Author of

• 20179

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  P2.15 - SCLC/Neuroendocrine Tumors (ID 716)

  • Event: WCLC 2017
  • Type: Poster Session with Presenters Present
  • Track: SCLC/Neuroendocrine Tumors
  • Presentations: 2
  • Moderators:
  • Coordinates: 10/17/2017, 09:30 - 16:00, Exhibit Hall (Hall B + C)

  • 23518

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    P2.15-003 - A Long Non-Coding RNA HOTTIP Expression Is Associated with Disease Progression and Predicts Outcome in Small Cell Lung Cancer Patients (ID 8801)

    09:30 - 09:30  |  Author(s): Qiongyao Wang
    • Abstract

    Background:
    Small cell lung cancer (SCLC), which accounts for approximately 15% of lung cancer, is one of the most malignant diseases world-wide, with a high mortality. Despite progress in treatment of small cell lung cancer (SCLC), the biology of the tumor still remains poorly understood. Recently, we globally investigated the contributions of lncRNA in SCLC with a special focus on sponge regulatory network. Here we report lncRNA HOTTIP, which is specifically amplified in SCLC, is associated with SCLC proliferation and poor prognosis of patients.
    
    Method:
    RT-qPCR was used to investigate the expression of HOTTIP in SCLC tissues and cell lines. The role of HOTTIP in SCLC cell proliferation was demonstrated by CCK8 assay, colony formation assay, flow cytometry analysis and in vivo models of transplant tumor in mice through HOTTIP loss- and gain-of function effects. Western blot assay was used to evaluated gene expression in cell lines at protein level. RNA pull-down, Mass spectrometry and RNA binding protein immunoprecipitation (RIP) were performed to confirm the molecular mechanism of HOTTIP involved in SCLC progression.
    
    Result:
    We found that HOTTIP was overexpressed in SCLC tissues, and its expression was correlated with the clinical stage and the shorter survival time of SCLC patients. Moreover, HOTTIP knockdown could impair cell proliferation, affect the cell cycle and inhibit tumor growth of mice, while HOTTIP overexpression might enhance cell proliferation and cell cycle in vitro and in vivo. Mechanistic investigations showed that HOTTIP functions as an oncogene in SCLC progression by sponging miR-574-5p and affecting the expression of several protein-coding cancer driver genes, such as polycomb group protein EZH1 and EZH2. By in-depth study of mechanism, we identified Ago2 as an RNA-binding protein that binds to HOTTIP, which confirmed miRNAs interact with HOTTIP by the RNA-induced silencing complex (RISC).

    
    Conclusion:
    Our findings not only illuminate how HOTTIP confers an oncogenic function in SCLC pathogenesis, but also underscore a novel gene expression governing hallmarks in the disease.
    
    

  • 23525

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    P2.15-010 - Etk Interacting with PFKFB4 Modulates Chemoresistance of Small Cell Lung Cancer by Regulating Autophagy (ID 9023)

    09:30 - 09:30  |  Presenting Author(s): Qiongyao Wang
    • Abstract

    Background:
    Epithelial and endothelial tyrosine kinase(Etk), also known as Bone marrow X kinase (Bmx), was found to be critical in modulating chemoresistance of small cell lung cancer(SCLC) in our preliminary study. However, the molecular mechanisms of Etk leading to chemoresistance in SCLC remain obscure.
    
    Method:
    Knockdown of Etk by siRNAs was performed to evaluate autophagy change in SCLC. Subsequently, a microarray analysis identified PFKFB4 as a downstream molecule of Etk, and CoIP and GST-pull down was used to test protein interaction. We then explored whether PFKFB4 affected autophagy of SCLC. Gain or loss-of-function in vitro or in vivo was used to evaluate the effects PFKFB4 on chemotherapy sensitivity. The expression of PFKFB4 in SCLC tissues were measured by immunohistochemistry(IHC). Besides, luciferase assays, Western blot and CCK8 assay were performed to confirmed whether miR-218 regulates Etk and its effect on chemoresistance. As Etk shares conserved domains with Btk(Bruton’s tyrosine kinase) family, we also explored whether ibrutinib, a Btk inhibitor used in leukemia, affected chemotherapy sensitivity of SCLC.
    
    Result:
    Etk affected autophagy in SCLC, and directly inhibition of autophagy sensitized cells to chemotherapy. PFKFB4 was found as a downstream molecule of Etk and they interacted with each other in protein level directly. Moreover, knockdown of PFKFB4 suppressed autophagy of SCLC. PFKFB4 affected chemoresistance of SCLC in vitro and in vivo, and high level of PFKFB4 was associated with poor therapeutic response and prognosis. Furthermore, miR-218 directly modulated Etk expression as a novel regulator and it affected chemoresistance in SCLC. We demonstrated that ibrutinib exhibited a synergistic effect with chemotherapy in SCLC.
    
    Conclusion:
    Figure 1 Our results demonstrated for the first time that Etk interacts with PFKFB4 to modulate the chemoresistance of SCLC by autophagy and Etk is a direct target of miR-218. These genes may be predictive factors for the chemotherapy response as well as potential therapeutic targets in SCLC.