Vitamin D receptor and growth inhibition by 1,25-dihydroxyvitamin D-3 in human malignant melanoma cell lines

The expression of vitamin D receptors (VDR) and growth inhibition induced by 1,25-dihydroxyvitamin D-3 have been noted in certain human malignant melanoma cell lines. In this study, widely disparate levels of VDR mRNA expression were demonstrated in a panel of eight human malignant melanoma cell lines. Quantitation of receptor level by ligand binding assay showed a similar pattern. Proliferation and growth curve analysis was performed in two cell lines: RPMI 7951 (high VDR) and SK-MEL-28 (low VDR). Significant growth inhibition was noted in RPMI 7951 cells at 10(-9) M 1,25-dihydroxyvitamin Ds SK-MEL-28 cells, which express much lower levels of VDR, did not show any growth inhibition except at extremely high concentrations of 1,25-dihydroxyvitamin D-3, namely 10(-6) M. These findings suggest a receptor-mediated mechanism of growth inhibition for 1,25-dihydroxyvitamin Ds and a role for this hormone in the growth of malignant melanoma cells. (C) 1996 Academic Press, Inc.