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NUCCA News - Nicotine activates enzyme aiding cancer
The enzyme prevents 'suicide' of cells damaged by tobacco chemicals, causing accumulation and cancer, says study http://straitstimes.asia1.com.sg/techscience/story/0,4386,164213,00.html WASHINGTON - Nicotine makes smoking addictive and is bad for the heart, but 60 other cigarette chemicals are blamed for causing cancer. Now, some biochemists say nicotine might help set the stage for those chemicals to do their dirty work. Nicotine is not a carcinogen but it facilitates cancer-causing tobacco chemicals to do their worst. Certain tobacco chemicals trigger cellular genetic damage. Damaged cells are supposed to 'commit suicide'; if they do not, the damage accumulates enough to turn cancerous. Nicotine activates an enzyme reaction which inhibits cellular suicide, says new research by scientists at the National Cancer Institute. Nicotine starts activating that enzyme, called Akt, within minutes, while cancer-causing genetic damage takes hours to begin, institute researchers report in the latest Journal of Clinical Investigation. That suggests nicotine, along with other chemicals which block cell suicide, may make cells more vulnerable to the cancer-causers. 'Nicotine is not a carcinogen; we're not trying to make that argument,' said study leader Phillip Dennis. But 'it may have a permissive effect' on cancer formation. Scientists first discovered nicotine may block cell suicide 10 years ago, said nicotine expert Neal Benowitz of the University of California, San Francisco. But the new research uncovers the actual enzyme involved. The question now is whether the effect matters to smokers using nicotine gum or patches in a bid to quit. 'It's clearly better for people to stop smoking and use a patch than to continue smoking,' Dr Dennis said, adding that the study reinforces that anti-smoking medicines are for short-term use only. But Dr Benowitz said the study had used cells in laboratory dishes, while previous studies of snuff users - who do not absorb as many carcinogens as smokers - suggest there is little cancer risk from nicotine. --AP ---------------------------------------------------------------------------- ---- Cells more vulnerable Scientists at the National Cancer Institute say nicotine is not a carcinogen. But it may pave the way for cancer formation. It kick-starts an enzyme, called Akt, which inhibits suicide in damaged cells. This means nicotine may make cells more vulnerable to cancer-causing chemicals. |
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