This article emphasizes the importance of DNA repair. When they are repaired well and quickly, cancer ensues.


http://www.geneticstimes.com/researc...d_repairs_.asp
Broken DNA must find right partners quickly amid repairs (7/24/2008)
Tags:
chromosomes, chromosome translocations, gene regulation

Gene called ATM suppresses break-induced chromosome translocations, study shows

Just as square dance partners join hands at a particular point in the music, so broken pieces of DNA in our cells reunite as they are repaired. Precisely and quickly, these DNA pieces identify each other and tether together. A tumor-suppressor gene called ATM choreographs this fast-paced, but reliable, reassembly operation.

Sometimes the process goes awry. An ATM mutation predisposes children to cancers. In this week's issue of Nature, researchers at The University of Texas Health Science Center at San Antonio describe this gene's regulatory work more fully than ever before.

The paper, from the UT Health Science Center's Institute of Biotechnology, is among the first to describe the molecular basis of chromosome translocations. These errors occur when genes from one chromosome glom onto another chromosome. Chromosomes are the tightly wrapped coils of DNA found in every cell.
Occasional glitches

Lead author Sang Eun Lee, Ph.D., associate professor of molecular medicine at the Health Science Center, suspected that chromosome translocations occur during DNA repair. DNA repair is the continuous process in which our genetic blueprint, or DNA, fixes damage caused by sunlight, diet, oxygen and chemicals that ding our DNA.

"This DNA repair process is usually highly accurate and reliable, but occasionally DNA makes the mistake of reshuffling or jumbling together material," said Dr. Lee, a member of the Cancer Development and Progression Program of the Cancer Therapy & Research Center at the UT Health Science Center. "Translocations are found in many cancers, particularly leukemia. The presence of translocations predicts the success or failure of treatments for these cancers."

Philadelphia chromosome-positive chronic myelogenous leukemia, a rare and aggressive cancer, involves translocation of genetic material from chromosomes 9 and 22, for example.

"The thing we haven't understood is how chromosome translocations happen," Dr. Lee said. "Our study recreated translocations in yeast cells. We monitored the translocation events in the context of DNA repair, which we believed to be the culprit."