LUNG-TUMORS IN STRAIN A MICE - APPLICATION FOR STUDIES IN CANCER CHEMOPREVENTION

Strain A mice develop a high incidence of spontaneous lung tumors duri ng their lifetime. These tumors may be found in some animals as early as 3 to 4 weeks of age, increasing to nearly 100% by 24 months of age. The strain A mouse is also highly susceptible to the induction of lun g tumors by several classes of chemical carcinogens and has been used extensively as a mouse lung tumor bioassay for assessing the carcinoge nic activity of a variety of chemicals. In addition to its use in carc inogen detection, the strain A mouse lung tumor model has been employe d extensively for the identification of inhibitors of chemical carcino genesis. A number of chemopreventive agents including beta-naphthoflav one, butylated hydroxyanisole, ellagic acid, phenethyl isothiocyanate, phenylpropyl isothiocyanate, phenylbutyl isothiocyanate, phenylhexyl isothiocyanate, indole-3-carbinol, etc., have been shown to inhibit ch emically induced lung tumors in strain A mice. In most instances, inhi bition of lung tumorigenesis has been correlated with effects of the c hemopreventive agent on the metabolic activation and/or detoxification of carcinogens. To date, no chemopreventive agent has been shown to i nhibit lung tumorigenesis in strain A mice when administered after the carcinogen, i.e., during the promotion/progression stages of tumor de velopment. Efforts should be made to develop a standardized protocol i n strain A mice for evaluating chemopreventive agents as inhibitors of both the initiation and progression stages of lung tumor development. (C) 1993 Wiley-Liss, Inc.