EFFECTS OF 1,25-DIHYDROXYVITAMIN-D3 AND RETINOIC ACID ON THE PROLIFERATION AND CELL-CYCLE PHASE DISTRIBUTION OF NEUROBLASTOMA SK-N-SH CELLS

The hormone 1,25-(OH)2D3 has been shown to modulate cell proliferation and induce differentiation in several normal and malignant cell lines . In this work, we examined the effect of the hormone on the neuroblas toma SK-N-SH cell line. The steroid did not influence cell growth and cell cycle distribution, while retinoic acid inhibited proliferation a nd induced an accumulation of the cells in the G0/G1 phase of the cell cycle. 1,25-(OH)2D3 did not alter cell morphology. The activities of the 1-alpha- and 24-hydroxylases were low and not regulated by the hor mone. The level of the total 1,25-(OH)2D3 receptor was low. We conclud e that the lack of effect of 1,25-(OH)2D3 on the SK-N-SH cell line is related to the low level of the 1,25-(OH)2D3 receptor.