Sema6D forward signaling impairs T cell activation and proliferation in head and neck cancer

Area of Science:

• Immunology
• Cancer Biology
• Molecular Signaling

Background:

• Immune checkpoint inhibitors (ICIs) are crucial cancer therapies, but their efficacy depends on the tumor immune microenvironment.
• T cell infiltration and activation within tumors significantly influence ICI treatment outcomes.

Purpose of the Study:

• To investigate the role of semaphorin 6D (Sema6D) forward signaling in regulating anti-tumor T cell responses.
• To determine if targeting Sema6D can enhance the effectiveness of immune checkpoint inhibitors.

Main Methods:

• Utilized murine oral tumor models to study Sema6D's effect on CD8+ T cell infiltration and activation.
• Examined Sema6D's impact on PD-1 blocking therapy efficacy in wild-type and Sema6d-knockout (KO) mice.
• Analyzed human head and neck squamous cell carcinoma and pan-cancer datasets for SEMA6D expression and its correlation with immune markers.

Main Results:

• Sema6D, expressed by non-hematopoietic cells, inhibited tumor-specific CD8+ T cell infiltration and activation via its receptor, Plexin-A4.
• Sema6d-KO mice showed improved responses to PD-1 blocking therapy compared to wild-type mice.
• Human cancer data revealed SEMA6D expression negatively correlated with CD8A, PDCD1, IFNG, and GZMB, indicating suppressed anti-tumor immunity.

Conclusions:

• Sema6D forward signaling acts as a barrier to effective anti-tumor T cell responses.
• Targeting Sema6D signaling presents a promising strategy to enhance the efficacy of immune checkpoint inhibitors in various cancers.