INHIBITORY EFFECTS OF MAGNESIUM-HYDROXIDE ON C-MYC EXPRESSION AND CELL-PROLIFERATION INDUCED BY METHYLAZOXYMETHANOL ACETATE IN RAT COLON

The effects of magnesium hydroxide were examined on methylazoxymethano l (MAM) acetate-induced c-myc expression and cell proliferation of col onic mucosal epithelium in rats. Rats were divided into four groups an d treated as follows: MAM acetate alone (25 mg/kg i.p.injection, five times, once a week for 5 weeks), MAM acetate and feeding of 0.2% magne sium hydroxide in diet, magnesium hydroxide alone and non-treatment. A t 4, 8 and 16 weeks after the start of experiment, 10 rats in each gro up were sacrificed. Magnesium hydroxide inhibited the MAM-induced expr ession of c-myc proto-oncogene, and also suppressed the increased brom odeoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA) lab elling indexes induced by MAM acetate in colon mucosa in initiation an d post-initiation phase. These results suggest that the anti-carcinoge nic effect of magnesium hydroxide on rat colon carcinogenesis induced by MAM acetate may be related to the inhibition of the carcinogen-indu ced expression of c-myc proto-oncogene and cell proliferation.