Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cancer sequencing initiative discovers mutations tied to aggressive childhood brain tumors

30.01.2012
St. Jude Children's Research Hospital – Washington University Pediatric Cancer Genome Project provides first evidence linking cancer to mutations in genes involved in DNA organization

Researchers studying a rare, lethal childhood tumor of the brainstem discovered that nearly 80 percent of the tumors have mutations in genes not previously tied to cancer. Early evidence suggests the alterations play a unique role in other aggressive pediatric brain tumors as well.

The findings from the St. Jude Children's Research Hospital – Washington University Pediatric Cancer Genome Project (PCGP) offer important insight into a poorly understood tumor that kills more than 90 percent of patients within two years. The tumor, diffuse intrinsic pontine glioma (DIPG), is found almost exclusively in children and accounts for 10 to 15 percent of pediatric tumors of the brain and central nervous system.

"We are hopeful that identifying these mutations will lead us to new selective therapeutic targets, which are particularly important since this tumor cannot be treated surgically and still lacks effective therapies," said Suzanne Baker, Ph.D., co-leader of the St. Jude Neurobiology and Brain Tumor Program and a member of the St. Jude Department of Developmental Neurobiology. She is a corresponding author of the study published in the January 29 online edition of the scientific journal Nature Genetics.

DIPG is an extremely invasive tumor that occurs in the brainstem, which is at the base of the skull and controls such vital functions as breathing and heart rate. DIPG cannot be cured by surgery and is accurately diagnosed by non-invasive imaging. As a result, DIPG is rarely biopsied in the U.S. and little is known about it.

Cancer occurs when normal gene activity is disrupted, allowing for the unchecked cell growth and spread that makes cancer so lethal. In this study, investigators found 78 percent of the DIPG tumors had alterations in one of two genes that carry instructions for making proteins that play similar roles in packaging DNA inside cells. Both belong to the histone H3 family of proteins. DNA must be wrapped around histones so that it is compact enough to fit into the nucleus. The packaging of DNA by histones influences which genes are switched on or off, as well as the repair of mutations in DNA and the stability of DNA. Disruption of any of these processes can contribute to cancer.

Researchers said that the mutations seem unique to aggressive childhood brain tumors.

"It is amazing to see that this particular tumor type appears to be characterized by a molecular 'smoking gun' and that these mutations are unique to fast-growing pediatric cancers in the brain," said Richard K. Wilson, Ph.D., director of The Genome Institute at Washington University School of Medicine in St. Louis and one of the study's corresponding authors. "This is exactly the type of result one hopes to find when studying the genomes of cancer patients."

The results are the latest from the PCGP, an ambitious three-year effort to sequence the complete normal and cancer genomes of 600 children with some of the most poorly understood and aggressive pediatric cancers. The human genome includes the complete set of instructions needed to assemble and sustain human life. The goal is to identify differences that explain why cancer develops, spreads and kills. Researchers believe the findings will provide the foundation for new tools to diagnose, treat or prevent the disease.

For this study, researchers sequenced the complete normal and cancer genomes of seven patients with DIPG. "The mutations were found at such high frequency in the cancer genomes of those seven patients that we immediately checked for the same alterations in a larger group of DIPGs," Baker said. When researchers sequenced all 16 of the related genes that make closely related variants of histone H3 proteins in an additional 43 DIPGs, they found many of the tumors contained the same mistakes in only two of these genes.

Of the 50 DIPG tumors included in this study, 60 percent had a single alteration in the makeup of the H3F3A gene. When the mutated gene was translated into a protein, the point mutation led to the substitution of methionine for lysine as the 27th amino acid in this variant of histone H3 protein. Another 18 percent of the DIPG patients carried the same mistake in a different gene, HIST1H3B.

Researchers are now working to understand how mutations in H3F3A and HIST1H3B impact cell function and contribute to cancer. Earlier research provides some clues. The lysine that is mutated is normally targeted by enzymes that attach other molecules to histone H3, influencing how it interacts with other proteins that regulate gene expression, Baker said. Mutations in the enzymes that target histone H3 have been identified in other cancers, but this is the first report showing a specific alteration of histones in cancer.

H3F3A and HIST1H3B were also mutated in other aggressive childhood brain tumors, glioblastoma, that develop outside the brain stem. Of 36 such tumors included in this study, 36 percent carried one of three distinct point mutations in the genes. The alterations included another single change in the makeup of H3F3A not found in DIPGs.

The histone H3 genes, however, were not mutated in any of the 252 other childhood tumors researchers checked for this study. The list included the brain tumors known as low-grade gliomas, medulloblastomas and ependymomas plus other cancers outside the brain and nervous system. The H3 changes have not been reported in any other cancers, including adult glioblastoma. "This suggests these particular mutations give a very important selective advantage, particularly in the developing brainstem and to a lesser degree in the developing brain, which leads to a terribly aggressive brain tumor in children, but not in adults," Baker said.

"This discovery would not have been possible without the unbiased approach taken by the Pediatric Cancer Genome Project," Baker said. "The mutations had not been reported in any other tumor, so we would not have searched for them in DIPGs. Yet the alterations clearly play an important role in generating this particular tumor."

The study's first authors are Gang Wu, Alberto Broniscer and Troy McEachron, all of St. Jude. The study's other corresponding authors are Jinghui Zhang and James Downing, both of St. Jude. The other study authors are Charles Lu, Li Ding and Elaine Mardis, all of Washington University; and Barbara Paugh, Jared Becksfort, Chunxu Qu, Robert Huether, Matthew Parker, Junyuan Zhang, Amar Gajjar, Michael Dyer, Charles Mullighan, Richard Gilbertson and David Ellison, all of St. Jude.

The research was funded in part by the PCGP, including Kay Jewelers, a lead project sponsor; the National Institutes of Health, the Sydney Schlobohm Chair of Research from the National Brain Tumor Society; the Cure Starts Now Foundation, Smile for Sophie Forever Foundation, Tyler's Treehouse Foundation, Musicians Against Childhood Cancer, the Noyes Brain Tumor Foundation and ALSAC.

St. Jude Children's Research Hospital

Since opening 50 years ago, St. Jude Children's Research Hospital has changed the way the world treats childhood cancer and other life-threatening diseases. No family ever pays St. Jude for the care their child receives and, for every child treated here, thousands more has been saved worldwide through St. Jude discoveries. The hospital has played a pivotal role in pushing U.S. pediatric cancer survival rates from 20 to 80 percent overall, and is the first and only National Cancer Institute-designated Comprehensive Cancer Center devoted to children. It is also a leader in the research and treatment of blood disorders and infectious diseases in children. St. Jude was founded by the late entertainer Danny Thomas, who believed that no child should die in the dawn of life. Join that mission by visiting http://www.stjude.org or following us on http://www.facebook.com/stjude and Twitter@StJudeResearch.

Washington University School of Medicine

Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

St. Jude Media Relations Contacts

Summer Freeman
(desk) 901-595-3061
(cell) 901-297-9861
summer.freeman@stjude.org
Carrie Strehlau
(desk) 901-595-2295
(cell) 901-297-9875
carrie.strehlau@stjude.org
Washington University Media Relations Contact
Caroline Arbanas
(cell) 314-445-4172
(desk) 314-286-0109
arbanasc@wustl.edu

Summer Freeman | EurekAlert!
Further information:
http://www.stjude.org

Further reports about: Brain Cancer DIPG DNA Gates Foundation Genom Neurobiology brain tumor childhood tumor nervous system

More articles from Life Sciences:

nachricht Colorectal cancer risk factors decrypted
13.07.2018 | Max-Planck-Institut für Stoffwechselforschung

nachricht Algae Have Land Genes
13.07.2018 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Research finds new molecular structures in boron-based nanoclusters

13.07.2018 | Materials Sciences

Algae Have Land Genes

13.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>