Targeting the αv integrin/TGF-β axis improves natural killer cell function against glioblastoma stem cells

Glioblastoma multiforme (GBM), the most aggressive brain cancer, recurs because glioblastoma stem cells (GSCs) are resistant to all standard therapies. We showed that GSCs, but not normal astrocytes, are sensitive to lysis by healthy allogeneic natural killer (NK) cells in vitro. Mass cytometry and single-cell RNA sequencing of primary tumor samples revealed that GBM tumor-infiltrating NK cells acquired an altered phenotype associated with impaired lytic function relative to matched peripheral blood NK cells from patients with GBM or healthy donors. We attributed this immune evasion tactic to direct cellto-cell contact between GSCs and NK cells via alpha v integrin-mediated TGF-beta activation. Treatment of GSC-engrafted mice with allogeneic NK cells in combination with inhibitors of integrin or TGF-beta signaling or with TGFBR2 gene-edited allogeneic NK cells prevented GSC-induced NK cell dysfunction and tumor growth. These findings reveal an important mechanism of NK cell immune evasion by GSCs and suggest the alpha v integrin/TGF-beta axis as a potentially useful therapeutic target in GBM.

Automated summary

Glioblastoma stem cells (GSCs) in the aggressive brain cancer Glioblastoma multiforme (GBM) evade immune responses by impairing the function of tumor-infiltrating NK cells through a direct cell-to-cell contact mechanism mediated by alpha v integrin and TGF-β activation. Treatment with inhibitors of integrin or TGF-β signaling, or with TGFBR2 gene-edited allogeneic NK cells, prevents GSC-induced NK cell dysfunction and tumor growth, suggesting a potential therapeutic strategy for GBM.