PKCI–YAP1–CCL7 axis and tumor-associated macrophage–mediated anti–PD-1 resistance in lung adenocarcinoma.

Abstract

e20619 Background: Immune checkpoint blockade targeting PD-1 has improved outcomes in non-small cell lung cancer (NSCLC), yet most patients fail to achieve durable responses. Tumor-intrinsic oncogenic signaling is increasingly recognized as a key driver of immunosuppressive tumor immune microenvironment (TIME) formation and therapeutic resistance. We investigated whether protein kinase Cι (PKCι), an oncogenic atypical PKC highly expressed in NSCLC, mediates resistance to anti-PD-1 therapy through regulation of myeloid cell recruitment. Methods: PKCι expression was examined in human NSCLC specimens and correlated with immune infiltration and clinical response to immune checkpoint inhibitors. Murine lung adenocarcinoma models with genetic knockdown or overexpression of PKCι, YAP1, or CCL7 were established. Tumor growth under anti-PD-1 therapy was evaluated in immunocompetent mice. Immune cell populations were characterized by flow cytometry and immunohistochemistry. Macrophage migration was assessed using transwell and 3D tumor-spheroid assays. RNA sequencing, qPCR, ELISA, and chromatin immunoprecipitation were performed to define PKCι downstream signaling. The clinically approved drug auranofin was tested as a pharmacologic PKCι inhibitor, alone or combined with anti-PD-1 therapy, in orthotopic and subcutaneous lung tumor models. Results: High PKCι expression in NSCLC correlated with poor response to PD-1 blockade, increased tumor-associated macrophage (TAM) infiltration, and reduced CD8⁺ T-cell abundance. Genetic inhibition of PKCι significantly enhanced anti-PD-1 efficacy in vivo and selectively reduced TAM accumulation without substantially affecting other suppressive immune subsets. Mechanistically, PKCι activated YAP1/TEAD-dependent transcription of the chemokine CCL7, which was required for macrophage recruitment and establishment of an immunosuppressive TIME. Knockdown of CCL7 or YAP1 abrogated TAM migration and restored sensitivity to PD-1 blockade, whereas re-expression of PKCι or CCL7 reinstated TAM infiltration and therapeutic resistance. Auranofin suppressed PKCι-YAP1-CCL7 signaling, reduced TAM recruitment, increased infiltration and activation of cytotoxic CD8⁺ T cells, and markedly improved antitumor efficacy when combined with anti-PD-1 therapy. CD8⁺ T-cell depletion abolished the therapeutic benefit of the combination regimen. Conclusions: The PKCι-YAP1-CCL7 axis is a critical driver of TAM-mediated immune suppression and resistance to PD-1 blockade in lung adenocarcinoma. Pharmacologic targeting of PKCι with the repurposed drug auranofin reprograms the TIME and sensitizes tumors to anti-PD-1 therapy, providing a mechanistic rationale for a clinically translatable combination strategy in NSCLC.