[Induction of expression of MDR 1 gene by retinoic acid and DMSO and effects on rhodamine-123 efflux in HL-60 cell lines and resistant sublines].

Using dot blot hybridization and flowcytometry, the effects of differentiation inducers retinoic acid (RA) and dimethyl sulfoxide (DMSO) on the resistant level of HL-60 cells and its resistant subline cells were studied. When the cells were treated with RA 1 mumol.L-1 for 24 h, the expression of MDR 1 mRNA evidently increased in both HL-60 and its multidrug resistant subline cells. The efflux of Rho-123 in the multidrug resistant subline cells was slightly decreased. But, when the cells were treated with 2% DMSO for 24 h the efflux of Rho-123 increased obviously. The results suggest that RA can induce the expression of MDR1 gene but perhaps inhibit the function of pump glycoprotein 170 (Pgp-170) through phosphorylation/dephosphorylation pathway. However, DMSO could induce the expression of full function of Pgp.