'Crime Boss' Gene May Spur Breast Cancer

By Kathleen Doheny
HealthDay Reporter
Wednesday, March 12, 2008; 3:00 PM

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WEDNESDAY, March 12 (HealthDay News) -- Scientists have identified a gene they say can promote aggressive breast cancer by acting as a kind of "crime boss," capable of changing the behavior of more than 1,000 genes within tumor cells.

So far, the research has been limited to mice. But if the finding holds true in planned human studies, it may help doctors predict which breast cancers are likely to be aggressive and spread, said Terumi Kohwi-Shigematsu, a senior scientist at the Lawrence Berkeley National Laboratory at the University of California, Berkeley. She is the corresponding author of the study along with her husband, fellow researcher Yoshinori Kohwi, who's also with the Berkeley laboratory.

The gene, SATB1, "is a regulator of whether the cancer spreads," Kohwi-Shigematsu said. "SATB1 was cloned by us [at the Berkeley lab] in 1992. The gene is already known to be expressed in activated T-cells in animals as part of the immune system response."

SATB1's normal roll in the cell is to "organize" other genes. But when SATB1 is overactivated, the legions of growth-promoting genes that it regulates can run amok, Terumi Kohwi-Shigematsu explained.

Now, the researchers have pinpointed it as the gene that can promote aggressive breast cancer. "SATB1 is a genome organizer, which allows a global change in gene expressions," Kohwi-Shigematsu said. "When it is expressed in breast cancer cells, the cells acquire metastatic activity and growth advantage."

"Once it is expressed," she added, "cancer will spread." Conversely, if SATB1 is silent, cancer doesn't grow.

For the research, the study authors took an established line of breast cancer cells and injected them into laboratory mice. When the scientists disrupted the SATB1 and stopped the expression of the SATB1 protein from the gene, the cancer cells stopped growing and dividing. And when they deliberately expressed the gene in the cancer cells, the tumors grew more aggressively, Kohwi-Shigematsu said.

The findings are published in the March 13 issue of Nature.