Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cigarette smoke blocks cell repair mechanism

25.08.2006
Cigarette smoke can turn normal breast cells cancerous by blocking their ability to repair themselves, eventually triggering tumor development, University of Florida scientists report.

While some cells nonetheless rally and are able to fix their damaged DNA, many others become unable to access their own cellular first aid kit, according to findings from a UF study published today (Aug. 21) in the journal Oncogene. If they survive long enough to divide and multiply, they pass along their mutations, acquiring malignant properties.

Past research has been controversial. Tobacco smoke contains dozens of cancer-causing chemicals, but until more recently many studies found only weak correlations between smoking and breast cancer risk, or none at all. Those findings are increasingly being challenged by newer studies that are focusing on more than just single chemical components of tobacco, as past research often has done. In the UF study, researchers instead used a tar that contains all of the 4,000 chemicals found in cigarette smoke.

"Our study suggests the mechanism by which this may be happening," said Satya Narayan, Ph.D., an associate professor of anatomy and cell biology at UF's College of Medicine. "This is basically the important finding in our case: We are now describing how cigarette smoke condensate, which is a surrogate for cigarette smoke, can cause DNA damage and can block the DNA repair of a cell or compromise the DNA repair capacity of a cell. That can be detrimental for the cell and can lead to transformation or carcinogenesis."

In their study, funded by the National Institutes of Health and the Miami-based Flight Attendant Medical Research Institute, UF researchers exposed normal breast epithelial cells to cigarette smoke condensate-a tar derived from a machine that literally "smokes" a cigarette in the laboratory-and found the cells acquired mutations characteristic of malignant cells.

The scientists say DNA repair appears to be compromised when chemical components of smoke activate a key gene. That gene interacts with an enzyme that plays a crucial role in repairing damaged DNA, preventing it from doing its job. The cell, despite its mutated form, can then multiply wildly.

A cell with damaged DNA has one of two fates, said Narayan, also a member of the UF Shands Cancer Center.

"Its DNA repair machinery can be enhanced and it can fix the damaged DNA and restore genomic stability, or if the DNA repair machinery becomes compromised within the cell, then it can lead to an accumulation of mutations because the DNA is not fixed before the cell begins to divide," he said. "The mutation then becomes a permanent part of the genome and causes genomic instability, and genomic instability can bring about several cellular dysfunctions, and one of them can lead to tumor formation."

Other UF research led by Xingming Deng, M.D., Ph.D., and published last month in the Journal of Biological Chemistry revealed that nicotine activates a protein in cancer cells that helps them live long, spread to new sites and grow resistant to chemotherapy.

Narayan's team has previously studied cells that were exposed to the chemicals found in cigarette smoke yet did not die. In general, about two-thirds of these cells will be growth-retarded, and some actually acquire cancer-like characteristics, he said.

"Some of these cells that survive are really acquiring true mutagenic characteristics," Narayan said. "A defect in only one cell is important for growth of a full-blown tumor. You don't need 1,000 or 1 million cells to be affected. Only a single cell which may have genomic instability due to compromised DNA repair capacity of the cell can be sufficient for a tumor to develop. That has to be considered also when we do these kinds of studies."

Narayan said the next step will be to find ways to manipulate cells' capacity for DNA repair and to prevent tumor formation.

Meanwhile, he cautions people to avoid smoking, especially teenagers. A study last year found teenage smokers are at especially high risk of breast cancer development later in life, he said.

"Teenagers should realize they are inhaling 4,000 chemicals, and these chemicals can do so much harm in the body, not only posing a breast cancer risk but for so many other things," Narayan said. "The consequence of these chemicals is not apparent in one day or two days or in months; it takes years and years for cancers to develop. Once the gene is damaged and sitting there it's going to provide some harmful effect later on."

Jose Russo, M.D., a researcher at the Fox Chase Cancer Center in Philadelphia who has studied how breast epithelial cells transform after exposure to the chemical benzo[a]pyrine, which is found in tobacco smoke, called the UF findings very interesting.

"We found significant alteration in many of the chromosomes in these cells induced by the effect of benzo[a]pyrine," Russo said. "We were the first ones to demonstrate in normal-like epithelial cells this compound produced a transformation. Cigarette smoke condensate contains more than one compound, so the UF experiment is more similar to the way any human being would be exposed to the carcinogens. It mimics the human situation more closely."

Melanie Fridl Ross | EurekAlert!
Further information:
http://www.ufl.edu

More articles from Health and Medicine:

nachricht World first: Massive thrombosis removed during early pregnancy
20.07.2017 | Universitätsspital Bern

nachricht Therapy of preterm birth in sight?
19.07.2017 | Universitätsspital Bern

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: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>