Association of IFN-γ signal transduction defects with impaired HLA class I antigen processing in melanoma cell lines

Annedore Respa, Juergen Bukur, Soldano Ferrone, Graham Pawelec, Yingdong Zhao, Ena Wang, Francesco M. Marincola, Barbara Seliger

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Abstract

Purpose: Abnormalities in the constitutive and IFN-γ-inducible HLA class I surface antigen expression of tumor cells is often associated with an impaired expression of components of the antigen processing machinery (APM). Hence, we analyzed whether there exists a link between the IFN-γ signaling pathway, constitutive HLA class I APM component expression, and IFN-γ resistance. Experimental Design: The basal and IFN-γ-inducible expression profiles of HLA class I APM and IFN-γ signal transduction cascade components were assessed in melanoma cells by real-time PCR (RT-PCR), Western blot analysis and/or flow cytometry, the integrity of the Janus activated kinase (JAK) 2 locus by comparative genomic hybridization. JAK2 was transiently overexpressed in JAK2- cells. The effect of IFN-γ on the cell growth was assessed by XTT [2,3-bis(2-methoxy-4-nitro-S-sulfophenynl)-H- tetrazolium-5-carboxanilide inner salt] assay. Results: The analysis of 8 melanoma cell lines linked the IFN-γ unresponsiveness of Colo 857 cells determined by lack of inducibility of HLA class I surface expression on IFN-γ treatment to a deletion of JAK2 on chromosome 9, whereas other IFN-γ signaling pathway components were not affected. In addition, the constitutive HLA class I APM component expression levels were significantly reduced in JAK2- cells. Furthermore, JAK2-deficient cells were also resistant to the antiproliferative effect of IFN-γ. Transfection of wild-type JAK2 into JAK2- Colo 857 not only increased the basal APM expression but also restored their IFN-γ sensitivity. Conclusions: Impaired JAK2 expression in melanoma cells leads to reduced basal expression of MHC class I APM components and impairs their IFN-γ inducibility, suggesting that malfunctional IFN-γ signaling might cause HLA class I abnormalities.

Original languageEnglish
Pages (from-to)2668-2678
Number of pages11
JournalClinical Cancer Research
Volume17
Issue number9
DOIs
Publication statusPublished - 1 May 2011
Externally publishedYes

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ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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