Pim-1 expression and monoclonal antibody targeting in human leukemia cell lines

Exp Hematol. 2009 Nov;37(11):1284-94. doi: 10.1016/j.exphem.2009.08.002. Epub 2009 Aug 21.


Objective: Based on our previous findings that Pim-1 was expressed on the cell surface and could be targeted with a highly specific anti-Pim-1 monoclonal antibody (P9), this study aims to evaluate the possibility that Pim-1 could be targeted for the treatment of human leukemia.

Materials and methods: Pim-1 expression was investigated in a series of human leukemia cell lines with immunohistochemistry and flow cytometry. The inhibitory effect of P9 on cell proliferation was evaluated with (3)H-thymidine incorporation assay. Cell apoptosis was assayed with Annexin-V/propidium iodide dual staining. The in vivo effect of P9 was evaluated with xenograft tumor models in severe combined immunodeficient mice.

Results: Pim-1 expression varied depending on the cell lines and correlated with the inhibitory effects mediated by P9. An association between Pim-1 expression and drug resistance was observed. Although the drug-resistant CEM/A7R cells were highly resistant to cytotoxic P-glycoprotein substrates, their growth was inhibited by P9 as demonstrated by in vitro proliferation assay and in vivo inhibition of xenograft tumors. P9 had little effect on P-glycoprotein expression and intracellular Rhodamine 123 accumulation, but it inhibited the phosphorylation of Bad and induced apoptosis.

Conclusions: Pim-1 is variably expressed in leukemia cell lines and associated with drug resistance. Targeting Pim-1 with monoclonal antibody could be explored for the treatment of leukemia and may represent a novel strategy to overcome drug resistance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Animals
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / pharmacology*
  • Antibodies, Monoclonal / therapeutic use
  • Antibodies, Neoplasm / immunology
  • Antibodies, Neoplasm / pharmacology*
  • Antibodies, Neoplasm / therapeutic use
  • Antineoplastic Agents / metabolism
  • Antineoplastic Agents / pharmacology
  • Apoptosis / drug effects
  • Cell Line, Tumor / drug effects
  • Cell Line, Tumor / metabolism
  • Drug Resistance, Neoplasm
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Leukemia / pathology*
  • Leukemia, Experimental / drug therapy
  • Mice
  • Mice, SCID
  • Neoplasm Proteins / antagonists & inhibitors*
  • Neoplasm Proteins / biosynthesis
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / immunology
  • Phosphorylation / drug effects
  • Protein Processing, Post-Translational / drug effects
  • Proto-Oncogene Proteins c-pim-1 / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-pim-1 / biosynthesis
  • Proto-Oncogene Proteins c-pim-1 / genetics
  • Proto-Oncogene Proteins c-pim-1 / immunology
  • Tumor Stem Cell Assay
  • Verapamil / pharmacology
  • Xenograft Model Antitumor Assays
  • bcl-Associated Death Protein / metabolism


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Antibodies, Monoclonal
  • Antibodies, Neoplasm
  • Antineoplastic Agents
  • BAD protein, human
  • Neoplasm Proteins
  • bcl-Associated Death Protein
  • Verapamil
  • PIM1 protein, human
  • Proto-Oncogene Proteins c-pim-1