1,25-dihydroxyvitamin D3 synthetic analogs inhibit spontaneous metastases in a 1,2-dimethylhydrazine-induced colon carcinogenesis model.

In order to substantiate the role of vitamin D applicability for the prevention of colon cancer and its spontaneous metastases, the effect of 1,25-dihydroxyvitamin D3 and its synthetic analogs, 1, 25-dihydroxy-16,23Z-diene-26,27-hexafluoro-D3 (Ro 25-5317) and 1, 25-dihydroxy-16,23E-diene-26,27-hexafluoro-19-nor-D3 (Ro 25-9022), have been evaluated in a 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis model in Sprague-Dawley rats. In animals maintained on 2.75 nmol/kg 1,25-dihydroxyvitamin D3 diet no statistical difference was seen in tumor incidence when compared with control while in animals on 3.

Novel 19-nor-hexafluoride vitamin D3 analog (Ro 25-6760) inhibits human colon cancer in vitro via apoptosis.

Our previously performed experiments clearly showed a significant VDR-mediated growth inhibitory effect of 1,25-dihydroxyvitamin D3 and its synthetic analogs in a variety of human cancer cells including human colon and breast cancer, soft tissue sarcoma, and malignant melanoma cell lines. The mechanisms by which 1, 25-dihydroxyvitamin D3 and its synthetic analogs growth inhibit human cancer cells is poorly elucidated. The exposure of human colon cancer cells HT-29 to 1,25-dihydroxyvitamin D3 or its analog, 1alpha, 25-dihydroxy-16-ene-23yne-26,27-hexafluoro-19-nor-choleca lci ferol (Ro 25-6760), at the 10(-6) M concentration resulted in significant growth inhibition with induction of the apoptotic process after three days of treatment detected by TUNEL assay and agarose gel electrophoresis of DNA.

Growth inhibitory effects of 1,25-dihydroxyvitamin D3 and its synthetic analogue, 1alpha,25-dihydroxy-16-ene-23yne-26,27-hexafluoro-19-nor-cholecalcifero l (Ro 25-6760), on a human colon cancer xenograft.

The effect of 1,25-dihydroxyvitamin D3 and its synthetic analogue, 1alpha,25-dihydroxy-16-ene-23yne-26,27-hexafluoro-19-n or-cholecalciferol (Ro 25-6760), have been evaluated both in vitro and in vivo in human colorectal cancer cell lines expressing high (HT-29) and low (SW-620) levels of vitamin D receptor. 1,25-Dihydroxyvitamin D3 caused significant dose-dependent growth inhibition of HT-29 cells at concentrations ranging from 10(-11) to 10(-6). The antiproliferative effect of Ro 25-6760 on HT-29 cells was also dose-dependent with cell counts on day 6, ranging from 98% of control at 10(-11) M to 14% of control at 10(-6) M.