[Effect of ZD6474 on the proliferation of imatinib-resistant K562 cells].
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.
Department of Laboratory Medicine, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou 510260, China.
Hong-Yun
HY
Jia
Xiao-Man
XM
Wu
Zhong-Ying
ZY
Wang
Xiao-Yan
XY
Deng
Zhen
Z
Lin
Gui-Ling
GL
Feng
Wen-Lin
WL
Huang
D017209:Apoptosis / Q000187:drug effects; D001549:Benzamides / Q000494:pharmacology; D006801:Humans; D000068877:Imatinib Mesylate; D020014:K562 Cells; D010879:Piperazines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology
D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate