Molecular mechanisms by which tumor cell CD73-mediated adenosine signaling drives M2 polarization of macrophages in non-small cell lung cancer.

Background: Immune checkpoint inhibitors have improved outcomes for a subset of patients with non-small cell lung cancer (NSCLC), but the immunosuppressive tumor microenvironment (TME) limits their efficacy. Polarization of tumor-associated macrophages (TAMs) toward an M2 phenotype is a key feature of immune escape in NSCLC. Objective: Using the CD73 (NT5E)-mediated adenosine metabolic pathway as an entry point, to elucidate its role and molecular mechanisms in driving immunosuppressive TAM polarization in NSCLC. Methods: Using TCGA datasets and clinical tissue samples, we analyzed correlations between CD73 expression, macrophage infiltration, and patient prognosis. NSCLC cell lines were used to establish CD73 knockdown/overexpression and pharmacological inhibition models and to quantify extracellular adenosine generation. Tumor cell-conditioned media and Transwell co-culture systems were constructed to induce THP-1 macrophage polarization. Flow cytometry, qPCR, and ELISA were used to assess M1/M2 markers and cytokine profiles. Rescue experiments were performed by supplementing exogenous adenosine or 5'-N-ethylcarboxamidoadenosine (NECA), and adenosine dependence was validated using an A2A receptor antagonist together with downstream cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA)-cAMP response element-binding protein (CREB) signaling measurements. Results: TCGA-based and clinical-sample analyses suggested that high CD73 expression was associated with poorer prognosis and increased infiltration of M2-like macrophages. Conclusions: CD73-driven adenosine signaling promotes immunosuppressive M2 polarization of NSCLC-associated macrophages through the adenosine-A2A receptor (A2AR)-cAMP/PKA/CREB signaling axis, providing