GCA links TRAF6-ULK1-dependent autophagy activation in resistant chronic myeloid leukemia

Autophagy. 2019 Dec;15(12):2076-2090. doi: 10.1080/15548627.2019.1596492. Epub 2019 Mar 30.

Abstract

Imatinib is the first molecularly targeted compound for chronic myeloid leukemia (CML) capable to inhibit BCR-ABL kinase activity. However, recent clinical evidence indicates that a substantial proportion of CML patients exhibit BCR-ABL-dependent or independent resistance to imatinib. Despite the importance of imatinib resistance in CML, the underlying molecular mechanisms of this resistance are largely unknown. Here, we identified GCA (grancalcin) as a critical regulator of imatinib resistance in chronic phase CML via activation of autophagy. Mechanistically, we demonstrated that GCA activates TRAF6 ubiquitin ligase activity to induce Lys63 ubiquitination of ULK1, a crucial regulator of autophagy, resulting in its stabilization and activation. We also highlighted the role of GCA-TRAF6-ULK1 autophagy regulatory axis in imatinib resistance. Our findings represent the basis for novel therapeutic strategies against CML.Abbreviation: ACTB/β-actin: actin beta; ADM: adrenomedullin; AMBRA1: autophagy and beclin 1 regulator 1; AMPK: AMP-activated protein kinase; ANXA5: annexin A5; CP: cytogenetic response; CML: chronic myeloid leukemia; CUL3: cullin 3; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GCA: grancalcin; Dx: at diagnosis; E-64-d: (2S,3S)-trans-Epoxysuccinyl-L-leucylamido-3-methylbutane ethyl ester; IMres: Imatinib resistance; KLHL20: Kelch-like protein 20; LRMP: lymphoid-restricted membrane protein; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MMR: major molecular response; NH4Cl: ammonium chloride; PBMCs: peripheral blood mononuclear cells; PTPRC: protein tyrosine phosphatase, receptor type, C; SQSTM1/p62: sequestosome 1; SYK: spleen associated tyrosine kinase; TAP1: transporter 1, ATP binding cassette subfamily B member; TKIs: ABL-specific tyrosine kinase inhibitors; TLR9: toll- like receptor 9; TRAF6: TNF receptor associated factor 6; ULK1: unc-51 like autophagy activating kinase 1.

Keywords: Autophagy; TRAF6; ULK1; chronic myeloid leukemia (CML); grancalcin (GCA); imatinib resistance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Autophagosomes / drug effects
  • Autophagosomes / metabolism
  • Autophagy / drug effects
  • Autophagy / genetics*
  • Autophagy-Related Protein-1 Homolog / chemistry
  • Autophagy-Related Protein-1 Homolog / genetics
  • Autophagy-Related Protein-1 Homolog / metabolism*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Drug Resistance, Neoplasm / drug effects
  • Female
  • Humans
  • Imatinib Mesylate / pharmacology*
  • Intracellular Signaling Peptides and Proteins / chemistry
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • K562 Cells
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics
  • Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism*
  • Leukocytes, Mononuclear / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Transcriptome / genetics
  • Transplantation, Heterologous
  • Ubiquitination / drug effects
  • Ubiquitination / genetics

Substances

  • Antineoplastic Agents
  • Calcium-Binding Proteins
  • GCA protein, human
  • Intracellular Signaling Peptides and Proteins
  • Tifab protein, human
  • Imatinib Mesylate
  • Autophagy-Related Protein-1 Homolog
  • ULK1 protein, human

Grants and funding

This work was supported by NRF-2016M3A9E1918329 to J.Y. Lee, IBS-R022-D1-2018-a00 to H. Kim, and NRF-2013M3A9B8031236 and Korea Leukemia Bank for Biomaterial Banking and Analysis to D.W. Kim. This work was also supported by Daewoong Corporation Co., Ltd . to H. Kim and D.W. Kim.