Virtual Library

 x 
My Library Virtual Library FAQ

Start Your Search

M.A. Hoda



Author of

  • +

    P2.05 - Poster Session 2 - Preclinical Models of Therapeutics/Imaging (ID 158)

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

      P2.05-012 - An inducible transition cell model reflecting epithelioid versus sarcomatoid differentiation of Malignant Pleural Mesothelioma (ID 1892)

      09:30 - 09:30  |  Author(s): M.A. Hoda

      • Abstract

      Background
      Malignant pleural mesothelioma (MPM) is an aggressive asbestos-related malignancy characterized by frequent resistance to chemo- and radiotherapy. Signals induced by Fibroblast growth factors (FGF) and their high-affinity receptors (FGFR) have been identified as important drivers for malignant growth in several tumor entities including thoracic malignancies. We have recently demonstrated that FGFR signals stimulate growth and migration in MPM cell models, whereas inhibition of FGFR1 reduced tumor growth and had an antagonistic effect on malignant behavior of MPM cells. In several cell models of biphasic MPM, FGF2 induced phenotypical changes reminiscent of epithelial-mesenchymal-transition (EMT). In this study we analyzed these FGF-induced morphological and functional alterations and the associated signal transduction mechanisms in more detail.

      Methods
      Cells were stimulated with recombinant FGF2 and analyzed by microscopy and ImageJ software. The specific inhibitors PD166866, UO126, MK2206, LY294002 and SB431542 were used to block FGFR1, MEK, AKT, PI3K and TGFbeta receptors, respectively. Alterations in gene expression were determined via whole-genome expression arrays and further evaluated by immunofluorescence. Downstream signaling was investigated by immunoblotting.

      Results
      In M38K and SPC212 cells FGF2 induced morphological alterations that were characterized by a more spindle-shaped appearance and reduced contacts with adjacent cells. This correlated with increased cell migration. With respect to signal transduction, the effects of FGF2 could be blocked by inhibition of FGFR1 or MEK, whereas inhibition of AKT, PI3K or receptors of the TGFbeta/activin family had no effect. Expression arrays of both cell models indicated regulation of several matrix metalloproteinases (MMP1, MMP4), the integrin subunit ITGA6 and the two TGFbeta family-related proteins INHBB and Smad7. Since the phenotypical changes were similar to EMT, genes previously connected to EMT were analyzed. Whereas slug/SNAI2 and ZEB1 were increased, other mesenchymal genes such as vimentin or N-cadherin were already expressed at high levels in the untreated cells, likely due to the mesodermal origin of mesothelial cells. In M38K, E-cadherin was decreased whereas in the more “fibroblastoid-type” SPC212 E-cadherin was generally expressed at very low levels.

      Conclusion
      Our data suggest that FGF2 induces morphological changes that result in a more sarcomatoid cell morphology and expression of some markers connected to EMT. These effects depend on the MAPK pathway and are connected to more aggressive cell behavior, paralleling the higher aggressiveness and worse prognosis of the sarcomatoid and biphasic compared to the epithelioid histological subtype of MPM.

  • +

    P2.06 - Poster Session 2 - Prognostic and Predictive Biomarkers (ID 165)

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

      P2.06-017 - Long non coding RNAs (lncRNAs) are dysregulated in malignant pleural mesothelioma (MPM) (ID 1524)

      09:30 - 09:30  |  Author(s): M.A. Hoda

      • Abstract

      Background
      Malignant Pleural Mesothelioma (MPM) is an aggressive disease, often diagnosed at an advanced stage. It is characterized by a long latency period and prior asbestos exposure. Currently accurate diagnosis of MPM is difficult due to the lack of sensitive biomarkers, and despite minor improvements in treatment, median survival rates rarely exceed 12 months. Accumulating evidence suggests that aberrant expression of long non-coding RNAs (lncRNAs) plays an important functional role in cancer biology. LncRNAs are a class of recently discovered non-protein coding RNAs >200 nucleotides in length with a role in regulating transcription. The aims of this study were to characterize the expression and function of these lncRNAs in MPM.

      Methods
      To identify novel lncRNAs involved in MPM, microarray profiling was performed on five cell lines - the immortalized normal mesothelial cell line (MeT-5A) and four MPM lines (two epithelioid H28 and H226 and two biphasic MM05 and MSTO) using Invitrogen’s NCode lncRNA microarrays. These allow simultaneous assessment of mRNA and lncRNA content. High priority candidate lncRNAs were selected on the basis of statistical (P<0.05) and biological (>3-fold difference) significance. Expression of high priority candidates were technically validated using RT-qPCR, and biologically validated in three independent test sets. Pathway analyses were performed to interrogate the relationship between lncRNA and mRNA expression. Cell proliferation and colony formation assays were used to investigate lncRNA function.

      Results
      Microarray profiling and real-time qPCR validation identified 9 lncRNA candidates with significant differential expression in MPM compared with normal mesothelial cells Validation in three independent test sets by RT-qPCR analysis demonstrated consistent up-regulation of four of these lncRNAs. Receiver Operating Curve analysis showed that two of these candidates were able to separate benign pleura and MPM with high sensitivity and specificity. In addition, high expression of AK054908 was associated with nodal metastases with lower levels of AK130275 and AF268386 observed in patients receiving induction chemotherapy. Cases with higher EF177379 levels also demonstrated a trend to improved survival. The majority of mRNAs co-expressed with candidate lncRNAs were associated with cellular and metabolic processes including cell cycle, cell death and apoptosis. In functional studies, siRNA knockdown of AK130275 showed suppression of cell growth and colony formation in MPM cells with moderate changes observed following knockdown of EF177379.

      Conclusion
      To our knowledge this is the first systematic study of lncRNA expression profiles in MPM. We have found that lncRNA expression profiles can distinguish malignant mesothelium from normal pleural tissue, and that some lncRNAs are associated with nodal metastasis and long term survival. We also demonstrate that lncRNAs have potential prognostic and diagnostic utility with functional roles in regulating cell growth. Further work is required to evaluate whether these lncRNAs are capable of differentiating mesothelioma from lung cancer and benign asbestos-related diseases, and to reveal their specific functions in MPM pathogenesis.