Agent orange chemical, dioxin, attacks the mitochondria to cause cancer, says Penn research team

Contact: Jordan Reese
jreese@upenn.edu
215-573-6604
University of Pennsylvania

PHILADELPHIA— Researchers with the University of Pennsylvania School of Veterinary Medicine have demonstrated the process by which the cancer-causing chemical dioxin attacks the cellular machinery, disrupts normal cellular function and ultimately promotes tumor progression.

The team identified for the first time that mitochondria, the cellular sub-units that convert oxygen and nutrients into cellular fuel, are the target of tetrachlorodibenzodioxin, or TCDD. The study showed that TCDD induces mitochondria-to-nucleus stress signaling, which in turn induces the expression of cell nucleus genes associated with tumor promotion and metastasis.

The mechanism the research team has described is directly relevant to understanding incidences of breast and other cancers in human populations exposed to these chemicals. With a better understanding of this underlying cellular mechanism, researchers hope to improve their understanding of tumor growth and promotion.

“Now that we have identified this signaling mechanism we can look at ways to disrupt this complex chain of events,” said Narayah Avadhani, chair of the Department of Animal Biology at Penn’s School of Veterinary Medicine and the study’s lead investigator. “Our ultimate goal is to block the propagation of this mitochondrial stress signaling and inhibit the expression of the proteins that combine to assist cancer growth.”

A well-characterized mechanism of TCDD action occurs through activation of arylhydrocarbon receptors, AhR, by directly binding to the protein subunits. Activated AhR mediates the transcriptional activation of many genes including those involved in fatty acid metabolism, cell cycle regulation and immune response. The present study, however, shows that TCDD starts the chain of events that promote tumor progression in vivo by directly targeting mitochondrial transcription and induction of mitochondrial stress signaling. A unique feature of this TCDD-induced signaling is that it does not involve the action of AhR but occurs through increased calcium levels in cells and activation of calcium responsive factors. A net result of signaling cascade is slowing down of cellular apoptosis, increased cell proliferation and tumor cell metastasis. Taken together, this study describes a novel mechanism of TCDD-induced tumor progression and emergence of metastatic cancer cells.

TCDD is the most toxic compound in the dioxin family. Formed as a by-product during waste incineration, paper, chemical and pesticide manufacturing, it was the toxic ingredient in Agent Orange and closed the Love Canal in Niagara Falls. The public health impact of dioxin, according to the Environmental Protection Agency, compares to that of the pesticide DDT.

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The study appears online and in the Dec. 17 issue of the Proceedings of the National Academy of Sciences and was performed by Avadhani, Gopa Biswas, Satish Srinivasan and Hindupur Anandatheerthavarada of the Penn School of Veterinary Medicine.

The research was supported by a grant from the National Cancer Institute and the National Institutes of Health.

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Cholesterol-lowering drugs and the risk of hemorrhagic stroke

Contact: Angela Babb
ababb@aan.com
651-695-2789
American Academy of Neurology

ST. PAUL, Minn. – People taking cholesterol-lowering drugs such as atorvastatin after a stroke may be at an increased risk of hemorrhagic stroke, or bleeding in the brain, a risk not found in patients taking statins who have never had a stroke. But researchers caution the risk must be balanced against the much larger overall benefit of the statin in reducing the total risk of a second stroke and other cardiovascular events when making treatment decisions. The research is published in the December 12, 2007, online issue of Neurology®, the medical journal of the American Academy of Neurology.

For the study, researchers conducted a secondary analysis of the results of the Stroke Prevention with Aggressive Reduction in Cholesterol Levels (SPARCL) clinical trial. The trial enrolled 4,731 people who were within one to six months of having had a stroke or transient ischemic attack, or mini-stroke, and with no history of heart disease. Half of the participants received atorvastatin and half received a placebo. The participants were then followed for an average of four and a half years.

Overall, treatment was associated with a 16-percent reduction in total stroke, the study’s primary endpoint, as well as significant reductions in coronary heart events. However, secondary analysis found that the overall reduction in stroke included an increase in the risk of brain hemorrhage. Of those people randomized to atorvastatin, the study found 2.3 percent experienced a hemorrhagic stroke during the study compared to 1.4 percent of those taking placebo. The study also found there was a 21-percent reduction in ischemic stroke, a more common type of stroke involving a block in the blood supply to the brain, among people taking atorvastatin.

Other factors were also found to increase the risk of brain hemorrhage. For example, those who had experienced a hemorrhagic stroke prior to the study were more than five times as likely to suffer a second stroke of this kind. Men were also nearly twice as likely as women to suffer a hemorrhagic stroke. People with severe high blood pressure at their last doctor’s visit prior to the hemorrhagic stroke had over six times the risk of those with normal blood pressure.

“Although treatment of patients with a stroke or transient ischemic attack was clearly associated with an overall reduction in a second stroke, hemorrhagic stroke was more frequent in people treated with atorvastatin, in those with a prior hemorrhagic stroke, in men and in those with uncontrolled hypertension,” according to study author Larry B. Goldstein, MD, with Duke University Medical Center in Durham, North Carolina, and Fellow of the American Academy of Neurology. “This risk of hemorrhagic stroke also increased with age.”

“Treatment with atorvastatin did not disproportionately increase the frequency of brain hemorrhage associated with these other factors. The risk of hemorrhage in patients who have had a transient ischemic attack or stroke must be balanced against the benefits of cholesterol-lowering drugs in reducing the overall risk of a second stroke, as well as other cardiovascular events,” said Goldstein.

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The SPARCL trial was funded by Pfizer, the maker of atorvastatin.

The American Academy of Neurology, an association of more than 20,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer’s disease, epilepsy, Parkinson disease, and multiple sclerosis.

For more information about the American Academy of Neurology, visit http://www.aan.com.

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Demand for Spanish-language cancer Web materials quadruples

Contact: Beth Bukata
bethb@astro.org
703-431-2332
American Society for Therapeutic Radiology and Oncology

Internet resources and access remain scarce

Although Spanish-speaking cancer patients are rapidly increasing their search for patient education resources on the Internet, there are very few Spanish-language Web sites available to provide this information, according to a study presented October 28, 2007, at the American Society for Therapeutic Radiology and Oncology’s 49th Annual Meeting in Los Angeles.

Spanish-speaking cancer patients were also shown to have more limited access to the Internet compared to English-speaking users of cancer information Web sites, based on the user patterns of the two groups.

“There is an urgent need for more Web-based information to be more available to Spanish-speaking patients with cancer, and Internet access needs to be more widely available,” said Charles Simone II, M.D., lead author of the study and a radiation oncologist at the Hospital of the University of Pennsylvania in Philadelphia. “The increased knowledge gained among these patients will help to eliminate healthcare disparities and lead to improved medical outcomes.”

The Spanish-language cancer information Web site, OncoLink en español, quadrupled their number of unique visitors last year, from 7,000 visitors per month in January 2006 to nearly 29,000 monthly visitors by the end of the year. More than 200,000 users visited the Web site in 2006.

In contrast, the English-language version of the site, OncoLink, had nearly 2 million visitors last year, although their number of unique visitors did not increase throughout the year. OncoLink en espanõl was launched in 2005 by OncoLink, one of the oldest and largest Internet-based cancer information resources. Both sites are managed by the University of Pennsylvania.

The study shows that OncoLink en español users were less likely to browse the Internet during weekends and morning hours, compared to the users who browsed OncoLink, suggesting that they are accessing the Internet more through work or specialized services.

In addition to when they accessed the Internet, OncoLink en español users also differed on the types of cancers they searched for, as well as the timing and method of their Internet search patterns.

“Awareness of these differences can assist cancer education Web sites to tailor their content to best meet the needs of their Spanish-speaking users,” said Dr. Simone.

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The study was carried out using AWStats, a Web-data analyzing program, to collect and compare statistical data from the secure servers of both language versions of OncoLink.

For more information on radiation therapy in English and in Spanish, visit http://www.rtanswers.org.

The abstract, “The Utilization of Radiation Oncology Web-based Resources in Spanish-speaking Oncology Patients,” will be presented for poster viewing starting at 10:00 a.m, Sunday, October 28, 2007. To speak to the study author, Charles Simone, II, M.D, please call Beth Bukata or Nicole Napoli October 28-31, 2007, in the ASTRO Press Room at the Los Angeles Convention Center at 213-743-6222 or 213-743-6223. You may also e-mail them at bethb@astro.org or nicolen@astro.org.

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Americans consider global warming an urgent threat, according to poll

Contact: Janet Rettig Emanuel
janet.emanuel@yale.edu
203-432-2157
Yale University

Links (in order of appearance in the text) to have active are: Anthony Leiserowitz Yale Project on Climate Change

New Haven, Conn. — A growing number of Americans consider global warming an important threat that calls for drastic action, and 40% say that a presidential candidate’s position on the issue will strongly influence how they vote, according to a national survey conducted by Yale University, Gallup and the ClearVision Institute.

“One of the most surprising findings was the growing sense of urgency,” said Anthony Leiserowitz, director of the Yale Project on Climate Change and the study’s principal investigator. “Nearly half of Americans now believe that global warming is either already having dangerous impacts on people around the world or will in the next 10 years—a 20-percentage-point increase since 2004. These results indicate a sea change in public opinion.”

The survey’s findings include:

Sixty-two percent of respondents believe that life on earth will continue without major disruptions only if society takes immediate and drastic action to reduce global warming.

Sixty-eight percent of Americans support a new international treaty requiring the United States to cut its emissions of carbon dioxide 90 percent by the year 2050. Yet, Leiserowitz notes, the United States has yet to sign the Kyoto Protocol, an international treaty that would require the United States to cut its emissions 7 percent by the year 2012.

A surprising 40 percent of respondents say a presidential candidate’s position on global warming will be either extremely important (16 percent) or very important (24 percent) when casting their ballots. “With the presidential primaries and general election near,” Leiserowitz said, “candidates should recognize that global warming has become an important issue for the electorate.”

Eight-five percent of those polled support requiring automakers to increase the fuel efficiency of cars, trucks and SUVs to 35 miles per gallon, even if it meant a new car would cost up to $500 more; and 82 percent support requiring electric utilities to produce at least 20 percent of their electricity from renewable energy sources, even if it cost the average household an extra $100 a year.

Majorities of Americans, however, continue to oppose carbon taxes as a way to address global warming — either in the form of gasoline (67 percent against) or electricity taxes (71 percent against). —.

Finally, 50 percent of respondents say they are personally worried —15 percent say a “great deal”— about global warming. “Many Americans, however, believe that global warming is a very serious threat to other species, people and places far away,” said Leiserowitz, “but not so serious of a threat to themselves, their own families or local communities. Nonetheless, they do strongly support a number of national and international policies to address this problem.”

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The survey was conducted July 23-26, 2007, using telephone interviews with 1,011 adults, aged 18-plus. Respondents came from Gallup’s household panel, which was originally recruited through random selection methods. The final sample is consideredto be representative of U.S. adults nationwide, with a margin of error of ±4 percentage points. Survey results are available online: http://environment.yale.edu/news/5305-american-opinions-on-global-warming/.

The Yale Project on Climate Change at the Yale School of Forestry & Environmental Studies supports public discourse and engagement with climate-change solutions.

Gallup, Inc., headquartered in Washington, D.C., is one of the world’s leading research companies focusing on studying human nature and behavior. The Gallup Poll has been monitoring U.S. public opinion since 1935, and Gallup now tracks public opinion in over 100 countries worldwide on an ongoing basis.

The ClearVision Institute is a nonprofit organization dedicated to applying entertainment education as a social-change strategy to address climate change through U.S. commercial television.

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A new molecular zip code, and a new drug target for Huntington’s disease

McMaster University researchers have first insight into how Huntington’s disease is triggered

McMaster University researchers have first insight into how Huntington’s disease (HD) is triggered. The research will be published online in the British Journal, Human Molecular Genetics, on Monday, August 20.

“These are exciting results by the McMaster team,” said Dr. Rémi Quirion, Scientific Director at the Canadian Institutes of Health Research, Institute of Neuroscience, Mental Health and Addiction. Even if the huntingtin protein has been known for almost 20 years, the cause of Huntington’s disease is still not clear. Data reported here shed new lights on this aspect and possibly leading to new therapeutic potential in the future.”

Ray Truant, professor in the Department of Biochemistry and Biomedical Sciences, has been studying the biological role of the huntingtin protein and the sequences in the protein that tell it where to go within a brain cell.

Huntington disease (HD) is a neurological disorder resulting from degeneration of brain cells. The degeneration causes uncontrolled limb movements and loss of intellectual faculties, eventually leading to death. There is no treatment. HD is a familial disease, passed from parent to child through a mutation in the normal gene. The disorder is estimated to affect about one in every 10,000 persons.

Truant and PhD candidate graduate student, Randy Singh Atwal, have discovered a small protein sequence in huntingtin that allows it to locate to the part of the cell critical for protein quality control. Similar findings have been seen to be very important for other neurodegenerative diseases such as Parkinson’s and Alzheimer’s diseases.

Huntingtin protein is essential for normal development in all mammals, and is found in all cells, yet its function was unknown. It appears that huntingtin is crucial for a brain cell’s response to stress, and moves from the endoplasmic reticulum into the nucleus, the control centre of the cell. When mutant huntingtin is expressed however, it enters the nucleus as it should in response to stress, but it cannot exit properly, piling up in the nucleus and leading to brain cell death in HD.

“What is important to Huntington disease research is that in the learning of the basic cell biology of this protein, we have also uncovered a new drug target for the disease,” says Atwal.

Atwal additionally found that huntingtin can be sent to the nucleus by protein modifying enzymes called kinases, and he has determined the three-dimensional shape of this sequence.

Truant and Atwal’s work indicates that if mutant huntingtin is prevented from entering the nucleus, it cannot kill a brain cell. This means that a kinase inhibitor drug may be effective for Huntington’s disease. Kinase inhibitors form the largest number of successful new generation drugs that are coming to market for a plethora of diseases including stroke, arthritis and cancer.

“This is most exciting to us, because we immediately have all the tools and support in hand at McMaster to quickly hunt this kinase down, and find potential new drugs for Huntington’s disease in ways that are similar or better than a large pharmaceutical company”, says Truant. Truant’s lab is also collaborating in the US with the Cure Huntington’s Disease Initiative (CHDI) a novel, non-profit virtual pharmaceutical company focused on HD.

A large portion of this work was completed in the new McMaster biophotonics facility (www.macbiophotonics.ca), and additional research will be done in McMaster’s unique high throughput screening lab (hts.mcmaster.ca) and other new labs being established at the University.

“We can actually watch huntingtin protein move inside of a single live brain cell in real time in response to stress, and we can watch mutant huntingtin kill that cell, even over days,” says Truant. “Using molecular tools, computer software and sophisticated laser microscopy techniques which we’ve been developing at McMaster over the last seven years, researchers can now use these methods to hopefully watch a drug stop this from happening.”

Truant’s laboratory is supported by grants from the United States High Q Foundation, the Canadian Institutes of Health Research, the Huntington Society of Canada and the Canada Foundation for Innovation.

“This discovery reflects Dr. Truant’s growing contribution to the international campaign to create a world free from Huntington disease,” says Don Lamont, CEO & Executive Director of the Huntington Society of Canada – Canada’s only organization focused on research, education and support in the HD field.

“Our families live on a ‘tightrope’ waiting for an effective treatment or a cure for HD”, says Lamont. “The discovery provides hope for the Huntington community – most of all, hope that their children will not have to suffer the devastation of this inherited disease.”

Contact: Veronica McGuire
vmcguir@mcmaster.ca
90-552-591-402-2169
McMaster University

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ESF EURYI award winner aims to stop cancer cells reading their own DNA

A promising new line in anti-cancer therapy by blocking the molecular motors involved in copying genetic information during cell division is being pursued by young Dutch researcher Dr. Nynke Dekker in one of this year’s EURYI award winning projects sponsored by the European Science Foundation (ESF) and the European Heads of Research Councils (EuroHORCS). Dekker and her team are trying to stop tumor development by interfering with the molecular motors that copy DNA during cell division. This will cut off the genetic information flow that tumours need to grow, and could complement existing cancer therapies, while in the longer term bringing the promise of improved outcomes with greatly reduced side effects.

There are three primary ways of treating cancer at present, and these have fundamentally changed little in 30 years. In the case of solid tumours, surgery can be used to cut out the cancerous tissue, while radiation therapy can kill the malignant cells, and chemotherapy stops them dividing. Dekker’s work is aiming towards a new generation of drugs that target cancer cells much more specifically than traditional chemotherapy, avoiding side effects such as temporary hair loss.

Dekker is focusing on an enzyme called Topoisomerase IB that plays a key role in some of the molecular motors involved in the processes of DNA and RNA copying during cell division. These are responsible for reading the genetic code and making sure it is encoded correctly in the daughter cell. In healthy cells it is important that this process works normally, but in cancer cells it is a natural target for disruptive therapy. “Specifically targeting these molecular motors in cancer cells would then prevent the cancer cells from growing into a larger tumor,” said Dekker. This molecular copying machinery, constructed mostly out of proteins, in effect walks along the DNA double helix reading the genetic code so that it can be copied accurately into new DNA during division. Other components of the machinery are responsible for slicing and assembling the DNA itself. All of these are potential targets for anti-cancer therapy, providing it is possible to single out the tumor cells. Most existing chemotherapy targets all dividing cells, and the aim to find more sensitive techniques.

However Dekker’s work is not just confined to cancer, having the broader goal within the ESF EURYI project of unraveling the underlying physical principles behind these molecular motors that operate at the nanometer scale to process and manipulate the information stored within the DNA and RNA of our cells. Dekker is exploiting a variety of new highly sensitive manipulation and imaging techniques capable of resolving single molecules. These include force spectroscopy, new forms of optical microscopy with greatly improved resolving power and field depth, as well as nanotechnologies. The research involves cross-disciplinary work among scientists in different fields with the long term goal of developing more precisely targeted molecular medicines for a variety of diseases involving disruption to normal cellular functions and not just cancer.

Dekker’s work has already shown great promise, and she has been able to predict what effect certain antitumor drugs would have on the basis of her molecular insights, confirming her hypotheses in yeast cells. “Indeed the work with antitumor drugs is, as far as I know, the first experiment in which single-molecule experiments have resulted in a prediction for a cellular effect,” said Dekker.

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Dekker, a 36-year-old Dutch associate professor at the Technische Universiteit Delft in the Netherlands, is currently undertaking single-molecule studies of DNA and RNA and their interactions with proteins, integrated with nanotechnology where appropriate. She gained her PhD in physics at Harvard University, having graduated from Yale.

As well as being awarded multiple grants and fellowship programmes, Dr. Dekker is a member of the Council of the Biophysical Society, and of the Young Academy of the Royal Academy of Arts and Sciences. She is actively involved in conference organization at the interface of biology and physics. Her group’s research has appeared in Nature and in The Proceedings of the National Academy, USA, among others.

The EURYI awards scheme, entering its fourth and final year, is designed to attract outstanding young scientists from around the world to create their own research teams at European research centres and launch potential world-leading research careers. Most awards are between €1,000,000 and €1,250,000, comparable in size to the Nobel Prize. Dekker will receive his award in Helsinki, Finland on 27 September 2007 with other 19 young researchers.

More on Dekker’s work http://www.esf.org/activities/euryi/awards/2007/nynke-hester-dekker.html

More on EURYI: http://www.esf.org/ext-ceo-news-singleview/article/2007-euryi-20-young-researchers-to-receive-nobel-prize-sized-awards-for-breakthrough-ideas-294.html

Contact: Thomas Lau
tlau@esf.org
33-388-762-158
European Science Foundation

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A pioneering study opens roads for tailor-made antidepressants

In spite that the causes of depression have not still been fully identified, scientists acknowledge that genetic and environmental factors play a common role in the onset of this disorder. One of the environmental risk factors more often related to depression is exposure to threatening life events. On the other side, from a genetic point of view, the serotonin transporter gene, with a crucial role in communication between neurons, could predispose to depression.

An international group of scientists, headed by professors Jorge Cervilla Ballesteros and Blanca Gutiérrez Martínez, from the department of Legal Medicine, Toxicology and Psychiatry of the University of Granada, has recently published in the prestigious journal Molecular Psychiatry the pioneering study PREDICT-gene, confirming the relation between allele s in the serotonin transporter gene and exposure to threatening life events in the onset of depression. The study proves, for a population sample accounting for gender, age and family history of psychiatric disorders, that 24% of the Spanish population, comprising people with the s/s genotype, need minimal exposure to threatening life events, unlike individuals with s/l or l/l genotypes, thus confirming the relation between genetic and environmental factors in this mental disorder.

Tailor-made antidepressants

The most important consequence of research on interaction between genetic and environmental factors is that, in a foreseeable future, scientists will be able to produce measures to predict response to antidepressants taking into account each individual’s genotype, i. e. they will be able to design tailor-made drugs according to each person’s genetic configuration and their exposure to environmental factors.

The research group headed by professor Cervilla Ballesteros and Gutiérrez Martínez is currently working at the University of Granada to open roads for psycho-pharmaco-genetics, a field that will allow for individual treatments, tailor-made drugs, for each patient with depression, a disorder affecting one in every five Spaniards visiting the doctor’s.

This study is framed in the international project PREDICT and is funded by the European Union and the Spanish Ministry of Education and Science. One of its most important novelties is that it has been carried out through a very representative sample: a total of 737 people agreed to participate in the genetic tests, with ages ranging from 18 to 75, patients of nine primary care centres in the South of Spain. That is why this is the first representative population-based replication of earlier research, as until now research had been done into restricted population samples, comprising only women, adolescents, twins or people with affective disorders.

Contact: Professor Jorge Cervilla Ballesteros
jacb@ugr.es
34-663-075-835
Universidad de Granada

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Multicenter study nets new lung tumor-suppressor gene

BOSTON–Collaborating scientists in Boston and North Carolina have found that a particular gene can block key steps of the lung cancer process in mice. The researchers report in the journal Nature that LKB1 is not only a “tumor-suppressor” gene for non-small cell lung cancer in mice, it also may be more powerful than other, better-known suppressors. The study will be published on the journal’s Web site on Aug. 5 and later in a print version.

If further research shows LKB1 has a similar effect in human lung cells, it could influence the way non-small cell lung cancer is diagnosed and treated, says the study’s senior author, Kwok-Kin Wong, MD, PhD, of Dana-Farber, one of three institutions, along with Massachusetts General Hospital and the University of North Carolina School of Medicine, leading the work. If tumors with LKB1 mutations are found to be especially fast-growing, for example, patients with such tumors might be candidates for more aggressive therapy.

People born with defective versions of LKB1 often develop Peutz-Jeghers syndrome, which is marked by intestinal growths and an increased risk for certain cancers. Non-inherited mutations of the gene have been found in some lung cancers. This suggested that LKB1 normally thwarts tumors from forming. Mutated versions may be unable to act as a brake on cancer.

To find out, the investigators ran a series of experiments in mice with a defective form of a gene called Kras, which drives the formation and growth of lung cancer. They tracked the development of lung cancer in animals with mutated LKB1 and compared it to the experience of animals with abnormalities in either of two well-known tumor-suppressor genes.

They found that while Kras “cooperated” with the mutated tumor-suppressor genes to produce lung cancer, it cooperated even more strongly with mutated LKB1. “The LKB1-deficient tumors grew more rapidly and spread more frequently than the others, and comprised all three types of non-small cell lung cancer — squamous cell carcinoma, large-cell carcinoma, and adenocarcinoma — rather than just one or two,” Wong says. “This suggests that LKB1 plays a role at major stages of the tumors’ development: initiation, differentiation of normal lung cells into cancer cells, and metastasis.”

An examination of human non-small-cell lung tissue suggests LKB1 mutations play a role there as well. Of 144 samples analyzed, 34 percent of the lung adenocarcinomas and 19 percent of the squamous cell carcinomas contained abnormal versions of the gene, researchers report.

“We were surprised at how significant a role LKB1 mutations play in non-small cell lung cancer development in mice,” say Wong, who is also an assistant professor of medicine at Harvard Medical School. “This suggests there may be additional lung tumor-suppressor genes yet to be discovered. We’re currently examining whether these results apply to human lung cancers as well and, if so, how such information can improve treatment.”

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The lead author of the study was Hongbin Ji, PhD, of Dana-Farber. Other Dana-Farber co-authors include Dongpo Cai, PhD, Liang Chen, PhD, Pasi Janne, MD, PhD, Bruce Johnson, MD, Jussi Koivunen, MD, PhD, Danan Li, Mei-Chih Liang, PhD, Kate McNamara, Matthew Meyerson, MD, PhD, Samanthi Perera, PhD, Geoffrey Shapiro, MD, PhD, and Takeshi Shimamura, PhD. Other authors were based at Children’s Hospital Boston, Brigham and Women’s Hospital, Broad Institute of Harvard University and Massachusetts Institute of Technology, University of Tennessee Health Science Center, and the University of Texas Southwestern Medical Center.

The research was supported by the National Institutes of Health, the Sidney Kimmel Foundation for Cancer Research, the American Federation of Aging, the Joan Scarangello Foundation to Conquer Lung Cancer, the Flight Attendant Medical Research Institute, the Waxman Foundation, the Harvard Stem Cell Institute, and the Linda Verville Foundation.

Dana-Farber Cancer Institute (www.dana-farber.org) is a principal teaching affiliate of the Harvard Medical School and is among the leading cancer research and care centers in the United States. It is a founding member of the Dana-Farber/Harvard Cancer Center (DF/HCC), designated a comprehensive cancer center by the National Cancer Institute.

Contact: Bill Schaller
william_schaller@dfci.harvard.edu
617-632-5357
Dana-Farber Cancer Institute

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European heat waves double in length since 1880

The most accurate measures of European daily temperatures ever indicate that the length of heat waves on the continent has doubled and the frequency of extremely hot days has nearly tripled in the past century. The new data shows that many previous assessments of daily summer temperature change underestimated heat wave events in western Europe by approximately 30 percent.

Paul Della-Marta and a team of researchers at the University of Bern in Switzerland compiled evidence from 54 high-quality recording locations from Sweden to Croatia and report that heat waves last an average of 3 days now—with some lasting up to 4.5 days—compared to an average of around 1.5 days in 1880. The results are published 3 August in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union. The researchers suggest that their conclusions contribute to growing evidence that western Europe’s climate has become more extreme and confirm a previously hypothesized increase in the variance of daily summer temperatures since the 19th century.

The study adds evidence that heat waves, such as the devastating 2003 event in western Europe, are a likely sign of global warming; one that perhaps began as early as the 1950s, when their study showed some of the highest trends in summer mean temperature and summer temperature variance.

“These results add more evidence to the belief among climate scientists that western Europe will experience some of the highest environmental and social impacts of climate change and continue to experience devastating hot summers like the summer of 2003 more frequently in the future,” Della-Marta said.

The authors note that temperature records were likely overestimated in the past, when thermometers were not kept in modern Stevenson screens, which are instrument shelters used to protect temperature sensors from outside influences that could alter its readings. The researchers corrected for this warm bias and other biases in the variability of daily summer temperatures and show that nearly 40 percent of the changes in the frequency of hot days are likely to be caused by increases in summer temperatures’ variability. This finding demonstrates that even a small change in the variance of daily summer temperatures can radically enhance the number of extremely hot days.

“These findings provide observational support to climate modeling studies showing that European summer temperatures are particularly sensitive to global warming,” Della-Marta said. “Due to complex reactions between the summer atmosphere and the land, the variability of summer temperatures is expected to [continue to] increase substantially by 2100.”

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The research was supported by the European Environment and Sustainable Development Program, the Swiss National Science Foundation and the National Center for Excellence in Climate Research (NCCR Climate).

Contact: Jonathan Lifland
jlifland@agu.org
202-777-7535
American Geophysical Union

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Identifying the mechanism behind a genetic susceptibility to type 2 diabetes

Type 2 diabetes is reaching epidemic proportions in the developed world. Determining if and how certain genes predispose individuals to type 2 diabetes is likely to lead to the development of new treatment strategies for individuals with the disease.

In a study appearing in the August issue of the Journal of Clinical Investigation Valeriya Lyssenko and colleagues from Lund University in Sweden show that certain variants of the gene TCF7L2 make individuals more susceptible to type 2 diabetes. The susceptibility variants were associated with increased expression of TCF7L2 in pancreatic islet cells and decreased islet cell secretion of insulin. Consistent with this, ectopic overexpression of TCF7L2 in human islet cells decreased insulin secretion in response to exposure to glucose. This study identifies TCF7L2 type 2 diabetes susceptibility variants and provides a mechanism by which these genetic variants might cause susceptibility to the disease. As discussed by the authors and in the accompanying commentary by Andrew Hattersley from Peninsula Medical School in the United Kingdom, future studies are likely to investigate the potential for manipulating the signaling pathways controlled by TCF7L2 for the development of new therapeutics for type 2 diabetes.

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TITLE: Mechanisms by which common variants in the TCF7L2 gene increase risk of type 2 diabetes

AUTHOR CONTACT:
Valeriya Lyssenko
Lund University, University Hospital Malma, Malma, Sweden.
Phone: 46-40-391214; Fax: 46-40-391222; E-mail: Valeri.Lyssenko@med.lu.se.

View the PDF of this article at: https://www.the-jci.org/article.php?id=30706

ACCOMPANYING COMMENTARY
TITLE: Prime suspect: the TCF7L2 gene and type 2 diabetes risk

AUTHOR CONTACT:
Andrew T. Hattersley
Institute of Biomedical and Clinical Sciences, Peninsula Medical School, Exeter, United Kingdom.
Phone: 44-1392-406806; Fax: 44-1392-406767; E-mail: Andrew.Hattersley@pms.ac.uk.

View the PDF of this article at: https://www.the-jci.org/article.php?id=33077

Contact: Karen Honey
press_releases@the-jci.org
215-573-1850
Journal of Clinical Investigation

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