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High-throughput Quantitative Real-time RT-PCR Assay for Determining Expression Profiles of Types I and III Interferon Subtypes
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Anti-tumorigenic effects of Type 1 interferon are subdued by integrated stress responses

S Bhattacharya1, W-C HuangFu, G Dong

  • 1Department of Animal Biology and Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-4539, USA.

Oncogene
|October 10, 2012
PubMed

Insights

Hypoxia and other cellular stresses activate eIF2α kinases, leading to the degradation of the Type 1 interferon receptor (IFNAR1). This evasion mechanism impairs anti-tumor immunity in cancer cells and the tumor microenvironment.

Area of Science:

  • Cellular Biology
  • Immunology
  • Cancer Research

Background:

  • Type 1 interferons (IFNs) are crucial for anti-tumor immunity.
  • The Type 1 interferon receptor (IFNAR1) mediates IFN signaling.
  • Viral and pharmacological agents can induce IFNAR1 degradation via protein kinase RNA-activated (PKR)-like ER kinase (PERK).

Purpose of the Study:

  • To investigate the role of hypoxia in IFNAR1 degradation.
  • To explore the involvement of PERK and other eIF2α kinases in regulating IFNAR1 stability and IFN responses.
  • To determine the implications of IFNAR1 downregulation in cancer cells and the tumor microenvironment.

Main Methods:

  • Investigated the effects of hypoxia on IFNAR1 phosphorylation and degradation.
  • Utilized cell models including human breast cancer cells and melanoma cells.
  • Employed techniques such as Western blotting and gene knockdown (e.g., GCN2 knockdown).
  • Assessed the impact on eIF2α phosphorylation, p38α kinase activation, and IFN responses.

Main Results:

  • Hypoxia induces IFNAR1 degradation in a PERK-dependent manner.
  • PERK-mediated IFNAR1 downregulation involves eIF2α phosphorylation and p38α kinase activation.
  • Other eIF2α kinases (PKR, GCN2) also mediate IFNAR1 degradation and blunt IFN responses.
  • Modulating PKR activity in breast cancer cells stabilizes IFNAR1 and enhances anti-tumorigenic effects.
  • GCN2 knockdown in melanoma cells reverses IFNAR1 downregulation and restores IFN signaling.

Conclusions:

  • Diverse eIF2α kinases activated by cellular stresses (like hypoxia or amino acid deficit) can downregulate IFNAR1.
  • IFNAR1 downregulation in cancer cells and the tumor microenvironment allows tumor tissues to evade Type 1 IFN-mediated anti-tumor effects.
  • Targeting eIF2α kinase pathways may represent a therapeutic strategy to restore IFN sensitivity in cancer.

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