DAP12-based activating chimeric antigen receptor for NK cell tumor immunotherapy

Area of Science:

• Immunology
• Cancer Biology
• Cell Therapy

Background:

• Natural Killer (NK) cells are crucial for cancer immunotherapy.
• Chimeric antigen receptors (CARs) genetically engineered into NK cells can target resistant tumors.
• DNAX-activation protein 12 (DAP12) is a key signaling adaptor in NK cell activation.

Purpose of the Study:

• To develop and evaluate a novel DAP12-based CAR targeting prostate stem cell antigen (PSCA).
• To compare the efficacy of the DAP12-CAR with a traditional CD3ζ-based CAR in NK cells.
• To assess the in vivo therapeutic potential of DAP12-CAR engineered NK cells against PSCA-positive tumors.

Main Methods:

• Generation of a DAP12-CAR construct targeting PSCA (anti-PSCA-DAP12).
• Engineering of NK cell line YTS and primary human NK cells with the anti-PSCA-DAP12 CAR.
• In vitro cytotoxicity assays against PSCA-positive tumor cells.
• In vivo studies using tumor xenograft models in mice.
• Analysis of signaling pathways (ZAP-70 phosphorylation) and cytokine release (IFN-γ).

Main Results:

• The anti-PSCA-DAP12 CAR significantly enhanced YTS NK cell cytotoxicity against PSCA-positive tumor cells compared to a CD3ζ-CAR.
• CAR-engineered NK cells showed DAP12-dependent ZAP-70 phosphorylation and IFN-γ release upon target cell contact.
• Infusion of anti-PSCA-DAP12 CAR-engineered YTS cells delayed tumor growth and achieved complete eradication in a fraction of treated mice.
• DAP12-CARs were feasible in primary human NK cells, demonstrating specific cytotoxicity enhanced by KIR-HLA mismatches.

Conclusions:

• DAP12-based CARs represent a novel and effective strategy for engineering NK cells in cancer immunotherapy.
• This approach overcomes NK cell resistance in tumors and shows significant therapeutic potential in preclinical models.
• DAP12-CARs offer a promising alternative signaling module for NK cell-based adoptive immunotherapy.