Gene causing colon cancer identified

September 15th, 2008 - 10:20 am ICT by IANS  

Washington, Sep 15 (IANS) Sophisticated new tools have helped identify an unsuspected gene behind colon cancer, according to a study. As these tools are refined, more such cancer genes are expected to identified, providing new avenues for therapy, the authors suggested. “This study provides confirmation that many of the genes involved in cancer have yet to be identified,” remarked the study’s co-author, William Hahn, of Dana-Farber and the Broad Institute of Harvard and MIT. “When it comes to identifying gene targets for therapy, we’ve really only scratched the surface.”

The study is noteworthy in another respect as well, the authors indicated. Many of the abnormal proteins linked to cancer are known as “transcription factors” because they’re able to “read” cell DNA and use that information for producing other cell proteins.

Although transcription factors are important regulators, this class of proteins has proven to be impossible to target with drugs. Genes that influence such transcription factors, however, make attractive targets for drugs, since they can potentially disrupt the cancer process and disable tumour cells. CDK8 is such a gene.

The new study began with a focus on a protein called beta-catenin, a transcription factor that is overactive in nearly all colorectal cancers (affecting the colon or the rectum).

Although overactive beta-catenin plays a role in the initial formation of tumours, other genetic abnormalities must occur for tumours to become fully malignant.

To determine which genes control the production of beta-catenin and are involved in the proliferation of colon cancer cells, the research team ran three screening tests.

In the first two, they used RNA interference to shut down more than a thousand genes one by one and recorded the instances where beta-catenin activity decreased and the cells stopped growing.

They then analysed colon cancers for genes that had extra copies. When they examined where the results of the three tests overlapped, one gene stood out — CDK8, explained Hahn, who is also an associate professor of medicine at Harvard Medical School

The findings were published in an advanced online edition of Nature Sunday.

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