Nicotine attaches itself to a specific receptor in the body and increases the tendency of nicotine addiction as well as breast cancer, a new study has revealed.
Yuan-Soon Ho of the Taipei Medical University, and colleagues found that human breast cancer cells consistently over-expressed the alpha 9 subunit of the nAChR (nicotinic acetylcholine receptor).
The expression was higher in advanced-stage breast cancer compared with early-stage cancer.
They also found that reducing the levels of nAChR inhibited tumour growth in laboratory experiments, whereas increasing its levels or treating more normal breast cells with nicotine promoted the development of cancer characteristics.
The authors say their study was limited by its small sample size, and the fact that it included only Asian patients.
Ilona Linnoila of the Center for Cancer Research at the National Cancer Institute writes that the study "suggests not only that smoking could be causally related to breast carcinogenesis but also that nicotine could directly contribute to the molecular mechanism of carcinogenesis in addition to indirectly contributing by promoting addiction to smoking."
The study is published online August 23 in The Journal of the National Cancer Institute.