Ibrutinib-007 shows potent anti-tumor effects towards EGFR wild-type and mutant non-small cell lung cancer cells via inhibiting mTOR-S6 signaling

Introduction: Ibrutinib is a Bruton’s tyrosine kinase inhibitor that has shown promising effects against non-small cell lung cancer (NSCLC) only in epidermal growth factor receptor (EGFR) sensitive mutation bearing NSCLC cells. To expand the applications of Ibrutinib, we synthesized a series derivatives of Ibrutinib, among which Ibrutinib-007 displayed potent antitumor activity in EGFR wild-type and mutant NSCLC cells.

Material and method: CCK-8 was used to determine the cytotoxicity of Ib-7 on human lung cancer cells. Flow cytometry was used to detect Ib-7 induced apoptosis. Confocal microscopy was used to observe the morphology and cell nuclear. Western blot was used to detect protein expression. Wound healing test was used to detect the migration ability of cells. Stable isotope labeling with amino acids in cell culture (SILAC) was used to analyze the protein expression and changes in phospho-proteins.

Results and discussion: Ibrutinib-007 greatly inhibits the proliferation of PC-9, NCI-H1975, A549 and NCI-H460 cells via dramatically suppressing mTOR-S6 pathway, which was not affected by Ibrutinib in A549 and H1975 cells. In freshly cultured primary lung cancer cells, Ibrutinib-007 showed much stronger anti-proliferation effect than Ibrutinib despite of their EGFR mutation status. Further, Ibrutinib-007 overcomes the elevation of Mcl-1 caused by ABT-199 mono-treatment through impairing the interaction between p-S6 and La-related protein 1 (LARP1), thus showing significantly synergistic effect combined with ABT-199 in treating NSCLC cells.

Conclusions: To conclude, our study illustrated a novel Ibrutinib derivative Ibrutinib-007 that exhibited potent antitumor effect against NSCLC by targeting mTOR-S6 signaling, and also synergized with ABT-199 by downregulating anti-apoptotic protein Mcl-1. These results shed light on the drug development treating non-driven gene bearing lung cancer, and provides an optimal combination regimen in treating NSCLC especially those with EGFR wild-type or resistance mutation.