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FasL gene knock-down therapy enhances the antiglioma immune response
Timothy Jansen1, Betty Tyler, Joseph L Mankowski
1Departments of Neurosurgery, Fondazione IRCCS Istituto Nazionale C Besta, Milan, Italy.
Abstract:
Malignant glioma is a lethal form of brain cancer that is very difficult to treat. The aggressive behavior of these neoplasms and their limited responsiveness to therapy has been attributed in part to the ability of these tumors to evade the immune system. Gliomas, like many other solid tumors, express components of numerous immune escape mechanisms, including immunosuppressive proteins such as TGF-beta, IL-10, and FasL. Here, we show that FasL expression can support the growth of experimental intracranial glioma. We show that FasL is readily detected in human glioblastoma multiforme clinical specimens. FasL was found to be expressed by three well-characterized rat glioma cell lines (9L, F98, and C6) and glioma cell-derived FasL mediated the death of phytohemagglutinin-stimulated Jurkat T-lymphocytes when cocultured with glioma cells in vitro. We asked if inhibiting 9L-derived FasL altered the growth of experimental glioma. FasL expression knockdown using shRNA reduced the growth of subcutaneous and intracranial 9L gliomas by approximately 50% in immune competent Fisher 344 rats. In contrast, FasL expression knockdown had no affect on the growth of intracranial 9L glioma in T-cell deficient athymic rats. Intracranial tumors derived from FasL knockdown 9L glioma cells contained up to 3-fold more tumor infiltrating T-cells than tumors derived from control 9L cells. These results demonstrate that down-regulating FasL expression and/or function in glial malignancies can enhance T-cell tumor infiltration and inhibit tumor growth. The findings suggest that targeting endogenous FasL in glial malignancies could enhance the efficacy of emerging immune-based treatment strategies.
Insights
Targeting FasL in malignant glioma inhibits tumor growth by increasing T-cell infiltration. Down-regulating FasL expression enhances immune response against brain cancer, suggesting new therapeutic strategies.
Area of Science:
- Neuro-oncology
- Immunology
- Cancer Biology
Background:
- Malignant glioma is an aggressive brain cancer with poor treatment outcomes.
- Tumor immune evasion, including the expression of immunosuppressive proteins like FasL (Fas ligand), contributes to glioma's resistance to therapy.
- FasL is detected in human glioblastoma multiforme and expressed by glioma cell lines.
Purpose of the Study:
- To investigate the role of FasL in experimental glioma growth.
- To determine if inhibiting FasL affects glioma progression and T-cell infiltration.
- To explore the potential of targeting FasL as a therapeutic strategy for malignant glioma.
Main Methods:
- Assessed FasL expression in human glioblastoma and rat glioma cell lines (9L, F98, C6).
- Evaluated the cytotoxic effect of glioma-derived FasL on Jurkat T-lymphocytes in vitro.
- Utilized shRNA to knockdown FasL expression in 9L glioma cells.
- Compared the growth of subcutaneous and intracranial gliomas in immune-competent and T-cell deficient rats after FasL knockdown.
- Quantified tumor-infiltrating T-cells in intracranial tumors.
Main Results:
- Glioma cell-derived FasL induced T-lymphocyte death in vitro.
- FasL knockdown significantly reduced subcutaneous and intracranial 9L glioma growth by approximately 50% in immune-competent rats.
- FasL knockdown did not affect tumor growth in T-cell deficient rats.
- Tumors from FasL knockdown cells showed a 3-fold increase in tumor-infiltrating T-cells compared to controls.
Conclusions:
- FasL expression supports the growth of experimental gliomas.
- Inhibiting FasL enhances T-cell infiltration into gliomas, thereby inhibiting tumor growth.
- Targeting endogenous FasL presents a promising strategy to improve the efficacy of immunotherapies for malignant gliomas.
