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 Electrical 'switch' in brain's capillary network monitors activity and controls blood flow
27.03.2017 | Larner College of Medicine at the University of Vermont

nachricht Laser activated gold pyramids could deliver drugs, DNA into cells without harm
24.03.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Big data approach to predict protein structure

27.03.2017 | Life Sciences

Parallel computation provides deeper insight into brain function

27.03.2017 | Life Sciences

Weather extremes: Humans likely influence giant airstreams

27.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>