title: Betulinic acid enhances 1alpha,25-dihydroxyvitamin D3-induced differentiation in human HL-60 promyelocytic leukemia cells.
abstract: Betulinic acid (BA) is a pentacyclic triterpene found in a number of medicinal plants and has been shown to cause apoptosis in a number of cell lines. We report here that BA may also have an effect on HL-60 cell differentiation. BA was cytotoxic to HL-60 cells with an IC50 of 5.7 microM after a 72-h treatment. Flow cytometry analysis showed that after exposure to 1-12 microM of BA for 72 h, approximately 10% of viable cells were in the sub-G1, presumably apoptotic, phase. At the same time differentiation was induced in approximately 10% (at 1 microM BA) to a maximum of 20% (at 6 microM BA) of cells as judged by the NBT-reduction test, and the expression of membrane markers CD11b and CD14. On the other hand, at 1 and 5 nM, 1alpha,25-dihydroxyvitamin D3 (DHD3) induced differentiation in approximately 10 and 70% of cells, respectively. At 1 nM DHD3, the addition of 1 microM BA increased differentiated cells from 10 to 43% and with 3 microM BA the increase was to 80%. BA also enhanced the effects of DHD3 in the expansion of the G1 cell population with a concomitant decrease of S phase cells. The effects of DHD3 and BA on CD11b and CD14 expression were inhibited by PD98059, a MEK inhibitor. Our results suggest that BA may enhance the effect of DHD3 in inducing mitogen-activated protein kinase kinase/extracellular signal-regulated protein kinase-mediated HL-60 cell differentiation.
authors.affiliation: Bioactive Products Research Group, Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
authors.forename: Ka-Hung
authors.initials: KH
authors.lastname: Poon
authors.forename: Jinxia
authors.initials: J
authors.lastname: Zhang
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Anfernee Kai-Wing
authors.initials: AK
authors.lastname: Tse
authors.forename: Chi-Keung
authors.initials: CK
authors.lastname: Wan
authors.forename: Wang-Fun
authors.initials: WF
authors.lastname: Fong
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D039481:CD11b Antigen / Q000096:biosynthesis / Q000235:genetics; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D005419:Flavonoids / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D018922:HL-60 Cells / Q000166:cytology*; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis / Q000235:genetics; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects; D053978:Pentacyclic Triterpenes; D014315:Triterpenes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D000094062:Betulinic Acid
chemical_list: D039481:CD11b Antigen; D005419:Flavonoids; D018950:Lipopolysaccharide Receptors; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D020929:Mitogen-Activated Protein Kinase Kinases; D002117:Calcitriol; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000094062:Betulinic Acid