title: Pycnogenol induces differentiation and apoptosis in human promyeloid leukemia HL-60 cells.
abstract: Pycnogenol, rich of many phytochemicals of medical value, is a commercialized nutrient supplement extracted from the bark of European coastal pine. In this study, we investigated the anti-tumor effects of Pycnogenol on HL-60, U937 and K562 human leukemia cell lines. We found that Pycnogenol inhibited cell proliferation dose- and time-dependently, and the IC(50)s of Pycnogenol on HL-60, U937 and K562 cells were 150, 40 and 100 microg/ml, respectively. When HL-60 cells were incubated with low concentrations of Pycnogenol (50, 100 and 125 microg/ml) for 24 h, a prominent G0/G1 arrest was observed, followed by gradual accumulation of sub-G0/G1 nuclei. At 48 h of treatment, 50-70% of HL-60 cells differentiated, as evidenced by morphological changes, NBT reduction, induction of NSE activity, and increases of cell surface expression of CD11b. However, results from Annexin V/PI staining, DAPI staining and DNA fragmentation assay indicated that Pycnogenol induced HL-60, U937 and K562 cell apoptosis at their respective IC(50)s after 24 h of treatments. Pretreatment of z-DEVD-fmk, a caspase-3 specific inhibitor, not only decreased caspase-3 activity but also reduced the percentage of apoptotic cells induced by Pycnogenol. This indicated that caspase-3 activation was involved in Pycnogenol induced-apoptosis. In conclusion, Pycnogenol induced differentiation and apoptosis in leukemia cells. Our data suggest that Pycnogenol could serve as a potent cancer chemopreventive or chemotherapeutic agent for human leukemia.
authors.affiliation: Department of Biology, China Medical University, 91 Hsueh-Shih Road, Taichung 404, Taiwan, ROC.
authors.forename: W W
authors.initials: WW
authors.lastname: Huang
authors.forename: J S
authors.initials: JS
authors.lastname: Yang
authors.forename: C F
authors.initials: CF
authors.lastname: Lin
authors.forename: W J
authors.initials: WJ
authors.lastname: Ho
authors.forename: M R
authors.initials: MR
authors.lastname: Lee
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D004247:DNA / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology*; D018922:HL-60 Cells; D006801:Humans; D020014:K562 Cells; D015473:Leukemia, Promyelocytic, Acute / Q000188:drug therapy* / Q000473:pathology; D010936:Plant Extracts; D013997:Time Factors; D020298:U937 Cells
chemical_list: D005419:Flavonoids; D010936:Plant Extracts; C024070:pycnogenols; D004247:DNA; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases