Receptor heterodimerization: A new mechanism for platelet-derived growth factor induced resistance to anti-epidermal growth factor receptor therapy for bladder cancer

Peter C. Black, Gordon A. Brown, Colin P. Dinney, Wassim Kassouf, Teruo Inamoto, Ameeta Arora, David Gallagher, Mark F. Munsell, Menashe Bar-Eli, David J. McConkey, Liana Adam

Research output: Contribution to journalArticle

Abstract

Purpose Human bladder cancer cells resistant to anti-epidermal growth factor receptor therapy often co-express platelet-derived growth factor receptor-β. We determined whether there is functional crosstalk between epidermal growth factor receptor and platelet-derived growth factor receptor-β, and how this regulates biological functions in bladder cancer cases. Materials and Methods We determined heterodimerization and co-localization of epidermal growth factor receptor and platelet-derived growth factor receptor-β by immunoprecipitation and confocal microscopy, respectively. We tested the antiproliferative effects of specific inhibitory monoclonal antibodies to each receptor by 3H-thymidine uptake assay. We transfected the nonplatelet-derived growth factor receptor-β expressing bladder cancer cell line UMUC5 with the platelet-derived growth factor receptor-β gene. These cells were analyzed in vitro by 3H- thymidine uptake and by Matrigel™ invasion assay, and in vivo for tumorigenicity, metastatic potential and orthotopic growth. In a treatment study nude mice were inoculated with orthotopic tumors and treated with the inhibitory antibodies alone and in combination. Results Immunoprecipitation revealed epidermal growth factor receptor/platelet-derived growth factor receptor-β heterodimers in all platelet-derived growth factor receptor-β expressing cell lines. Forced expression of platelet-derived growth factor receptor-β in epidermal growth factor receptor sensitive UMUC5 cells (50% inhibitory concentration less than 10 nM) significantly decreased responsiveness to epidermal growth factor receptor inhibition (50% inhibitory concentration greater than 100 nM) and increased invasive potential 3-fold as well as tumorigenicity. Increased invasiveness was associated with epidermal growth factor triggered platelet-derived growth factor receptor-β transactivation, increased mitogen activated protein kinase and glycogen synthase kinase-3β phosphorylation, and decreased E-cadherin. Inhibition of epidermal growth factor receptor and platelet-derived growth factor receptor-β receptors blocked cell invasion, decreased cell proliferation, reduced xenograft tumor growth and increased E-cadherin expression. Conclusions In epidermal growth factor receptor expressing bladder cancer co-expression of platelet-derived growth factor receptor-β has implications for tumor biology. Thus, it should be further evaluated as a strategy involving dual receptor targeting.

Original languageEnglish (US)
Pages (from-to)693-700
Number of pages8
JournalJournal of Urology
Volume185
Issue number2
DOIs
StatePublished - Feb 1 2011
Externally publishedYes

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Keywords

  • drug resistance
  • epidermal growth factor
  • receptor, platelet-derived growth factor beta
  • urinary bladder
  • urinary bladder neoplasms

ASJC Scopus subject areas

  • Urology

Cite this

Black, P. C., Brown, G. A., Dinney, C. P., Kassouf, W., Inamoto, T., Arora, A., Gallagher, D., Munsell, M. F., Bar-Eli, M., McConkey, D. J., & Adam, L. (2011). Receptor heterodimerization: A new mechanism for platelet-derived growth factor induced resistance to anti-epidermal growth factor receptor therapy for bladder cancer. Journal of Urology, 185(2), 693-700. https://doi.org/10.1016/j.juro.2010.09.082