Chemoprevention of vinyl carbamate-induced lung tumors in strain a mice

The ability of potential chemopreventive agents to prevent vinyl carbamate- induced lung turners was determined in 2 different experiments. Female stra in A mice adminstered intraperitoneally either a single injection of 60 mg/ kg vinyl carbamate that induced 24.0 +/- 1.72 tumors/mouse at 24 weeks or 2 injections of 16 mg/kg vinyl carbamate each (32 mg/kg total dose) that ind uced 43.2 +/- 3.2 tumors/mouse at 20 weeks. Lung carcinomas were Sound as e arly as 16 weeks. Dexamethasone and piroxicam provided in the diet were fou nd to significantly inhibit lung tumors induced by 60 mg/kg vinyl carbamate at 24 weeks whereas myo-inositol also provided in the diet, did not signif icantly inhibit tumor formation. In animals given 6 16-mg/kg doses of vinyl carbamate, tumor multiplicity was reduced roughly 25% by alpha -difluorome thylornithine and green tea and reduced 50% by dexamethasone and piroxicam. Combinations of these agents were also tested using a total dose of 32 mg/ kg of vinyl carbamate. Although alpha -difluoromethylornithine and green te a did not result in a significant inhibition of lung tumor formation if use d alone, the combination of alpha -difluoromethylornithine and green tea re sulted in a significant reduction of tumor multiplicity. The combinations o f alpha -difluoromethylornithine or green tea with either dexamethasone or piroxicam or the combination of dexamethasone and piroxicam did not decreas e tumor multiplicity greater than achieved by dexamethasone and piroxicam a lone. In summary, selected chemopreventive agents previously shown to inhib it lung tumors by other chemical carcinogens also inhibited vinyl carbamate -induced lung tumors.