Polarization of M1 tumor associated macrophage promoted by the activation of TLR3 signal pathway

Objective: To investigate the correlation between activation of toll-like receptors 3 (TLR3) signaling pathway and tumor-associated macrophage and its effect on the tumor growth. Methods: The mice Lewis lung cancer cell lines 3LL and melanoma B 16H10 were used to construct the subcutaneous transplantation tumor models and then they were treated with Poly-ICLC. The curative effect was observed and then the T cell and macrophage phenotypes infiltrated in local tumor were detected by flow cytometry. After the in vitro culture of mouse bone marrow-derived macrophage, the real-time PCR and western blot were applied to detect the expression of macrophage activation markers and the activation of intracellular signaling pathways. Results: The survival time of mice with brown tumor treated with Poly-ICLC significantly increased and the tumor growth was inhibited. The ratio of local tumor-infiltrated Treg decreased, while the ratio of CD8(+) T cell increased significantly. The macrophages surface CD206 expression was down-regulated while the expression of iNOS increased. The Poly-ICLC could promote the expression of Ml markers (IL-I (3, TNF-alpha and iNOS) in bone marrow-derived macrophage and inhibited the expression of M2 molecules (Arg-1, YM-1 and CD206). The phosphorylation level of downstream p65, TBK1 and IRF3 increased significantly. Conclusions: The Poly-ICLC can activate the TLR3 downstream signaling pathway to induce a M1 polarization of tumor associated macrophage, thereby inhibiting the tumor growth.