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Smoking influences gene function, scientists say
By Dross at 2010-07-14 03:34
Smoking influences gene function, scientists say

SAN ANTONIO, July 13, 2010 – In the largest study of its kind, researchers at the Southwest Foundation for Biomedical Research (SFBR) have found that exposure to cigarette smoke can alter gene expression -- the process by which a gene's information is converted into the structures and functions of a cell. These alterations in response to smoking appear to have a wide-ranging negative influence on the immune system, and a strong involvement in processes related to cancer, cell death and metabolism.

The scientists indentified 323 unique genes whose expression levels were significantly correlated with smoking behavior in their study of 1,240 people. The changes were detected by studying the activity of genes within white blood cells of study participants.

"Our results indicate that not only individual genes but entire networks of gene interaction are influenced by cigarette smoking," wrote lead author Jac Charlesworth, Ph.D., in the July 15 issue of the open access journal BMC Medical Genomics. Charlesworth, formerly at SFBR, is now a research fellow at the Menzies Research Institute at the University of Tasmania in Australia.

The study was funded by the National Institutes of Health and the Azar and Shepperd families of San Antonio, ChemGenex Pharmaceuticals and the AT&T Foundation. The study is part of SFBR's San Antonio Family Heart Study (SAFHS) which includes 40 families in the Mexican American community.

"Previous studies of gene expression as influenced by smoking have been seriously limited in size with the largest of the in vivo studies including only 42 smokers and 43 non-smokers. We studied 1,240 individuals, including 297 current smokers" Charlesworth said. "Never before has such a clear link between smoking and transcriptomics been revealed, and the scale at which exposure to cigarette smoke appears to influence the expression levels of our genes is sobering".

"Our results indicate that not only individual genes but entire networks of gene interaction are influenced by cigarette smoking. It is likely that this observed effect of smoking on transcription has larger implications for human disease risk, especially in relation to the increased risk of a wide variety of cancers throughout the body as a result of cigarette smoke exposure," Charlesworth said.

 

 



5 comments | 1692 reads

by gdpawel on Wed, 2010-07-21 01:12
"Since a substantial number of patients presenting with lung cancer either smoked in the recent past or continue to do so, it is important to make sure that the patient stops smoking as soon as possible to improve their treatment outcome," says Dr. Carolyn M. Dresler, Head, Tobacco and Cancer Group of the International Agency for Research on Cancer. She added, "the emphasis should be on improvement of treatment outcome and future health improvement."

There are guidelines regarding smoking cessation techniques that have resulted from reviews of the world's literature and are very well accepted throughout the medical and psychological fields. However, "the biggest problem remains in having healthcare providers implement them routinely," Dr. Dresler says, "Most have emphasized the role of the primary healthcare provider in providing smoking cessaton advice to patients, whereas the specialists, such as medical oncologists, radiation oncologists, thoracic surgeons or pulmonary care specialists should be dealing with the health problems resulting from the smoking as the patient faces imminent interventions such as radiation therapy, chemotherapy or surgery."

She makes the point that since ongoing smoking may significantly affect the outcome of subsequent surgery or therapy and negatively impact long-term survival, it is now the specialists' turn to provide the urgent smoking cessation treatment. With the advent of medicare changes under the new Medicare Modernization Act (MMA), the specialists will be reimbursed for providing evaluation and management services, making referrels for diagnostic testing, radiation therapy, surgery and other procedures as necessary, and offer any other support needed to reduce patient morbidity and extend patient survival. I certainly hope they add smoking cessation guidance and support.

Source: (Cancer Epidemiol Biomarkers Prev 2005;14(10):2287–93)

[url]www.treatobacco.net is an evidence-based site containing information in 11 languages on tobacco dependence treatment relative to efficacy, safety, demographics and health effects, health economics, and policy.

[url]www.cdc.gov/tobacco/ is a site to let you know everything you wanted to know about tobacco at the CDC.

[url]www.guideline.gov/summary/summary.aspx?doc_id=2958&nbr=2184 is the National Guideline Clearinghouse web site for smoking cessation.

by gdpawel on Wed, 2010-07-21 01:17
No "pharmaceutical" trial ever followed whether patients smoked during their clinical trials, despite dosing themselves daily with cigarettes with hundreds chemicals in them. Dr. Dresler stated that "the addition of nicotine inhibits the ability of a chemo drug (like etoposide) to induce apoptosis by 61%." If a drug like nicotine, which occurs in the highest concentration of any drug in a cigarette, inhibits the ability of a major chemotherapy drug by 61%, a medical oncologist should care if it was being ingested during treatment.

In the article, "Smoking, The Missing Drug Interaction in Clinical Trials: Ignoring the Obvious" (Cancer Epidemiol Biomarkers Prev 2005;14(10):2287?93), Dr. Dresler and her colleagues concluded that we can no longer ignore the obvious: smoking is a critical variable that affects cancer treatment and outcome and has been shown to vitiate or interact with the effects of some therapeutic agents and chemopreventive agents. Measurement of smoking history and status in clinical trials of cancer therapy will increase our knowledge of the adverse effects of the constituents of tobacco smoke, including nicotine, and of drug interactions.

Oncology health professionals have called for increased advocacy for tobacco control. Furthermore, the routine inclusion of smoking status and cessation need to become a standard of care for all patients. The inclusion of smoking data in oncology clinical trials will also provide clinicians with improved means of delivering individualized advice to patients with cancer that may be critical in motivating their cessation efforts and sustained abstinence.

Scientific, financial, and clinical support is critical to this goal. The failure to date to assess, analyze, and report smoking status has limited our ability to investigate the effect of smoking on treatment efficacy and outcome. The time has come to integrate data about the single most important lifestyle risk factor in cancer prevention into cancer treatment and survivorship trials.

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