Heat shock protein 90 interacts with vitamin D receptor in human leukemia cells.

The active form of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1,25D), has a broad range of effects which are mediated by nuclear vitamin D receptor (VDR). Many experiments that investigate the role of VDR can be done in human acute myeloid leukemia (AML) cells, since these cells are responsive to 1,25D and express VDR in a 1,25D-regulated manner. In this paper we show that in HL60 and in THP-1 cells VDR protein interacts with heat shock protein 90 (Hsp90) and that Hsp90 is important for differentiation of AML cells. Geldanamycin (GA), an Hsp90 inhibitor, is able to suppress 1,25-induced differentiation of HL60 cells.