Author of

• 11481

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  P2.02 - Poster Session 2 - Novel Cancer Genes and Pathways (ID 148)

  • Event: WCLC 2013
  • Type: Poster Session
  • Track: Biology
  • Presentations: 1
  • Moderators:
  • Coordinates: 10/29/2013, 09:30 - 16:30, Exhibit Hall, Ground Level

  • 11493

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    P2.02-012 - Long non-coding RNA BC070487 Represses the Novel Tumor Suppressor Gene ZNFX1 During Tobacco-Induced Human Pulmonary Carcinogenesis (ID 2373)

    12:37 - 12:54  |  Author(s): S. Xi
    • Abstract

    Background
    Limited information exists regarding long non-coding RNAs (lncRNAs) which regulate gene expression during initiation and progression of human lung cancers. The present study was undertaken to utilize a novel in vitro model system to examine long non-coding RNA alterations mediated by cigarette smoke in normal respiratory epithelia and lung cancer cells.

    Methods
    Normal human small airway epithelial cells (SAEC) and cdk-4/h-TERT immortalized human bronchial epithelial cells (HBEC), as well as Calu-6 and H-841 lung cancer cells were cultured in the presence or absence of cigarette smoke condensate (CSC). Array and qRT-PCR techniques were used to assess lncRNA and gene expression profiles in CSC-treated or control cells. qRT-PCR techniques were used to evaluate expression levels of BC070487 and its target gene, ZNFX1 in primary lung cancers relative to paired normal lung tissues. Chromatin immunoprecipitation (ChIP), RNA-crosslink immunoprecipitation (CLIP), and methyl DNA immunoprecipitation (MeDIP) techniques were used to evaluate chromatin alterations within the ZNFX1 promoter region mediated by BC070487. MTS, invasion, and murine xenograft experiments were performed to examine proliferation, invasion and tumorigenicity of lung cancer cells following manipulation of BC070487 or ZNFX1 expression.

    Results
    Under relevant exposure conditions, CSC mediated a 4-7 fold up-regulation of BC070487, with a 4-8 fold down-regulation of ZNFX1 in normal respiratory epithelia and lung cancer cells. BC070487 epression correlated inversely with expression of ZNFX1 (BC070487: 1.38-10.31 fold up vs ZNFX1: 2.26-26.29 fold down) in primary lung cancers relative to adjacent normal lung tissues. Over-expression or depletion of BC070487 inhibited or enhanced expression, respectively, of ZNFX1 in normal respiratory epithelia and lung cancer cells. CSC as well as BC070487-mediated repression of ZNFX1 coincided with increased occupancy of EZH2, SUZ12 and BMI1, as well as increased H3K27Me3 and decreased H3K4Me3 levels within the ZNFX1 promoter region. CSC or over-expression of BC070487 enhanced binding of BC070487 with EZH2, SUZ12 and BMI1 proteins in SAEC and Calu-6 cells. CSC exposure mediated a significant increase in DNA methylation in one of two CpG islands spanning the ZNFX1 regulatory region in SAEC and Calu-6 cells; this phenomenon coincided with enhanced binding of BC070487 with DNMT3a and 3b, and recruitment of these de-novo DNA methyltransferases to the ZNFX1 regulatory region in these cells. Over-expression of BC070487 increased proliferation and invasion potential of lung cancer cells in-vitro, and enhanced growth of lung cancer xenografts in nude mice. Consistent with these findings, ZNFX1 depletion enhanced, whereas constitutive over-expression of ZNFX1 inhibited growth and tumorigenicity of lung cancer cells.

    Conclusion
    Cigarette smoke induces expression of LncRNA BC070487, which in turn represses ZNFX1 in normal respiratory epithelia and lung cancer cells. These findings provide a novel mechanism by which cigarette smoke mediates initiation and progression of lung cancers, and highlight the potential implications of smoking status of lung cancer patients at diagnosis or during therapy.