Virtual Library

Start Your Search

C. Kong



Author of

  • +

    MO03 - Thymic Malignancies (ID 123)

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

      MO03.08 - Increased Galectin-1 Expression in a Thymic Epithelial Tumor Tissue Microarray (TMA) and Galectin-1 Knockdown Studies in a Thymoma Cell Line (ID 1238)

      11:15 - 11:20  |  Author(s): C. Kong

      • Abstract
      • Presentation
      • Slides

      Background
      Thymoma is a rare malignancy with a paucity of data on biology. Thymic epithelial tumors are often admixed with developing T-lymphocytes in the microenvironment. Galectin-1 (gal-1) is a beta-galactosidase binding protein involved in T-cell development via thymic stromal and thymocyte interaction as well as thymocyte development through negative selection. Gal-1 also induces apoptosis of effector T-lymphocytes, promotes angiogenesis, and is a poor prognostic indicator when overexpressed in several tumor types. To our knowledge expression of gal-1 has not been examined in thymic epithelial tumors.

      Methods
      A TMA was constructed from 68 patients with thymic malignancies and 8 benign thymic controls at Stanford University School of Medicine (Stanford, CA). Immunohistochemical stains for galectin-1 (1:200 dilution; citrate pre-treatment; mouse monoclonal; Novocastra) were performed on 4 µM-thick TMA sections. Galectin-1 cytoplasmic staining of the epithelial cell component was scored as negative (0), focal positive (1+), or strong positive (2+) by a Stanford pathologist, who was blinded to the clinical data. Gal-1 expression was averaged for each patient sample. Statistical analysis was performed using SAS Enterprise Guide v5.0 (Cary, NC). Non-parametric statistical analyses were used to compare average patient gal-1 expression between thymic tumors and benign thymic controls. Stable gal-1 knockdown was achieved in IU-TAB1, a human thymoma WHO type AB cell line, using the pLKo.1 vector with gal-1 shRNA (Open Biosystems). Lentivirus was produced using the Trans-Lentiviral Packaging System (Thermo Scientific). In vitro proliferation cell counts were performed by hemocytometer. After hypoxia exposure (0.5% O~2~), apoptotic cells were labeled using the APO-Direct kit and quantified by flow cytometry (BD Biosciences).

      Results
      Demographics for 68 patients: M:F (53%/47%), Mean age at diagnosis: 55 years, WHO Histology: A (10%), B (57%), AB (24%), C (4%), unclassified (4%), Pathologic Maseoka Stage: I (46%), IIa (18%), IIb (4%), III (18%), IVa (9%) IVb (6%). Gal-1 expression was increased among thymic tumor tissue compared to unpaired controls (mean avg gal-1 expression 1.5 vs. 0.125, p=0.0012, Kruskal-Wallis test). Logistic regression of tumor vs. control thymus by gal-1 generated a C-statistic of 0.845. A significant increase in gal-1 expression was noted across all WHO thymoma subtypes except thymic carcinoma (type C) (p < 0.05, non-parametric ANOVA with post-hoc ranked Dunnett’s t-test). Among 11 thymic tumors analyzed with paired adjacent resected benign thymus tissue from the same patient, a significant increase was noted in gal-1 expression among tumor compared with adjacent resected normal benign thymus (mean avg gal-1 1.82 vs. 0.35, p=0.004, sign-rank test). In vitro, gal-1 knockdown did not affect IU-TAB1 proliferation. Preliminary results showed gal-1 knockdown increased apoptosis under hypoxia compared to scramble control.

      Conclusion
      Gal1 expression was increased among thymoma compared with benign thymus controls and paired adjacent resected benign thymus. A robust C-statistic of 0.845 indicates that gal-1 expression may discriminate tumor from benign thymus. Increased gal-1 expression was conserved across WHO histologic subtype except for thymic carcinoma—whose analysis was limited due to small sample size. Gal-1 knockdown might increase apoptosis under hypoxia. We are continuing to investigate the biologic and clinical significance of increased gal-1 expression in thymoma.

      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.