title: 19-nor vitamin-D analogs: a new class of potent inhibitors of proliferation and inducers of differentiation of human myeloid leukemia cell lines.
abstract: We have studied the in vitro biological activities and mechanisms of action of 1,25-dihydroxyvitamin D3 (1,25D3) and nine potent 1,25D3 analogs on proliferation and differentiation of myeloid leukemia cell lines (HL-60, retinoic acid-resistant HL-60 [RA-res HL-60], NB4 and Kasumi-1). The common novel structural motiff for almost all the analogs included removal of C-19 (19-nor); each also had unsaturation of the side chain. All the compounds were potent; for example, the concentration of analogs producing a 50% clonal inhibition (ED50) ranged between 1 x 10(-9) to 4 x 10(-11) mol/L when using the HL-60 cell line. The most active compound [1, 25(OH)2-16,23E-diene-26-trifluoro-19-nor-cholecalciferol (Ro 25-9716)] had an ED50 of 4 x 10(-11) mol/L; in contrast, the 1,25D3 produced an ED50 of 10(-9) mol/L with the HL-60 target cells. Ro 25-9716 (10(-9) mol/L, 3 days) was a strong inducer of myeloid differentiation because it caused 92% of the HL-60 cells to express CD11b and 75% of these cells to reduce nitroblue tetrazolium (NBT). This compound (10(-8) mol/L, 4 days) also caused HL-60 cells to arrest in the G1 phase of the cell cycle (88% cells in G1 v 48% of the untreated control cells). The p27(kip-1), a cyclin-dependent kinase inhibitor which is important in blocking the cell cycle, was induced more quickly and potently by Ro 25-9716 (10(-7) mol/L, 0 to 5 days) than by 1,25D3, suggesting a possible mechanism by which these analogs inhibit proliferation of leukemic growth. The NB4 promyelocytic leukemia cells cultured with the Ro 25-9716 were also inhibited in their clonal proliferation (ED50, 5 x 10(-11) mol/L) and their expression of CD11b was enhanced (80% positive [10(-9) mol/L, 4 days] v 27% untreated NB4 cells). Moreover, the combination of Ro 25-9716 (10(-9) mol/L) and all-trans retinoic acid (ATRA, 10(-7) mol/L) induced 92% of the NB4 cells to reduce NBT, whereas only 26% of the cells became NBT positive after a similar exposure to the combination of 1,25D3 and ATRA. Surprisingly, Ro 25-9716 also inhibited the clonal growth of poorly differentiated leukemia cell lines (RA-res HL-60 [ED50, 4 x 10(-9) mol/L] and Kasumi-1 [ED50, 5 x 10(-10) mol/L]). For HL-60 cells, Ro 25-9716 markedly decreased the percent of the cells in S phase of the cell cycle and increased the expression of the cyclin-dependent kinase inhibitor, p27(kip-1). In summary, 19-nor vitamin D3 compounds strongly induced differentiation and inhibited clonal proliferation of various myeloid leukemia cell lines, suggesting a therapeutic niche for their use in myeloid leukemia.
authors.affiliation: Division of Hematology/Oncology, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA 90048, USA.
authors.forename: H
authors.initials: H
authors.lastname: Asou
authors.forename: M
authors.initials: M
authors.lastname: Koike
authors.forename: E
authors.initials: E
authors.lastname: Elstner
authors.forename: M
authors.initials: M
authors.lastname: Cambell
authors.forename: J
authors.initials: J
authors.lastname: Le
authors.forename: M R
authors.initials: MR
authors.lastname: Uskokovic
authors.forename: N
authors.initials: N
authors.lastname: Kamada
authors.forename: H P
authors.initials: HP
authors.lastname: Koeffler
mesh_terms: D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019008:Drug Resistance, Neoplasm; D016193:G1 Phase; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D018922:HL-60 Cells / Q000187:drug effects; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology*; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics; D015394:Molecular Structure; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D009580:Nitroblue Tetrazolium; D010084:Oxidation-Reduction; D013329:Structure-Activity Relationship; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000187:drug effects; D025521:Tumor Suppressor Proteins; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D018797:Cell Cycle Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D025521:Tumor Suppressor Proteins; D014807:Vitamin D; D050760:Cyclin-Dependent Kinase Inhibitor p27; D009580:Nitroblue Tetrazolium; D014212:Tretinoin