PUBLIC RELEASE DATE:
3-Aug-2014
Contact: Scott LaFee slafee@ucsd.edu 619-543-6163 University of California - San Diego
Although mutations in a gene dubbed "the guardian of the genome" are widely recognized as being associated with more aggressive forms of cancer, researchers at the University of California, San Diego School of Medicine have found evidence suggesting that the deleterious health effects of the mutated gene may in large part be due to other genetic abnormalities, at least in squamous cell head and neck cancers.
The study, published online August 3 in the journal Nature Genetics, shows that high mortality rates among head and neck cancer patients tend to occur only when mutations in the tumor suppressor gene coincide with missing segments of genetic material on the cancer genome's third chromosome.
The link between the two had not been observed before because the mutations co-occur in about 70 percent of head and neck tumors and because full genetic fingerprints of large numbers of cancer tumors have become available only recently.
"These two genetic malfunctions are not two separate stab wounds to the body," said co-senior author Trey Ideker, PhD, chief of the Division of Genetics. "One exposes the Achilles tendon and the other is a direct blow to it."
To patients with these cancers, the study's results mean that there may be therapeutic value in testing tumors for the two genetic identifiers, known as a TP53 mutation (short for tumor protein 53) and a 3p deletion (short for deletions of genetic information on the short arm "p" of the third chromosome).
TP53 plays a key role in regulating cell growth, detecting and fixing DNA, and directing cell apoptosis (death) if the DNA damage is irreparable. Because of this, the TP53 protein is sometimes called the "guardian of the genome."
The study's findings suggest that if both markers are present, treatment should be intensified. If only one mutation is present, treatment might be de-intensified because the TP53 mutation alone is less deadly than previously thought. The latter would have immediate benefits in reducing deaths caused by complications related to medical care.
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Tumor suppressor mutations alone don't explain deadly cancer