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posted on 2023-03-31, 19:28 authored by Azusa Tanimoto, Shinji Takeuchi, Sachiko Arai, Koji Fukuda, Tadaaki Yamada, Xavier Roca, S. Tiong Ong, Seiji Yano A, Comparison of ratio of BIM exon 3 to exon 4 transcripts in PC-9, PC-3, and PC-9BIMi2-/- cells. *, P < 0.05 PC-9 versus PC-3 or PC-3 versus PC-9BIMi2-/-. B, Alteration of transcripts containing BIM exon 2A, exon 3, and exon 4 in PC-9BIMi2-/- cells after treatment with gefitinib (1 µmol/L), osimertinib (1 µmol/L), and/or vorinostat (3 µmol/L) for 12 hours.
Funding
JSPS
Cancer Research and Therapeutic Evolution
Japan Agency for Medical Research and Development
National Medical Research Council
Clinician Scientist
History
ARTICLE ABSTRACT
Purpose: The BIM deletion polymorphism is associated with apoptosis resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI), such as gefitinib and erlotinib, in non–small cell lung cancer (NSCLC) harboring EGFR mutations. Here, we investigated whether the BIM deletion polymorphism contributes to resistance against osimertinib, a third-generation EGFR-TKI. In addition, we determined the efficacy of a histone deacetylase (HDAC) inhibitor, vorinostat, against this form of resistance and elucidated the underlying mechanism.Experimental Design: We used EGFR-mutated NSCLC cell lines, which were either heterozygous or homozygous for the BIM deletion polymorphism, to evaluate the effect of osimertinib in vitro and in vivo. Protein expression was examined by Western blotting. Alternative splicing of BIM mRNA was analyzed by RT-PCR.Results: EGFR-mutated NSCLC cell lines with the BIM deletion polymorphism exhibited apoptosis resistance to osimertinib in a polymorphism dosage–dependent manner, and this resistance was overcome by combined use with vorinostat. Experiments with homozygous BIM deletion–positive cells revealed that vorinostat affected the alternative splicing of BIM mRNA in the deletion allele, increased the expression of active BIM protein, and thereby induced apoptosis in osimertinib-treated cells. These effects were mediated predominantly by HDAC3 inhibition. In xenograft models, combined use of vorinostat with osimertinib could regress tumors in EGFR-mutated NSCLC cells homozygous for the BIM deletion polymorphism. Moreover, this combination could induce apoptosis even when tumor cells acquired EGFR-T790M mutations.Conclusions: These findings indicate the importance of developing HDAC3-selective inhibitors, and their combined use with osimertinib, for treating EGFR-mutated lung cancers carrying the BIM deletion polymorphism. Clin Cancer Res; 23(12); 3139–49. ©2016 AACR.
