Scientists Find Way to Dim Cancer Switch

TUESDAY July 1, 2008 -- Scientists have discovered that they can use a kind of dimmer switch to stop a "cancer signal" from contributing to the development of tumors.

The findings don't represent a cure, and no one knows if they will even lead to better treatments for cancer. But the research does clear a pathway for scientists to follow as they determine which "switches" they need to turn off to stop cancer in its tracks, said study senior author Dr. Dean Felsher, an associate professor of medicine and oncology at Stanford University School of Medicine.

"You do not have to completely shut off a cancer switch to have a beneficial effect on cancer," he said. "It's a useful improvement over how we've been understanding things."

Normally, cells are programmed to commit suicide if they detect that they're damaged. "The cell says, 'I shouldn't be alive, something is wrong with me, I'm broken.' And it decides to kill itself," Felsher said.

But in some cases, the cells don't automatically kill themselves as they're programmed to do. Instead, proteins send signals that tell the cells to keep growing, said William Tansey, a professor at Cold Spring Harbor Laboratory who studies how tumors develop. "As a result of this push, cancer can develop."

A gene known as Myc is considered a major player in this process. At times, it doesn't cause problems. But its "Jekyll and Hyde" nature can turn it into a villain that sends marching orders to cells, Felsher said.

In the new research, Felsher and colleagues worked with genetically engineered mice to develop a way to slightly adjust the Myc switch instead of turning it on or off.

The study was published in the July 1 issue of Cancer Research.

The researchers found that by turning down the Myc switch, like using a dimmer switch on a lamp, they could shrink tumor cells to normal sizes and restore their ability to die as they're supposed to.

The findings suggest that researchers trying to turn off the signal may not need to go that far, Felsher said. "Before, we thought there were these switches that you had to turn on and off," he said. "Now, we've added a dimmer. To me, that's really exciting."

But he cautioned that there's no treatment based on this approach yet, and fixing the genetic signals won't work for every type of cancer.

However, scientists have implicated the Myc signal in cancers of the immune system and the lungs. "It is estimated that problems with Myc contribute to the cancer-related deaths of as many as 70,000 Americans every year," said Tansey. "So, it's a huge issue."

As for the current study, Tansey said it's an "important step."

"But cancer is a very tough problem," he said, "and a cure will only come once all its facets have been revealed, and the technology required to manipulate the cancers refined."

More information

Learn more about cancer genetics from the National Cancer Institute.

Posted: July 2008


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