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    P2.06 - Mesothelioma (ID 170)

    • Event: WCLC 2019
    • Type: Poster Viewing in the Exhibit Hall
    • Track: Mesothelioma
    • Presentations: 1
    • Now Available
    • Moderators:
    • Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
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      P2.06-06 - Y-box Binding Protein-1, a Potential Target in Malignant Pleural Mesothelioma, Drives Growth Through Distinct Mechanisms (Now Available) (ID 2042)

      10:15 - 18:15  |  Presenting Author(s): Thomas George Johnson

      • Abstract
      • Slides


      Malignant pleural mesothelioma (MPM) is an asbestos-related disease with a five‑year survival of five percent. Current therapy provides limited success and finding other targetable molecules remains a top priority. We recently identified Y-box binding protein-1 (YB‑1) as a significantly overexpressed oncogene with prognostic relevance in MPM. YB-1 is a multifunctional transcription and translation factor of the cold-shock protein family. Using siRNA‑mediated knockdown of YB-1 we showed that silencing YB-1 inhibited the proliferation, migration and invasion of four MPM cells by an unknown mechanism. Here we extend this work to examine how YB-1 regulates MPM growth.


      Functional activity of YB-1 was investigated by siRNA-mediated knockdown in MPM cells followed by TALI apoptosis assays, multi-dimension flow cytometry or live-cell imaging. Transcript expression was determined using reverse transcription qPCR (RT-qPCR) and RNA sequencing (RNA‑seq) with poly(A) selection.


      Following our previous data demonstrating growth inhibition after YB-1 knockdown, we transfected three MPM cell lines with YB-1 siRNA and conducted multi‑dimension flow cytometry and TALI apoptosis assays to begin understanding how this growth inhibition was occurring. We found that cells underwent either apoptosis or a G0/G1 cell cycle arrest. Using live-cell imaging and single cell fate mapping we found that each cell line undertook a distinct mechanism of growth inhibition. MSTO cells displayed apoptosis during interphase, VMC23 cells showed no death but underwent a G0/G1 cell cycle arrest, while REN cells did not delay during interphase but entered prolonged aberrant mitosis resulting in mitotic catastrophe and cell death. To examine the interphase arrest in MSTO and VMC23 further we analysed the expression of cyclin D1 and Myc, known cell cycle targets of YB-1, in knockdown samples using RT-qPCR. Transcripts of cyclin D1 and Myc were downregulated in both cell lines in response to reducing YB‑1, partially explaining the growth inhibition observed. To further understand the effects of YB-1 inhibition we have undertaken a global analysis of downstream targets and pathways after YB‑1 siRNA transfection in all three cell lines using RNA‑seq analysis.


      This project delves into the complex mechanism underlying YB-1-driven MPM proliferation and found it plays a broader role than expected due to its influence over multiple cancer-promoting genes and pathways. Our study significantly extends our understanding of this important protein in MPM, a disease in dire need of actionable targets.

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