Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study suggests reason for high incidence of cancer in the prostate

12.04.2007
Cancer occurs more frequently in the prostates of men than in any organ other than the skin. While DNA damage caused by exposure to the sun is likely the cause of many skin cancers, the cause of prostate cancer remains largely unknown.

Research conducted by the group of Marikki Laiho, M.D., Ph.D., a Professor at the University of Helsinki, Finland, in collaboration with Donna Peehl, Ph.D., an Associate Professor (Research) at Stanford University, US, points to absence of critical mechanisms protecting prostate cells from DNA damage as a key contributor to the development of prostate cancer.

Results of the study will be published in the online Early Edition of the Proceedings of the National Academy of Sciences, USA, during the week of April 9-13.

The investigators used primary cultures of normal epithelial cells derived from patients’ surgical specimens to examine responses to DNA damage induced by irradiation or chemicals. These cultured cells are the “progenitor” cells in the prostate in which cancer may originate, and therefore provide a realistic experimental model in which to study carcinogenic processes.

After exposure to DNA damaging agents, cells typically mount several types of defensive mechanisms to allow repair of DNA damage prior to cell division. These mechanisms prevent the passage of damaged genetic material to daughter cells, which would contribute to the conversion of those damaged cells to cancer. One of these protective mechanisms is cell cycle checkpoint arrest, which is mediated by a series of molecular events triggered by DNA damage.

Surprisingly, normal prostate cells were unable to enforce cell cycle checkpoint arrest and continued to proliferate following DNA damage. Early events involving cellular recognition of DNA damage were intact, so lack of checkpoint arrest in these cells was not due to inability to recognize DNA damage. Rather, inability to enforce cell cycle arrest was linked to low levels of the protein Wee1A, a tyrosine kinase that phosphorylates and inhibits cyclin dependent kinase 2 (cdk2). In the absence of Wee1A activity, cdk2 remained active and continued to drive the prostate cells to undergo cell division. In conjunction, slower clearance of DNA damage foci suggested persistent DNA damage. When Wee1A protein was restored in these cells, checkpoint control was rescued, showing that Wee1A was indeed critical to this important pathway.

When using cultured cells, there is always a concern that the in vitro environment may alter cellular behavior. To confirm that the observed results were not an artifact of cell culture, the investigators used a novel model system of “tissue slice cultures”, developed by Peehl. Cores of fresh tissue were bored from surgical specimens, then were precision-cut to thicknesses of only a few hundred microns. These slices were incubated and retained their structure and function for several days. The value of tissue slice cultures is that all elements of the whole tissue remain intact, permitting realistic experiments that are not feasible to perform directly in humans. The responses to DNA damage of the normal epithelial cells in these tissues were similar to those of the cell cultures, signifying that defensive mechanisms against DNA damage are indeed lacking in the human prostate.

The lack of Wee1A-mediated DNA damage-induced checkpoint enforcement is not the only defective protective mechanism in prostate cells. In 1995, Peehl in collaboration with another investigator at Stanford, Amato Giaccia, Ph.D., reported in Cancer Research that normal prostatic epithelial cells lacked the p53 response to DNA damage. The p53 protein is a major tumor suppressor and lack of p53 function leads to genomic instability and malignancy. The defects in the two checkpoint enforcement pathways, mediated by p53 in one and by Wee1A in the other, are unrelated, since correcting the Wee1A pathway did not restore p53 function in prostate cells.

The use of human cells and tissues in these studies was key to the medical relevance of the findings. The human prostate is almost unique among mammals in having a high incidence of prostate cancer. Rodents, most commonly used in the laboratory to study mechanisms of cancer, do not develop prostate cancer spontaneously. The absence of at least two key checkpoint elements in the DNA damage response pathways may predispose human prostatic epithelial cells to accrual of DNA lesions and provide a mechanistic basis for the high incidence of cancer in the prostate.

Why prostate cells lack these mechanisms is unknown, but discovery of ways to restore these checkpoints controls might protect against prostate cancer.

The study was funded by the Department of Defense Prostate Cancer Research Program, the Academy of Finland, Biocentrum Helsinki, the Finnish Cancer Organizations and the Finnish Cultural Foundation.

Paivi Lehtinen | alfa
Further information:
http://www.helsinki.fi
http://research.med.helsinki.fi/cancerbio/laiho/default.htm

More articles from Studies and Analyses:

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>