MHC class I dysfunction of glioma stem cells escapes from CTL-mediated immune response via activation of Wnt/β-catenin signaling pathway.

Glioma stem cells (GSCs) decrease T cells cognition and evade systemic immunosurveillance via downregulations or defects of major histocompatibility complex class I (MHC-I) molecule and antigen-processing machinery (APM) components. Improvement of tumor surface antigens of GSCs may be effective strategy to trigger an adaptive immune response and activate cytotoxic T cells (CTLs) to eliminate glioma. In this study, our data indicated that downregulations of MHC-I and APM components expressions were associated with Wnt pathway activation in GSCs. Histone deacetylases (HDAC) inhibition improved MHC-I and APM components expressions, which could be partly reverted by Wnt pathway activation. Blocking CTLs-mediated killing decreased the anti-tumor effect of tumor lysate vaccine. The enhancement of T cells immune response resulting from HDAC inhibition was dependent on CTLs cognition on tumor antigens presented by upregulated MHC-I molecule in GSCs. These data suggest that suppression of stemness pathway may be effective for GSCs-based immunotherapy against immune-escaped tumors.