VITAMIN-D-RECEPTOR AND GROWTH-INHIBITION BY 1,25-DIHYDROXYVITAMIN D-3IN HUMAN-MALIGNANT MELANOMA CELL-LINES

The expression of vitamin D receptors (VDR) and growth inhibition indu ced by 1,25-dihydroxyvitamin D-3 have been noted in certain human mali gnant melanoma cell lines. In this study, widely disparate levels of V DR mRNA expression were demonstrated in a panel of eight human maligna nt melanoma cell lines. Quantitation of receptor level by ligand bindi ng assay showed a similar pattern. Proliferation and growth curve anal ysis was performed in two cell lines: RPMI 7951 (high VDR) and SK-MEL- 28 (low VDR). Significant growth inhibition was noted in RPMI 7951 cel ls 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 a t extremely high concentrations of 1,25-dihydroxyvitamin D-3, namely 1 0(-6) M. These findings suggest a receptor-mediated mechanism of growt h inhibition for 1,25-dihydroxyvitamin Ds and a role for this hormone in the growth of malignant melanoma cells. (C) 1996 Academic Press, In c.