Time rhythm of homoharringtonine inducing K562 cell apoptosis and its mechanism / 中国实验血液学杂志

This study was aimed to explore the change of K562 cell apoptosis at different time point after homoharringtonine (HHT) treatment and its mechanism. After treatment of K562 cells with 10 ng/ml HHT, the cell viability was tested with MTT assay; the expression of caspase-3 was detected with Western blot; the BCL-2 expression was analyzed with flow cytometry; the autophagosome was observed by electron microscopy. The results showed that the viability of K562 cells reduced gradually from day 1 to day 5 and ascended from day 6 to day 8 after HHT treatment. At the same time, the cleaved caspase-3 expression level of K562 cells increased gradually from day 1 to day 7, but reduced at the day 8 (P < 0.05). From day 1 to day 8 after HHT treatment, the BCL-2 expression level declined firstly and then went up (P < 0.05). Autophagosome was also seen remarkably at day 8 after HHT treatment. It is concluded that the apoptosis level of K562 cells after being treated with HHT enhances firstly and then declines , which may be associated with higher autophagy level in the late stage of HHT treatment.

Effect of homoharringtonine on expression of NF-κB and BCL-2 proteins in K562 cells / 中国实验血液学杂志

This study was aimed to investigate the effect of homoharringtonine (HHT) on K562 cell proliferation, apoptosis and expression of BCL-2 and NF-κB proteins. The cells proliferation was assayed with MTT method, the cell apoptosis, cell cycle and BCL-2 expression were analyzed with flow cytometry, NF-κB protein expression was detected with Western blot. The results showed that HHT concentration-dependently inhibited proliferation of K562 cells, the IC50 at 48 h was 43.89 ng/ml. Treated with HHT 10 ng/ml for 48 h, K562 cell apoptosis significantly increased, cell cycle was blocked at G0/G1, the expression level of BCL-2 and NF-κB proteins was lower than that in control group (P < 0.05). It is concluded that HHT may inhibit the proliferation of K562 cells, and down-regulating expression levels of BCL-2 and NF-κB may be one of its anti-CML mechanisms.

Effects of interferon-α combined with homoharringtonine on K562 cell proliferation and β-catenin expression / 中国实验血液学杂志

The study was aimed to investigate the synergistically effect of interferon-α (IFN-α) and homoharringtonine (HHT) on the proliferation, apoptosis, cell cycle of K562 cells and the expression of β-catenin. The proliferation, apoptosis, cell cycle and β-catenin mRNA expression of K562 cells treated with IFN-α and/or HHT were assayed with MTT, flow cytometry or RT-PCR respectively. The results showed that HHT alone, but not IFN-α alone, displayed a proliferation inhibition, apoptosis induction, G(0)/G(1) phase block and down-regulation of β-catenin expression in K562 cells with concentration- and time-dependent manners. The expression level of β-catenin mRNA after being treated with HHT was 0.5576 ± 0.0373, which were lower than that in control group (0.9369 ± 0.0142). The down-regulation of β-catenin expression in group of IFN-α combined with HHT was higher significantly than that in HHT group (0.3737 ± 0.0529 vs 0.5576 ± 0.0373, P < 0.05). Otherwise, HHT combined with IFN-α did not demonstrate obvious toxicologic effect on bone marrow mononuclear cells. It is concluded that IFN-α combined with HHT can enhance the cytotoxic effect of HHT on K562 cells, which may be associated with down-regulation of β-catenin expression.

Influence of celecoxib combined with IFN-alpha on proliferation, apoptosis, cell cycle and CD117 expression of K562 cells / 中国实验血液学杂志

The aim of this study was to investigate the effects of Celecoxib on the proliferation, apoptosis, cell cycle and CD117 expression of K562 cells, and to explore its synergistic effect with IFN-alpha. K562 cells were treated with IFN-alpha, Celecoxib and combination of Celecoxib with IFN-alpha at different concentrations. The inhibitory effect of Celecoxib and IFN-alpha on cell proliferation was detected with MTT assay, the cell apoptosis, cell cycle and CD117 expression were determined by morphology observation and flow cytometry. The results showed that the Celecoxib inhibited proliferation of K562 cells in concentration-dependent manner (r=-0.91). After culture of K562 cells for 72 hours, the rates of K562 cell proliferation in control group, IFN-alpha group, Celecoxib group and IFN-alpha-combined Celecoxib group were (96.1+/-0.5)%, (90.2+/-0.4)%, (57.2+/-0.9)% and (21.9+/-0.3)% respectively. The cell apoptosis rates in 4 groups were (5.5+/-0.8)%, (6.3+/-0.6)%, (26.4+/-3.9)% and (57.3+/-4.5)% respectively. The CD117 expression rates in 4 groups were 54.7%, 10.5%, 36.3% and 7.3% respectively. Combination of Celecoxib with IFN-alpha might block K562 cells in G0/G1 phase. In conclusion, Celecoxib and IFN-alpha both may inhibit K562 cell proliferation, induce apoptosis, reduce CD117 expression and produce G0/G1 phase block to various degree and the two drugs have a synergistic effect.