"EB1089: A new vitamin D analogue that inhibits the growth of breast cancer cells in vivo and in vitro" by Colston, Mackay, James, Binderup, Chanders, and Coombes (1992), reports results of an investigation regarding the effects of a vitamin D analogue on breast cancer inhibition. The authors state that conventional vitamin D metabolites, when used as therapeutic agents, produce hypercalcaemia (doses over a few micrograms per day). Synthetic vitamin D analogues are found to be active in the promotion of cellular differentiation and inhibition of cell growth, and they have reduced calcaemic activity. There have been studies of the effects of calcipotriol (synthetic vitamin D analogue); findings show anti-tumor effects. However the metabolic half-life of calcipotriol is short (minutes) and therefore studies with new vitamin D analogues are needed.
The authors point out that other studies have shown anti-proliferative versus calcaemic activity with in vitro methods. Vitamin D metabolites and synthetic analogue effects on cell growth and differentiation with leukaemia cell lines have been done and effects on calcium homeostasis in vivo have been investigated in chickens or rodents. There is less data available for the effects of synthetic analogues on growth and differentiation of epithelial cells.
Positive anti-cancer results with other vitamin D analogues such as calcipotriol (MC903) and 20-epi-vitamin D3 analogues such as KH1060 as well as related problems of increased serum calcium and short half-life of the compounds used, were reported. Considerations for the present study included these factors that were not accounted for in previous investigations. For example the metabolic half-life of calcipotriol (minutes) may account for reduced calcaemic activity in vivo.
For this study effects were studied in MCF-7 human breast cancer cells grown and in rats with induced mammary tumors. Percentage change found in each tot...