THE ANTIPROLIFERATIVE EFFECT OF VITAMIN-D ANALOGS ON MCF-7 HUMAN BREAST-CANCER CELLS

We analyzed the antiproliferative effect of 1,25-dihydroxyvitamin D-3 and four vitamin D analogs on MCF-7, a human breast cancer cell line known to express the vitamin D receptor. Growth curve studies and [H-3]thymidine incorporation assays were used to assess the antiproliferative effect of 1,25-dihydroxyvitamin D-3 (vitamin D), Ro 23-7553, Ro 24-5531, Ro 25-5317, and Ro 24-5583. Growth of MCF-7 cells was significantly inhibited by 1,25-dihydroxyvitamin D-3 and all four analogs at 10(-8) M (P < 0.05). MCF-7 cells treated with analog had significantly less [H-3]thymidine incorporation than cells treated with 1,25-dihydroxyvitamin D-3 (P < 0.05). The affinity of the analogs for the vitamin D receptor was similar to that of 1,25-dihydroxyvitamin D-3. These results demonstrate that analogs of 1,25-dihydroxyvitamin D-3 are potent antiproliferative agents on human breast cancer cells and that this activity is likely mediated through the vitamin D receptor.