Signal regulatory protein α associated with the progression of oral leukoplakia and oral squamous cell carcinoma regulates phenotype switch of macrophages

// Xiaojing Ye 1 , Jing Zhang 1, 2 , Rui Lu 1, 2 , Gang Zhou 1, 2 1 The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, P.R. China 2 Department of Oral Medicine, School and Hospital of Stomatology, Wuhan University, Wuhan, P.R. China Correspondence to: Gang Zhou, email: gordonzhou@tom.com Keywords: signal regulatory protein α, macrophage, oral leukoplakia, oral squamous cell carcinoma Received: May 29, 2016      Accepted: September 24, 2016      Published: October 25, 2016 ABSTRACT Signal regulatory protein α (SIRPα) is a cell-surface protein expressed on macrophages that are reg arded as an important component of the tumor microenvironment. The expression of SIRPα in oral leukoplakia (OLK) and oral squamous cell carcinoma (OSCC), and further explored the role of SIRPα on the phenotype, phagocytosis ability, migration, and invasion of macrophages in OSCC were investigated. The expression of SIRPα in OLK was higher than in OSCC, correlating with the expression of CD68 and CD163 on macrophages. After cultured with the conditioned media of oral cancer cells, the expression of SIRPα on THP-1 cells was decreased gradually. In co-culture system, macrophages were induced into M2 phenotype by oral cancer cells. Blockade of SIRPα inhibited phagocytosis ability and IL-6, TNF-α productions of macrophages. In addition, the proliferation, migration, and IL-10, TGF-β productions of macrophages were upregulated after blockade of SIRPα. Macrophages upregulated the expression of SIRPα and phagocytosis ability, and inhibited the migration and invasion when the activation of NF-κB was inhibited by pyrrolidine dithiocarbamate ammonium (PDTC). Hence, SIRPα might play an important role in the progression of OLK and oral cancer, and could be a pivotal therapeutic target in OSCC by regulating the phenotype of macrophages via targeting NF-κB.