Blockade of Y177 and Nuclear Translocation of Bcr-Abl Inhibits Proliferation and Promotes Apoptosis in Chronic Myeloid Leukemia Cells

Int J Mol Sci. 2017 Mar 2;18(3):537. doi: 10.3390/ijms18030537.

Abstract

The gradual emerging of resistance to imatinib urgently calls for the development of new therapy for chronic myeloid leukemia (CML). The fusion protein Bcr-Abl, which promotes the malignant transformation of CML cells, is mainly located in the cytoplasm, while the c-Abl protein which is expressed in the nucleus can induce apoptosis. Based on the hetero-dimerization of FKBP (the 12-kDa FK506- and rapamycin-binding protein) and FRB (the FKBP-rapamycin binding domain of the protein kinase, mTOR) mediated by AP21967, we constructed a nuclear transport system to induce cytoplasmic Bcr-Abl into nuclear. In this study, we reported the construction of the nuclear transport system, and we demonstrated that FN3R (three nuclear localization signals were fused to FRBT2098L with a FLAG tag), HF2S (two FKBP domains were in tandem and fused to the SH2 domain of Grb2 with an HA tag) and Bcr-Abl form a complexus upon AP21967. Bcr-Abl was imported into the nucleus successfully by the nuclear transport system. The nuclear transport system inhibited CML cell proliferation through mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 5 (STAT5) pathways mainly by HF2S. It was proven that nuclear located Bcr-Abl induced CML cell (including imatinib-resistant K562G01 cells) apoptosis by activation of p73 and its downstream molecules. In summary, our study provides a new targeted therapy for the CML patients even with Tyrosine Kinase Inhibitor (TKI)-resistance.

Keywords: Bcr-Abl; apoptosis; nuclear; proliferation; transport.

MeSH terms

  • Apoptosis
  • Cell Line, Tumor
  • Cell Nucleus / metabolism*
  • Cell Proliferation / drug effects
  • Drug Resistance, Neoplasm / drug effects
  • Fusion Proteins, bcr-abl / chemistry
  • Fusion Proteins, bcr-abl / metabolism*
  • Humans
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism*
  • MAP Kinase Signaling System / drug effects
  • Nuclear Localization Signals / pharmacology*
  • Protein Transport / drug effects
  • STAT5 Transcription Factor / metabolism
  • Sirolimus / analogs & derivatives
  • Sirolimus / pharmacology
  • Tyrosine / antagonists & inhibitors*

Substances

  • AP 21967
  • Nuclear Localization Signals
  • STAT5 Transcription Factor
  • Tyrosine
  • Fusion Proteins, bcr-abl
  • Sirolimus