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[Effect of ZD6474 on the proliferation of imatinib-resistant K562 cells]
Hong-Yun Jia1, Xiao-Man Wu, Zhong-Ying Wang
1Department of Laboratory Medicine, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510260, China.
Objective:
To investigate the effect of tyrosine kinase inhibitor ZD6474 (Vandetanib) on the proliferative inhibition of K562 cells and its derived imatinib-resistant K562/G cells and its mechanism.
Methods:
Imatinib-resistant K562/G cells were obtained by culturing cells in gradually increasing concentrations of imatinib. The changed factors related to drug-resistance were tested by Western blot. ZD6474 and imatinib affected K562/G and parental K562 cells proliferation were analyzed by WST assay. Flow cytometry was used to analyze cell cycle. Direct inhibition of Src activity by ZD6474 was measured by a colorimetric ELISA assay with recombinant human Src kinase.
Results:
10 µmol/L imatinib failed to inhibit K562/G cells proliferation or induce cell cycle arrest. Compared with that in parental K562 cells, there were marked high levels of p-Src and Src protein in K562/G cells. The expression of Bcl-2 and p-STAT3 also increased in K562/G cells. After 48 hours incubation, the IC(50) values of ZD6474 in K562 and K562/G cells were 1.61 µmol/L and 3.18 µmol/L, respectively. ZD6474 treatment caused accumulation of cells in the G(0)/G(1) fraction and cell apoptosis in K562 and K562/G cells. ZD6474 decreased the expression of p-Src and Src at post-transcriptional level. Moreover, ZD6474 increased the ratio of Bax/Bcl-2 and decreased the expression of p-STAT3 at the same concentration for inducing apoptosis.
Conclusions:
ZD6474 is effective in inhibiting the proliferation of imatinib-resistant K562/G cells and parental K562 cells, and induces their apoptasis by significant inhibition of Src kinase activity. Our study provides a reliable experimental basis for chronic myeloid leukemia treatment with ZD6474.
Insights
Tyrosine kinase inhibitor ZD6474 effectively inhibits imatinib-resistant K562/G cells and parental K562 cells. ZD6474 induces apoptosis by significantly inhibiting Src kinase activity, offering a potential treatment for chronic myeloid leukemia.
Area of Science:
- Pharmacology
- Molecular Biology
- Cancer Research
Background:
- Imatinib resistance is a significant challenge in treating chronic myeloid leukemia (CML).
- K562/G cells exhibit imatinib resistance due to altered drug-resistance factors, including elevated p-Src, Src, Bcl-2, and p-STAT3.
- Understanding mechanisms of resistance is crucial for developing alternative therapeutic strategies.
Purpose of the Study:
- To evaluate the efficacy of ZD6474 (Vandetanib) in inhibiting K562 and imatinib-resistant K562/G cell proliferation.
- To elucidate the underlying mechanism of ZD6474's action, focusing on Src kinase inhibition.
- To assess ZD6474's potential as a treatment for imatinib-resistant CML.
Main Methods:
- Imatinib-resistant K562/G cells were generated through stepwise imatinib concentration increases.
- Cell proliferation was assessed using WST assays; cell cycle analysis was performed via flow cytometry.
- Western blot analyzed protein expression changes; Src kinase activity was measured using ELISA.
Main Results:
- ZD6474 demonstrated significant antiproliferative effects on both K562 and K562/G cells, with IC50 values of 1.61 µmol/L and 3.18 µmol/L, respectively.
- ZD6474 treatment induced G0/G1 cell cycle arrest and apoptosis, evidenced by increased Bax/Bcl-2 ratio and decreased p-STAT3 expression.
- ZD6474 effectively inhibited Src kinase activity, reducing p-Src and Src protein levels post-transcriptionally.
Conclusions:
- ZD6474 is a potent inhibitor of K562 and imatinib-resistant K562/G cell proliferation.
- The mechanism involves direct inhibition of Src kinase activity, leading to apoptosis.
- ZD6474 shows promise as a therapeutic agent for chronic myeloid leukemia, particularly in cases of imatinib resistance.
