Luteolin promotes macrophage-mediated phagocytosis by inhibiting CD47 pyroglutamation

Zhiqiang Li; Xuemei Gu; Danni Rao; Meiling Lu; Jing Wen; Xinyan Chen; Hongbing Wang; Xianghuan Cui; Wenwen Tang; Shilin Xu; Ping Wang; Lei Yu; Xin Ge

doi:10.1016/j.tranon.2021.101129

Luteolin promotes macrophage-mediated phagocytosis by inhibiting CD47 pyroglutamation

Transl Oncol. 2021 Aug;14(8):101129. doi: 10.1016/j.tranon.2021.101129. Epub 2021 May 26.

Authors

Zhiqiang Li¹, Xuemei Gu², Danni Rao³, Meiling Lu⁴, Jing Wen¹, Xinyan Chen⁵, Hongbing Wang⁵, Xianghuan Cui¹, Wenwen Tang¹, Shilin Xu³, Ping Wang⁶, Lei Yu⁷, Xin Ge⁸

Affiliations

¹ Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China.
² Shanghai Clinical Medical College, Anhui Medical University, Hefei 230031, China.
³ Department of Medicinal Chemistry, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China; University of Chinese Academy of Science, 19 Yuquan Road, Beijing 110039, China.
⁴ Department of Central Laboratory, Shanghai Tenth People's Hospital of Tongji University, School of Medicine, Tongji University, Shanghai 200092, China.
⁵ Putuo District People's Hospital, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
⁶ Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China; Shanghai Clinical Medical College, Anhui Medical University, Hefei 230031, China. Electronic address: wangp@tongji.edu.cn.
⁷ Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China. Electronic address: yulei31@tongji.edu.cn.
⁸ Department of Clinical Laboratory Medicine, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China. Electronic address: xin.ge@tongji.edu.cn.

Abstract

'Don't eat me' signal of CD47 is activated via its interaction with SIRPα protein on myeloid cells, especially phagocytic cells, and prevents malignant cells from anti-tumor immunity in which pyroglutamate modification of CD47 by glutaminyl-peptide cyclotransferase-like protein (isoQC) takes an important part evidenced by our previous report that isoQC is an essential regulator for CD47-SIRPα axis with a strong inhibition on macrophage-mediated phagoctyosis. Therefore, we screened for potential isoQC inhibitors by fluorescence-activated cell sorting assay and identified luteolin as a potent compound that blocked the pyroglutamation of CD47 by isoQC. We further demonstrated that luteolin directly bound to isoQC using pull-down assay and isothermal calorimetric (ITC) assay. In consistency, we showed that luteolin markedly abrogated the cell-surface interaction between CD47 and SIRPα in multiple myeloma H929 cells and consequently promoted the macrophage-mediated phagocytosis. Collectively, our study discovered a promising lead compound targeting isoQC, luteolin, which functions distinctly from current CD47 antibody-based drugs and therefore may potentially overcome the clinical side effects associated with CD47 antibody treatment-induced anemia.

Keywords: CD47-SIRPα; Luteolin; Phagocytosis; Tumor immunotherapy; isoQC.