NT5E promotes colorectal cancer progression and correlates with PD-L1 expression: evidence from multi-omics analysis, clinical samples, and cellular functional assays.

Extracellular 5'-nucleotidase (NT5E/CD73) plays a pivotal role in the tumor immune microenvironment by catalysing the production of adenosine.

This study aims to evaluate the expression and function of NT5E in colorectal cancer progression, and to explore its potential as a novel biomarker and for associated immunotherapy. Genomic alterations, prognostic significance, and immune landscape of NT5E were analyzed using cBioPortal, Kaplan‑Meier Plotter, the cancer genome atlas(TCGA)and the Human Protein Atlas. Following siRNA‑mediated knockdown in HCT116 cells, proliferation, migration, and invasion were assessed. NT5E and PD‑L1 expression were examined in 40 paired colorectal cancer specimens by qRT‑PCR.

The regulatory relationship between PD‑L1 and NT5E was further validated in vitro. NT5E alterations were identified in 5.17% of CRC patients, primarily manifested as high mRNA expression and amplification. Elevated NT5E expression was significantly correlated with poorer overall survival and relapse‑free survival, particularly in patients with advanced stage, CMS1 (Consensus Molecular Subtypes 1), CMS4, and high microsatellite instability (MSI-H) subtypes. Gene set enrichment analysis revealed enrichment of purine metabolism, sphingolipid signaling, focal adhesion, and T cell receptor signaling pathways in NT5E‑high tumors.

NT5E expression was positively correlated with helper T cells, macrophages, and mast cells, while negatively correlated with NK CD56dim cells. A significant positive correlation was observed between NT5E and PD‑L1, HAVCR2, and TIGIT. In clinical specimens, NT5E was upregulated in 65% of colorectal cancer tissues and positively associated with lymph node metastasis and PD‑L1 expression. In vitro experiments demonstrated that NT5E knockdown suppressed the proliferation, migration, and invasion of colorectal cancer cells, and confirmed that PD‑L1 regulates NT5E expression in colon cancer cells.

NT5E accelerates disease progression by promoting malignant biological behaviors in colorectal cancer and synergistically shaping an immunosuppressive microenvironment with PD-L1. Its overexpression constitutes an independent adverse prognostic factor. This discovery offers novel insights for anti-PD-1/PD-L1 combination immunotherapy.