CRTC1 enhances PD-L1-mediated tumor immunosuppression in non-small cell lung cancer via the Notch1/Akt signaling pathway

Front Immunol. 2025 Sep 5:16:1658679. doi: 10.3389/fimmu.2025.1658679. eCollection 2025.

Abstract

Background: While programmed death-ligand 1 (PD-L1)-targeted immunotherapy represents an advancement in non-small cell lung cancer (NSCLC), patient outcomes remain suboptimal. Aberrant activation of the cyclic adenosine monophosphate (cAMP) response element binding protein (CREB)-regulated transcription coactivator (CRTC) is linked to malignant proliferation and functionality in lung cancer cells. This study investigates the involvement of CRTC1 in tumor immunity.

Methods: CRTC1 and Notch1 expression were regulated in A549 and NCI-H1299 NSCLC lines through plasmid-mediated overexpression/silencing to assess their effects on cell viability, apoptosis, migration, and invasion. CRTC1/Notch1-dysregulated Lewis lung carcinoma (LLC) cells were co-cultured with T cells to evaluate T cell activation and function. The efficacy of combined CRTC1 knockdown/overexpression and atezolizumab (anti-PD-L1) was tested in an LLC xenograft mouse model.

Results: CRTC1 promoted cell viability, migration, and invasion while suppressing apoptosis across NSCLC models. In LLC cells, CRTC1 upregulated tumor cell PD-L1 expression, suppressed T cell-derived IFN-γ and IL-2 production, diminished endogenous CXCL10/11 secretion, and impaired T cell proliferation and cytotoxicity. Mechanistically, CRTC1 interacted with Notch1 to activate the Notch1/Akt pathway, stimulating PD-L1 upregulation, thereby facilitating tumor immunosuppression and growth. Notably, CRTC1 overexpression reversed the protective effects of atezolizumab on tumor growth. Combining CRTC1 knockdown with atezolizumab synergistically enhanced anti-tumor T cell immunity, achieving the most significant tumor regression in xenografts.

Conclusion: These findings indicate that CRTC1 in tumor cells suppresses PD-L1-mediated anti-tumor immunity and promotes tumorigenesis via the Notch1/Akt signaling axis. Dual targeting of CRTC1 and PD-L1 demonstrates therapeutic synergy, suggesting CRTC1 pathway inhibition could optimize immunotherapy outcomes in NSCLC patients.

Keywords: CRTC; Notch/Akt signaling; immunosuppression; immunotherapy; non-small cell lung cancer.

MeSH terms

  • Animals
  • Antibodies, Monoclonal, Humanized / pharmacology
  • Apoptosis
  • B7-H1 Antigen* / antagonists & inhibitors
  • B7-H1 Antigen* / immunology
  • B7-H1 Antigen* / metabolism
  • Carcinoma, Non-Small-Cell Lung* / drug therapy
  • Carcinoma, Non-Small-Cell Lung* / immunology
  • Carcinoma, Non-Small-Cell Lung* / metabolism
  • Carcinoma, Non-Small-Cell Lung* / pathology
  • Cell Line, Tumor
  • Humans
  • Lung Neoplasms* / drug therapy
  • Lung Neoplasms* / immunology
  • Lung Neoplasms* / metabolism
  • Lung Neoplasms* / pathology
  • Mice
  • Proto-Oncogene Proteins c-akt* / metabolism
  • Receptor, Notch1* / metabolism
  • Signal Transduction / immunology
  • Transcription Factors* / genetics
  • Transcription Factors* / immunology
  • Transcription Factors* / metabolism
  • Xenograft Model Antitumor Assays

Substances

  • Receptor, Notch1
  • B7-H1 Antigen
  • Transcription Factors
  • Proto-Oncogene Proteins c-akt
  • CD274 protein, human
  • CRTC1 protein, human
  • NOTCH1 protein, human
  • atezolizumab
  • Antibodies, Monoclonal, Humanized