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Protein discovery could lead to new drug treatment

5 December 2011

Researchers from the US are one step closer to designing a drug that targets a key protein involved in cancer.

Researchers from the US are one step closer to designing a drug that targets a key protein involved in cancer.

Researchers at Genentech have made a group of small molecules that can target and block a protein called Ras, which is prevalent in about a quarter of all tumours.

The findings were presented in Denver at a conference organised by the American Society for Cell Biology. The Genentech team hopes their findings will allow a drug to be developed that can target the Ras family of proteins.

The only way that Ras could be switched off would be by blocking a binding site or opening using a small molecule. Genentech researchers told attendees at the conference that they have found an opening on Ras with which they can target drugs.

To find a suitable target opening, they used a technique called fragment-based drug discovery- a technique that has been used previously to discover drugs against skin cancer. The researchers used this method to test thousands of small molecules for their ability to block the Ras protein.

In fact, 25 such molecules were found to bind to Ras out of the 3,000+ screened. Although none switched off the Ras protein they were studying, all the molecules that bound did so at the same site.

The researchers hope to use these molecules to design a drug that could switch off the mutated Ras protein in tumours, providing a novel therapy for effective cancer treatment in the future.

This aim will take time to achieve because the molecules screened by the Genentech team bound to the part of the Ras protein that receives signals from other proteins, rather than the area that sends out growth signals, causing tumours.

Although this is a limitation of the work and the molecules found would never be used as drugs on their own, researchers are excited because the findings describe a ‘proof-of-concept’- that Ras proteins in tumours can be targeted. Previously, it had been thought to be an ‘undruggable’ protein.

Therefore, although the findings from the US are a break-through, much more work needs to be done to work out how to turn off the Ras proteins in a way that can be used as a treatment for cancer.

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