Tumoral NOX4 recruits M2 tumor-associated macrophages via ROS/PI3K signaling-dependent various cytokine production to promote NSCLC growth

M2-type tumor-associated macrophages (TAMs) infiltration contributes to cancer malignant progression. However, the mechanisms for controlling recruitment and M2 polarization of macrophages by cancer cells are largely unclear. NADPH oxidase 4 (NOX4) is abundantly expressed in non-small cell lung cancer (NSCLC) and mediates cancer progression. NOXs are in close relation with cancer-related inflammation, nevertheless, whether tumoral NOXs influence microenvironmental macrophages remains undentified. This study found that there was a close association between NOX4 expression and macrophage chemotaxis in patients with NSCLC analyzed using TCGA RNA-sequencing data. NOX4 in NSCLC cells (A549 and Calu-1 cell lines) efficiently enhanced murine peritoneal macrophage migration and induces M2 polarization. Immunohistochemical analysis of clinical specimens confirmed the positive correlation of NOX4 and CD68 or CD206. The mechanical study revealed that tumoral NOX4-induced reactive oxygen species (ROS) stimulated various cytokine production, including CCL7, IL8, CSF-1 and VEGF-C, via PI3K/Akt signaling-dependent manner. Blockade of the function of these cytokines reversed NOX4 effect on macrophages. Specifically, the results showed that tumoral NOX4-educated M2 macrophages exhibited elevated JNK activity, expressed and released HB-EGF, thus facilitating NSCLC proliferation in vitro. Pretreatment of macrophages with JNK inhibitor blocked tumoral NOX4-induced HB-EGF production in M2 macrophages. Finally, in a xenograft mouse model, overexpression of NOX4 in A549 cells enhanced the tumor growth. Elimination of ROS by NAC or inhibition of NOX4 activity by GKT137831 suppressed tumor growth accompanied by reduction in macrophage infiltration and the percentage of M2 macrophages. In conclusion, our study indicates that tumoral NOX4 recruits M2 TAMs via ROS/PI3K signaling-dependent various cytokine production, thus contributing NSCLC cell growth. Keywords: NOX4, Macrophages, NSCLC, M2 polarization, Chemotaxis