Differentiation-promoting drugs up-regulate NKG2D ligand expression and enhance the susceptibility of acute myeloid leukemia cells to natural killer cell-mediated lysis

Leuk Res. 2007 Oct;31(10):1393-402. doi: 10.1016/j.leukres.2007.02.020. Epub 2007 Mar 27.


Natural killer (NK) cells are potent effectors of innate antitumor defense and are currently exploited for immune-based therapy of human leukemia. However, malignant blood cells in acute myeloid leukemia (AML) display low levels of ligands for the activating immunoreceptor NKG2D and can thus evade NK immunosurveillance. We examined the possibility of up-regulating NKG2D-specific UL16-binding protein (ULBP) ligands using anti-neoplastic compounds with myeloid differentiation potential. Combinations of 5-aza-2'-deoxycytidine, trichostatin A, vitamin D3, bryostatin-1, and all-trans-retinoic acid, used together with myeloid growth factors and interferon-gamma, increased cell surface ULBP expression up to 10-fold in the AML cell line HL60 and in primary AML blasts. Up-regulation of ULBP ligands was associated with induction of myelomonocytic differentiation of AML cells. Higher ULBP expression increased NKG2D-dependent sensitivity of HL60 cells to NK-mediated killing. These findings identify NKG2D ligands as targets of leukemia differentiation therapy and suggest a clinical benefit in combining a pharmacological approach with NK cell-based immunotherapy in AML.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Azacitidine / administration & dosage
  • Azacitidine / analogs & derivatives
  • Bryostatins / administration & dosage
  • Cell Differentiation
  • Cell Line, Tumor
  • Cholecalciferol / administration & dosage
  • Cytotoxicity, Immunologic*
  • Decitabine
  • Flow Cytometry
  • GPI-Linked Proteins
  • Humans
  • Hydroxamic Acids / administration & dosage
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Killer Cells, Natural / immunology*
  • Leukemia, Myeloid / immunology
  • Leukemia, Myeloid / metabolism*
  • Leukemia, Myeloid / pathology
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tretinoin / administration & dosage
  • Up-Regulation


  • Bryostatins
  • GPI-Linked Proteins
  • Hydroxamic Acids
  • Intercellular Signaling Peptides and Proteins
  • ULBP2 protein, human
  • Cholecalciferol
  • bryostatin 1
  • trichostatin A
  • Tretinoin
  • Decitabine
  • Azacitidine