Virtual Library

Start Your Search

A. Tanimoto

Author of

  • +

    MINI 09 - Drug Resistance (ID 107)

    • Event: WCLC 2015
    • Type: Mini Oral
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
    • +

      MINI09.12 - HDAC Inhibitors Overcome New Generation EGFR-TKI-Resistance Caused by Homozygous BIM Polymorphism in EGFR Mutant Lung Cancer (ID 885)

      16:45 - 18:15  |  Author(s): A. Tanimoto

      • Abstract
      • Slides

      The BIM deletion polymorphism in intron 2 was found in a significant percent (~13%) of the Asian population, with 0.5% of individuals being homozygous for this deletion. Patients with EGFR mutant lung cancers harboring this BIM polymorphism have shorter progression free survival and overall response rates to 1[st] generation EGFR-TKIs, gefitinib and erlotinib. We recently reported that the histone deacetylase (HDAC) inhibitor vorinostat can epigenetically restore BIM function and death sensitivity of EGFR-TKI, in cases of EGFR mutant lung cancer where resistance to 1[st] generation EGFR-TKI is associated with a heterozygous BIM polymorphism. Here, we examined 1) whether BIM polymorphism associated with resistance to new generation EGFR-TKIs and 2) whether vorinostat could overcome EGFR-TKI resistance in EGFR mutant lung cancer cells with a homozygous BIM polymorphism.

      We used EGFR mutant lung cancer cells lines, PC-9, PC-9[i2BIM-/-] (a genetically engineered subclone that was homozygous for BIM deletion polymorphism), and PC-3 (heterozygous for BIM deletion polymorphism). These cell lines were treated with gefitinib, afatinib (2[nd] generation), and AZD9291 (3[rd] generation). Apoptosis was evaluated by FACS and expression of cleaved-caspase 3/7 and PARP by western blot.

      While PC-9 cells were sensitive to all EGFR-TKIs in terms of apoptosis induction, both of PC-3 and PC-9[i2BIM-/- ] cells were resistant to 1[st] generation EGFR-TKIs and new generation EGFR-TKIs as well. Vorinostat combined with new generation EGFR-TKIs induced apoptosis of PC-3 and PC-9[i2BIM-/- ] cells in vitro. In the subcutaneous tumor model, AZD9291 regressed the tumors produced PC-9 cells but not PC-9[i2BIM-/- ] cells, indicating in vivo resistance of PC-9[i2BIM-/- ] cells to EGFR-TKIs. Combined use of vorinostat with AZD9291 successfully decreased the size of tumors produced by PC-9[i2BIM-/-] cells by inducing tumor cell apoptosis.

      These observations indicated that BIM deletion polymorphism is associated with apoptosis resistance caused not only by 1[st] generation EGFR-TKIs but also by new generation EGFR-TKIs. Moreover, combined use of HDAC inhibitor may overcome EGFR-TKI resistance associated not only with heterozygous deletion but also with homozygous deletion in the BIM gene.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.