• Open Access

Hypoxia induces gefitinib resistance in non-small-cell lung cancer with both mutant and wild-type epidermal growth factor receptors

Authors

  • Kunihiko Minakata,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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    • These authors contributed equally to this work.

  • Fumiyuki Takahashi,

    Corresponding author
    1. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
    • Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
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    • These authors contributed equally to this work.

  • Takeshi Nara,

    1. Department of Molecular and Cellular Parasitology, School of Medicine, Juntendo University, Tokyo, Japan
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  • Muneaki Hashimoto,

    1. Department of Molecular and Cellular Parasitology, School of Medicine, Juntendo University, Tokyo, Japan
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  • Ken Tajima,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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  • Akiko Murakami,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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  • Fariz Nurwidya,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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  • Suzu Yae,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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  • Fumiaki Koizumi,

    1. Shien-Lab, National Cancer Center Hospital, Tokyo, Japan
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  • Hiroyuki Moriyama,

    1. Pharmaceutical Research and Technology Institute, School of Medicine, Kinki University, Osaka, Japan
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  • Kuniaki Seyama,

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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  • Kazuto Nishio,

    1. Department of Genome Biology, School of Medicine, Kinki University, Osaka, Japan
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  • Kazuhisa Takahashi

    1. Department of Respiratory Medicine, Juntendo University, Tokyo, Japan
    2. Research Institute for Diseases of Old Age, Juntendo University, Tokyo, Japan
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To whom correspondence should be addressed.

E-mail: fumiyuki@dol.hi-ho.ne.jp

Abstract

Somatic mutations in the epidermal growth factor receptor (EGFR) gene, such as exon 19 deletion mutations, are important factors in determining therapeutic responses to gefitinib in non-small-cell lung cancer (NSCLC). However, some patients have activating mutations in EGFR and show poor responses to gefitinib. In this study, we examined three NSCLC cell lines, HCC827, PC9, and HCC2935, that expressed an EGFR exon 19 deletion mutation. All cells expressed mutant EGFR, but the PC9 and HCC2935 cells also expressed wild-type EGFR. The HCC827 cells were highly sensitive to gefitinib under both normoxia and hypoxia. However, the PC9 and HCC2935 cells were more resistant to gefitinib under hypoxic conditions compared to normoxia. Phosphorylation of EGFR and ERK was suppressed with gefitinib treatment to a lesser extent under hypoxia. The expression of transforming growth factor-α (TGFα) was dramatically upregulated under hypoxia, and the knockdown of TGFα or hypoxia-inducible factor-1α (HIF1α) reversed the resistance to gefitinib in hypoxic PC9 and HCC2935 cells. Finally, introduction of the wild-type EGFR gene into the HCC827 cells caused resistance to gefitinib under hypoxia. This phenomenon was also reversed by the knockdown of TGFα or HIF1α. Our results indicate that hypoxia causes gefitinib resistance in EGFR-mutant NSCLC through the activation of wild-type EGFR mediated by the upregulation of TGFα. The presence of wild-type and mutant EGFR along with tumor hypoxia are important factors that should be considered when treating NSCLC patients with gefitinib.

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