Background:Understanding how the tumor microenvironment is shaped by various factors is important for the development of new therapeutic strategies.Tumor cells often undergo spontaneous apoptotic cell death in tumor m...Background:Understanding how the tumor microenvironment is shaped by various factors is important for the development of new therapeutic strategies.Tumor cells often undergo spontaneous apoptotic cell death in tumor microen-vironment,these apoptotic cells are histologically co-localized with immunosup-pressive macrophages.However,the mechanism by which tumor cell apoptosis modulates macrophage polarization is not fully understood.In this study,we aimed to explore the tumor promoting effects of apoptotic tumor cells and the signal pathways involved.Methods:Apoptotic cells and macrophages in tumors were detected by immunohistochemical staining.Morphological analysis was performed with Giemsa staining.Lipids generated from apoptotic cells were detected by liq-uid chromatography-mass spectrometry.Phosphatidylserine-containing lipo-somes were prepared to mimic apoptotic cells.The expression of protein was determined by real-time PCR,immunohistochemistry enzyme-linked immunosorbent assay and Western blotting.Mouse malignant ascites and subcu-taneous tumor models were designed for in vivo analysis.Transgenic mice with specific genes knocked out and inhibitors specific to certain proteins were used for the mechanistic studies.Results:The location and the number of apoptotic cells were correlated with that of macrophages in several types of carcinomas.Phosphatidylserine,a lipid molecule generated in apoptotic cells,induced polarization and accumulation of M2-like macrophages in vivo and in vitro.Moreover,sustained administration of phosphoserine promoted tumor growth in the malignant ascites and subcuta-neous tumor models.Further analyses suggested that phosphoserine induced a M2-like phenotype in macrophages,which was related to the activation of phosphoserine receptors including T-cell immunoglobin mucin 4(TIM4)and the FAK-SRC-STAT3 signaling pathway as well as elevated the expression of the histone demethylase Jumonji domain-containing protein 3(JMJD3).Adminis-tration of specific inhibitors of these pathways could reduce tumor progression.Conclusions:This study suggest that apoptotic cell-generated phosphoserine might be a notable signal for immunosuppressive macrophages in tumors,and the related pathways might be potential therapeutic targets for cancer therapy.展开更多
基金NationalNatural Science Foundation of China:National Science Foundation for ExcellentYoung Scholars,Grant/Award Number:32122052NationalNatural Sci-ence Foundation of China:NationalNat-ural Science FoundationRegional Inno-vation and Development,Grant/Award Number:U19A2003NationalNatural Science Foundation ofChina:National Science Foundation forYoung Scholars,Grant/Award Number:81902662。
文摘Background:Understanding how the tumor microenvironment is shaped by various factors is important for the development of new therapeutic strategies.Tumor cells often undergo spontaneous apoptotic cell death in tumor microen-vironment,these apoptotic cells are histologically co-localized with immunosup-pressive macrophages.However,the mechanism by which tumor cell apoptosis modulates macrophage polarization is not fully understood.In this study,we aimed to explore the tumor promoting effects of apoptotic tumor cells and the signal pathways involved.Methods:Apoptotic cells and macrophages in tumors were detected by immunohistochemical staining.Morphological analysis was performed with Giemsa staining.Lipids generated from apoptotic cells were detected by liq-uid chromatography-mass spectrometry.Phosphatidylserine-containing lipo-somes were prepared to mimic apoptotic cells.The expression of protein was determined by real-time PCR,immunohistochemistry enzyme-linked immunosorbent assay and Western blotting.Mouse malignant ascites and subcu-taneous tumor models were designed for in vivo analysis.Transgenic mice with specific genes knocked out and inhibitors specific to certain proteins were used for the mechanistic studies.Results:The location and the number of apoptotic cells were correlated with that of macrophages in several types of carcinomas.Phosphatidylserine,a lipid molecule generated in apoptotic cells,induced polarization and accumulation of M2-like macrophages in vivo and in vitro.Moreover,sustained administration of phosphoserine promoted tumor growth in the malignant ascites and subcuta-neous tumor models.Further analyses suggested that phosphoserine induced a M2-like phenotype in macrophages,which was related to the activation of phosphoserine receptors including T-cell immunoglobin mucin 4(TIM4)and the FAK-SRC-STAT3 signaling pathway as well as elevated the expression of the histone demethylase Jumonji domain-containing protein 3(JMJD3).Adminis-tration of specific inhibitors of these pathways could reduce tumor progression.Conclusions:This study suggest that apoptotic cell-generated phosphoserine might be a notable signal for immunosuppressive macrophages in tumors,and the related pathways might be potential therapeutic targets for cancer therapy.
