Atractylenolide II inhibits tumor-associated macrophages (TAMs)-induced lung cancer cell metastasis

M2-like tumor-associated macrophages (TAMs) play a crucial role in promoting tumor proliferation, angiogenesis, and metastasis. In the current study, we investigated the relationship between macrophage polarization and the antitumor effect of Atractylenolide II (AT-II) in lung cancer cells.Cell viability, migration, and invasion were determined by MTT assay, wound healing assay, and transwell assay, respectively. Flow cytometry analysis showed the percentage of CD206+ cells. Gene expression was determined by real-time PCR, western blotting, and immunofluorescence staining. Lewis lung carcinoma mouse xenograft and metastasis models were used to examine the effects of AT-II on lung cancer in vivo.AT-II (2.5 and 5 µM) did not cause significant inhibition of A549 cell viability but markedly inhibited IL-4/IL-13-induced M2-like polarization, evidenced by the decreased expression of the M2 surface marker CD206, down-regulation of specific M2-marker genes (Arg-1, IL-10 and TGF-β) as well as inhibition of M2 macrophages-mediated invasion and migration of A549 cells. In addition, AT-II inhibited IL-4/IL-13-induced activation of the STAT6 signaling pathway that is vital in the M2-like polarization of macrophages. In animal models, administration of AT-II (50 mg kg-1, i.g., QD for 21 days) significantly inhibited tumor growth, reduced pulmonary metastatic nodules, and down-regulated the percentages of M2 macrophages (F4/80+ and CD206+) in total macrophages (F4/80+) in tumor tissues and pulmonary metastatic nodules.AT-II effectively inhibits M2-like polarization, thereby inhibiting lung cancer cell metastasis both in vivo and in vitro, revealing a novel potential strategy for the antitumor effect of AT-II.