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Archive - Apr 27, 2012

Mayo Scientists ID Single Gene Driving Most Common Form of Lung Cancer

A single gene that promotes initial development of the most common form of lung cancer and its lethal metastases has been identified in a mouse model by researchers at the Mayo Clinic in Florida. Their study suggests other forms of cancer may also be driven by this gene, matrix metalloproteinase-10 (MMP-10). The study, published in PLoS ONE on April 24, 2012, shows that MMP-10 is a growth factor secreted and then used by cancer stem-like cells to keep themselves vital. These cells then drive lung cancer and its spread, and are notoriously immune to conventional treatment. The findings raise hope for a possible treatment for non-small cell lung cancer, the leading cause of U.S. cancer deaths. Researchers discovered that by shutting down MMP-10, lung cancer stem cells lose their ability to develop tumors. When the gene is given back to the cells, they can form tumors again. The power of this gene is extraordinary, says senior investigator Alan Fields, Ph.D., the Monica Flynn Jacoby Professor of Cancer Research within the Department of Cancer Biology at the Mayo Clinic in Florida. "Our data provides evidence that MMP-10 plays a dual role in cancer. It stimulates the growth of cancer stem cells and stimulates their metastatic potential," he says. "This helps explain an observation that has been seen in cancer stem cells from many tumor types, namely that cancer stem cells appear to be not only the cells that initiate tumors, but also the cells that give rise to metastases." Dr. Fields says the findings were unexpected, for several reasons. The first is that the cancer stem cells express MMP-10 themselves, and use it for their own growth. Most of the known members of the matrix metalloproteinase gene family are expressed in the tumor's microenvironment, the cells and tissue that surround a tumor, he says.

Progress on Understanding Pathology of Deadly Amphibian Fungus

The fungal infection that killed a record number of amphibians worldwide leads to deadly dehydration in frogs in the wild, according to results of a new study. High levels of an aquatic, chytrid fungus called Batrachochytrium dendrobatidis (Bd) disrupt fluid and electrolyte balance in wild frogs, the scientists say, severely depleting the frogs' sodium and potassium levels and causing cardiac arrest and death. Their findings confirm what researchers have seen in carefully controlled lab experiments with the fungus, but San Francisco State University biologist Dr. Vance Vredenburg said the data from wild frogs provides a much better idea of how the disease progresses. "The mode of death discovered in the lab seems to be what's actually happening in the field," he said, "and it's that understanding that is key to doing something about it in the future." Results of the study were published online on April 25, 2012 in the journal PLoS ONE. "Wildlife diseases can be just as devastating to our health and economy as agricultural and human diseases," said Sam Scheiner, NSF program officer for the joint National Science Foundation-National Institutes of Health Ecology and Evolution of Infectious Diseases program, which funded the research. "Bd has been decimating frog and salamander species worldwide, which may fundamentally disrupt natural systems," said Scheiner. "This study is an important advance in our understanding of the disease--a first step in finding a way to reduce its effects." At the heart of the new study are blood samples drawn from mountain yellow-legged frogs by Dr. Vredenburg and colleagues in 2004, as the chytrid epidemic swept through California's Sierra Nevada mountains.

Mirror MicroRNAs Control Multiple Aspects of Brain Function

Our genes control many aspects of who we are — from the color of our hair to our vulnerability to certain diseases — but how are the genes, and consequently the proteins they make, themselves controlled? Researchers have discovered a new group of molecules that control some of the fundamental processes behind memory function and may hold the key to developing new therapies for treating neurodegenerative diseases. The research, led by academics from the UK’s University of Bristol's Schools of Clinical Sciences, Biochemistry and Physiology and Pharmacology and published in the April 27, 2012 issue of the Journal of Biological Chemistry, has revealed a new group of molecules called mirror-microRNAs. MicroRNAs are non-coding genes that often reside within 'junk DNA' and regulate the levels and functions of multiple target proteins — responsible for controlling cellular processes. The study's findings have shown that two microRNA genes with different functions can be produced from the same piece (sequence) of DNA — one is produced from the top strand and another from the bottom complementary 'mirror' strand. Specifically, the research has shown that a single piece of human DNA gives rise to two fully processed microRNA genes that are expressed in the brain and have different and previously unknown functions. One microRNA is expressed in the parts of nerve cells that are known to control memory function and the other microRNA controls the processes that move protein cargos around nerve cells. Dr. James Uney, Professor of Molecular Neuroscience in the University's School of Clinical Sciences, said: "These findings are important as they show that very small changes in miRNA genes will have a dramatic effect on brain function and may influence our memory function or likelihood of developing neurodegenerative diseases.

Scientists Identify Element of GPS in Pigeons

Birds do not need the latest in navigational technology when it comes to flying south for the winter; they come with their own built-in GPS system that uses the Earth’s magnetic field. But just how they detect the magnetic force is still unknown. Researchers at Baylor College of Medicine (BCM) are now closer to answering that question. In a study that was published online in Science on April 26, 2012, Drs. Le-Qing Wu, post-doctoral fellow, and J. David Dickman, professor of neuroscience, both at BCM, have shown how certain brain cells in pigeons encode the direction and intensity of the Earth’s magnetic field. "We know birds and many other animals can sense the magnetic force; behavioral studies show that birds fly along magnetic routes during seasonal changes," said Dr. Dickman, who conducted much of the research while at Washington University in St. Louis. "It is still unknown what exactly acts as a receptor within the bird; however, in our current study we are able to show how neurons in the pigeon’s brain encode magnetic field direction and intensity. This is how we believe birds know their position on the surface of the Earth." Dr. Dickman said certain areas of the brain are activated when a particular area of the inner ear, known as the lagena, is exposed to a magnetic field. Without it, several of these corresponding areas in the brain show no activity. Drs. Dickman and Wu used electrodes in one brain area, known as the vestibular nuclei, to record activity when the bird was exposed to a changing magnetic field. "The cells responded to the angle and intensity of the magnetic field. Some cells were more sensitive depending on what direction we aimed the magnetic field around the bird’s head," Dr. Dickman said.