Targeting acute hypoxic cancer cells by doxorubicin-immunoliposomes directed by monoclonal antibodies specific to RON receptor tyrosine kinase

Cancer Chemother Pharmacol. 2011 May;67(5):1073-83. doi: 10.1007/s00280-010-1408-8. Epub 2010 Jul 25.


Purpose: Hypoxia contributes to acquired drug resistance in various cancer cells. The underlying mechanism is cellular insensitivity regulated by hypoxia-inducible factors (HIF), which impairs drug uptake, transport, and metabolism. The current study determines anti-RON antibody-directed cytotoxicity of doxorubicin (Dox)-immunoliposomes (IL) in hypoxic colon cancer cells.

Methods: Cells were cultured under hypoxia (1% O(2), 5% CO(2), and 96% N(2)) for 24 h. Dox-loaded IL were formulated followed by post-insertion of monoclonal antibody Zt/g4 specific to RON. Western blotting was used to detect HIF-1α and RON expression. Cellular uptake of Zt/g4-conjugated IL was determined by confocal and internalization assays. Cell viability was assessed by the MTT assay.

Results: RON and HIF-1α expression were observed in hypoxic colon HCT116 and SW620 cells. Resistance to Dox-induced cytotoxicity was acquired in hypoxic cells with increased IC(50) values. However, acquired resistance was attenuated by Zt/g4-directed Dox-IL, which displays increased cytotoxic activities. IL binding and uptake revealed that hypoxic RON expression is functional, which mediates high levels of Zt/g4-Dox-IL binding and cytoplasmic internalization. Zt/g4-Dox-IL is effective in killing hypoxic HCT116 and SW620 cells with reduced IC(50) values compared to Dox and pegylated-liposomal Dox. These effects were dependent on hypoxic RON expression. HCC1937 cells with diminished RON expression under hypoxia were insensitive to Zt/g4-Dox-IL-induced cytotoxic effect.

Conclusions: RON expressed by hypoxic colon cancer cells is thus a potential targeting molecule for delivery of chemotherapeutics. The ability of anti-RON mAb to direct Dox-IL cytotoxicity could be developed for attenuating hypoxia-acquired drug resistance in various cancer cells.

Publication types

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

MeSH terms

  • Antibiotics, Antineoplastic / administration & dosage
  • Antibiotics, Antineoplastic / pharmacology*
  • Antibiotics, Antineoplastic / toxicity
  • Antibodies, Monoclonal*
  • Breast Neoplasms
  • Cell Hypoxia
  • Cell Line, Tumor
  • Colonic Neoplasms
  • Dose-Response Relationship, Drug
  • Doxorubicin / administration & dosage
  • Doxorubicin / pharmacology*
  • Doxorubicin / toxicity
  • Drug Resistance, Neoplasm
  • Female
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Liposomes
  • Receptor Protein-Tyrosine Kinases / biosynthesis
  • Receptor Protein-Tyrosine Kinases / immunology*
  • Time Factors


  • Antibiotics, Antineoplastic
  • Antibodies, Monoclonal
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Liposomes
  • Doxorubicin
  • RON protein
  • Receptor Protein-Tyrosine Kinases