Scientific Reports (Jul 2017)

TKI-addicted ROS1-rearranged cells are destined to survival or death by the intensity of ROS1 kinase activity

  • Hayato Ogura,
  • Yuka Nagatake-Kobayashi,
  • Jun Adachi,
  • Takeshi Tomonaga,
  • Naoya Fujita,
  • Ryohei Katayama

DOI
https://doi.org/10.1038/s41598-017-05736-9
Journal volume & issue
Vol. 7, no. 1
pp. 1 – 17

Abstract

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Abstract ROS1 rearrangement is observed in 1–2% of non-small cell lung cancers (NSCLC). The ROS1 tyrosine kinase inhibitor (TKI) crizotinib has induced marked tumour shrinkage in ROS1-rearranged cancers. However, emergence of acquired resistance to TKI is inevitable within a few years. Previous findings indicate that cabozantinib overcomes secondary mutation–mediated crizotinib-resistance in ROS1-fusion-positive cells. Here we attempted to establish cabozantinib-resistant cells by N-ethyl-N-nitrosourea mutagenesis screening using CD74-ROS1–expressing Ba/F3 cells. Two resistant cell lines with CD74-ROS1 F2004V or F2075C mutations, which are homologous to ALK F1174 or F1245 mutations, survived in the presence of a low dose of ROS1-TKI. Removal of ROS1-TKI from these TKI-addicted cells induced excessive activation of ROS1 tyrosine kinase followed by apoptosis. We succeeded in recapturing the TKI-addicted phenotype using doxycycline-inducible CD74-ROS1 mutant over-expression in Ba/F3 cells, suggesting that excessive ROS1 oncogenic signaling itself induced apoptosis instead of cell growth. Phosphoproteomic analysis and high-throughput inhibitor screening revealed that excessive ROS1 signaling in the TKI-addicted cells phosphorylated or activated apoptosis-related molecules such as FAF1 or p38. Collectively, our findings partly clarify molecular mechanisms of excessive ROS1 oncogenic signaling that mediates paradoxical induction of apoptosis.