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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.

Next-Gen Sequencing Reveals Single Genetic Change in Some Ovarian Cancers

Using powerful “next-generation” sequencing technology, researchers in Canada have sequenced the entire genome of a rare and often untreatable form of ovarian cancer (granulosa cell tumors) from four individuals and shown that the tumors share a single base change in the gene FOXL2. This gene encodes a transcription factor known to be critical for granulosa cell development. The research team further validated its work by examining a large number of additional tumor samples from across Canada and around the world, and the team is satisfied it has been able to validate that this mutation is present in almost all granulosa cell tumors and not in unrelated cancers. Most types of cancers, including most ovarian cancers, have a broad range of genetic abnormalities. The current finding shows that granulosa cell tumors have a characteristic single DNA spelling mistake that can serve as an easy-to-read identity tag for this cancer type. "This is really a two-fold discovery," said Dr. David Hunstman, senior author of the research report. "It clearly shows the power of the new generation of DNA sequencing technologies to impact clinical medicine, and for those of us in the area of ovarian cancer research and care, by identifying the singular mutation that causes granulosa cell tumours, we can now more easily identify them and develop news ways to treat them." For this effort, the research team used next-generation sequencing machines that are able to decode billions of nucleotides at rapid speed, together with new computer techniques to quickly assemble the data. "This task would have been unfathomable in terms of both cost and complexity even two years ago," said Dr. Marco Marra, also an author of the report. This work was published in the June 11 issue of the New England Journal of Medicine.

Four New Targets (LPA Pathway) for Breast Cancer Therapies

Researchers at the M.D. Anderson Cancer Center have identified four related new potential targets for breast cancer therapies. These potential targets are three lysophosphatidic acid (LPA) receptors (LPA1, LPA2, and LPA3) and the LPA-producing enzyme, autotoxin (ATX). "Lysophosphatidic acid is the single most potent known cellular survival factor," said senior author Dr. Gordon Mills. It binds to a series of G protein-coupled receptors to spark normal cell proliferation, viability, production of growth factors, and survival. The current research shows that this powerful network is hijacked to initiate breast cancer and fuel tumor growth, invasion, and metastasis. The authors show that breast cancer-resistant mice, when engineered to overexpress any one of the four molecules, develop invasive and metastatic mammary cancers. “We've compiled lots of evidence that they (LPA1, LPA2, LPA3, and ATX) are associated with cancer; what's been missing is proof that they could cause cancer. There are no questions left; they should be targeted." A number of drugs that target the receptors and ATX are currently in preclinical development, Dr. Mills said. "Now we have transgenic mouse models to test drugs to go forward against these targets." The current research was published in the June edition of Cancer Cell. [Press release] [Cancer Cell abstract]

Beetle Shell May Be Clue to Whiter, Lighter Paper

The brilliant white shell of an obscure beetle (Cyphochilus) has provided scientists with insights as to how to produce a brighter coating for white paper. The novel coating would also be thinner and lighter than current coatings and this would translate into reduced transportation costs, while simultaneously reducing the economic and environmental costs of manufacture. Cyphochilus is native to south-east Asia, and it is believed that its whiteness evolved to mimic local white fungi as a form of camouflage. In 2007, research conducted at the University of Exeter and Imerys Minerals Ltd., and published in Science, revealed how the beetle produces its brilliant whiteness using a unique surface structure of long, flat, ultrathin scales with highly random internal 3-D structures--ideal for creating whiteness, which results from the scattering of all colors simultaneously. In the new work, members of the same research team showed how some of the beetle’s shell structure can be mimicked to produce thinner, whiter coatings for white paper. "It is interesting to consider that clues found in a small, obscure beetle could find application in large-scale industry,” one of the researchers noted. “Taking this concept forward is an interesting challenge, but we have good ideas about our next steps and, if successful, feel that such developments might have profound implications for future commercial white coatings.” The current research was published in the June 10 issue of Applied Optics. [Press release] [Applied Optics abstract]

Termite Results Suggest Non-Toxic Approach to $30 Billion Pest Problem

Scientists at MIT and collaborating institutions have shown that a naturally occurring, non-toxic glucose derivative, GLD, can be used to compromise the immunity of termites and make them more vulnerable to lethal microbial infections. Insect pests such as termites cause damage to crops and man-made structures estimated at over $30 billion per year, imposing a global challenge on the human economy, the authors noted. They said that the use of GLD may lead to the development of non-toxic, sustainable pest control methods. Termites normally secrete a form of an antimicrobial protein into their nests to prevent pathogenic infections. The authors reported a technique to block this protein’s effects with GDL. They found that adding GDL to termite nests caused the termites to die more quickly at the hands of fungi that normally infect termites, as well as at the hands of opportunistic bacteria. The authors suggested that GDL, which is also biodegradable, and other similar molecules could be developed for food processing and storage and for use in building materials to protect against insect attacks. Plants could be engineered to produce GDL at high amounts in specific locations to increase their immunity, the authors suggested. This work was published online on June 8 in PNAS. [PNAS abstract]

New Angiogenesis Target Discovered

A new angiogenesis-promoting growth factor has been identified by researchers at the University of North Carolina and collaborating institutions. The newly identified growth factor protein, SFRP2, was found in the blood vessels of numerous tumor sites, including breast, prostate, lung, pancreas, ovarian, colon, kidney, and angiosarcomas. “The discovery that SFRP2 stimulates angiogenesis and is present in blood vessels of a wide variety of tumors provides us with a new target for drug design,” said Dr Nancy Klauber-DeMore, the senior author of the study. One growth factor that causes angiogenesis has been previously identified--vascular endothelial growth factor or VEGF--and drugs to inhibit VEGF are already in use. But not all tumors respond to the therapy initially or over the long term. Thus, new growth factors need to be identified to aid in developing the next generation of angiogenesis inhibitors. The current work was reported online in Cancer Research. [Press release]

Primary Insomnia Linked to Neurochemical Abnormality

For the first time, researchers have identified a specific neurochemical abnormality in adults with primary insomnia. Primary insomnia is difficulty getting to sleep or staying asleep, or having non-refreshing sleep, for at least one month without any known physical or mental condition. The current study results indicate that gamma-aminobutyric acid (GABA), the most common inhibitory transmitter in the brain, is reduced by nearly 30 percent in individuals who suffer from primary insomnia for more than six months. These findings suggest that primary insomnia is a manifestation of a neurobiological state of hyperarousal, which is present during both waking and sleep at physiological and cognitive levels. "Recognition that insomnia has manifestations in the brain may increase the legitimacy of those who have insomnia and report substantial daytime consequences," said Dr. John Winkelman, of Brigham and Women’s Hospital at Harvard Medical School, the principal investigator on the study. "Insomnia is not just a phenomenon observed at night, but has daytime consequences for energy, concentration, and mood." This work was reported June 9 at SLEEP 2000, the 23rd Annual Meeting of the Associated Professional Sleep Societies. [Press release]

Active Microenvironment May Provide Treatment Targets for Prostate Cancer

In a study of the response of prostate stroma (the surrounding structural framework of the prostate gland) to prostate cancer, researchers at the Baylor College of Medicine have identified 1,141 genes whose expression is altered in this response. Among the gene expression changes are ones that induce the formation of new structures such as blood vessels, nerves, and parts of nerves. These changes may explain why men with reactive stroma face a more aggressive disease, said Dr. Michael Ittmann, a senior author of the report. "Often in prostate cancer, you don't see much change in the stromal cells," said Dr. Ittmann. "However, in this subgroup of patients (in which the stroma become visibly reactive), you see a histologically recognizable change in the appearance of the stroma. Dr. (Gustavo) Ayala (another senior author of the report) has shown previously that this correlates with a bad prognosis. We know the stroma are doing something to promote bad behavior in cancer cells." "These findings are very important as this is the first step in discovering pathways and mechanisms in the tumor microenvironment that could be targeted as a novel therapeutic approach to treat prostate cancer by treating the cancer microenvironment niche,” said Dr. David Rowley, another author of the report, which was published in Clinical Cancer Research. [Press release]

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