Calcitriol supplementation effects on Ki67 expression and transcriptional profile of breast cancer specimens from post-menopausal patients.

Background & Aims: High concentration of 1,25(OH)2D3 (50-100 nM), which cause hypercalcemia in vivo, induce the hormone transcriptional targets and exert antiproliferative effects in cultured breast cancer lineages, however, no studies investigated whether these effects might be reproduced in tumor specimens in vivo. Our aim was to evaluate the effects of calcitriol supplementation on the proliferative index (Ki67 expression) and gene expression profile of post-menopausal breast cancer samples.

Methods & Results: Tumor samples were collected from 33 patients, most of whom (87.