MDPHD student Mayo Clinic College of Medicine and Science Rochester, Minnesota, United States
Introduction/Rationale: Cancer immunotherapy has transformed the treatment landscape by leveraging the immune system to eradicate malignant cells. Among immune effectors, CD8⁺ T cells play a pivotal role in tumor clearance through recognition and destruction of cancer cells. To effectively counter the rapid proliferation and continuous evolution of cancer, robust effector function of cytotoxic CD8⁺ T cells is essential. The expression of effector genes in CD8⁺ T cells is tightly regulated, ensuring that cytotoxic molecules are expressed only at appropriate times and in relevant contexts. We previously reported that upregulation of the gene NKG7 following immunotherapy is critical for clinical response and demonstrated that NKG7 expression is both necessary and sufficient for T cell cytotoxicity. However, the mechanisms governing NKG7 expression in CD8⁺ T cells remain poorly defined.
Methods: We performed a cytokine screen to identify potential drivers of NKG7 expression at both the transcriptional and protein levels in cell lines and healthy donor peripheral blood mononuclear cells (PBMC). We employed quantitative RT-PCR, flow cytometry, and Western blotting to determine and validate the expression level of NKG7 and relevant signal molecules. We validated the signal pathways identified in single cell RNAseq data analysis in PD-1 therapy-responsive CD8⁺ T cells.
Results: In PBMC derived CD8+ T cells, we found that IL-2 increases NKG7 mRNA levels, correlating with a dose dependent increase in NKG7 protein expression. IL-2–induced NKG7 expression is associated with elevated levels of T-bet, a transcription factor essential for effector T cell differentiation. Consistent with this, scRNA-seq analysis revealed enrichment of the IL-2 signaling pathway in CD8⁺ T cells responsive to anti–PD-1 therapy.
Conclusion: Our results suggest that NKG7 is upregulated by IL-2 and T-bet signaling. Due to the critical role of this signaling axis during effector CD8⁺ T cell differentiation, NKG7 expression may be determined during this phase.
