lnc-MRGPRF-6:1 Promotes ox-LDL-Induced Macrophage Ferroptosis via Suppressing GPX4.

Background: Ferroptosis, a newly discovered mode of cell death, emerges as a new target for atherosclerosis (AS). Long noncoding RNAs (lncRNAs) are involved in the regulation of ferroptosis. In our previous study, lnc-MRGPRF-6:1 was highly expressed in patients with coronary atherosclerotic disease (CAD) and closely associated with macrophage-mediated inflammation in AS. In the present study, we aim to investigate the role of lnc-MRGPRF-6:1 in oxidized-low-density lipoprotein (ox-LDL)-induced macrophage ferroptosis in AS. Methods: Firstly, ox-LDL-treated macrophages were used to simulate macrophage injury in AS. Then, ferroptosis-related biomarkers and mitochondrial morphology were detected and observed in ox-LDL-treated macrophages. Subsequently, we constructed lnc-MRGPRF-6:1 knockdown and overexpression of THP-1-derived macrophages and investigated the role of lnc-MRGPRF-6:1 in ox-LDL-induced ferroptosis. Then human monocytes were isolated successfully and were used to explore the role of lnc-MRGPRF-6:1 in macrophage ferroptosis. Likely, we constructed lnc-MRGPRF-6:1 knockdown and overexpression of human monocyte-derived macrophages and detected the expression levels of ferroptosis-related biomarkers. Then, transcriptome sequencing, literature searching, and following quantitative real-time polymerase chain reaction and western blot were implemented to explore specific signaling pathway in the process. It was demonstrated that lnc-MRGPRF-6:1 may regulate ox-LDL-induced macrophage ferroptosis through glutathione peroxidase 4 (GPX4). Eventually, the correlation between lnc-MRGPRF-6:1 and GPX4 was measured in monocyte-derived macrophages of CAD patients and controls. Results: The ox-LDL-induced injury in macrophages was involved in ferroptosis. The knockdown of lnc-MRGPRF-6:1 could alleviate ox-LDL-induced ferroptosis in macrophages. Meanwhile, the overexpression of lnc-MRGPRF-6:1 could intensify ox-LDL-induced ferroptosis. Furthermore, the knockdown of lnc-MRGPRF-6:1 could alleviate the decrease of GPX4 induced by RAS-selective lethal compounds 3 (RSL-3). These indicated that lnc-MRGPRF-6:1 may suppress GPX4 to induce macrophage ferroptosis. Eventually, lnc-MRGPRF-6:1 was highly expressed in the monocyte-derived macrophages of CAD patients and was negatively correlated with the expression of GPX4. Conclusion: lnc-MRGPRF-6:1 can promote ox-LDL-induced macrophage ferroptosis through inhibiting GPX4.

Targeting Ferroptosis in Colorectal Cancer.

Ferroptosis is a unique way of regulating cell death (RCD), which is quite different from other programmed cell deaths such as autophagy. It presents iron overload, accumulation of reactive oxygen species (ROS), and lipid peroxidation. A ferroptotic cell usually has an intact cell structure as well as shrinking mitochondria with decreased or vanishing cristae, concentrated membrane density, and ruptured outer membrane. Recently, increasing investigations have discovered that tumor cells have a much greater iron demand than the normal ones, making them more sensitive to ferroptosis. In other words, ferroptosis may inhibit the progress of the tumor, which can be used in the therapy of tumor patients, especially for those with chemotherapy resistance. Therefore, ferroptosis has become one hot spot in the field of tumor research in recent years. Colorectal cancer (CRC) is one common type of gastrointestinal malignancy. The incidence of CRC appears to have an upward trend year by year since the enhancement of living standards. Although surgery and chemoradiotherapy have largely improved the prognosis of patients with CRC, some patients still appear to have severe adverse reactions and drug resistance. Moreover, much research has verified that ferroptosis has a necessary association with the occurrence and progression of gastrointestinal tumors. In this review, we provide a comprehensive evaluation of the main mechanisms of iron metabolism, lipid metabolism, and amino acid metabolism involved in the occurrence of ferroptosis, as well as the research progress of ferroptosis in CRC.

lnc-MRGPRF-6:1 Promotes M1 Polarization of Macrophage and Inflammatory Response through the TLR4-MyD88-MAPK Pathway.

BACKGROUND: Macrophage-mediated inflammation plays an essential role in the development of atherosclerosis (AS). Long noncoding RNAs (lncRNAs), as crucial regulators, participate in this process. We identified that lnc-MRGPRF-6:1 was significantly upregulated in the plasma exosomes of coronary atherosclerotic disease (CAD) patients in a preliminary work. In the present study, we aim to assess the role of lnc-MRGPRF-6:1 in macrophage-mediated inflammatory process of AS. METHODS: The correlation between lnc-MRGPRF-6:1 and inflammatory factors was estimated firstly in plasma exosomes of CAD patients. Subsequently, we established lnc-MRGPRF-6:1 knockout macrophage model via the CRISPR/Cas9 system. We then investigated the regulatory effects of lnc-MRGPRF-6:1 on macrophage polarization and foam cell formation. Eventually, transcriptome analysis by RNA sequencing was carried out to explore the contribution of differential genes and signaling pathways in this process. RESULTS: lnc-MRGPRF-6:1 was highly expressed in the plasma exosomes of CAD patients and was positively correlated with the expression of inflammatory cytokines in plasma. lnc-MRGPRF-6:1 inhibition significantly reduced the formation of foam cells. The expression of lnc-MRGPRF-6:1 was upregulated in M1 macrophage, and lnc-MRGPRF-6:1 knockout decreased the polarization of M1 macrophage. lnc-MRGPRF-6:1 regulates macrophage polarization via the TLR4-MyD88-MAPK signaling pathway. CONCLUSIONS: lnc-MRGPRF-6:1 knockdown can inhibit M1 polarization of macrophage and inflammatory response through the TLR4-MyD88-MAPK signaling pathway. lnc-MRGPRF-6:1 is a vital regulator in macrophage-mediated inflammatory process of AS.