Tiny RNA Molecules Control Breast Cancer's Spread

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"Indeed, when I looked at two of the microRNAs, women who had lost either of them had a significantly higher risk for having the cancers come back," Tavazoie said. "This supported the hypothesis that these small RNA molecules could be playing an important role in regulating the spread of cancers."

Tavazoie then identified six genes or "players" that one of these "supervisors" regulated. He took out two of the genes in lab mice and watched the cancer become more aggressive.

"The 'supervisors' put the brakes on the 'players,' so when you take out the players, the cells can't spread any more," Tavazoie explained.

When he analyzed genes from more than 300 cancer patients, he found that women with higher levels of the six genes had a greater chance of having the cancer move to the lung and bone.

"The story suggests that these small RNAs seem to play an important supervisory or regulatory role in putting a brake on some of these genes," Tavazoie said. "In women whose cancers have lost this brake, it seems that they're more likely for the cancer to spread."

More information

The American Cancer Society has more on breast cancer.