If you are a scientist and you want to turn off a gene, one option that’s been gaining traction is RNA interference (or RNAi). In this molecular process—first discovered in plants and only 12 years ago detected in mammals—bits of RNA called small interfering RNAs (siRNAs) cancel out a gene’s messenger RNA, effectively muffling that gene.
Labs can order custom-made, chemically synthesized siRNAs for just about any DNA sequence they want to silence. The tricky part is deciding what the right sequence is—especially when that gene is part of a virus, where genes can mutate pretty quickly.
However, a biotechnology approach to producing siRNAs could make it relatively easy for just about any lab that can master recombinant DNA technologies to make a number of siRNAs against multiple sequences within the same target gene: a potential bonus for companies seeking to make drugs that rely on RNAi. …
Breast cancers whose cells carry the HER2 protein are pretty tough customers. They only account for about 20 percent of all breast cancers, but they are some of the most aggressive. While targeted drugs like trastuzumab (Herceptin) and lapatinib (Tykerb) have made these tumors easier to treat, those that resist these drugs, relapse or don’t have HER2 on their cells’ surfaces can still stymie oncologists.
A molecular phenomenon called RNA interference (RNAi)—in which small pieces of RNA silence the expression of individual genes—could provide an alternative solution for breast and other cancers.
Though it was first discovered in plants, researchers have known for about a decade that small interfering RNAs (siRNAs) are active in mammals like us, and are already working on ways to harness them for shutting down genes promoting cancer and other diseases.
The problem with siRNAs for treatment, however, is making sure they get exactly where they need to go. That’s a problem that Judy Lieberman, MD, PhD, has taken a big step toward solving. …
This month marks an anniversary that no one wants to see: 30 years since the first paper describing what we know now as HIV/AIDS.
Over those three decades, more than 30 million people worldwide have died from the disease. We have learned a great deal – how HIV is passed from person to person, how long it circulated among humans before it was recognized, how to control it with antiretroviral drugs. Yet HIV still spreads: An additional 2.6 million people were infected with it in 2009 alone. Safe sex practices like condom use provide an effective barrier against passage of the virus, but don’t affect HIV’s ability to gain a foothold should the barrier fail.
Judy Lieberman and Lee Adam Wheeler want to move prevention beyond one-time physical blockades to longer-lasting, more reliable molecular resistance. “The current model of HIV transmission holds that the virus is localized to the genital tract for about a week,” says Lieberman, “which could provide a window of opportunity to intervene and prevent the infection from establishing itself throughout the body.” …
HIV is unique among viruses in many ways. Here’s another: upon breaking into a cell, it erases evidence of its presence by exploiting a natural cellular “cleanup” mechanism. It thereby manages to dodge the innate immune system, the body’s first line of attack against invaders.