RUNX1 promotes NSCLC progression by ACP5/SMAD3-mediated M2 macrophage polarization

Regarding the participation of RUNX1 in lung cancer, we investigated its mechanism in regulating M2 polarization of tumor-associated macrophages in lung cancer.

The extracted bone marrow cells were differentiated into macrophages (BMDMs), followed by tumor-conditioned medium (CM) stimulation to simulate the impact of tumor cells on macrophages in vivo, and treatment with RUNX1 shRNA, or pCDNA3.1-ACP5 and SIS3. Macrophage polarization and cytokine secretion were assessed by flow cytometry and ELISA, followed by evaluations of RUNX1, ACP5, p-β-catenin, β-catenin and p-SMAD3 levels. The ACP5-β-catenin interaction was detected by Co-IP. BMDMs were co-cultured with Lewis lung carcinoma cells using Transwell. The malignant behaviors of cells were assessed by CCK-8 and Transwell assays. In vivo experiments were conducted to verify roles of RUNX1.

Tumor-CM stimulated BMDM M2 polarization. RUNX1 was up-regulated in tumor-CM-stimulated macrophages and M2-type BMDMs, and was poorly expressed in M1-type BMDMs. RUNX1 knockdown induced M1 marker expression and reduced M2 marker expression, and repressed non-small cell lung cancer (NSCLC) cell malignant behaviors. The effects of RUNX1 silencing were partly abrogated by ACP5 overexpression. ACP5 interacted with β-catenin to promote SMAD3 phosphorylation. Downregulation of SMAD3 phosphorylation partially reversed tumor-CM-promoted BMDM M2 polarization and NSCLC cell malignant behaviors. RUNX1 promoted M2 polarization and NSCLC cell malignant behaviors by promoting ACP5-mediated SMAD3 phosphorylation. RUNX1 knockdown inhibited M2 polarization in LLC mice to suppress tumor growth in vivo.

RUNX1 promoted BMDM M2 polarization by facilitating the interaction between ACP5 and β-catenin to elevate SMAD3 phosphorylation, thus promoting NSCLC progression.