Effect of selenomethionine on N-methylnitronitrosoguanidine-induced colonic aberrant crypt foci in rats

An association between low selenium intake and the incidence or prevalence of cancers is well known. Selenium in the form of selenomethionine suppleme nted in drinking water has been found to be highly effective in reducing tu mour incidence and preneoplastic foci during the development of hepatocarci nogenesis in rats in our previous studies. Here, an attempt has been made t o investigate whether the dose and form of selenium found to be effective d uring hepatocarcinogenesis is equally effective in N-methylnitronitrosoguan idine-induced colorectal carcinogenesis in terms of antioxidant defence enz yme systems, DNA chain breaks and incidences of aberrant crypt foci. Treatm ent with selenomethionine either on initiation or on selection/promotion, o r during the entire experiment showed that selenomethionine was most effect ive in regulating the cellular antioxidant defence systems, DNA chain break control and reducing aberrant crypt foci in the colorectal tissues of rats . Our results also confirm that selenium is particularly effective in limit ing the action of the carcinogen during the initiation phase of this colore ctal carcinogenesis, just as we found with hepatocarcinogenesis in our prev ious studies. (C) 2001 Lippincott Williams & Wilkins.