Smoking a pack a day causes 150 mutations in every lung cell, research shows
admin • November 4, 2016 • 13308
A man smokes a cigarette along a road in Mumbai, India, October 26, 2016. REUTERS/Danish Siddiqui/File Photo
Scientists have found that smoking a pack a day of cigarettes can cause 150 damaging changes to a smoker’s lung cells each year.
The findings come from a study of the devastating genetic damage, or mutations, caused by smoking in various organs in the body.
Publishing in the journal Science on Thursday, the researchers said the findings show a direct link between the number of cigarettes smoked in a lifetime and the number of mutations in the DNA of cancerous tumors.
The highest mutation rates were seen in lung cancers, but tumors in other parts of the body – including the bladder, liver and throat – also had smoking-associated mutations, they said. This explains why smoking also causes many other types of cancer beside lung cancer.
Smoking kills six million people a year worldwide and, if current trends continue, the World Health Organization predicts more than 1 billion tobacco-related deaths this century.
Cancer is caused by mutations in the DNA of a cell. Smoking has been linked with at least 17 types of cancer, but until now scientists were not clear on the mechanisms behind many of them.
Ludmil Alexandrov of Los Alamos National Laboratory in the United States, one of those who carried out the research, explained that in particular, it had until now been difficult to explain how smoking increases the risk of cancer in parts of the body that don’t come into direct contact with smoke.
“Before now, we had a large body of epidemiological evidence linking smoking with cancer, but now we can actually observe and quantify the molecular changes in the DNA,” he said.
This study analyzed over 5,000 tumors, comparing cancers from smokers with those from people who had never smoked.
It found certain molecular fingerprints of DNA damage – called mutational signatures – in the smokers’ DNA, and the scientists counted how many of these were in different tumors.
In lung cells, they found that on average, smoking a pack of cigarettes a day led to 150 mutations in each cell every year. Each mutation is a potential start point for a “cascade of genetic damage” that can eventually lead to cancer, they said.
The results also showed that a smoking a pack of cigarettes a day led to an average 97 mutations in each cell in the larynx, 39 mutations for the pharynx, 23 for the mouth, 18 for the bladder, and six mutations in every cell of the liver each year.
Mike Stratton, who co-led the work at Britain’s Wellcome Trust Sanger Institute, said it was a bit like digging in to the archaeology of each tumor
“The genome of every cancer provides a kind of archaeological record, written in the DNA code itself, of the exposures that caused the mutations,” he said. “Looking in the DNA of cancers can provide provocative new clues to how (they) develop and thus, potentially, how they can be prevented.” — Reuters
The U.S. investigation into hundreds of cases of life-threatening lung illnesses related to vaping is turning up new clues and helping researchers across the country trying to make sense of the situation.
Robert Tarran, a physiologist and vaping expert at the University of North Carolina School of Medicine, is one of a group of researchers studying collections of lung cell samples, looking for answers about the outbreak.
“In my lab we study real world vapers who vape normally. So we’ve been collecting people who’ve been vaping for six months to a couple of years and then taken their lungs as they are. So I think the people we’ve been studying are representative of people being hospitalized. And I think it’s important to say that in the all the vapers that we’ve studied we’re seeing changes in their lungs,” he told Reuters.
Many of the victims had pockets of oil clogging up cells responsible for removing impurities in the lungs.
The answer to where that oil comes from will help explain whether these cells play a key role in the vaping-related outbreak that has killed atleast seven people and sickened 530 so far.
It may also reveal whether some of these cases have been occurring all along, undetected.
A group of researchers who have been studying the long-term effects of vaping told Reuters they have taken up the challenge. They have begun to re-examine lung cell samples they have collected in recent years for evidence of these oil-filled immune cells in people who vaped but didn’t get sick.
One possibility: The deposits are residue from inhaling vaping oils, such as those containing the marijuana ingredient tetrahydrocannabinol (THC) or vitamin E acetate. Both are considered possible contributors to the current illnesses.
Some researchers suspect the oils are formed inside the lungs as part of the body’s natural response to chemicals found in many commercial vaping devices. One theory is that vaping these chemicals may impair the immune system, and make people who vape more vulnerable to respiratory distress, they say.
“One of the things we found there is a wide variety some liquids are more toxic than others and we found there is a correlation the more flavors in a liquid the more likely it was to be toxic. But there’s also an incredible diversity of flavors. So in 150 e-liquids we found about 200 different chemical constituents. And so really the flavors e-liquid really are all over the map,” Tarrant said.
A study published in the Journal of Clinical Investigation earlier this month has fueled the latter theory.
It found that mice exposed to aerosols of propylene glycol and vegetable glycerin – common solvents used in conventional nicotine vaping devices – developed these same fat-clogged immune cells even though they were never exposed to vaping oils. These mice also had impaired immune systems compared to mice exposed to room air.
The study set off alarm bells for Thomas Eissenberg, co-director of the Center for Tobacco Products at Virginia Commonwealth University. For years, doctors have reported isolated cases of pneumonia-like illnesses in people who vaped. In many cases, patients also had these fat-filled immune cells – called lipid-laden macrophages.
Now, these same abnormalities have been found in mice, and in at least some of the people who have fallen ill recently.
They want to help determine is whether these abnormalities have been present for years, and whether they have made vapers generally more vulnerable to severe disease, possibly triggered by some new vaping substance.
The group’s members say they have been in regular contact with officials at the CDC and the National Institutes of Health on how they can best help with the multistate investigation.
They include Tarran, a physiologist and vaping expert at the University of North Carolina School of Medicine, and Dr. Peter Shields, a lung cancer specialist at The Ohio State University Wexner Medical Center, who has one of the country’s largest sets of lung samples from vapers, smokers and never-smokers.
Investigators at the CDC and the U.S. Food and Drug Administration (FDA) have pointed to THC vaping oils or vitamin E, a substance used in some THC products, as a possible cause of these illnesses. But they have not ruled out anything yet, including conventional nicotine liquids.
“So we’ve been able to break some of our studies down to study just the nicotine or the solvent the propane glycol vegetable glycerin. And we’ve been finding changes due to both of these components. So we can help identify things in any liquids which are having these effects and then potentially we could extend these studies and study cannabinoids or the vitamin E oils,” Tarrant said.
CDC pathologists are examining hundreds of lung cell samples gathered from patients in the outbreak. Meanwhile, forensic chemists at the FDA are testing more than 120 products to determine whether there is a common ingredient that may explain the illnesses. (REUTERS)
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President Rodrigo Duterte signed on Thursday (July 25) the law imposing higher excise taxes on tobacco products, Executive Secretary Salvador Medialdea has confirmed.
“To address the urgent need to protect the right to health of the Filipino people and to maintain a broader fiscal space to support the implementation of the Universal Health Care Act, the President has signed into law HB no. 8677/ SB no. 2233 Increasing the Excise Tax on Tabacco Products,” he said in a statement.
Meanwhile, health advocates including the Sin Tax Coalition lauded the signing of the law on increasing tobacco taxes.
“This latest tax increase represents another positive step in protecting more Filipinos from the harmful effects of cigarette smoking,” said Dr. Anthony Leachon, health advocate and former independent director of PhilHealth.
President Rodrigo Duterte will sign the proposed tobacco excise tax law this week according to the Department of Finance (DOF) on Wednesday (July 24).
Finance Undersecretary Karl Chua said the law is ready for signature and it will lapse into law by July 27.
“I was told it would be signed this week because that is a priority measure certified urgent by the President in the previous Congress and mentioned by the President in the SONA (state of the nation address),” he said.
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