MEMORANDUM FOR: Science Writers and Editors on the Journal Press List: Compounds in Smoke Linked to Specific Cancer-Related Genetic Changes

Extract

May 11, 2000 (EMBARGOED FOR RELEASE 4 P.M. EDT May 16)

Chemicals formed by the burning of organic materials, including tobacco, can cause a specific pattern of genetic mutation often seen in human lung cancers.

This research is presented by Leslie Smith, Ph.D., and Gerd Pfeifer, Ph.D., City of Hope Cancer Center in Los Angeles, and colleagues, in the May 17 issue of the Journal of the National Cancer Institute.

Polycyclic aromatic hydrocarbons (PAHs) are present in our environment from gasoline and diesel engines and industrial sources. However, the largest concentrations of PAHs are inhaled by cigarette smokers. PAHs are thought to be major factors in the development of lung cancer, since they can cause mutations of the p53 tumor suppressor gene. Mutations of this gene are seen in 60% of human lung cancers.

The authors exposed cultures of normal human bronchial epithelial cells to various concentrations of five different PAHs. After this exposure, DNA from the cells was analyzed for mutational damage patterns—specifically, for the formation of covalent adducts at certain sites along the DNA in the p53 gene.