Acute Myeloid Leukemia Research Today is a free monthly online journal that collates and summarizes the latest research about Acute Myeloid Leukemia, including details on aml, symptoms, treatment, information. | ||||||||
|
19-Nor-1,25(OH)2D2 (a novel, noncalcemic vitamin D analogue), combined with arsenic trioxide, has potent antitumor activity against myeloid leukemia.Kumagai T, Shih LY, Hughes SV, Desmond JC, O'Kelly J, Hewison M, Koeffler HP Division of Hematology/Oncology, University of California at Los Angeles School of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA. kumamed1_2001@yahoo.co.jp Recently, we reported that a novel, noncalcemic vitamin D analogue (19-nor-1,25(OH)2D2; paricalcitol) had anticancer activity. In this study, we explored if paricalcitol enhanced anticancer effects of other clinically useful drugs in vitro against a large variety of cancer cells. Paricalcitol, when combined with As2O3, showed a markedly enhanced antiproliferative effect against acute myeloid leukemia (AML) cells. This combination induced monocytic differentiation of NB-4 acute promyelocytic leukemia (APL) cells and HL-60 AML cells and caused both to undergo apoptosis associated with down-regulation of Bcl-2 and Bcl-x(L). Paricalcitol induced monocytic differentiation of U937 AML cells, which was partially blocked by inducing expression of APL-related PML-retinoic acid receptor alpha (RARalpha) chimeric protein in the U937 cells containing a Zn2+-inducible expression vector coding for this fusion protein (PR9 cells). Exposure to As2O3 decreased levels of PML-RARalpha in PR9 cells, and the combination of paricalcitol and As2O3 enhanced their monocytic differentiation in parallel with the As2O3-mediated decrease of PML-RARalpha. Furthermore, As2O3 increased the transcriptional activity of paricalcitol probably by increasing intracellular levels of paricalcitol by decreasing the function of the mitochondrial enzyme 25-hydroxyvitamin D3-24-hydroxylase, which functions to metabolize the active vitamin D in cells. In summary, the combination of paricalcitol and As2O3 potently decreased growth and induced differentiation and apoptosis of AML cells. This probably occurred by As2O3 decreasing levels of both the repressive PML-RARalpha fusion protein and the vitamin D metabolizing protein, 25-hydroxyvitamin D3-24-hydroxylase, resulting in increased activity of paricalcitol. The combination of both of these Food and Drug Administration-approved drugs should be considered for treatment of all-trans retinoic acid-resistant APL patients as well as those with other types of AML. Published 22 March 2005 in Cancer Res, 65(6): 2488-97.
© 2004-2008 Acute Myeloid Leukemia Research Today. All Rights Reserved. |
| ||||||
