Signal Transducer and Activator of Transcription6 Signaling Pathway in Tumor-Associated Macrophage Aggravates Lung Cancer Progression

Abstract

Lung cancer is a most common cancer worldwide. Tumor-associated macrophage (TAM) is known a key effector cell in tumor microenvironment. Meanwhile, STAT6 is crucial to cancer development. We aimed to determine the interaction between STAT6 and TAMs in lung cancer. In this work, firstly, we established mouse model of lung cancer. Then, immunofluorescence was performed to determine STAT6 and CD206 level in lung cancer tissue and adjacent normal tissues as well as model mice. RT-qPCR was applied to detect differentiation of macrophage and determine related gene expression. After treatment of siRNA of STAT6 or STAT6 inhibitor (AS1517499), Transwell assay and MTT were used to determine cell proliferation and migration. STAT6 was upregulated in lung cancer tissues while arginase was more active in M2 macrophage rather than M1 macrophage. Transfection of si-STAT6 not only decreased differentiation in M2 macrophage but also inhibited proliferative, migratory and invasive ability of cancer cells while AS1517499 led to reduced tumor growth. STAT6 inhibition caused decreased expression of M2 macrophages. Similarly, intratumoral T cell markers showed that CD8+T cell gene expression and CD4-mediated T cell marker FoxP3 was increased slightly. Taken altogether, macrophage-STAT6 promotes cell migration and proliferation in lung cancer.