INHIBITION OF 4-(METHYLNITROSAMINO)-1-(3-PYRIDYL)-1-BUTANONE TUMORIGENICITY IN MOUSE LUNG BY THE SYNTHETIC ORGANOSELENIUM COMPOUND, 1,4-PHENYLENEBIS(METHYLENE)SELENOCYANATE

The chemopreventive effect of 5, 10 and 15 p.p.m. (as selenium) of 1,4 -phenylenebis(methylene)selenocyanate (p-XSC) on lung tumor induction by the tobacco-specific 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was examined in female A/J mice by administering p-XSC in the d iet. Sodium selenite (5 p.p.m. selenium) was given in the same manner for comparison with p-XSC. Mice were fed experimental diets containing the selenium compounds 1 week before i.p. injection of 10 mumol NNK i n 0.1 ml saline and throughout the experiment until termination, 16 we eks after carcinogen administration. Body weights of the mice in the d ifferent dietary groups did not differ significantly. p-XSC significan tly inhibited lung tumor multiplicity from 7.6 tumors per mouse in the control group to 4.1, 3.3 and 1.8 tumors per mouse in animals given 5 , 10 and 15 p.p.m. of selenium respectively. In contrast, 5 p.p.m. sod ium selenite had no protective effect against lung tumor induction. Th e results of this study clearly indicate that the structure of seleniu m-containing compounds is important in determining their efficacy as c hemopreventive agents.