1,25-Dihydroxyvitamin D-3 synthetic analogs inhibit spontaneous metastasesin a 1,2-dimethylhydrazine-induced colon carcinogenesis model

In order to substantiate the role of vitamin D applicability for the preven tion of colon cancer and its spontaneous metastases, the effect of 1,25-dih ydroxyvitamin D-3 and its synthetic analogs, 1,25-dihydroxy-16,23Z-diene-26 ,27-hexafluoro-D-3 (Ro 25-5317) and 1,25-dihydioxy-16,23E-diene-26,27-hexaf luoro-19-nor-D-3 (Ro 25-9022), have been evaluated in a 1,2-dimethylhydrazi ne (DMH)-induced colon carcinogenesis model in Sprague-Dawley rats. In anim als maintained on 2.75 nmol/kg, 1,25-dihydroxyvitamin D-3 diet no statistic al difference was seen in tumor incidence when compared with control while in animals on 3.0 nmol/kg 1,25-dihydroxyvitamin D-3 diet, the incidence of tumors was significantly lower. In animals maintained on 3.0 nmol/kg Ro 25- 5317 diet also no statistical difference was seen in tumor incidence compar ed with control while in animals on 3.5 nmol/kg Ro 25-5317 diet the inciden ce of tumors was significantly lower. The incidence of tumors in the group of animals maintained on 3.0 nmol/kg and 3.5 nmol/kg Ro 25-9022 was signifi cantly lower, at 32.1% and 27.6% respectively, compared to control. In the two groups of animals maintained on the 1,25-dihydroxyvitamin D-3 diet no s ignificant difference in the incidence of metastasis was seen. In the group of animals maintained on 3.0 nmol/kg Ro 25-5317 diet only regional metasta ses were seen. However, no metastases developed in the rats on 3.5 nmol/kg Ro 25-5317 diet. After administration of 3.0 nmol/kg Ro 25-9022 diet, metas tases developed in a significantly less number of animals while no metastas es occurred in the rats maintained on the 3.5 nmol/kg Ro 25-9022 diet. The above studies will provide a scientific basis for the progression into furt her clinical trials in the treatment, and/or chemoprevention of human color ectal cancer.