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Mutant Gene Causes Some Cancer Types, Researchers Say

Todd Waldman, David Solomon

Cancer geneticist Todd Waldman, right, and David Solomon (G'10, M'12) discovered that mutations of the STAG2 gene may cause cells to develop an abnormal amount of chromosomes, which can lead to the formation of cancer cells.

January 5, 2012 – Georgetown researchers have discovered a mutant gene that causes brain, skin, bone and other types of cancer.

Cancer geneticist Todd Waldman and his team at the Georgetown University Medical Center (GUMC) have found that mutations of the STAG2 gene cause cells to develop too many or too few chromosomes.

Scientists have long known that cells with an abnormal chromosome count are significantly more likely to develop cancer. But until now, the source of this abnormality has been unknown.

First Step

“In the cancers we studied, mutations in STAG2 appear to be a first step in the transformation of a normal cell into a cancer cell,” says Waldman, an associate professor oncology at GUMC’s Lombardi Comprehensive Cancer Center.

The findings come from a study funded by the National Institutes of Health and the American Cancer Society and have been published in the scholarly journal Science. Part of a doctoral thesis by David Solomon (G’10, M’12), the study aimed to identify mutated genes in the most common and lethal form of brain cancer – glioblastoma multiforme.

The research team found that 20 percent of the brain, skin and bone cancer samples they examined made no STAG2 protein, often due to a missing or mutated STAG2 gene.

New Direction

Waldman supervised Solomon’s research in his cancer genetics lab at Lombardi.

“These findings may lead to a new direction for cancer therapy,” says Solomon, the study’s lead author. The team is now focusing on developing a drug to kill cancer cells with STAG2 mutations.

A crucial moment in his research, he says, came after studying the mutations in a few brain tumors. At that point, he was still unsure of its importance as a broad-spectrum cancer gene in other tumor types.

But then he looked at 10 Ewing’s sarcoma tumors, and found that six out of the 10 bone tumors had similar mutations or deletions.

“I knew then that STAG2 was indeed an important tumor suppressor gene in several tumor types,” Solomon says.  

Next Steps

The Georgetown research team is continuing to collaborate with investigators at the National Institutes of Health, University of Texas Southwestern Medical Center, Memorial Sloan-Kettering Cancer Center and the University of California, San Francisco, to better understand STAG2.

“We are now looking at whether STAG2 might be mutated in breast, colon, lung and other common human cancers,” Waldman says.

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