Detoction of Anti-Tumor-Promoters by Soft Agar Colony Forming Assay and Application to Inhibition of Urinary Bladder Carcinogenesis

Previously，we reported that colony formation in soft agar was shown with rat bladder cells prior to papilloma development in rat treated BBN。And we provided a short-term screening method for detecting new carcinogens，promoters and anti-tumor-promoters.We also evaluated NDG A inhibited saccharin-induced colony formation，suggesting that it has anti-tumor-promoting activity in rat bladder carcinogenesis。We studied long-term experiment on the anti-tumor-promoting effect of NDGA on urinary bladder carcinogenesis in rats induced by BBN。Six-wk-old male Fischer344 rats were distributed among8groups。The were given drinking with(groups5-8)or without(groups1-4)0.05%BBN for 4weeks，and then for 36weeks，they were given powdered diet containing5%Sodium Saccharin(Groups2and6)。All surviving animals were killed in week40.Histological abnormalities were investigated.The incidence and numbers of precarcinomatous lesions were significantly lower in group6(87%)than7(55%)。Group1，2，3，and4did not show any abnormalities of the bladder epithelium。These results confirm that NDGA have anti-tumor-promoting effects on bladder carcinogenesis in rats.

Previously, we reported that colony formation in soft agar was shown with rat bladder cells prior to papilloma development in rat treated BBN. And we provided a short-term screening method for detecting new carcinogens, promoters and antiーtumor-promoters. We also evaluated NDG A inhibited saccharin-induced colony formation, suggesting that it has anti-tumor-promoting activity in rat bladder carcinogenesis. We studied long-term experiment on the anti-tumor-promoting effect of NDGA on urinary bladder carcinogenesis in rats induced by BBN. Six-wk-old male Fischer 344 rats were distributed among 8 groups. The were given drinking with (groups 5-8) or without (groups 1-4) 0.05% BBN for 4weeks, and then for 36weeks, they were given powdered diet containing 5% Sodium Saccharin (groups 2and 6). All surviving animals were killed in week 40. Histological abnormalities were investigated. The incidence and numbers of precarcinomatous lesions were significantly lower in group 6 (87%) than 7 (55%). Group 1, 2, 3, and 4 did not show any abnormalities of the bladder epithelium. These results confirm that NDGA have anti-tumor-promoting effects on bladder carcinogenesis in rats.