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  P3.05 - Poster Session 3 - Preclinical Models of Therapeutics/Imaging (ID 159)

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

  • 12421

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    P3.05-003 - Role of ATM in response of non-small cell lung cancer cell lines to therapeutic agents (ID 839)

    09:30 - 09:30  |  Author(s): E. Kubota
    • Abstract

    Background
    Lung cancer is the leading cause of cancer death worldwide. Non-Small Cell Lung Cancer (NSCLC) which is the predominant type is mostly advanced stage disease at diagnosis. Cytotoxic agents including chemotherapeutic drugs and radiation therapy, the mainstay of advanced NSCLC treatment are neither specific nor curative and are significant causes of morbidity in patients. This poor NSCLC outlook therefore requires a novel therapy as well as predictive markers of treatment response for an improvement. We propose Ataxia Telangiectasia Mutated (ATM), a critical player in the DNA double strand break repair pathway, as a potential predictor of treatment response in NSCLC. Radiation sensitivity is one of the hallmarks of ataxia telangiectasia (A-T), a condition due to ATM mutations. Our lab has previously demonstrated ATM deficiency in about 20% of resected NSCLC tumors and this is associated with poorer survival outcomes; however, no treatment guidelines currently take this into consideration.

    Methods
    We assessed in vitro the altered sensitivity of ATM deficient NSCLC cell lines to both targeted agents (e.g. Poly (ADP) ribose polymerase (PARP) inhibitors) and non-targeted agents (e.g. DNA damaging agents including ionizing radiation (IR) and the commonly used cytotoxic chemotherapies in NSCLC) using the clonogenic survival assay. A panel of NSCLC cell lines (NCI-H23, NCI-H226, NCI-H460, NC1-H522, NCI-H1793, NCI-H1395 and HCC 4006) were characterised for pre-existing ATM deficiency in terms of ATM protein expression levels and functionality using western blot. By examining the cells’ responses to IR, confirmation of ATM deficiency was achieved with clonogenic assay to assess cellular viability and western blot for the expression of IR inducible ATM-dependent phosphorylation sites on target proteins including phosphorylation of serine 1981 of ATM (p-S1981 ATM), serine 15 of p53 (p-S15 p53) and serine 824 of KAP1 (KRAB-associated protein 1).

    Results
    We identified NCI-H23 cells with pre-existing low ATM protein levels (11% relative to BT cells) and undetectable ATM protein in NCI-H1395 cells compare to our positive (BT cells) and negative (L3 cells) control lymphoblastoid cells derived from normal and A-T patients respectively. In addition, H23 and H1395 cells display altered ATM signaling as evidenced by no detectable level of p-S1981 ATM expression post-irradiation. There is increased sensitivity of H23 cells to DNA-damaging agents (such as IR, topotecan and cisplatin) and PARP inhibition compare to ATM proficient NSCLC cell lines.

    Conclusion
    Our results seem to delineate the therapeutic sensitivity of ATM deficient versus ATM proficient cell lines to both non-targeted agents (chemotherapy and radiation therapy) and to targeted agents (PARP inhibitors). ATM could serve as a potential marker in guiding the use of 1) targeted agents such as PARP inhibitors, and 2) conventional chemo-radio therapeutic agents in the treatment of NSCLC. We are in the process of establishing ATM knock-down cells from ATM proficient NSCLC cell lines. Results of the altered sensitivity of established ATM deficient NSCLC cells to our investigative agents will be discussed and presented.