T cells enhance stem-like properties and conditional malignancy in gliomas

Area of Science:

• Oncology
• Immunology
• Neuroscience

Background:

• Cancer stem cells (CSCs) drive tumor regeneration, including in malignant brain tumors (gliomas).
• Previous characterization of glioma stem cells (GSCs) often occurred in non-physiological conditions.
• Understanding GSCs in a physiological context is crucial for developing effective therapies.

Purpose of the Study:

• To investigate the role of gene expression similarity in defining glioma stemness.
• To examine GSC enrichment in human glioblastoma (GBM) and murine GL26 tumors following dendritic cell (DC) vaccine therapy.
• To analyze the impact of anti-tumor T cell activity on GSC properties and tumorigenicity.

Main Methods:

• Defined GSC "stemness" using gene expression similarity, noting its inverse correlation with tumor grade.
• Administered DC vaccine therapy to human GBM and analyzed GSC markers.
• Performed gene expression, phenotypic, and functional analyses on murine GL26 tumors from various host environments (nude, wild-type, DC-vaccinated).

Main Results:

• GSC similarity increased in post-vaccine GBMs, correlating with gene expression changes and T cell activity.
• Murine GL26 tumors showed immune alterations, acquired stem cell markers, and increased sensitivity to anti-stem drugs.
• Tumorigenicity of vaccine-exposed GL26 cells was dependent on host T cell presence, suggesting immune-mediated enrichment.
• Both vaccine-exposed GBM and GL26 cells displayed homogeneous expression patterns related to progenitor cells and differentiation.

Conclusions:

• T cell activity is an inducible, physiological process that enriches GSCs in gliomas.
• Gliomas enriched by T cell activity may exhibit stem-like properties distinct from those associated with increased malignancy or heterogeneity.
• These findings highlight the complex interplay between the immune system and cancer stem cells in gliomas.