Assessment of angiogenic potential--the use of AIDS-KS cell supernatants as an in vitro model

Metastasis, the passage of primary tumour cells throughout the body via the vascular system and their subsequent proliferation into secondary lesions in distant organs, represents a poor prognosis and therefore an understandably feared event for cancer patients. Despite considerable advances in cancer diagnosis and treatment, most deaths are the result of metastases resistant to conventional treatment [1]. Rather than being a random process, metastasis involves a series of organised steps leading to the growth of a secondary tumour. Malignant tumours stimulate the production of new vessels by the host, and this process is a prerequisite for the increase in size of a new tumour [2]. Angiogenesis, not only permits tumour expansion but also allows the entry of tumour cells into the circulation and is probably the most vital event for the metastatic process [3]. Metastasis and angiogenesis [4] have received much attention in recent years. A biological understanding of both phenomena seems to be an urgent priority towards the search for an effective prevention and treatment of tumour progression. Studies in vitro and in vivo have shown that one of the most important barriers to the passage of malignant cells is the basement membrane. The crossing of such barriers is a vital step in the formation of a metastasis [5].