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Satoru Ito

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    P1.03 - Biology (Not CME Accredited Session) (ID 935)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
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      P1.03-18 - Mechanobiology of Lung Cancer Cells: Regulation of PD-L1 Expression by Matrix Stiffness (ID 11153)

      16:45 - 18:00  |  Author(s): Satoru Ito

      • Abstract
      • Slides


      Expression of programmed death-ligand 1 (PD-L1) in tumor cells plays an important role in mechanisms underlying evasion of an immune check point system. PD-L1 expression is regulated by multiple mechanisms such as the tumor microenvironment. Lung cancer tissue with increased deposition of extracellular matrix is much stiffer than normal lung tissue. There is emerging evidence that the matrix stiffness of cancer tissue affects the phenotypes and properties of cancer cells. Nevertheless, the effects of substrate rigidity on expression of PD-L1 in lung cancer cells remain elusive. This study was designed to determine whether substrate stiffness affects the regulation of PD-L1 in lung cancer cells.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We evaluated PD-L1 expression levels in HCC827 human lung cancer cell line. Commercially available polyacrylamide hydrogels of different stiffnesses bound to 6-well polystyrene plates or polystyrene dishes coated with type I collagen were utilized. We used 2 and 25 kPa gels as substrates of normal (soft) human lung and cancer-associated (stiff) tissue. Western blotting and Immunofluorescence staining were performed for evaluating PD-L1 expression levels. A colorimetric viability assay was performed for evaluating of PD-L1 expression and cell proliferation by using transfection with short interfering RNA (siRNA) for PD-L1.

      4c3880bb027f159e801041b1021e88e8 Result

      Expression of PD-L1 protein was higher on the stiffer substrates (25 kPa gel and plastic dish) than on the soft 2 kPa gel. PD-L1 expression was reduced by detachment of cells adhering to the substrate. Interferon-γ enhanced expression of PD-L1 protein cultured on stiff (25 kPa gel and plastic dishes) and soft (2 kPa gel) substrates and in the cell adhesion-free condition. As the stiffness of substrates increased, formation of actin stress fiber and cell growth were enhanced. Transfection of the cells with siRNA for PD-L1 inhibited cell growth without affecting stress fiber formation. Treatment of the cells with cytochalasin D, an inhibitor of actin polymerization, significantly reduced PD-L1 protein levels.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Stiff substrates enhanced PD-L1 expression via actin cytoskeleton-dependent mechanisms in HCC827 lung cancer cell line. It is suggested that stiffness as a tumor environment regulates PD-L1 expression, which leads to evasion of the immune system and tumor growth.


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