Laboratory for Reproductive Immunology, Hospital of Obstetrics and Gynecology, Fudan University, Shanghai, People's Republic of China.
Medical Center of Diagnosis and Treatment for Cervical and Intrauterine Diseases, Obstetrics and Gynecology Hospital of Fudan University, Shanghai, People's Republic of China.
Am J Reprod Immunol. 2024 Aug;92(2):e13916. doi: 10.1111/aji.13916.
Uterine endometrial cancer (UEC) is a common gynecological estrogen-dependent carcinoma, usually accompanied by intermenstrual bleeding. Active heme metabolism frequently plays an increasingly important role in many diseases, especially in cancers. Tumor-associated macrophages (TAMs) are the major population in the immune microenvironment of UEC. However, the roles of heme metabolisms in the crosstalk between UEC cells (UECCs) and macrophages are unclear.
In our study, by using TCGA database analysis, integration analysis of the protein-protein interaction (PPI) network and sample RNA transcriptome sequencing were done. The expression level of both heme-associated molecules and iron metabolism-related molecules were measured by quantitative real-time polymerase chain reaction. Heme level detection was done through dehydrohorseradish peroxidase assay. In addition to immunohistochemistry, phagocytosis assay of macrophages, immunofluorescence staining, intracellular ferrous iron staining, as well as enzyme-linked immune sorbent assay were performed.
In the study, we verified that heme accumulation in UECCs is apparently higher than in endometrial epithelium cells. Low expression of succinate dehydrogenase B under the regulation of estrogen contributes to over-production of succinate and heme accumulation in UECC. More importantly, excessive heme in UECCs impaired macrophage phagocytosis by regulation of CD36. Mechanistically, this process is dependent on toll-like receptor (TLR4)/type I interferons alpha (IFN Iα) regulatory axis in macrophage.
Collectively, these findings elucidate that active heme metabolism of UECCs directly decreases phagocytosis by controlling the secretion of TLR4-mediated IFN Iα and the expression of CD36, and further contributing to the immune escape of UEC.
子宫内膜癌（Uterine Endometrial Cancer，UEC）是一种常见的妇科雌激素依赖性癌，通常伴有月经间期出血。活性血红素代谢在许多疾病中，尤其是癌症中，起着越来越重要的作用。肿瘤相关巨噬细胞（Tumor-Associated Macrophages，TAMs）是 UEC 免疫微环境中的主要群体。然而，血红素代谢在 UECC 细胞（Uterine Endometrial Cancer Cells，UECCs）与巨噬细胞之间的串扰中的作用尚不清楚。
在我们的研究中，通过使用 TCGA 数据库分析、蛋白质-蛋白质相互作用（Protein-Protein Interaction，PPI）网络的整合分析和样本 RNA 转录组测序，我们测量了血红素相关分子和铁代谢相关分子的表达水平。通过脱氢辣根过氧化物酶测定法检测血红素水平。除了免疫组织化学、巨噬细胞吞噬作用测定、免疫荧光染色、细胞内亚铁染色以及酶联免疫吸附测定外，我们还进行了这些实验。
在这项研究中，我们验证了 UECC 中的血红素积累明显高于子宫内膜上皮细胞。雌激素调节下的琥珀酸脱氢酶 B 低表达导致琥珀酸和血红素在 UECC 中的过度产生。更重要的是，UECC 中过多的血红素通过调节 CD36 损害了巨噬细胞的吞噬作用。从机制上讲，这个过程依赖于巨噬细胞中的 Toll 样受体（Toll-Like Receptor，TLR4）/I 型干扰素 α（Type I Interferons Alpha，IFN Iα）调节轴。
总之，这些发现阐明了 UECC 中活跃的血红素代谢通过控制 TLR4 介导的 IFN Iα和 CD36 的表达来直接降低吞噬作用，从而进一步促进 UEC 的免疫逃逸。
