Zinc finger protein, X-linked (ZFX) mediates the development and progression of human cancers. However, its potential role in chronic myeloid leukemia (CML) is still unknown. The ZFX expression was significantly increased in CML patients and cell lines. Based on loss-of-function experiments in CML cells, we found that knockdown of ZFX expression impaired cell proliferation and induced mitotic arrest in G0/G1 stage and apoptosis. In addition, ZFX silencing sensitized CML cells to imatinib treatment. Further, phospho-Akt (p-Akt), CyclinD1, CyclinE1, and Bcl-2 were downregulated, and Caspase-3 was upregulated in ZFX-silenced cells. In summary, our data suggest that ZFX is a novel oncogene promoting cell proliferation and inducing imatinib resistance via PI3K/Akt signaling pathway. ZFX may represent a potential therapeutic target in CML.
BackgroundThe anti-leukemic mechanism of homoharringtonine (HHT) differs from that of IM, and HHT is one of the most useful agents for use in patients with IM resistance or intolerance. The Bcl-6/p53 pathway has been shown to regulate the sensitivity of tumor cells to antitumor drugs. We tested whether HHT blocked the Bcl-6/p53 pathway in order to promote the apoptosis of IM-resistant cells in vitro and in vivo.ResultsPh+ acute lymphoblastic leukemia (ALL) cells and IM-resistant chronic myeloid leukemia (CML) cells showed high expression of Bcl-6 protein. Bcl-6 mediated the upregulation of p53, and and Bcl-6 induced growth inhibition of IM-resistant cells as well as its apoptosis by targeting p53. In addition, Bcl-6 was downregulated moderately after HHT treatment in different cells. The Bcl-6 expression was significantly increased in patients with CML when compared with healthy subjects. Furthermore, the expression of Bcl-6 was higher in patients with CML-blastic phase (CML-BP) than in those with CML-chronic phase (CML-CP).MethodsThe inhibitory effect of drugs on cell growth was detected by Cell Counting Kit-8 (CCK-8), The apoptosis rate and the cell cycle were investigated by flow cytometry. The expression of Bcl-6, p53, Bcl-2, caspase9, and caspase3 proteins was assayed by western blot, Real- Time PCR (qPCR) detect Bcl-6 and p53 mRNA.ConclusionsHHT can suppress the growth and induce apoptosis of IM-resistant cells, the mechanism of which is associated with blocking of the Bcl-6/p53 pathway. Our results could offer a theoretical explanation for HHT use in patients with IM resistance or intolerance.
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