A6
Neovascularisation in tumour-derived cancer stem cells: are current anti-angiogenic therapy trials facing serious challenge?
Hamid Reza Mirzaei, Abbas Rezaei, Ali Mohammadi Bardbori
1School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
The relationships of angiogenesis with cancer have special relevance, since angiogenesis has been described as one of the hallmarks of cancer, playing an essential role in tumour growth, invasion, and metastasis. Recently, some studies have shown that endothelial microvascular channels in some tumours are generated from genetically deregulated and aggressive tumour cells, cancer stem cells - a rare population of tumours that have stem-like properties and having capability of self-renewal and multi-potency of differentiation, this phenomenon also called tumour mimicry. Tumour mimicry is an alternative way to provide blood supply to tumours and is independent of conventional angiogenesis and would occur in least some but not all tumours-derived cancer stem cells through mechanisms that are as yet unknown. On the other hand, bone marrow-derived microvessels naturally express CD31, CD105 and CD309 (as human vascular endothelial cell markers) but a few tumour-derived microvessels shown that do not express these but express CD309 (VEGF-R2).
Hence, these studies not only suggest that some tumour microvessels do not originate from bone marrow-derived endothelial cells but also they suggest that at least some tumours may originate from cancer stem cells. Furthermore, since tumour blood vessels shown many differences from normal vessels such as resistance to apoptosis, current chemotherapy and antiangiogenic therapy so tumour blood vessels are potential targets for therapy of all tumours-derived cancer stem cells. Thereby and in consistent with our explanations, we will not only explain why current cancer antiangiogenic therapy trials are facing serious challenge but also suggest that future antiangiogenic therapies that target cancers, at least in tumours-derived cancer stem cells, have to be directed against neoplastic stem cells.
