Syndicate content

Archive - Jun 11, 2009

MicroRNA Halts Liver Cancer in Mice

By administering a specific miRNA molecule that is reduced in hepatocellular carcinoma (HCC), scientists have halted the progression of liver tumors in mice. The results demonstrate for the first time that therapeutic delivery of a miRNA in an animal can result in tumor suppression, without the need for specifically targeting the cancer-causing oncogene. "This concept of replacing microRNAs that are expressed in high levels in normal tissues, but lost in diseases hasn't been explored before," said Dr. Joshua Mendell, senior author of the study. "Our work raises the possibility of a more general therapeutic approach that is based on restoring microRNAs to diseased tissues." HCC, which is the third leading cause of cancer deaths, expresses a reduced number of miRNAs, including miR-26a. By combining miRNA technology developed at Johns Hopkins, with the gene delivery expertise at Nationwide Children's Hospital, the reporting researchers were able to successfully deliver a recombinant adeno-associated virus (AAV) carrying miR-26a in a mouse model of HCC. This gene therapy strategy inhibited growth of cancer cells and led to tumor reduction and cell death, without causing toxic side effects to the remainder of the liver. The research team was made up of collaborators from Johns Hopkins, Nationwide Children’s Hospital, and Ohio State University. This work was published in the June 12 issue of Cell. [Press release 1] [Press release 2] [Cell abstract]

Idol Enzyme Seizes Spotlight in Cholesterol Control

In a mouse system, UCLA researchers have identified an enzyme (Idol) that orchestrates the breakdown of LDL receptors and results in higher levels of LDL (“bad cholesterol”) in the blood stream. By blocking Idol’s activity, the researchers triggered cells to make more LDL receptors and to remove more LDL from the body. Statin drugs also reduce LDL levels by boosting cells' production of the LDL receptor. The current findings could lead to a new drug that works in conjunction with statins, or that could be taken by patients who cannot tolerate statins' side effects. "We only know of three pathways that regulate the LDL receptor. The first two are already targeted by existing drugs," explained Dr. Peter Tontonoz, senior author of the report. "Idol is the first mechanism discovered in several years that may lead to a new medication designed to control cholesterol levels." The work was published in the June 11 online edition of Science. [Press release] [Science abstract]

Revival of American Chestnut Tree Could Slow Global Warming

According to a Purdue University study, the introduction of a new hybrid of the all-but-extinct American chestnut tree might bring back the tree and serve to reduce the amount of carbon in the atmosphere and slow global climate change. Dr. Douglass Jacobs, the lead author of the report, found that American chestnuts grow much faster and larger than other hardwood species, allowing these trees to sequester more carbon than other trees over the same period. And because American chestnut trees are more often used for high-quality hardwood products such as furniture, they hold the carbon longer than does wood used for paper or other low-grade materials. Carbon dioxide is considered a major greenhouse gas, responsible for rising global temperatures. Dr. Jacobs said that trees absorb about one-sixth of the carbon emitted globally each year. Increasing the amount that can be absorbed annually could make a considerable difference in slowing climate change, he said. At the beginning of the last century, the chestnut blight, caused by a fungus, rapidly spread throughout the American chestnut's natural range, which extended from southern New England and New York, southwest to Alabama. About 50 years ago, the species was nearly gone. New efforts to hybridize remaining American chestnuts with blight-resistant Chinese chestnuts have resulted in a species that is about 94 percent American chestnut with the protection found in the Chinese species. Dr. Jacobs said that these new trees could be ready to plant in the next decade, either in existing forests or former agricultural fields that are being returned to forested land. This work was published in the June issue of Forest Ecology and Management.