Proteins battle for control of cancer cells, researchers reveal
Two proteins battle it out in our blood to control the spread of cancerous cells around the body, according to new research from scientists in the UK, the Netherlands and Japan. If diseases such as breast, lung and colorectal cancer are caught early, the tumours can be effectively removed surgically. However, if the cancer cells invade the blood, the effectiveness of surgery is reduced as the likelihood of the cancer cells forming secondary tumours elsewhere in the body is increased. However, even if cancer cells do enter the blood stream, all is not lost. A large protein called MUC1, found on the cell surface, acts as a shield, preventing the cancer cells from attaching to the blood vessel walls and so causing secondary tumours. Cancer cells isolated by the shield are destroyed by the immune system. It has been known for some time that people suffering from breast, gastrointestinal and lung cancers have higher concentrations than normal of a small protein called galectin-3. Furthermore, those whose cancer has spread from the original site have higher concentrations of the protein in their blood than people with localised tumours. In this latest study, the scientists have uncovered how these two proteins fight to control the spread of cancerous cells. Their findings are published in the latest edition of the Journal of Biological Chemistry. 'We have discovered that a small protein called galecti-3 attacks MUC1 and breaks up its protective shield, forcing large areas of the cancer cell to become exposed,' explained Dr Lu-Gang Yu of the University of Liverpool in the UK. 'The exposed areas of the cell allow the cancer to attach to the blood vessel wall. The cancer cells then eventually penetrate the blood wall to form tumours at secondary sites.' According to Dr Yu, the attachment of cancer cells to the blood vessel wall is one of the key steps in the spread of cancer. However, until now the role of galectin-3 in this process was not known. 'Our study indicates that galectin-3 may play a critical role and may have significant implications for future developments of drugs for the treatment of the disease,' added Dr Yu.
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