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K. Coombes



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    P1.02 - Biology/Pathology (ID 614)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: Biology/Pathology
    • Presentations: 1
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      P1.02-019 - Dual Role of Notch in Lung Cancer (ID 7578)

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

      • Abstract

      Background:
      Anomalies in the family of Notch receptors (1, 2, 3, and 4) have been implicated in a range of solid tumors, including lung cancer. There is growing evidence that Notch plays an oncogenic and tumor suppressor role in adenocarcinoma and lung squamous cell carcinoma, respectively. Gaining a complete understanding of the mechanisms underlying these opposing activities in lung cancer is key to the development of novel targeted therapy approaches.

      Method:
      The Cancer Genome Atlas (TCGA) datasets were used to look at gene co-expression patterns of Notch in lung adenocarcinoma and lung squamous cell carcinoma. Biological pathways implicated by gene families were assessed using functional annotation tools (DAVID, ToppGene, and IPA). In vitro and in vivo knockdown studies assessed the functional role of Notch in lung cancer.

      Result:
      Co-expression analysis supports the hypothesis that Notch is co-expressed with different genes in lung adenocarcinoma and squamous cell carcinoma. Knockdown of Notch in vitro and in vivo support our in silico finding of opposing effects of Notch. Our analysis implicates genes associated with metabolic pathways, angiogenesis and cell cycle that may underlie the differential role of Notch in lung adenocarcinoma and squamous cell carcinoma.

      Conclusion:
      These results support the hypothesis differences in the Notch co-expression may underlie its opposing roles in lung adenocarcinoma and squamous cell carcinoma. These finding help unravel the context dependent role of Notch as an oncogene and tumor suppressor in subtypes of lung cancer. Understanding the similarities and differences in co-expression patterns can improve our understanding of the regulatory mechanisms of Notch and strategies for its clinical development as single agent or in combination.

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    P3.03 - Chemotherapy/Targeted Therapy (ID 719)

    • Event: WCLC 2017
    • Type: Poster Session with Presenters Present
    • Track: Chemotherapy/Targeted Therapy
    • Presentations: 1
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      P3.03-013 - Identification of Proteasomal Catalytic Subunit PSMA6 as a Therapeutic Target for Lung Cancer through a Pooled shRNA Screen (ID 8867)

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

      • Abstract

      Background:
      Recent advances in high-throughput genetic analysis revealed that single lung cancer cells harbour a number of genetic and epigenetic changes. Nevertheless, findings from cancer epidemiology and the experimental models of the multi-step lung carcinogenic process, which were developed by our group and others, suggested that only a handful of changes are ‘drivers’ whereas others are only ‘passengers’. Thus, it is very important to identify those that truly contribute to the oncogenic properties of cancer cells by performing functional screening. To this end, we performed screening with a pooled shRNA library in search for genes that are critical for the survival and/or proliferation of lung cancer cells using a lung cancer cell line.

      Method:
      NCI-H460 cell line was used for semi-genome-wide dropout viability analysis using a pooled shRNA library that targeted 5,043 genes. Two Cdk4/hTERT-immortalised normal human bronchial epithelial cell lines, HBEC3 and HBEC4 were used as controls. Pathway analysis was done using NIH-DAVID. Microarray gene expression analysis was done using Illumina Human WG-6 v3.0 Expression BeadChip for 163 non-small cell lung cancer (NSCLC) cell lines and 59 normal control cell lines. DNA copy number analysis with array CGH was done for 108 NSCLC cell lines. Proteasome activity was measured using a 20S proteasome activity assay kit. 20 pairs of resected lung cancer and matched normal lung samples were used for immunohistochemistry of PSMA6. Cell growth was evaluated by WST-1 colorimetric proliferation assay. Cell cycle analysis was done using FACS for cells stained with propidium iodide.

      Result:
      shRNA screening targeting 5,043 genes in NCI-H460 identified 51 genes as candidates for therapeutic targets. Pathway analysis revealed that the 51 genes were enriched for the five pathways, including ribosome, proteasome, RNA polymerase, pyrimidine metabolism and spliceosome pathways. We focused on the proteasome pathway that involved six candidate genes because its activation has been demonstrated in diverse human malignancies, including lung cancer. Microarray expression and array CGH data showed that PSMA6, a proteasomal subunit of a 20S catalytic core complex, was highly expressed in lung cancer cell lines, with recurrent gene amplifications in some cases. Therefore, we further examined the roles of PSMA6 in lung cancer. Silencing of PSMA6 induced apoptosis or G2/M cell cycle arrest in cancer cell lines but not in an immortalised normal lung cell line.

      Conclusion:
      Our data suggested that PSMA6 serves as an attractive target with a high therapeutic index for lung cancer.