Cell proliferation in cancer prevention; effects of preventive agents on estrogen-related endometrial carcinogenesis model and on an in vitro model in human colorectal cells

Proto-oncogenes such as c-fos, c-jun and c-myc are known to relate to cell proliferation and differentiation. Some oriental herbal medicines like Glyc yrrhizae radix or Juzen-taiho-to were found to suppress estradiol-17 beta ( E2)-induced expression of c-fos/jun in uterine corpus and inhibited N-methy l-N-nitrosourea and E2-induced endometrial carcinogenesis in mice. It is su ggested that the effects of such oriental drugs are exerted probably throug h suppression of estrogen-induced c-fos/jun expression and they are promisi ng preventing agents for endometrial cancers. In the combined in vitro assa y for cell proliferation (NITS assay) and apoptosis (DNA fragmentation) in human colorectal cancer cells (Colo 320), a number of naturally occurring c hemopreventive agents such as curcumin, quercetin, auraptene, 1 ' -acetoxyc havicol acetate (ACA) and indole-3-carbinol were shown to generate apoptosi s as well as to inhibit cell proliferation. The results suggest a mode of a ction of these chemopreventive agents and also imply that such in vitro sho rt term assay is useful for detection of new agents for cancer prevention. (C) 2001 Elsevier Science B.V. All rights reserved.