Suspect protein promotes DNA repair, prevents cancer

July 22nd, 2008 - 2:16 pm ICT by IANS  

Washington, July 22 (IANS) A chromosomal protein that binds to damaged DNA and speeds up its repair becomes instrumental in preventing cancer, according to Texas University researchers. Identification and repair of DNA damage is the primary defence against birth and reproduction of mutant cancer causing cells.

The protein, HMGB1, was previously suspected of blocking DNA repair, said Karen Vasquez, co-author of the study and associate professor in TU’s MD Anderson’s Department of Carcinogenesis, Smithville in Texas.

Pinpointing HMGB1’s role in repair raises a fundamental question about drugs under development to block the protein, Vasquez said. The protein also plays a role in inflammation, so it’s being targeted in drugs under development for rheumatoid arthritis and sepsis.

“Arthritis therapy involves long-term treatment,” Vasquez said. “Our findings suggest that depleting this protein may leave patients more vulnerable to developing cancer.”

Long known to attach to sites of damaged DNA, the protein was suspected of preventing repair. “That did not make sense to us, because HMGB1 is a chromosomal protein that’s so abundant that it would be hard to imagine cell repair happening at all if that were the case,” Vasquez said.

In a series of experiments, Vasquez and co-author Sabine Lange tracked the protein’s impact on all three steps of DNA restoration: access to damage, repair and repackaging of the original structure, a combination of DNA and histone proteins called chromatin.

These findings have been reported online this week in the Proceedings of the National Academies of Science.

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