 |
Schematic of YAP/TAZ-mediated immune evasion. YAP/TAZ hyperactivation is associated with genomic instability that may make cancer cells more recognizable to CD8+ T cells, immune cells that can recognize and kill abnormal cells, including cancer cells. At the same time, YAP/TAZ hyperactivation can increase PD-L2, which binds to PD-1 receptors on CD8+ T cells and suppresses their attack. Together, these effects may help explain why certain Hippo pathway alterations were linked to better outcomes following immune checkpoint inhibitor therapy. Image Credit: Toshinori Ando/Hiroshima University |
Scientific Frontline: Extended "At a Glance" Summary: Hippo Pathway Dysregulation and PD-L2-Mediated Immune Evasion
The Core Concept: Hyperactive YAP and TAZ proteins, driven by dysregulation in the Hippo signaling pathway, simultaneously induce genomic instability that flags cancer cells to the immune system and increase PD-L2 expression to suppress targeted T-cell attacks.
Key Distinction/Mechanism: Unlike typical immune evasion mechanisms, YAP/TAZ hyperactivation creates a paradoxical state where tumors are highly recognizable to CD8+ T cells due to DNA damage, yet remain protected because elevated PD-L2 binds to PD-1 receptors on the T cells, effectively neutralizing the immune response.
Origin/History: Detailed in a recent study published in Communications Biology by Hiroshima University researchers and international collaborators, this mechanism was identified by analyzing laboratory cancer models and clinical data from 1,662 patients treated with immune checkpoint inhibitors.
Major Frameworks/Components:
- The Hippo signaling pathway, specifically the loss of regulators LATS1 and LATS2, which unleashes YAP/TAZ activity.
- CD8+ T cells, which recognize and target abnormal cells exhibiting high mutational burdens.
- PD-L2, an immune checkpoint ligand regulated by TEAD and BRD4 that binds to PD-1 receptors on T cells to inhibit their lethal function.
- Head and neck squamous cell carcinoma (HNSCC), the primary cancer model used to test engineered T-cell vulnerability.