Ethacrynic acid and 1 alpha,25-dihydroxyvitamin D3 cooperatively inhibit proliferation and induce differentiation of human myeloid leukemia cells.
The active form of vitamin D, 1 alpha,25-dihydroxyvitamin D3 (VD3), inhibits proliferation and induces differentiation of leukemia cells, but its clinical use is limited by the adverse effect of hypercalcemia. In this study we found that the loop diuretic ethacrynic acid, which is used to treat hypercalcemia, enhanced the differentiation of human leukemia cells induced by VD3. Ethacrynic acid alone inhibited the proliferation of human promyelocytic HL-60 cells while only slightly increasing differentiation markers such as nitroblue tetrazolium (NBT)-reducing and lysozyme activities. Ethacrynic acid effectively enhanced the growth-inhibiting action of VD3. In the presence of ethacrynic acid, VD3 increased the NBT-reducing and lysozyme activities and the CD11b expression of HL-60 cells more effectively than VD3 alone. Other loop diuretics, furosemide and bumetanide, also enhanced the differentiation of HL-60 cells induced by VD3, but to a lesser extent than ethacrynic acid. The differentiation of HL-60 cells induced by all-trans retinoic acid, dimethyl sulfoxide or phorbol-12-myristate 13-acetate was also enhanced by ethacrynic acid with increasing NBT-reducing and lysozyme activities and the expression of CD11b or CD14 surface antigen. Morphologically, ethacrynic acid enhanced the monocytic differentiation of HL-60 cells induced by VD3 and phorbol ester and the granulocytic differentiation by retinoic acid and dimethyl sulfoxide. Other human myelomonocytic leukemia ML-1, U937, P39/TSU and P31/FUJ cells were induced to differentiate by VD3 and this was also enhanced by ethacrynic acid. The long-term culture of HL-60 cells showed that ethacrynic acid plus VD3 induced the complete growth arrest of HL-60 cells. Therefore ethacrynic acid, which is used to treat hypercalcemia, enhanced the proliferation-inhibiting and differentiation-inducing activities of VD3 and the combination of ethacrynic acid and VD3 may be useful in therapy for myeloid leukemia.
Makishima
M
M
Department of Chemotherapy, Saitama Cancer Center Research Institute, Japan.
Honma
Y
Y
D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004232:Diuretics / Q000494:pharmacology*; D004357:Drug Synergism; D004976:Ethacrynic Acid / Q000494:pharmacology*; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology*; D014410:Tumor Stem Cell Assay
D004232:Diuretics; D002117:Calcitriol; D004976:Ethacrynic Acid