Break in the Program

Scientists find that an overactive gene controller called micro RNA causes cancer in mice—and potentially humans

By Victor Limjoco|Tuesday, August 22, 2006

Ever since the discovery in 1993 of a new class of genes, scientists have suspected that these genes might be a significant cause of many cancers. Thanks to new research from genetics researcher Carlo Croce, scientists now have proof—and the discovery could help them develop much more successful cancer treatments.

The recent finding involves "micro RNA genes," which act as controllers of other genes in our bodies, activating and deactivating them. Micro RNA binds to and controls the expression of messenger RNA, which shuttles genetic information from DNA to protein factories in the body's cells. While Croce and others have found altered micro RNA genes in many types of cancerous cells there had been no proof that they actually caused cancer.

So Croce's team at Ohio State University inserted a hyperactive version of micro RNA called miR-155 into mice. As the researchers noted in Proceedings of the National Academy of Sciences, this single alteration caused the mice to develop leukemia and lymphomas, two major types of cancer. This discovery could result in major applications for cancer treatment in humans: Croce says miR-155 "is very active in a variety of common human cancers," including those of the lung, breast, and colon.

The next challenge, Croce says, is to develop treatments based on alterations on miR-155. "These micro RNA can be used as drugs because they are so small," he says. "We can synthesize a lot of them." Croce says his team is already testing whether this strategy can kill cancer cells in mice. If successful in mice, the genes could later end up in human medicines.

This is not the first time Croce has made an important finding concerning human oncogenes, or genes that produce cancers. In the 1970s and '80s he discovered several others, and treatments that focus on those oncogenes have helped countless patients, especially those with lymphoma and leukemia.

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