Virtual Library

 x 
My Library Virtual Library FAQ

Start Your Search

K. Umezawa



Author of

  • +

    MO09 - Mesothelioma I (ID 120)

    • Event: WCLC 2013
    • Type: Mini Oral Abstract Session
    • Track:
    • Presentations: 1
    • +

      MO09.08 - NF-kB in cisplatin resistance and as a prognostic marker in Malignant pleural mesothelioma (ID 3338)

      16:55 - 17:00  |  Author(s): K. Umezawa

      • Abstract
      • Presentation
      • Slides

      Background
      Malignant pleural mesothelioma (MPM) is an aggressive inflammatory cancer associated with exposure to asbestos. Currently rates of MPM are rising and estimates indicate that the incidence of MPM will peak in western world within the next 10-15 years. Untreated, MPM has a median survival time of 6 months, with poor survival rates for most patients after 24 months of diagnosis. Nuclear Factor kappa B (NF-kB) is a pro-inflammatory transcription factor which is activated in many cancer types, including MPM. The NF-kB pathway regulates important cellular processes including survival and proliferation signals, which are often found to be dysregulated in cancer. Furthermore, we and others have shown that increased NF-kB activation is linked to development of cisplatin resistance. We aim to outline the potential role of NF-kB as a mediator of cisplatin resistance in MPM and determine its value as a potential candidate for therapeutic intervention.

      Methods
      NF-kB expression was examined in a cohort of MPM patients (n=200) by IHC, and correlated with clinicopathological variables and survival. NF-kB expression was examined in both a panel of MPM cell lines and isogenic parent/cisplatin resistant cell lines by Western blot analysis. The effect of NF-kB inhibition on cellular proliferation was measured by BrdU assay, in a panel of MPM and isogenic parent/cisplatin resistant cell lines, using the novel NF-kB inhibitor Dehydroxymethylepoxyquinomicin (DHMEQ). In addition, the effect of DHMEQ on nuclear translocation of NF-kB was examined by high content screening (HCS).

      Results
      Cytoplasmic or membranous immunostaining was seen in the majority of tumour samples (96.5%), but nuclear localisation of NF-kB was seen in only 11% cases. Kaplan-Meier survival analysis showed that nuclear NF-kB expression correlated with reduced survival (p=0.05). There was no significant correlation between the level of expression of NF-kB and standard clinicopathological parameters. NF-kB was expressed in all MPM cell lines tested to a varying extent (n=20), with no associations to histology. NF-kB levels were shown to be elevated in cisplatin resistant cell lines when compared to the isogenic parent from which they were derived. DHMEQ was shown to reduce nuclear translocation of NF-kB, inhibiting cell proliferation in all cell lines but to a lesser extent in NCI 2596 cells which have low NFkB expression.

      Conclusion
      Nuclear NFkB expression is a poor prognostic factor in MPM. DHMEQ, which inhibits nuclear translocation of NF-kB, inhibits cell proliferation in MPM cell lines. Furthermore, increased NF-kB expression in resistant cells suggests this pathway may play a role in development of cisplatin resistance in MPM. Inhibition of NF-kB may therefore prove to be of potential therapeutic benefit in MPM treatment and re-sensitisation of resistant MPM to cisplatin.

      Only Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login, select "Add to Cart" and proceed to checkout. If you would like to become a member of IASLC, please click here.

      Only Active Members that have purchased this event or have registered via an access code will be able to view this content. To view this presentation, please login or select "Add to Cart" and proceed to checkout.

  • +

    P1.01 - Poster Session 1 - Cancer Biology (ID 143)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
    • +

      P1.01-016 - Targeting NF-κB regulated pathways to overcome cisplatin resistance in non small cell lung cancer (ID 3270)

      13:00 - 13:14  |  Author(s): K. Umezawa

      • Abstract

      Background
      Cisplatin based doublet chemotherapy is the mainstay of non small cell lung cancer (NSCLC) treatment with an initial objective response rate of approximately 40-50%. However, intrinsic and acquired resistance to cisplatin constitutes a major clinical obstacle in lung cancer management and has yet to be fully understood. Inflammatory mediators may play an important role in the development of cisplatin resistance, such as those regulated by NF-κB. We have previously demonstrated that levels of NF-κB are increased in cisplatin resistant cells compared with sensitive Parent cells. We are currently assessing a number of NF-κB regulated targets in cisplatin resistant cell line models, using DHMEQ, a specific NF-κB inhibitor. DHMEQ treatment results in greater cell death in the cisplatin resistant cells compared with Parent. This study will elucidate the efficacy of DHMEQ to overcome cisplatin resistance and identify novel targets within the NF-κB pathway that may improve therapeutic strategies for NSCLC patients.

      Methods
      NF-κB downstream targets and signalling mediators were examined using NF-κB signalling and target pathway qPCR arrays (168 genes) in the H460 CisR and Parent cell line model. Targets identified are currently undergoing validation using qPCR and western blot. Biological and functional relevance of these targets in the development of cisplatin resistance will be examined further using DHMEQ and siRNA knockdown strategies. In addition, a xenograft murine model will be utilised to assess the effect of DHMEQ alone and in combination with cisplatin on tumour growth in vivo.

      Results
      Data from qPCR arrays have demonstrated that a number of genes are differentially regulated between the CisR and Parent cell lines. These include genes which activate the NF-κB signalling cascade (TLR3, TLR4), regulators of the pathway (BIRC3, CASP1), transcription factors (Myc) and NF-κB responsive genes (TNF, CXCL8). A number of these genes will be modulated to determine their involvement in cisplatin resistance. In addition, DHMEQ is being used in combination studies to determine, whether it can re-sensitise cells to cisplatin therapy. At present a dosing study is ongoing to establish the effect of DHMEQ on xenograft tumours derived from Parent and CisR cells. The results of which will be presented.

      Conclusion
      Preliminary data indicates that NF-κB and a number of its downstream targets are deregulated in cisplatin resistant cells. This project aims to validate the role of these NF-κB regulated genes in cisplatin resistant NSCLC. It will also determine whether DHMEQ may be a novel targeted agent for the treatment of NSCLC. The data obtained in this study will ultimately benefit patients by providing insights into novel druggable targets and new clinical strategies to re-sensitise patients to cisplatin therapy.

  • +

    P2.01 - Poster Session 2 - Cancer Biology (ID 145)

    • Event: WCLC 2013
    • Type: Poster Session
    • Track: Biology
    • Presentations: 1
    • +

      P2.01-016 - Targeting the PI3K-mTOR-NFκB pathway to overcome cisplatin resistance in NSCLC. (ID 2788)

      09:30 - 09:30  |  Author(s): K. Umezawa

      • Abstract

      Background
      Non-small cell lung cancer (NSCLC) is the leading cause of cancer morbidity and mortality in the Western world with a poor overall 5 year survival of <15%. The most effective systemic chemotherapy for NSCLC is cisplatin-based combination treatment. However, chemoresistance is a major therapeutic problem and understanding the mechanisms involved is critical to the development of new therapeutic intervention strategies. The PI3K pathway plays an important role in NSCLC and we and others have shown increased PI3K signaling to be associated with a more aggressive disease with poor prognosis. Several proteins in this pathway have been indicated as potential mediators of cisplatin resistance in other cancers, and our group has previously identified the PI3K-activated transcription factor NFκB as a key player in this setting. In this study, targeted inhibition of three strategic points of the PI3K pathway was carried out with the aim of overcoming acquired resistance to cisplatin in these cell lines.

      Methods
      A panel of cisplatin resistant cell lines was previously generated in our laboratory through prolonged exposure to the drug. Expression of PI3K pathway related genes was compared between H460 parent (H460PT) and H460 cisplatin resistant (H460CR) cells using a PI3K pathway SABiosciences RTPCR array. Identified genes of interested were further investigated via PCR and Western blot in these cells as well as A549 parent (A549PT) and A549 cisplatin resistant (A549CR) cells. Three strategic points of the pathway were inhibited using GDC-0980, a dual PI3K-mTOR inhibitor currently in Phase II clinical trials in NSCLC, and DHMEQ, an inhibitor of NFkB translocation which has been used extensively both in vitro and in vivo. Effects of the two inhibitors on the parent & cisplatin resistant cell lines both with and without cisplatin were assessed by BrdU proliferation assay and multiparameter apoptosis assay (High Content Analysis).

      Results
      One of the most notable targets to emerge from the PI3K pathway RTPCR array screen was NFKBIA; the gene which codes for NFκB inhibitor IκBα. This gene was shown to be 12 fold overexpressed in H460CR compared to H460PT. This finding was validated at both the RNA and protein level by PCR and Western blot. NFκB was also found to be overexpressed in cisplatin resistant cells compared to their respective parent cells. Inhibition of NFκB by DHMEQ led to significantly improved inhibition of proliferation and induction of apoptosis in cisplatin resistant cells compared to parent cells. Preliminary data indicates that inhibition of PI3K and mTOR by GDC-0980 did not offer as significant a benefit as inhibition of NFκB in the cisplatin resistance setting, though further data from combination studies will be presented.

      Conclusion
      We conclude that the PI3K pathway plays an important role in resistance to cisplatin in NSCLC, particularly when signaling proceeds through the transcription factor NFκB. Targeting this pathway may be of benefit in re-sensitizing cisplatin resistant tumours to the drug.