US discovery could lead to better radiotherapy with fewer side effects
US scientists have found that blocking a particular biological pathway can protect healthy cells from the damaging effect of radiotherapy, while also promoting the death of tumour cells.
The study was done on cells in the laboratory, but if the results hold true in people the discovery could lead to new ways to increase the effectiveness of radiotherapy, whilst lessening the side-effects.
Radiation therapy is a vital form of cancer treatment which is administered to more than half of all patients. But it can also harm healthy tissue, leading to side-effects such as nausea, vomiting, skin sores, weakness and fatigue.
A new study, published in the journal Science Translational Medicine and conducted by researchers at the University of Pittsburgh School of Medicine and the US National Cancer Institute (NCI), has shown that it may be possible to prevent healthy cells from being damaged, thereby helping to reduce side-effects.
The team identified a biochemical signalling pathway that influences the effect of radiation on both cancerous and healthy cells.
They found that by blocking a molecule called thrombospondin-1 from binding to its cell surface receptor, CD47, in mice, they were able to give healthy cells almost complete protection from very high doses of radiation.
Co-author Dr Jeff Isenberg, associate professor in the Division of Pulmonary, Allergy and Critical Care Medicine at the Pitt School of Medicine, commented: "We almost couldn't believe what we were seeing.
"This dramatic protective effect occurred in skin, muscle and bone marrow cells, which is very encouraging.
"Cells that might have died of radiation exposure remained viable and functional when pre-treated with agents that interfere with the thrombospondin-1/CD47 pathway."
Senior author Dr David Roberts, from the NCI's Centre for Cancer Research, noted that despite protecting healthy cells, the new approach does not provide this same level of protection to cancer cells.
Dr Ester Hammond, a Cancer Research UK scientist at the University of Oxford, commented: "This work is particularly exciting because it's a step towards developing drugs that could be given alongside radiotherapy to protect healthy cells, while destroying the cancerous ones."
Dr Hammond noted that the way in which normal cells are protected when the thrombospondin-1/CD47 cell signalling pathway is disrupted is not yet clear.
"Future work will undoubtedly shed more light on this and could lead to new treatments for cancer patients," she added.
Maxhimer, J., Soto-Pantoja, D., Ridnour, L., Shih, H., DeGraff, W., Tsokos, M., Wink, D., Isenberg, J., & Roberts, D. (2009). Radioprotection in Normal Tissue and Delayed Tumor Growth by Blockade of CD47 Signaling Science Translational Medicine, 1 (3), 3-3 DOI: 10.1126/scitranslmed.3000139