Author of

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  P3.02 - Poster Session 3 - Novel Cancer Genes and Pathways (ID 149)

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

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    P3.02-014 - Interaction between environmental exposure and HPV infection on developing lung cancer among Taiwanese nonsmokers (ID 2533)

    09:30 - 09:30  |  Author(s): Y. Cheng
    • Abstract

    Background
    Majority of investigation is focused on lung tumorigenesis in smokers, little in nonsmokers. Previously, Benzo[a]pyrene (B[a]P)-DNA adducts levels in nonsmoking female patients were higher than in nonsmoking male patients. However, p53 mutation rate in female patients did not differ from male patients. Moreover, HPV16/18 infection rate in female patients was much higher than in male patients. We therefore hypothesized that HPV infection could synergistically increased chromosomal instability (CIN) induced by B[a]P-DNA adducts and might contribute to lung tumorigenesis.

    Methods
    Herein, three HPV-positive and five HPV-negative lung cancer cells were enrolled to test the hypothesis. FISH analysis was used to determine the micronuclei formation when these cells were treated with various concentrations of B[a]P for different time-intervals.

    Results
    The efficacy of micronuclei and DNA adduct formation induced by B[a]P in HPV-positive cells were significantly higher than HPV-negative cells. Mechanistically, the micronuclei and DNA adduct formation are dependent on HPV E6 oncoprotein expression. We next questioned whether B[a]P-induced CIN enhanced by E6 could be through altering DNA repair gene expressions. The promoter hypermethylation and mRNA expression of six DNA repair genes including hMLH1, hMSH2, BRCA1, and BRCA2, and XRCC3, and XRCC5 were evaluated by MSP and real-time RT-PCR, and data indicated that XRCC3 and XRCC5 expressions in E6-positive cells were markedly lower than in E6-negative cells and the reduction of both genes was caused by promoter hypermethylation.

    Conclusion
    Collectively, the promoter hypermethylation of XRCC3 and XRCC5 induced by E6 may increase B[a]P-induced CIN and contribute to lung tumorigenesis in nonsmokers.