Study reveals cancer-linked epigenetic effects of smoking

October 9, 2010

For the first time, UK scientists have reported direct evidence that taking up smoking results in epigenetic changes associated with the development of cancer.

The results were reported at the 35th Congress of the European Society for Medical Oncology (ESMO) in Milan, Italy.

The link between smoking and cancer has been established for decades, explained Dr Yuk Ting Ma from the Cancer Research UK Institute of Cancer Studies, Birmingham, who presented the results. Smoking is the single biggest cause of cancer in the world, and years of research have confirmed that carcinogenic substances in can damage DNA.

Scientists have also suspected that smoking causes so-called epigenetic changes, such as methylation, which alter without causing changes to the actual DNA sequence.

"Until now, however, there has been no direct evidence that smoking induces in humans," Dr Ma said. "Cross-sectional surveys restricted to patients with cancer have revealed that aberrant methylation of several tumor suppressor genes is associated with smoking. But such surveys cannot distinguish those epigenetic changes that are a consequence of the disease process from those which are directly attributable to smoking."

In a study funded by Cancer Research UK, the British team set out to clarify the link between smoking and methylation in a cohort of 2,011 healthy young women aged 15-19 who were originally recruited as part of a study of pre-cancerous changes to cells of the cervix.

"For this particular study we have identified all the women from that cohort who had normal smears and who also tested negative for throughout follow-up," Dr Ma explained. "In this subgroup of disease-free women we have then tested the cervical smears of all the women who first started to smoke following study entry for p16 methylation, and compared them to women who were never smokers."

The researchers selected this group of women to ensure there were no potential cofounding factors for the detection of p16 methylation in otherwise healthy young women.

The particular gene the researchers were studying was p16, a so-called tumor suppressor gene. When it is methylated, this gene's normal tumor-suppressing function is inactivated.

"DNA methylation is a type of epigenetic change that can result in being inactivated," said Dr Ma. "Methylation of p16 has been frequently associated with the development of cancer in many parts of the body."

Because the women were all taking part in a study of cervical neoplasia, Dr Ma used cells from cervical smears to test for methylation of p16. Her group found that women who took up smoking during the study were more than three times as likely (odds ratio of 3.67) to acquire p16 methylation.

"Our study showed that compared with never-smokers, women who first started to smoke during follow-up had an increased risk of acquiring methylation of p16," Dr Ma said. "Our choice of study design and our study population allowed us to reveal, for the first time, the relationship between starting to smoke and the subsequent appearance of an epigenetic change."

The results provide evidence that smoking does induce DNA methylation, Dr Ma said. "The next step is now to show that women who acquire such smoking-induced methylation have an increased risk of developing malignancy."

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4 comments

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Quantum_Conundrum
1.8 / 5 (5) Oct 09, 2010
Ban this crap.

Why are we growing tobacco anyway instead of more food to feed the hungry?

Oh yeah, capitalism...
zslewis91
not rated yet Oct 10, 2010
Ban this crap.


jesus man, you just want to "Ban" everything. thoughtless being...i wish we could ban the garbage dripping from your finger tips. think before you speak sir.
dtxx
not rated yet Oct 10, 2010
Ban posting comments on message boards. They obviously only cause arguments and hurt feelings.

I just want to ask, QC. What do you think of the current state of prohibition in the US? Is it stopping drug use? What about when alcohol was prohibited? These days people are turning to chemicals (designer drugs/research chems) that are more dangerous and have no history of human use as the familiar ones get banned. Even if you gotta ban 'em all (pokemon!!), people will STILL use them and have terrible legal consequences. How does prohibition gain anything?
Shootist
not rated yet Oct 10, 2010
Ban this crap.

Why are we growing tobacco anyway instead of more food to feed the hungry?

Oh yeah, capitalism...


uh, "forget left or right, progressive or conservative; there are two types of people in the world, those who wish to control others, and those who have no such desire". - Robert A. Heinlein

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