Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Brain tumors may originate with neural stem cells

16.08.2005


Researchers at UT Southwestern Medical Center have determined that stem cells in a certain region of the brain may be the source of a particular type of incurable brain tumor and may be implicated in other types of brain cancers as well.



The research, conducted in mice, appears in the August issue of the journal Cancer Cell. The findings support growing evidence that adult stem cells may play a role in the development of some forms of cancer, said Dr. Luis Parada, senior author on the paper and director of the Center for Developmental Biology and the Kent Waldrep Center for Basic Research on Nerve Growth and Regeneration at UT Southwestern.

"Continued research into the biology of adult stem cells will aid in the understanding of how cancers originate and develop and may lead to possible new therapies for treating aggressive, currently incurable brain tumors," said Dr. Parada.


Malignant astrocytoma, or glioma, is one of the most common types of brain tumor in adults. The tumors are thought to arise from glial cells, which are non-nerve cells that provide support and nutrition to cells of the nervous system.

Because these incurable cancers generally are not detected until they are advanced, when symptoms have begun to develop, scientists have been unsure where, or what, initiates the process of uncontrolled cell replication that leads to the formation of the tumors.

Dr. Parada and his research group, including former UT Southwestern postdoctoral researcher and lead author Dr. Yuan Zhu, now at the University of Michigan Medical School, developed a strain of genetically engineered mice that served as models for their human brain-cancer studies and allowed researchers to track down the origins of such tumors. The mice lacked a tumor suppressor gene called p53 and also had a mutated version of another tumor suppressor gene called NF1. The mutated NF1 resulted in an increase in a biochemical reaction called Ras signaling, which has been implicated in the initiation of some cancers.

As infants, the mutant mice showed no sign of cancer, but as they grew older, they all developed brain tumors. By observing and evaluating "snapshots" of changes in the mouse brains over time, Dr. Parada’s research team determined that the tumors originated in neural stem cells. Those cells that became cancerous then migrated to other areas of the brain and caused tumors.

Previous research has demonstrated that adult neural stem cells are isolated in only a few regions of the mammalian brain, with the highest densities of such cells occurring in the hippocampus, an area important for learning and memory, and the subventricular zone of the forebrain.

The UT Southwestern researchers found that stem cells in the subventricular zone gave rise to malignant astrocytoma in the genetically engineered mice.

"While our study cannot rule out alternative explanations for the initiation of astrocytoma, the identification of the subventricular zone as the site of tumor origin in our models may have implications on therapeutic strategies for preventing and treating a subset of human malignant astrocytomas," Dr. Parada said. "Our results challenge current dogma, which assumes that tumors of this type arise from glial cells located throughout the brain."

The results offer an explanation for why current treatment for malignant astrocytoma in humans ultimately fails. Strategies that focus only on treating localized lesions would not be sufficient to eradicate tumor cells because these cells may eventually be replenished from the cell pool within the subventricular zone, the researchers said.

They also determined that inactivation of both p53 and NF1 is sufficient to initiate the formation of the brain cancer, and that the timing of the inactivation of each gene is critical. For the malignant astrocytoma to begin forming, p53 inactivation must either precede or coincide with the increase in Ras signaling associated with the loss of NF1.

Stem cells are unspecialized cells, capable of dividing and renewing themselves for long periods of time. They can give rise to many types of specialized cells, such as blood, nerve and muscle cells. While embryonic stem cells, which are derived from very early embryos, are capable of generating all types of cells in the body during normal development, adult stem cells have lost this potential. Adult stem cells differentiate to produce cells from the tissue where they originate.

Amanda Siegfried | EurekAlert!
Further information:
http://www.utsouthwestern.edu

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>