Study Shows Gene Silencing Acts Broadly

U.S. scientists say they’ve discovered that a technique to silence the expression of genes also acts on many genes, rather than just one.

The technique uses synthetic molecules called small-interfering RNA, or siRNA, that suppress, or silence, genes that promote the growth of blood vessels. Drugs containing the molecules could be used to stop the growth of blood vessels that nourish cancer cells, thereby starving the cancer.

But the study’s findings show such drugs might also stop the growth of blood vessels in healthy cells, harming people the drugs were intended to treat.

University of Kentucky Professor Jayakrishna Ambati, the paper’s senior author, said siRNAs are thought to be exquisitely specific in targeting a single gene. But the researchers discovered siRNAs act on many genes, and block blood vessel growth in the eye, skin and a variety of other organs, said Ambati.

Blocking blood vessel growth is beneficial in diseases such as age-related macular degeneration, an eye disease characterized by the abnormal growth of blood vessels beneath the retina, and in some cancers. However, blocking blood vessel growth is other organs could be harmful.

The study appeared in a recent issue of the journal Nature.