors. Pathological angiogenesis in tumour tissues and the production of angiogenic factors have been recognised as key features responsible for cancerous development and distant metastasis formation since 1971. A phenomenon known as an angiogenic switch allows neoplasm to transform from an avascular to a vascular phase. The emerging new network of blood vessels allows cancer cells to efficiently exchange gases, provide nutrients and eliminate metabolic waste products. The main factors stimulating the angiogenesis process are VEGF, FGF, EGF, PDGF, and TGF-β1. To date, the most specific, strongest and most widely studied factor is VEGF. It is regarded as the main mitogen for vascular endothelial cells, stimulating their proliferation, and it is therefore referred to as a survival factor for cancer cells. Several mechanisms of new blood-vessel formation in cancerous tissue have also been identified. The three dominant processes include vascular sprouting, intussusceptive angiogenesis and vessel co-option. Angiogenesis in cancer tissues remains a subject of numerous scientific studies. A thorough understanding of the mechanism of oncogenesis and tumour expansion appears to be the starting point for future research aimed at finding effective anti-cancer therapy.

Keywords: VEGF; angiogenesis; intussusceptive angiogenesis; tumour; vascular sprouting; vasculogenic mimicry.

Figure 1

Models of blood vessel formation in tumours—diagram.

Figure 2

Squamous cell carcinoma—immunohistochemical staining—an anti FVIII antibody (200×).

Figure 3

Fibrosarcoma—immunohistochemical staining an anti—FVIII antibody (200×).