`We were able to significantly reduce the spread of the disease and decrease tumour growth without any evidence of toxicity,` says Gary Jarvis, a microbiologist at the University of California in San Francisco. `If we can stop metastasis in humans, we will have gone a long way towards successfully treating cancer.`
`It`s when tumours spread to essential organs, such as the liver or lung, that they become fatal,` says colleague Constance John, a research chemist. `There is nothing to date that has been approved by the Food and Drug Administration for treatment of cancer that works on that process.`
Stick together
The team modified a protein that seems play an important role in helping cells stick to each other. This ability aids metastasis by allowing cancerous cells that enter the bloodstream to lodge themselves in other parts of the body.
The team, lead by Jarvis in the US and Hakon Leffler at the University of Lund in Sweden, singled out a human protein named galectin-3. This is from a family of proteins called lectins that bind to sugar molecules on the surfaces of cells.
Galectin-3 is known to play a role in cancer formation, particularly in promoting cell-to-cell adhesion. `The idea was to break that contact and inhibit secondary cancer formation,` says Jarvis. So the team removed the key part of galectin-3 that normally allows cells to stick to each other. The modified protein also occupies the site on a cell`s surface blocking normal galectin-3 from binding. This stops cells from adhering to each other.
The modified protein more than halved the number of mice that developed metastatic tumours. Cancer implanted into the mice spread to the lymph nodes or other organs in 11 of the 20 control mice given sham injections, but only four of the 20 mice given the truncated protein.
Slow growth
The growth of the implanted tumours was also significantly less in mice treated with the modified protein compared to the control mice.
`It`s not only affecting metastasis,` Leffler told New Scientist. `It`s reducing the primary tumour a lot.` Importantly, he adds, the novel treatment did not cause any adverse reactions.
A drug therapy targeting galectin-3 might one day be effectively used in combination with currently available cancer medications like chemotherapy and radiation, say the researchers. Although, the results are `optimistic`, Leffler cautions that `an animal model is not human`.
`We`re not trying to develop a cure for cancer,` says John. `What we`re trying to do is make cancer a disease that one can live with.`
Source: http://www.newscientist.com/news/news.jsp?id=ns99993801
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