Virtual Library

Start Your Search

T. Hong



Author of

  • +

    Poster Display Session (ID 63)

    • Event: ELCC 2017
    • Type: Poster Display Session
    • Track:
    • Presentations: 2
    • Moderators:
    • Coordinates: 5/07/2017, 12:30 - 13:00, Hall 1
    • +

      32P - Effects of BTK inhibitor on gefitinib-resistance non-small cell lung cancer (ID 162)

      12:30 - 13:00  |  Author(s): T. Hong

      • Abstract

      Background:
      Lung cancer is the most frequent cause of cancer death in the world. EGFR-mutant lung cancer is a subtype of non–small cell lung cancer (NSCLC) that exhibits sensitivity to EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib (Iressa); however, acquired resistance was developed after a median of 9–14 months. In our previous study, we used two primary TKI-resistant lung cancer cell lines (CL25 and CL100) and a genome-wide human kinase and phosphatase RNAi screening and found that silencing Bruton tyrosine kinase (BTK) significantly inhibited the NSCLC viability. BTK is a non-receptor tyrosine kinase of the Tec kinase family and plays an important role in B-cell receptor signaling. Therefore, we wanted to combine primary TKI (Iressa) with BTK inhibitors (Ibrutinib and CC-292) as a cancer treatment for EGFR TKI-resistant NSCLC patients.

      Methods:
      First, we verified that BTK knockdown decreased cell viability in EGFR TKI-resistant CL25 cells and enhanced the sensitivity to Iressa treatment. Second, we test the 50% inhibitory concentration (IC50) of BTK inhibitors (Ibrutinib and CC-292) in NSCLC cells by WST-1 assay. Next, we analyzed the effects of BTK inhibitors on the downstream signaling of BTK by western blot. Furthermore, we investigated the mechanism of growth inhibition triggered by BTK inhibitors in CL25 cells. The cell cycle distribution and cell death were examined. Finally, we tried to understand whether BTK inhibitors could enhance the gefitinib -induced cell death in EGFR TKI-resistant CL25 cells by combined treatment with gefitinib and BTK inhibitors.

      Results:
      By a genome-wide human kinase and phosphatase RNAi screening and found that BTK may contribute to the primary resistance. Knockdown of BTK expression decreased the NSCLC cell viability in a dose dependent manner and increased the gefitinib-induced cell death in both EGFR TKI-resistant CL25 and CL100 cells. BTK knockdown increased the levels of apoptotic and autophagic markers and cyclinD1 by western blot analysis. Moreover, BTK inhibitors affected BTK, NFkB, PI3K/AKT and EGFR signaling in EGFR TKI-resistant CL25 cells. Besides, treatment with Ibrutinib or CC-292 at the concentration of 4 fold IC50 induced G1 arrest in CL25 cells. Finally, combination of BTK inhibitors and gefitinib could not enhance the gefitinib-induced cell death.

      Conclusions:
      According to above results, we found that BTK may be a candidate contributing to the primary EGFR-TKI resistance in NSCLC cells. Knockdown of BTK induces the autophagic cell death and the G1 arrest in primary EGFR TKI-resistant CL25 cells and enhances the gefitinib-induced cell death while BTK inhibitors induce G1 arrest but cannot enhance the gefitinib-induced cell death.

      Clinical trial identification:


      Legal entity responsible for the study:
      National Cheng Kung University

      Funding:
      Ministry of Science and Technology, Taiwan.

      Disclosure:
      All authors have declared no conflicts of interest.

    • +

      33P - The screening and characterization of aptamer against gefitinib-resistant cells (ID 161)

      12:30 - 13:00  |  Author(s): T. Hong

      • Abstract

      Background:
      The EGFR tyrosine kinase inhibitor (TKI) gefitinib serves as first-line drug for patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR mutation. The challenge of this target therapy is the acquired resistance due to T790M mutation after gefitinib treatment. Aptamers are single-strand DNA molecules that form 3D structures and specifically bind to target components. In this study, we wanted to isolate aptamers with recognition ability for gefitinib-resistant NSCLC cells and look for another mechanism that contributes to the acquired resistance that is not caused by T790M mutation.

      Methods:
      We used PC9 (gefitinib-sensitive cells) and PC9-IR (gefitinib-resistant cells with no T790M mutation) cells to select specific aptamers that bound to membrane proteins which were overexpressed in PC9-IR cells. We used suction-type microfluidic control module to perform cell-systematic evolution of ligands by exponential enrichment (Cell-SELEX) and obtained some aptamers that had more affinity to bind to PC9-IR. We examined the specificity of the aptamers and observed whether aptamers could bind to cell membranes of PC9-IR. In addition, we tested the cell cytotoxicity of the aptamers.

      Results:
      We obtained the aptamer, AP16-23F, which had greater affinity to bind to PC9-IR. In order to test whether AP16-23F could recognize the cells with gefitinib resistance, we used AP16-23F to isolate cells from PC9 by fluorescence-activated cell sorting (FACS). The results showed that the cells selected by AP16-23F were more resistant to gefitinib.

      Conclusions:
      We have isolated an aptamer with specificity for binding and capturing gefitinib-resistant NSCLC cells. This aptamer may be useful for drug resistance detection and may have the potential to deliver anti-cancer drug to gefitinib-resistant cells in the future.

      Clinical trial identification:


      Legal entity responsible for the study:
      National Cheng Kung University

      Funding:
      Ministry of Science and Technology, Taiwan

      Disclosure:
      All authors have declared no conflicts of interest.