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Archive - Jul 3, 2012

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Pathway Understanding Key to Cancer Drug Discovery

As the Genetics Society of America's Model Organism to Human Biology (MOHB): Cancer Genetics Meeting in Washington, D.C. drew to a close, it was clear that the mantra for drug discovery to treat cancers in the post-genomic era is pathways. Pathways are ordered series of actions that occur as cells move from one state, through a series of intermediate states, to a final action. Because model organisms – fruit flies, roundworms, yeast, zebrafish, and others – are related to humans, they share many of the same pathways, but in systems that are much easier to study. Focusing on pathways in model organisms can therefore reveal new drug targets that may be useful in treating human disease. "By reading evolution's notes, we can discover what really matters in the genome," keynote speaker Eric Lander, Ph.D., founding director of the Broad Institute of Harvard and MIT and professor of biology at MIT, told a packed crowd at the MOHB: Cancer Genetics Meeting on June 19, 2012. What matters the most in the genome of a cancer cell may be the seeds of drug resistance, the genetic changes that enable cells to evade our best drugs, Bert Vogelstein, M.D., director of the Ludwig Center at Johns Hopkins University and an investigator with the Howard Hughes Medical Institute and a keynote speaker on June 17, told participants. He called drug resistance to single agents a "fait accompli," as a side effect of the evolution of cancer. "About 3,000 resistant cells are present in every visible metastasis," said Dr. Vogelstein. "That's why we see resistance with all therapeutics, even when they work. And we can't get around it with single agents.

Epigenetics Alters Genes in Rheumatoid Arthritis

It's not just our DNA that makes us susceptible to disease and influences its impact and outcome. Scientists are beginning to realize more and more that important changes in genes that are unrelated to changes in the DNA sequence itself – a field of study known as epigenetics – are equally influential. A research team at the University of California (UC), San Diego – led by Dr. Gary S. Firestein, professor in the Division of Rheumatology, Allergy, and Immunology at UC San Diego School of Medicine – investigated a mechanism usually implicated in cancer and in fetal development, called DNA methylation, in the progression of rheumatoid arthritis (RA). The researchers found that epigenetic changes due to methylation play a key role in altering genes that could potentially contribute to inflammation and joint damage. Their study was published online on June 26, 2012 in the Annals of the Rheumatic Diseases. "Genomics has rapidly advanced our understanding of susceptibility and severity of rheumatoid arthritis," said Dr. Firestein. "While many genetic associations have been described in this disease, we also know that if one identical twin develops RA that the other twin only has a 12 to 15 percent chance of also getting the disease. This suggests that other factors are at play – epigenetic influences." DNA methylation is one example of epigenetic change, in which a strand of DNA is modified after it is duplicated by adding a methyl group to any cytosine molecule (C) – one of the 4 main bases of DNA. This is one of the methods used to regulate gene expression, and is often abnormal in cancers and plays a role in organ development.

Honey Bees Can Reverse Brain Aging

Scientists at Arizona State University (ASU) have discovered that older honey bees effectively reverse brain aging when they take on nest responsibilities typically handled by much younger bees. While current research on human age-related dementia focuses on potential new drug treatments, researchers say these findings suggest that social interventions may be used to slow or treat age-related dementia. In a study published online on May 21, 2012 in Experimental Gerontology, a team of scientists from ASU and the Norwegian University of Life Sciences, led by Dr. Gro Amdam, an associate professor in ASU’s School of Life Sciences, presented findings that show that tricking older, foraging bees into doing social tasks inside the nest causes changes in the molecular structure of their brains. “We knew from previous research that when bees stay in the nest and take care of larvae – the bee babies – they remain mentally competent for as long as we observe them,” said Dr. Amdam. “However, after a period of nursing, bees fly out gathering food and begin aging very quickly. After just two weeks, foraging bees have worn wings, hairless bodies, and more importantly, lose brain function – basically measured as the ability to learn new things. We wanted to find out if there was plasticity in this aging pattern so we asked the question, ‘What would happen if we asked the foraging bees to take care of larval babies again?” During experiments, scientists removed all of the younger nurse bees from the nest – leaving only the queen and babies. When the older, foraging bees returned to the nest, activity diminished for several days. Then, some of the old bees returned to searching for food, while others cared for the nest and larvae.