Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers identify a mechanism for the transformation of colon polyps

03.12.2012
Researchers from the University of Geneva demonstrate that, in this type of lesion, the rate of progression from a precancerous state to the tumor stage accelerates over time

The causes underlying the development of certain types of common cancers have not yet been elucidated. In order to better determine the origin and the sequence of events responsible for the onset of colon cancer, the teams led by Thanos Halazonetis and Stylianos Antonarakis, professors at the University of Geneva (UNIGE), Switzerland, have sequenced the DNA of biopsied tissue from colon polyps.

The results show that these precancerous lesions have a specific profile called 'mutator', which is associated with an increased frequency of acquisition of certain mutations. The study, published December 1, 2012 in the journal Cancer Research, also designates mutations in three specific genes as being the likely initiators of the progression towards malignancy.

At each cell division, the entirety of our DNA, that is some 6.4 billion base pairs, must be replicated. The enzymes engaged in this task work at a prodigious rate of about 1000 base pairs per minute. This sometimes leads to errors, which are usually corrected by other enzymes. However, the repair mechanisms do not work when there is a defect in the DNA replication process, which is the case for cancer cells.

The genome of human cancer cells is generally unstable. The different forms and causes of this characteristic, which results in a greater susceptibility to acquire mutations, are not all known. "In order to explore the genesis and better understand the sequence of events leading to tumor development, we probed the DNA of precancerous lesions," explains Thanos Halazonetis, Professor at the Departments of Molecular Biology and Biochemistry of the UNIGE's Faculty of Science. To do this, the team led by the professor sequenced the exome, which is the part of DNA that codes for proteins, from colon polyps sampled from patients. The researchers were thus able to pinpoint mutations in three specific genes, constituting the likely initial cause on the road to malignancy. "These genes, named APC, CTNNB1 and BRAF, all have a vital role in the cell. In particular, they are involved in cell division and adhesion to other cells, as well as various intracellular signaling pathways," explains Sergey Nikolaev, at the Department of Genetic Medicine and Development of the Faculty of Medecine, and first author of the article.

The researchers also compared the DNA of polyps, which most were precancerous, to that of healthy colon tissue. They discovered in the former an abnormally high frequency of mutations called SNS, characterized by the substitution of a single DNA base by another. "These precancerous lesions have a profile called 'mutator' which is associated with an increase in the frequency of acquiring SNS type mutations. During early development of the polyp, the mutation rate in these cells is normal, and then it accelerates over time," says Thanos Halazonetis.

The mutation rate observed in polyps was sometimes 200 times greater than that present in normal cells, which greatly increases their progression towards a cancerous stage. According to the professor, these polyps become cancerous in five to ten years. Thanks to these findings, recommendations for routine biopsies, usually conducted every five years, could henceforth be refined on a case to case basis.

Thanos Halazonetis | EurekAlert!
Further information:
http://www.unige.ch

More articles from Health and Medicine:

nachricht Correct connections are crucial
26.06.2017 | Charité - Universitätsmedizin Berlin

nachricht One gene closer to regenerative therapy for muscular disorders
01.06.2017 | Cincinnati Children's Hospital Medical Center

All articles from Health and Medicine >>>

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

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>