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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

  • 12399

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    P3.02-013 - ATF2 contributes to Platinum resistance in Non Small Cell Lung Cancer and cJUN/ATF2 Celastrol mediated modulation restores Platinum sensitization. (ID 2275)

    09:30 - 09:30  |  Author(s): S. Saviozzi
    • Abstract

    Background
    ATF2 is a member of the basic helix-loop-helix (b-ZIP) transcription factor family playing important roles in Stress and DNA damage. Several studies reported correlation between ATF2/JNK-mediated activation and resistance to damaging agents. Celastrol is an ATF2 inhibitor extracted from a Chinese plant known as “Tunder of God Vine”. Celastrol is used in traditional Chinese medicine for anti-inflammatory properties. In addition, Celastrol is a triterpene with promising anticancer activity in several cancer models both in vivo and in vitro. The purpose of the present study was to investigate whether ATF2 might play a role in inducing drug resistance in Non-Small Cell Lung Cancer (NSCLC).

    Methods
    In NSCLC cell lines ATF2 expression levels were evaluated by quantitative PCR (qPCR) and Western Blot (WB) and correlated to cisplatin (CDDP) resistance. Celastrol mediated ATF2/cJUN activity was assessed by Luminometry, qPCR and western blotting (WB). Furthermore, matched tumors and corresponding normal tissues of 88 surgically resected NSCLC specimens, were collected and both qPCR and immunohistochemical analyses for ATF2 were performed.

    Results
    NSCLC cell lines CDDP-resistant (H522 and H1395) expressed high levels of ATF2 protein. Moreover, CDDP treatment increased ATF2 phosphorylation levels leading to an enrichment within the nuclear cell compartment. In our study, Celastrol reduced ATF2 activity by decreasing the production of ATF2 mRNA and blocking the CDDP-mediated phosphorylation/mRNA expression of cJUN, a main ATF2 partner. Furthermore, ATF2/cJUN functional inhibition mediated by Celastrol restored the response to CDDP in resistant lung cell Lines. ATF2, at both protein and mRNA level, was significantly up-modulated in NSCLC tumor samples compared to the paired normal lung tissue (mRNA: p<<0.01, mean Log2(FC)=+4.7). Moreover, high expression of ATF2 mRNA was correlated with the smoking status of the patients. Relevantly, smoker or former smoker patients expressed significantly high ATF2 mRNA levels compared to non-smokers (p=0.02 and p=0.04, respectively).

    Conclusion
    This study shows that in NSCLC cell lines a correlation between ATF2 protein expression and CDDP resistance occurs. Furthermore, our results suggest a potential increase of CDDP sensitivity, following the Celastrol-mediated ATF2/cJUN inhibition. For the first time it has been shown in NSCLC an up-regulation of ATF2 mRNA/protein levels compared to normal tissues and consistent with that detected in CDDP resistant cell lines. This data suggest a possible involvement of ATF2 in NSCLC CDDP-resistance.