Abstract
Purpose: To investigate the effects of luteoloside on the proliferation of human chronic myeloid leukemia K562 cells and whether luteoloside induces cell cycle arrest and apoptosis in K562 cells. Methods: Luteoloside’s cytotoxicity was assessed using a cell counting kit. Cell cycle distribution was analysed by flow cytometry after propidium iodide (PI) staining. Cell apoptosis was assayed with apoptosis detection kit and Hoechst staining followed by observation under a fluorescence microscope. The expression of cell cycle- and apoptosis-related proteins was examined by Western blot analysis. Results: Luteoloside inhibited the proliferation of K562 cells in a dose- and time- dependent manner (IC 50 = 30.7 μM) with less toxicity in a normal human cell line (IC 50 = 91.8 μM). Moreover, antiproliferative effect of luteoloside was accompanied with G2/M phase arrest（p ＜ 0.05 or p＜0.01） and apoptosis（p ＜ 0.01 or p ＜ 0.001）. Further studies revealed that the expression level of cyclinB1 was down-regulated by luteoloside treatment. Furthermore, luteoloside treatment also increased proapoptotic protein Bax expression and decreased anti-apoptotic protein Bcl-2 expression. Conclusion: These results suggest that the inhibitory effect of luteoloside on K562 cell proliferation is associated with inducing G2/M phase arrest and apoptosis, and that luteoloside is worth further studying for anticancer potential. Keywords: Luteoloside, Myeloid leukemia, Proliferation, Cell cycle arrest, Apoptosis, Anticancer
Highlights
Chronic myeloid leukemia (CML) is a malignant hematological disease characterized by the deregulated growth of myeloid leukemia cells in the bone marrow and their accumulation in the blood
Since an important mechanism for anticancer agents is to trigger apoptosis [12] and cell cycle arrest [13] in cancer cells while disturbing their proliferation, we evaluated the effects of luteoloside on cell cycle and apoptosis together with cell growth of K562 cells
These results demonstrate that luteoloside induces G2/M phase cell cycle arrest in K562 cells in a concentration- and time-dependent manner
Summary
Chronic myeloid leukemia (CML) is a malignant hematological disease characterized by the deregulated growth of myeloid leukemia cells in the bone marrow and their accumulation in the blood. K562 cells were seeded into 96 well microtiter plate (3 × 103 cells per well) together with various concentrations of luteoloside. After treatment for 48 and 72 h, the cytotoxicities of luteoloside against K562 and HUVEC12 cells were assessed using CCK-8 assay. K562 cells were treated with luteoloside for 48h at concentrations of 50 and 200 μM or for 24 and 48 h at 50 μM. K562 cells were treated with luteoloside at different concentrations (50 and 200 μM) for 48 or 72 h. After incubation for 15 min in the dark at room temperature, cells were diluted with binding buffer again and the ratio of apoptotic cells was measured within 1h with a flow cytometer. Hoechst 33342 was added to the treated cells at a final concentration of 10 μg/mL, and the cells were incubated for another 10 min at 37 oC.
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