Smoking Smothers Your Genes

ScienceNOW ^ | 21 December 2012 | Karl Gruber

[neverdem]

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Risk factor. Smoking may cause chemical modifications of DNA.

Credit: Hemera/Thinkstock

Cigarettes leave you with more than a smoky scent on your clothes and fingernails. A new study has found strong evidence that tobacco use can chemically modify and affect the activity of genes known to increase the risk of developing cancer. The finding may give researchers a new tool to assess cancer risk among people who smoke.

DNA isn't destiny. Chemical compounds that affect the functioning of genes can bind to our genetic material, turning certain genes on or off. These so-called epigenetic modifications can influence a variety of traits, such as obesity and sexual preference. Scientists have even identified specific epigenetic patterns on the genes of people who smoke. None of the modified genes has a direct link to cancer, however, making it unclear whether these chemical alterations increase the risk of developing the disease.

In the new study, published in Human Molecular Genetics, researchers analyzed epigenetic signatures in blood cells from 374 individuals enrolled in the European Prospective Investigation into Cancer and Nutrition. EPIC, as it's known, is a massive study aimed at linking diet, lifestyle, and environmental factors to the incidence of cancer and other chronic diseases. Half of the group consisted of people who went on to develop colon or breast cancer 5 to 7 years after first joining the study, whereas the other half remained healthy.

The team, led by James Flanagan, a human geneticist at Imperial College London, discovered a distinct "epigenetic footprint" in study subjects who were smokers. Compared with people who had never smoked, these individuals had fewer chemical tags known as methyl groups—a common type of epigenetic change—on 20 different regions of their DNA. When the researchers extended the analysis to a separate group of patients and mice that had been exposed to tobacco smoke, they narrowed down the epigenetic modifications to several sites located in four genes that have been weakly linked to cancer before. All of these changes should increase the activity of these genes, Flanagan says. It's unclear why increasing the activity of the genes would cause cancer, he says, but individuals who don't have cancer tend not to have these modifications.

The study is the first to establish a close link between epigenetic modifications on a cancer gene and the risk of developing the disease, says Robert Philibert, a behavioral geneticist at the University of Iowa in Iowa City. "To the best of my knowledge, no previous genome-wide epigenetics study has taken such efforts from initial discovery to replication to experimental validation," adds Lutz Breitling, an epidemiologist at the German Cancer Research Center in Heidelberg, Germany.

The work may lead to new ways to asses cancer risks from smoking. "Previous research into smoking has often asked people to fill out questionnaires, … which have their obvious drawbacks and inaccuracies," Flanagan says. The new study, he says, may make it possible for doctors to quantify a person's cancer risk simply through an epigenetic analysis of their DNA.

[stubernx98]

Racking leaves may cause.......constant back pain

Talking back to wife after the look may cause - Fill in the blank

Fill in the Blank _________ may cause ________

I know, I am a PhD

[neverdem]

Tracking the origins of HIV

6 anti-polio workers killed in Pakistan

Overcoming small obstacles (Nanofabrication methods)

DNA hydrogel has a long memory

FReepmail me if you want on or off my health and science ping list.

[tallyhoe]

Car Crashes might be dangerous to your health! So can falls!!!

[dubyagee]

Perhaps the holiday spirits I have had are having an ill effect on my comprehension, but I read the first two paragraphs and they seem to completely contradict one another. So I stopped...reading, that is.

[elkfersupper]

Since nobody will talk about the gene that theoretically causes male homosexuality and the damage it does, I'm waiting for discovery and elimination of the gene that causes people to hang a bunch of crap from their windshield rear-view mirror.

The amount of that crap swinging around tends to have an inverse relationship to the driver's willingness or ability to control their vehicle and behave like a human being on the road.

[Mears]

Thanks for posting this.

I occasionally have trouble sleeping and I will bookmark this article to read if that occurs tonight.

.

[mrsmith]

“Little George, did you chop down that cherry tree?”

“I cannot tell a lie, my epigenetic modifications made me do it!”

[Just another Joe]

From the article.
None of the modified genes has a direct link to cancer, however, making it unclear whether these chemical alterations increase the risk of developing the disease.

And yet the title of the article is, "Smoking Smothers Your Genes"

What a load of cr@p.

[RegulatorCountry]

Most of human history involves heavy exposure to and inhalation of smoke from fires for cooking and warmth. While I wouldn't qualify this as having been healthy it was necessary. If such “gene smothering” and associated epigenetic changes are detrimental now they were detrimental then and we're living, breathing examples of it walking the earth today.

[nightlight7]

This is another statistical study on non-randomized sample of self-selected smokers/non-smokers, analogous to "discovering" that lung cancer is statistically associated with yellowing of the fingernails (or with any other proxy/marker for smoking). In this study, instead of yellowing of the fingernails, they use epigenetic markers for smoking (such as hypomethylation of 'aryl hydrocarbon receptor repressor'/AHRR gene; their 'mouse model' merely verifies smoking <-> AHRR hypo-methylation association).

This type of statistical associations on 'non-randomized samples' are equally indicative of causal role of a substance X (tobacco smoke) in disease D (lung cancer), as it is for protective/therapeutic role of X for D or D's precursors/causes. For example, people taking high blood pressure meds are statistically more likely to suffer heart attacks and strokes than those not taking these medications. This association doesn't mean that these meds cause heart attacks and strokes. In fact they protect against underlying causes of these very same events with which they associate (that's what gives rise to this association).

Since tobacco smoke happens to have potent anti-inflammatory effects and it also upregulates key detox and antioxidant enzymes (nearly doubling glutathione, catalase and SOD), one would expect it to be statistically associated with variety of toxic, including carcinogenic, exposures since it provides relief against the effects of such exposures (e.g. doubling the detox rate and reducing inflammatory reactions).

While there were no genuine randomized smoking experiments on humans, there were thousands such experiments on animals but you will never hear about these findings since they all went the "wrong way" -- smoking animals get fewer cancers and live ~20% longer than non-smoking animals, while staying thinner (by 15%) and sharper into the old age.

You can find references and discussions of the above facts in the longevity/nootropics forum (longecity) in a thread "Smoking is good for you" (I post as 'nightlight'). The TOC of the thread topics is in another post on that site.

[nightlight7]

{ --- From the article. None of the modified genes has a direct link to cancer, however, making it unclear whether these chemical alterations increase the risk of developing the disease.

And yet the title of the article is, "Smoking Smothers Your Genes"

What a load of cr@p. --- }

Good catch (thanks, the paper is behind paywall and the quoted admission is not in the free abstract). They simply picked yet another statistical marker for smoking (epigenetic) and established a mere non-randomized association with 'smoking related' disease.

By using epigenetic markers for smoking they wish to create an illusion that their result is from hard science (experiments, uncovering of biochemical mechanism), instead of being junk science, observation of a mere non-randomized statistical associations (which could imply mutually opposite conclusions).

[GOPJ]

Yes, I want to live a long time so some liberal death panel can decide my life ends with a withdrawal of food and water. Maybe they’ll pull finger nails out with pliers for extra fun. At a certain age, it’s best to start smoking again...

[xrmusn]

At a certain age, it’s best to start smoking again...
= = = = = = = = = = = = = = =
DR: “Do you smoke, drink, carouse, etc”
Man: “No, NO, No”.
Dr: “What is your long term goal”?
Man: “to live to be 100”
Dr: “Why bother”?

[vigilante2]

I quit smoking two years ago, best thing I ever did. I can't stand the smell of them anymore. Save a lot of money too.

[GOPJ]

LOL - Thanks for sharing.

[Just another Joe]

I quit smoking two years ago

Good for you.

I quit 5 years ago. Can't say it was the best thing I ever did. I haven't seen very many things change since stopping.

As long as you don't become an anti-smoker you're fine.

[Just another Joe]

I used to debunk studies such as these on a semi-regular basis.
All you have to do is study them closely and the inconsistencies almost jump out at you.

[Just another Joe]

While there were no genuine randomized smoking experiments on humans, there were thousands such experiments on animals but you will never hear about these findings since they all went the "wrong way" -- smoking animals get fewer cancers and live ~20% longer than non-smoking animals, while staying thinner (by 15%) and sharper into the old age.

Sonds like the study done by the World Health Organization that you won't find bandied about by any anti-smoker, even though it's the largest study on smoking ever done.

I'll give you one guess on that outcome.

[nightlight7]

I'll give you one guess on that outcome.

The results were so bad, they even removed the news stories which initially reported on it (such as the U.K. Telegraph story below).

Passive smoking doesn't cause cancer - official
By Victoria Macdonald, Health Correspondent (U.K. Telegraph)

THE world's leading health organization has withheld from publication a study which shows that not only might there be no link between passive smoking and lung cancer but that it could even have a protective effect.

The astounding results are set to throw wide open the debate on passive smoking health risks. The World Health Organisation, which commissioned the 12-centre, seven-country European study has failed to make the findings public, and has instead produced only a summary of the results in an internal report.
...