Abstract
The impact of combustible cigarettes on active and passive smokers has become a medical and social problem. In recent years, heated tobacco products (HTPs) have been available in Japan. HTPs are tobacco products in which the user inhales the aerosol produced by heating the tobacco. HTPs do not produce secondhand smoke from combustion and are therefore expected to reduce the adverse effects on human health. However, the health impact of HTPs has not been fully understood. Recent studies reported that HTPs have basically reduced levels of some chemicals, compared to combustible cigarettes; however, several chemicals have been reported to be increased in HTP. Because of the insufficient scientific evidence, there is concern about the long-term effects of exposures to HTPs. To understand the relationship between cigarette smoking and cancer, we have investigated the component of cigarette smoking using cancer stem cells, which give rise to many types of cancer. We identified that nicotine and NNK can induce the proliferation of human cancer stem cells. We also found that tobacco smoke extracts from HTPs induce the proliferation of cancer stem cells. It is necessary to identify other chemicals in tobacco smoke extracts from HTPs to understand the health risk of the long-term use of HTPs.
