Inhibition of Cancer Growth by Vitamin D Requires Receptor Induction

A recent paper regarding the inhibitory effect of vitamin D on the growth of breast cancer cells highlighted the important role of the CCAAT-enhancer binding protein (C/EBP-alpha). C/EBP proteins interact with the CCAAT (cytidine-cytidine-adenosine-adenosine-thymidine) nucleoside box motif, which is present in several gene promoters.

Investigators at the University of Medicine and Dentistry of New Jersey-New Jersey Medical School (Newark, USA) studied the effect of calcitriol, the active form of vitamin D, on breast cancer cells growing in tissue culture.

They reported in the January 30, 2009, online issue of The Journal of Biological Chemistry that C/EBP-alpha was induced by calcitriol (1,25(OH)2D3) and was a potent enhancer of vitamin D receptor transcription in MCF-7 breast cancer cells. C/EBP-alpha was not detected in MDA-MB-231 cells that were poorly responsive to calcitriol. Induction of vitamin D receptors was observed in MDA-MB-231 cells transfected with C/EBP-alpha, while knockdown of C/EBP-alpha in MCF-7 cells suppressed vitamin D receptors and reversed the antiproliferative effects of calcitriol. In other words, cancer cells that were unable to activate receptors for vitamin D were not inhibited by exposure to the vitamin.

"These results provide an important process in which the active form of vitamin D may work to reduce growth of breast cancer cells," said senior author Dr. Sylvia Christakos, professor of biochemistry and molecular biology at the University of Medicine and Dentistry of New Jersey-New Jersey Medical School. "These studies provide a basis for the design of new anticancer agents that can target the protein as a candidate for breast cancer treatment."

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University of Medicine and Dentistry of New Jersey-New Jersey Medical School