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DNA adducts linked to oral cancer in smokers

Source: www.news-medical.net
Author: Sarah Guy, medwireNews Reporter

Having a high susceptibility to certain types of DNA damage caused by tobacco smoking could significantly increase the risk for oral cancer, show results of a Taiwanese study.

Levels of BaP 7,8-diol 9,10-epoxide (BPDE) – a metabolite of Benzo[a]pyrene, an important carcinogen found in cigarette smoke – correlated positively with smoking status in a cohort of individuals with oral cancer, report the researchers.

The findings also indicate a significantly increased risk for oral cancer among individuals with high DNA adduct levels compared with their peers with low levels.

“Based on our finding, we suggest that detected BPDE-like DNA adducts could be used as a biomarker for oral cancer risk,” write Huei Lee (Taipei Medical University) and colleagues in the Archives of Oral Biology.

The team analyzed BPDE-DNA adduct levels in oral tissue samples from 158 oral cancer patients and 64 individuals without cancer (controls), using immunohistochemistry and enzyme-linked immunosorbent assay (ELISA).

The results of these assays significantly and positively correlated , so that immunohistochemistry-negative patients did not have detectable DNA adduct levels using ELISA and vice versa.

DNA adduct levels also positively correlated with smoking status among the cancer patients, note the researchers, with significantly higher adduct levels among smokers than nonsmokers, at 93.18 versus 0.04 adducts per 108 nucleotides.

Lee and co-workers also observed that cancer patients had significantly higher DNA adduct levels than controls, at a range of 0-358.00 versus 0-39.50 adducts per 108 nucleotides.

Indeed, DNA adduct level was an independent risk biomarker for oral cancer in multivariate analysis, which indicated a 9.94-fold increased risk for the disease among individuals with high levels, defined as more than two standard deviations above the mean adduct level in the low group – which equates to 34.03 adducts per 108 nucleotides.

“These results strongly suggest that a high susceptibility to DNA damage derived from exposure to cigarette carcinogens is associated with the high risk of oral cancer in Taiwanese oral cancer patients,” conclude Lee et al.

Source: medwireNews

January, 2013|Oral Cancer News|
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New Study Indicates Tobacco Industry Was Aware of Their Own Products Dangers

Source: USA Today

A new study says tobacco companies knew for decades that cigarette smoke was radioactive and potentially carcinogenic.

Tobacco companies knew for decades that cigarette smoke was radioactive and potentially carcinogenic but kept that information from the public, according to a new study.

The tobacco industry began investigations into the possible effects of these radioactive particles, identified as polonium-210, on smokers as early as the 1960s, says the study by UCLA researchers who analyzed dozens of previously unexamined industry documents.

“I’ve not seen a document before that’s specifically cited the industry’s own internal research finding that sufficient levels of polonium-210 can cause cancer,” says Matt Myers of the Campaign for Tobacco-Free Kids. He says the study reinforces the need for the U.S. Food and Drug Administration to scrutinize tobacco products. This week, the FDA began requiring tobacco companies to disclose detailed information about new products and changes to existing ones. The study, published in the peer-reviewed journal Nicotine & Tobacco Research, suggests the FDA make removal of the radioative particles from tobacco products a top priority. “We used to think that only the chemicals in the cigarettes were causing lung cancer,” said Hrayr S. Karagueuzian, lead author of the study. Now, Karagueuzian said, the industry’s own research shows that polonium-210, absorbed by tobacco leaves and inhaled by smokers, is dangerous. He said UCLA researchers found that the radioactivity could cause 120 to 138 deaths for every 1,000 regular smokers over a 25-year period. Karagueuzian said tobacco companies have declined techniques that could help eliminate polonium-210 from tobacco because of concern that smokers might lose the “instant nicotine rush” that fuels their addiction. David Sutton, spokesman for Philip Morris USA, the largest U.S. tobacco manufacturer, said the company does not add polonium-210 to its products. He said it’s a “naturally occurring element in the air” and has been widely discussed by the public health community for years. Industry critic Greg Connolly, who directs Harvard University’s Center for Global Tobacco Control, agrees that polonium-210’s risks have long been known. He said the study, however, reinforces the need for the FDA to regulate tobacco companies, adding, “The $64,000 question is: have they changed?”

This news story was resourced by the Oral Cancer Foundation, and vetted for appropriateness and accuracy.

September, 2011|Oral Cancer News|
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A step toward a saliva test for cancer

Source: www.sciencedaily.com
Author: staff

A new saliva test can measure the amount of potential carcinogens stuck to a person’s DNA — interfering with the action of genes involved in health and disease — and could lead to a commercial test to help determine risks for cancer and other diseases, scientists reported in Denver during the 242nd National Meeting & Exposition of the American Chemical Society (ACS).

“The test measures the amount of damaged DNA in a person’s body,” said Professor Hauh-Jyun Candy Chen, Ph.D., who led the research team. “This is very important because such damaged DNA — we call this ‘DNA adducts’ — is a biomarker that may help doctors diagnose diseases, monitor how effective a treatment is and also recommend things high-risk patients can do to reduce the chances of actually getting a disease,” said Chen. The research team is at National Chung Cheng University (NCCU) in Taiwan. “We tried urine and blood and found these adducts. Then we turned our attention to saliva. It’s much more convenient to collect a sample of saliva.”
A DNA adduct forms when a potentially cancer-causing substance is chemically attached to a strand of DNA, which makes up genes. People come into contact with such substances in the environment, certain workplaces and through everyday activities. Cigarette smoke, for instance, contains at least 20 known cancer-causing substances. When such a substance binds to DNA, it changes the DNA so that genes may not work normally. Our body has a built-in repair system that can naturally clear up such damage. If that system fails, however, a DNA adduct could lead to mutations or genetic changes that, in turn, could lead to cancer. DNA adducts also accumulate with aging and have been linked to other health problems, including inflammatory diseases and chronic brain disorders like Alzheimer’s disease.

The new test measures the levels of five key DNA adducts, including some that form as a result of cigarette smoking. Traditionally, DNA for such tests had to be obtained by taking a blood sample and processing the white blood cells, which contain large amounts of the genetic material. More recently, however, scientists found that DNA samples could be obtained more conveniently from saliva. The DNA is present in white blood cells found naturally in saliva and from cells shed from the lining of the mouth. Chen uses a very sensitive laboratory instrument called a mass spectrometer to analyze for DNA adducts.

Chen envisions several uses for any potential commercial version of the test, which she said would probably cost several hundred dollars. One, for example, might be health promotion among people exposed to carcinogens due to lifestyle, occupation or other factors. Detection of high levels of DNA adducts in cigarette smokers, for instance, could encourage them to stop. Follow-up tests showing a decline in DNA adducts could reinforce their healthier lifestyle.

September, 2011|Oral Cancer News|
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