Targeting CD36 Research Articles

MiR-1268a Regulates Fatty Acid Metabolism by Targeting CD36 in Angiotensin II-induced Heart Failure.

Multiple RNAs have been involved in the progress of heart failure. However, the role of miR-1268a in heart failure is still unclear. The differentially expressed miRNAs in heart failure was analyzed based on GEO dataset GSE104150. AC16 cells were treated with Angiotensin II (Ang II) to explore the role of miR-1268a in heart failure. The web tool miRWalk was used to analyze the targets of miR-1268a. miR-1268a was up-regulated in Ang II-treated AC16 cells. Ang II treatment markedly inhibited cell proliferation, ATP production, fatty acid (FA) uptake and enhanced levels of HF markers BNP and ST2, and oxidative stress of AC16 cells. Notably, inhibition of miR-1268a eliminated the inhibiting effect of Ang II on cell proliferation, ATP production, FA uptake and decreased levels of BNP an ST2, and oxidative stress on AC16 cells. Furthermore, CD36 was a target of miR-1268a and the CD36 level was decreased by miR-1268a mimics but increased by miR-1268a inhibitor in AC16 cells. miR-1268a regulates FA metabolism and oxidative stress in myocardial cells by targeting CD36 in heart failure.

Macrophage expressed CD36 promotes plaque vulnerability in atherosclerosis

Abstract Background Atherosclerosis is characterised by a chronic lipid-driven inflammation that accounts for the majority of deaths worldwide. CD36 is an immunoregulatory scavenger receptor at the interface of lipid metabolism and inflammation that is critically involved in atherogenesis. However, due to the lack of cell-specific in vivo models the exact role of CD36 on macrophages in atherosclerosis remains unknown to date. Purpose Here we aimed to evaluate the role of macrophage expressed CD36 in atherogenesis. Approach & Results: To screen for a potential role of macrophage expressed CD36 in atherosclerosis we assessed CD36 gene expression across different leukocyte populations in single-cell-RNA Sequencing (scRNAseq) data from atherosclerotic LDLR-/- mice. Here, we identified macrophages as the main CD36 expressing cell type. In line, CD36 protein expression in aortic cell suspensions from LDLR-/- mice was significantly higher in macrophages compared to B and T cells as assessed by flow cytometry. To assess the role of macrophage expressed CD36 in atherogenesis, we generated macrophage specific CD36 deficient mice on an atherosclerotic prone LDLR deficient (LDLR-/-) background. CD36fl/fl-CXC3R1Cre LDLR-/- mice (termed iMΦ-CD36) and CD36fl/fl-CXC3R1Wt LDLR-/- controls (termed CD36fl/fl) were injected with tamoxifen for 5 consecutive days and placed on a high cholesterol diet for 16 weeks to induce atherogenesis. At harvest the aortic root was obtained from whole heart, embedded in OCT, cut and stained with Oil Red O staining for histological analyses of atherosclerotic lesions. Macrophages were differentiated from isolated bone marrow cells for in vitro assessment of ROS production and oxLDL uptake. Notably, Macrophage-specific CD36 deficiency did not affect atherosclerotic lesion size but substantially reduced the necrotic core area indicating ameliorated plaque vulnerability. In vitro, macrophage CD36 deficiency ameliorated ROS production and facilitated oxLDL uptake. Further, macrophage-specific CD36 deficiency reduced circulating MCP-1 levels. To interrogate a potential role of CD36 in human atherosclerosis, human atherosclerotic plaques were studies by scRNAseq. Similar to our observations in mice, cellular CD36 expression was highest in human macrophages/monocytes. Further pathway analysis revealed that CD36-expressing macrophages exhibited a significantly more pro-inflammatory gene signature than CD36-negative macrophages. Down this line, CD36 expression was significantly higher in unstable carotid plaques compared to stable lesions indicating that CD36 expression correlates with plaque vulnerability in humans. Conclusion All in all, our data indicates a pro-inflammatory role of macrophage expressed CD36 in murine and human atherosclerosis. These findings suggest that targeting CD36 on macrophages may represent a potential target for anti-atherosclerotic therapy.

Abstract 17224: Macrophage Expressed CD36 Promotes Plaque Vulnerability in Atherosclerosis

Introduction: Atherosclerosis is characterised by a chronic lipid-driven inflammation that accounts for the majority of deaths worldwide. CD36 is an immunoregulatory scavenger receptor at the interface of lipid metabolism and inflammation that is critically involved in atherogenesis. However, due to the lack of cell-specific animal models the exact role of CD36 on macrophages in atherosclerosis remains unknown to date. Research Question: Here, we aimed to study the role of macrophage expressed CD36 in atherogenesis. Methods: To screen for a potential role of macrophage expressed CD36 in atherosclerosis we assessed CD36 gene expression across different leukocyte populations in scRNAseq data from atherosclerotic LDLR-/- mice. To evaluate the role of macrophage expressed CD36 in atherogenesis, we generated tamoxifen inducible macrophage (CX3CR1)-specific CD36-deficient mice on a LDLR-/- background. To interrogate a potential role of CD36 in human atherosclerosis, human atherosclerotic plaques were studied by scRNAseq. Results: Analysis of murine scRNAseq data identified macrophages as the main CD36 expressing cell type. In line, CD36 protein expression in aortic cell suspensions from LDLR-/- mice was significantly higher in macrophages compared to B and T cells as assessed by flow cytometry. Notably, macrophage-specific CD36 deficiency substantially reduced lesional necrotic core area after 16 weeks of high cholesterol diet feeding indicating ameliorated plaque vulnerability. In vitro, macrophage-specific CD36 deficiency reduced ROS production and oxLDL uptake. Similar to our observations in mice, cellular CD36 expression was highest in human macrophages/monocytes. Pathway analysis revealed that CD36-expressing macrophages exhibited a more pro-inflammatory gene signature than CD36-negative macrophages. Finally, unstable carotid plaques displayed a significantly higher CD36 expression compared to stable lesions. Conclusion: All in all, our data indicates a pro-inflammatory role of macrophage expressed CD36 in murine and human atherosclerosis. These findings suggest that targeting CD36 on macrophages may represent a potential target for anti-atherosclerotic therapy.

Targeting neoadjuvant chemotherapy-induced metabolic reprogramming in pancreatic cancer promotes anti-tumor immunity and chemo-response

The molecular dynamics of pancreatic ductal adenocarcinoma (PDAC) under chemotherapy remain incompletely understood. The widespread use of neoadjuvant chemotherapy (NAC) provides a unique opportunity to investigate PDAC samples post-chemotherapy. Leveraging a cohort from Fudan University Shanghai Cancer Center, encompassing PDAC samples with and without exposure to neoadjuvant albumin-bound paclitaxel and gemcitabine (AG), we have compiled data from single-cell and spatial transcriptomes, proteomes, bulk transcriptomes, and metabolomes, deepening our comprehension of the molecular changes in PDACs in response to chemotherapy. Metabolic flux analysis reveals that NAC induces a reprogramming of PDAC metabolic patterns and enhances immunogenicity. Notably, NAC leads to the downregulation of glycolysis and the upregulation of CD36. Tissue microarray analysis demonstrates that high CD36 expression is linked to poorer survival in patients receiving postoperative AG. Targeting CD36 synergistically improves the PDAC response to AG both invitro and invivo, including patient-derived preclinical models.

Molecular Drug Simulation and Experimental Validation of the CD36 Receptor Competitively Binding to Long-Chain Fatty Acids by 7-Ketocholesteryl-9-carboxynonanoate.

Long-chain fatty acids (LCFAs) are one of the main energy-supplying substances in the body. LCFAs with different lengths and saturations may have contrasting biological effects that exacerbate or alleviate progress against a variety of systemic disorders of lipid metabolism in organisms. Nonalcoholic fatty liver disease is characterized by chronic inflammation and steatosis, mainly caused by the ectopic accumulation of lipids in the liver, especially LCFAs. CD36 is a scavenger receptor that recognizes and mediates the transmembrane absorption of LCFAs and is expressed in a variety of cells throughout the body. In previous studies, our group found that 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) has the biological effect of targeting CD36 to inhibit oxidized low-density lipoprotein lipotoxicity-induced lipid metabolism disorder; it has an ω-carboxyl physiologically active center and is structurally similar to LCFAs. However, the biological mechanism of oxLig-1 binding to CD36 and competing for binding to different types of LCFAs is still not clear. In this study, molecular docking and molecular dynamics simulation were utilized to simulate and analyze the binding activity between oxLig-1 and different types of LCFAs to CD36 and confirmed by the enzyme-linked immunosorbent assay (ELISA) method. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) platform was applied to predict the drug-forming properties of oxLig-1, and HepG2 cells model of oleic acid and nonalcoholic fatty liver disease (NAFLD) model mice were validated to verify the biological protection of oxLig-1 on lipid lowering. The results showed that there was a co-binding site of LCFAs and oxLig-1 on CD36, and the binding driving forces were mainly hydrogen bonding and hydrophobic interactions. The binding abilities of polyunsaturated LCFAs, oxLig-1, monounsaturated LCFAs, and saturated LCFAs to CD36 showed a decreasing trend in this order. There was a similar decreasing trend in the stability of the molecular dynamics simulation. ELISA results similarly confirmed that the binding activity of oxLig-1 to CD36 was significantly higher than that of typical monounsaturated and saturated LCFAs. ADMET prediction results indicated that oxLig-1 had a good drug-forming property. HepG2 cells model of oleic acid and NAFLD model mice study results demonstrated the favorable lipid-lowering biological effects of oxLig-1. Therefore, oxLig-1 may have a protective effect by targeting CD36 to inhibit the excessive influx and deposition of lipotoxicity monounsaturated LCFAs and saturated LCFAs in hepatocytes.

Targeting CD36 determines nicotine derivative NNK-induced lung adenocarcinoma carcinogenesis

Smoking carcinogen nicotine-derived nitrosamine ketone (NNK) is the most potent contributor to lung adenocarcinoma (LUAD) development, but the mechanism has not been fully elucidated. Here, we reported that fatty acid translocase CD36 was significantly overexpressed in both human LUAD tissues and NNK-induced A/J mice LUAD tumors. The overexpressed CD36 was positively correlated with Src kinase activation, smoking status, metastasis, and worse overall survival of patients with smoking history. Upon NNK binding with α7 nicotinic acetylcholine receptor (α7nAChR), sarcolemmal CD36 was increased and it interacted with surface α7nAChR and cytosol Src simultaneously, which in turn activated Src and downstream pro-carcinogenic kinase ERK1/2 and Akt, and finally caused LUAD cells to form subcutaneous and pulmonary metastatic tumors. This process could be blocked by CD36 knockdown and CD36 irreversible inhibitor SSO. Furthermore, the effect of NNK was inhibited obviously in CD36-/- A/J mice. Thus, targeting CD36 may provide a breakthrough therapy of LUAD.

The Role of CD36 in Cancer Progression and Its Value as a Therapeutic Target.

Cluster of differentiation 36 (CD36) is a cell surface scavenger receptor that plays critical roles in many different types of cancer, notably breast, brain, and ovarian cancers. While it is arguably most well-known for its fatty acid uptake functions, it is also involved in regulating cellular adhesion, immune response, and apoptosis depending on the cellular and environmental contexts. Here, we discuss the multifaceted role of CD36 in cancer biology, such as its role in mediating metastasis, drug resistance, and immune evasion to showcase its potential as a therapeutic target. We will also review existing approaches to targeting CD36 in pre-clinical studies, as well as discuss the only CD36-targeting drug to advance to late-stage clinical trials, VT1021. Given the roles of CD36 in the etiology of metabolic disorders, such as atherosclerosis, diabetes, and non-alcoholic fatty liver disease, the clinical implications of CD36-targeted therapy are wide-reaching, even beyond cancer.

Hepatocyte CD36 modulates UBQLN1-mediated proteasomal degradation of autophagic SNARE proteins contributing to septic liver injury

ABSTRACT Macroautophagy/autophagy plays a protective role in sepsis-induced liver injury. As a member of class B scavenger receptors, CD36 plays important roles in various disorders, such as atherosclerosis and fatty liver disease. Here we found that the expression of CD36 in hepatocytes was increased in patients and a mouse model with sepsis, accompanied by impaired autophagy flux. Furthermore, hepatocyte cd36 knockout (cd36-HKO) markedly improved liver injury and the impairment of autophagosome-lysosome fusion in lipopolysaccharide (LPS)-induced septic mice. Ubqln1 (ubiquilin 1) overexpression (OE) in hepatocyte blocked the protective effect of cd36-HKO on LPS-induced liver injury in mice. Mechanistically, with LPS stimulation, CD36 on the plasma membrane was depalmitoylated and distributed to the lysosome, where CD36 acted as a bridge molecule linking UBQLN1 to soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and hence promoting the proteasomal degradation of SNARE proteins, resulting in fusion impairment. Overall, our data reveal that CD36 is essential for modulating the proteasomal degradation of autophagic SNARE proteins in a UBQLN1-dependent manner. Targeting CD36 in hepatocytes is effective for improving autophagic flux in sepsis and therefore represents a promising therapeutic strategy for clinical treatment of septic liver injury. Abbreviations: AAV8: adeno-associated virus 8; AOSC: acute obstructive suppurative cholangitis; ATP1A1: ATPase, Na+/K+ transporting, alpha 1 polypeptide; CASP3: caspase 3; CASP8: caspase 8; CCL2: chemokine (C-C motif) ligand 2; cd36-HKO: hepatocyte-specific cd36 knockout; Co-IP: co-immunoprecipitation; CQ: chloroquine; Cys: cysteine; GOT1: glutamic-oxaloacetic transaminase 1, soluble; GPT: glutamic–pyruvic transaminase, soluble; IL1B: interleukin 1 beta; IL6: interleukin 6; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LDH, lactate dehydrogenase; LPS: lipopolysaccharide; LYPLA1: lysophospholipase 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; OE: overexpression; qPCR: quantitative polymerase chain reaction; SNAP29: synaptosome associated protein 29; SNARE: soluble N-ethylmaleimide-sensitive factor attachment protein receptor; SQSTM1/p62: sequestosome 1; STX17: syntaxin 17; TNF: tumor necrosis factor; TRIM: tripartite motif-containing; UBA: ubiquitin-associated; UBL: ubiquitin-like; UBQLN: ubiquilin; VAMP8: vesicle associated membrane protein 8; WT: wild-type.

Humanized CD36 (hCD36) mouse model supports the preclinical evaluation of therapeutic candidates targeting CD36.

CD36 (also known as scavenger receptor B2) is a multifunctional receptor that mediates lipid uptake, advanced oxidation protein products, and immunological recognition, and has roles in lipid accumulation, apoptosis, as well as in metastatic colonization in cancer. CD36 is involved in tumor immunity, metastatic invasion, and therapy resistance through various molecular mechanisms. Targeting CD36 has emerged as an effective strategy for tumor immunotherapy. In this study, we have successfully generated a novel hCD36 mouse (Unless otherwise stated, hCD36 mouse below refer to homozygous hCD36 mouse) strain where the sequences encoding the extracellular domains of the mouse Cd36 gene were replaced with the corresponding human sequences. The results showed that the hCD36 mice only expressed human CD36, and the proportion of each lymphocyte was not significantly changed compared with wild-type mice. Furthermore, CD36 monoclonal antibody could significantly inhibit tumor growth after treatment. Therefore, the hCD36 mouse represent a validated preclinical mouse model for the evaluation of tumor immunotherapy targeting CD36.

CD36-mediated metabolic crosstalk between tumor cells and macrophages affects liver metastasis

Liver metastasis is highly aggressive and treatment-refractory, partly due to macrophage-mediated immune suppression. Understanding the mechanisms leading to functional reprogramming of macrophages in the tumor microenvironment (TME) will benefit cancer immunotherapy. Herein, we find that the scavenger receptor CD36 is upregulated in metastasis-associated macrophages (MAMs) and deletion of CD36 in MAMs attenuates liver metastasis in mice. MAMs contain more lipid droplets and have the unique capability in engulfing tumor cell-derived long-chain fatty acids, which are carried by extracellular vesicles. The lipid-enriched vesicles are preferentially partitioned into macrophages via CD36, that fuel macrophages and trigger their tumor-promoting activities. In patients with liver metastases, high expression of CD36 correlates with protumoral M2-type MAMs infiltration, creating a highly immunosuppressive TME. Collectively, our findings uncover a mechanism by which tumor cells metabolically interact with macrophages in TME, and suggest a therapeutic potential of targeting CD36 as immunotherapy for liver metastasis.

CD36: an emerging therapeutic target for cancer and its molecular mechanisms.

Tumor cells need to rewire their metabolic pathways to regulate the nutrient uptake and metabolism to sustain the energy production. Lipids are important components of energy sources for tumor metabolism. Tumor cells rely on various transporters to mediate the trafficking of lipids for oxidation or activate oncogenic signaling pathways. CD36, a membrane glycoprotein presenting on the surface of cells, binds fatty acids to facilitate their transport for lipid utilization. Upregulated CD36 expression has been observed in multiple cancer types including acute myeloid leukemia, breast cancer, colorectal cancer, gastric cancer, etc. Moreover, CD36 is correlated with poor clinical outcomes and adverse clinicopathological features in various cancer types. In vitro and vivo studies have confirmed that CD36 participates in the regulation of tumor growth, metastasis, drug resistance through diverse molecular mechanisms. Thus, we firstly discussed the role of CD36 in the regulation of metabolic phenotypes, especially in glucose and fatty acid metabolism. Furthermore, we specifically focused on the molecular mechanisms of CD36 in the occurrence and development of multiple tumor types. Collectively, we explored the connection between CD36 and tumors, providing new insights for developing potential therapeutic strategies and tumor stratification targeting CD36.

Myocardial lipid metabolism Targeting CD36 to treat cardiac disease

Myocardial lipid metabolism Targeting CD36 to treat cardiac disease

Abstract P263: Interaction between CD36 and FABP4 regulates the import and metabolism of fatty acid in breast cancer cells

Abstract The breast cancer microenvironment is unique since the breast tissue within which the tumour originates comprises predominantly adipocytes. Adipocytes secrete various growth factors and cytokines that are reported to influence tumour progression by induction of epithelial-mesenchymal transition (EMT) which enhances cancer cell migration, invasion, and metastasis. Immunohistochemical analysis reveals that the invading breast cancer invades surrounding adipose tissues resulting in the delipidation of adipose tissues. To determine the molecular mechanism underlying these events, we co-cultured human adipocytes and breast cancer cells. Co-cultured cells had increased CD36 expression, with fatty acid import. Genetic ablation of CD36 attenuates adipocyte-induced EMT and stemness. Molecular screening for pathways potentially involved in adipocyte-induced CD36 expression reveals activation of the STAT3 signaling axis. Our study identifies a feedforward loop between CD36 and STAT3; where STAT3 binds to the CD36 promoter, activating its expression and CD36 upregulates STAT3 signaling. Breast cancer cells co-cultured with adipocytes actively accumulate fatty acids and undergo metabolic reprogramming, with a shift towards fatty acid oxidation. Seahorse metabolic analysis reveals that co-cultured CD36-expressing cells assumed an energetic phenotype, indicating enhanced mitochondrial respiration. Thus, breast cancer cells alter their metabolic programs, with increased mitochondrial respiration, to meet their energy needs, with the availability of fatty acids. Analysis of breast cancer patient data reveals that increased CD36 expression occurs with increased FABP4 expression. Mechanistic experiments reveal that CD36 directly interacts with FABP4 to regulate fatty acid import, transport, and metabolism in co-cultured breast cancer cells. In vivo studies in mouse models reveal that combined chemical inhibition of CD36 and FABP4 resulted in a significant reduction in tumour growth rate. The study presents an alternative approach by which adipocytes may enhance cancer progression via the transfer of free fatty acids from tumour-associated adipocytes to breast cancer cells. The uptake of free fatty acid subsequently serves as a secondary source of energy to drive breast cancer cell progression. Targeting CD36 in combination with FABP4 may have a potential for therapies targeting the breast cancer microenvironment. Citation Format: Jones Gyamfi, Junjeong Choi, Doru Kwon, JaSeung Koo. Interaction between CD36 and FABP4 regulates the import and metabolism of fatty acid in breast cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P263.

Gene Expression Patterns and Functional Characterization of CD36 in Normal Hematopoietic Cells

Metabolic reprogramming is a hallmark of cancer development and progression. Lipid metabolism is among the most deregulated metabolic pathways in cancer contributing to cell survival and invasion. The fatty acid translocase CD36 has attracted attention in cancer research in recent years due to its role in fatty acid transport as a scavenger receptor. We have recently reported that upregulated APOC2 cooperates with CD36 contributing to leukemia growth by promoting the LYN-ERK signaling mediated metabolic activities of acute myeloid leukemia (AML) cells. Consistently, the knockdown of CD36 or treatment with anti-CD36 antibody reduced the leukemia progression and promoted the overall survival of AML xenograft mice. CD36 is also present on various types of normal cells, including monocytes, macrophages, endothelial cells, adipocytes, and platelets and contribute to their normal functions. Thus, whether targeting CD36 in normal hematopoietic cells poses any toxicity warrants investigation to bring the therapeutic strategy of targeting CD36 in AML to maturity. Here, we leveraged public data to assess the expression patterns of CD36 in normal hematopoietic cells. We found that CD36 expression is several folds higher in dendritic cells, monocytes, and NK cells compared with B cells, eosinophils, neutrophils, and T cells (ANOVA P < 0.001). To investigate the role of Cd36 in normal hematopoietic cells, we carried out gain- and loss-of-function approaches in murine normal hematopoietic primary cells. We engineered a tet-on inducible shRNA lentiviral plasmid targeting two different sequences of the mouse Cd36. In both healthy mouse primary spleen and bone marrow cells, the two pairs of shRNAs reduced the Cd36 mRNA levels compared with scramble control group (~70-90% reduction in mRNA expression). We also engineered two different lentivirus ectopic expression plasmid to overexpress murine Cd36 (PLVX-Cd36 virus and PCDH-Cd36). Lentiviral transduction of both spleen and bone marrow mouse cells confirmed by microscopy visualization of GFP-expressing cells showed several folds increase in Cd36 expression for both plasmids measured by qPCR and western blot. We assessed the effect of Cd36 knockdown on the expansion of spleen and bone marrow hematopoietic cells over five days of cell culture. Relative to the 1 st day of cell count, there was no significant decrease in the mean bone marrow cell and spleen count between the two pair of shRNA compared with scramble control group at day 3 and day 5 post doxycycline treatment (P > 0.05). Cells in the different groups showed about 2 folds expansion on day 5 relative to day 1. Our preliminary data suggest that Cd36 knockdown has limited impact on the survival of normal hematopoietic cells. In vivo experiments assessing the effect of Cd36 gain and loss of function on the engraftment of normal hematopoietic cells in mice are ongoing to further establish the functional impact of Cd36 manipulation on normal hematopoietic cells. Altogether, our studies will demonstrate whether CD36 is dispensable for the survival of normal hematopoietic cells and thus may potentially present a viable therapeutic approach in AML. DisclosuresYaghmour: Jazz: Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Astellas: Speakers Bureau; Alexion: Speakers Bureau; BMS: Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Agios: Consultancy, Speakers Bureau.

Interaction between CD36 and FABP4 modulates adipocyte-induced fatty acid import and metabolism in breast cancer

Adipocytes influence breast cancer behaviour via fatty acid release into the tumour microenvironment. Co-culturing human adipocytes and breast cancer cells increased CD36 expression, with fatty acid import into breast cancer cells. Genetic ablation of CD36 attenuates adipocyte-induced epithelial-mesenchymal transition (EMT) and stemness. We show a feedforward loop between CD36 and STAT3; where CD36 activates STAT3 signalling and STAT3 binds to the CD36 promoter, regulating its expression. CD36 expression results in metabolic reprogramming, with a shift towards fatty acid oxidation. CD36 inhibition induces de novo lipogenesis in breast cancer cells. Increased CD36 expression occurs with increased FABP4 expression. We showed that CD36 directly interacts with FABP4 to regulate fatty acid import, transport, and metabolism. CD36 and FABP4 inhibition induces apoptosis in tumour cells. These results indicate that CD36 mediates fatty acid import from adipocytes into cancer cells and activates signalling pathways that drive tumour progression. Targeting CD36 may have a potential for therapy, which will target the tumour microenvironment.

CD36-mediated ferroptosis dampens intratumoral CD8+ T cell effector function and impairs their antitumor ability

Understanding the mechanisms underlying how T cells become dysfunctional in a tumor microenvironment (TME) will greatly benefit cancer immunotherapy. We found that increased CD36 expression in tumor-infiltrating CD8+ T cells, which was induced by TME cholesterol, was associated with tumor progression and poor survival in human and murine cancers. Genetic ablation of Cd36 in effector CD8+ T cells exhibited increased cytotoxic cytokine production and enhanced tumor eradication. CD36 mediated uptake of fatty acids by tumor-infiltrating CD8+ T cells in TME, induced lipid peroxidation and ferroptosis, and led to reduced cytotoxic cytokine production and impaired antitumor ability. Blocking CD36 or inhibiting ferroptosis in CD8+ T cells effectively restored their antitumor activity and, more importantly, possessed greater antitumor efficacy in combination with anti-PD-1 antibodies. This study reveals a new mechanism of CD36 regulating the function of CD8+ effector T cells and therapeutic potential of targeting CD36 or inhibiting ferroptosis to restore T cell function.

Peptide-directed delivery of drug-loaded nanocarriers targeting CD36 overexpressing cells

We describe in this work a general strategy for improving receptor-specificity of the drug-loaded nanoscale micelles using a peptide ligand (Pep2) targeting CD36 receptor. By introducing Pep2 to the surface of doxorubicin encapsulated DSPE-PEG2000 micelles (M-Dox) via co-assembly process, the obtained construct of Pep2-M-Dox demonstrated appreciably enhanced specificity and sensitivity towards CD36-overexpressing cell lines in comparison with that of pristine M-Dox. It was also observed that such peptide-ligand-enabled active targeting capability of Pep2-M-Dox leads to improved cellular uptake and cytotoxicity. The reported efforts illustrate the feasibility of rational engineering the potency and specificity of peptide-directed drug delivery systems.

Fatty-Acid Receptor CD36 Functions As a Hydrogen Sulfide-Targeting Receptor with Its Cys333-Cys272 Disulfide Bond Serving As a Specific Molecular Switch to Accelerate Gastric Cancer Metastasis

Background: There is a large body of evidence suggesting that hydrogen sulfide (H2S) plays an important role in cancer metastasis; however, the molecular mechanisms of H2S-mediated acceleration of cancer metastasis remain unknown. Methods: We used RNA-sequencing to identify potential differences in gene expression in vitro. Using mass spectrometry, we identified a disulfide complex within CD36 that was labile to H2S-mediated modification. Targeting CD36 in vivo blocked H2S-promoted gastric cancer (GC) metastasis and improved animal survival. Tumor patients' samples were used for clinical translational significance evaluation. Findings: H2S triggered lipid metabolism reprogramming by significantly up-regulating the expression of the fatty-acid receptor CD36 and directly activating CD36 in GC cells. Mechanistically, a disulfide bond located between cysteine (Cys)333 and Cys272 within the CD36 protein structure that was labile to H2S-mediated modification. The long chain-fatty acid (LC-FA) binding pocket was capped by a turn in the CD36 protein, located between helical and sheet structures that were stabilized by the Cys333-Cys272. This limited the secondary binding between LC-FAs and lysine (Lys)334. Breaking the Cys333-Cys272 disulfide bond restored the second LC-FA binding conformation of CD36. Interpretation: CD36 gene transcription and CD36 subcellular recycling formed a positive feedback loop, and this disulfide bond within CD36 acted as a special molecular for this positive feedback. H2S opened the switch and induced LC-FA-mediated signaling, thus accelerating the metastasis of GC. Genetic and pharmacological blockade of CD36 function could be harnessed as an anti-metastasis therapeutic strategy. Therefore, we propose an effective strategy for anti-metastasis by blocking CD36. Funding: This work was supported by the Strategic Priority Research Program of the Science and Technology Commission of Shanghai (1312JC1408402 for Zhirong Wang). Declaration of Interest: All authors have no potential conflicts of interest. Ethical Approval: This animal study was conducted in accordance with the rules and regulations of the Institutional Animal Care and Use Committee (IACUC) at the Department of Laboratory Animal Science, Fudan University (Shanghai, P.R. China). Informed consent was approved by the Ethics Committees of Tongji Hospital and all subjects gave written informed consent.

Fatty-acid receptor CD36 functions as a hydrogen sulfide-targeted receptor with its Cys333-Cys272 disulfide bond serving as a specific molecular switch to accelerate gastric cancer metastasis.

BackgroundHydrogen Sulfide (H2S), a third member of gasotransmitter family along with nitric oxide (NO) and carbon monoxide (CO), exerts a wide range of cellular and molecular actions in our body. There is a large body of evidence suggesting that H2S plays an important role in cancer metastasis; however, the molecular mechanisms of H2S-mediated acceleration of cancer metastasis remain unknown.MethodsWe examined the promote effects of H2S on phenotype of gastric cancer (GC) cells (including those of express wild type CD36 and mutant CD36) in vitro and in vivo. GC patients' samples were used for clinical translational significance evaluation.FindingsH2S triggered lipid metabolism reprogramming by significantly up-regulating the expression of the fatty-acid receptor CD36 (CD36) and directly activating CD36 in GC cells. Mechanistically, a disulfide bond located between cysteine (Cys)333 and Cys272 within the CD36 protein structure that was labile to H2S-mediated modification. The long chain-fatty acid (LC-FA) binding pocket was capped by a turn in the CD36 protein, located between helical and sheet structures that were stabilized by the Cys333-Cys272. This limited the secondary binding between LC-FAs and lysine (Lys)334. Breaking the Cys333-Cys272 disulfide bond restored the second LC-FA binding conformation of CD36. Targeting CD36 in vivo blocked H2S-promoted metastasis and improved animal survival.InterpretationThese findings identify that the Cys333-Cys272 disulfide bond disrupted the integrity of the second LC-FA binding conformation of CD36. Therefore, CD36 can directly activate LC-FA access to the cytoplasm by acting as a direct target molecule for H2S.

Abstract A223: CD36-mediated metabolic adaptation guides regulatory T-cells in tumors

Abstract Regulatory T-cells (Tregs) play an indispensable role in maintaining peripheral tolerance and preventing autoimmune disease. In addition to modulating tissue homeostasis, the suppressive properties of Tregs can also be harnessed by cancers to evade immunosurveillance. Therefore, depleting Tregs has been shown to unleash antitumor immunity and interrupt formation of an immunosuppressive tumor microenvironment (TME). However, systemic loss of Tregs due to Treg depletion also leads to severe autoimmunity. Therefore, the identification of novel approaches that specifically target intratumoral Tregs is direly needed for unleashing antitumor immunity and cancer immunotherapy. Here we show that intratumoral Tregs increase lipid uptake and content and elevated expression of CD36, a fatty acid translocase, as compared to Tregs in circulation and other normal tissues, in several cancer types. By using the transgenic mice model, we found that Treg-specific ablation of CD36 reduces accumulation of intratumoral Treg and suppresses tumor growth. Importantly, Treg-specific CD36 deficiency does not lead to autoimmunity in aged mice and CD36-deficient Tregs remain their suppressive activity on restraining CD4 T-cell-induced inflammatory bowl disease. Mechanistically, CD36 expression supports survival of intratumoral Tregs by fine-tuning their mitochondrial fitness via PPAR signaling. Thus, high expression of CD36 in intratumoral Tregs orchestrates Treg metabolic adaptation in tumors by intervening metabolic regulations, and further promotes tumor growth by suppressing the antitumor immune responses. Ultimately, anti-PD-1 blockade treatment elicits therapeutic benefits in mice with Treg-specific ablation of CD36. Altogether, our study suggests that CD36 might be a potential target for specifically waning down intratumoral Tregs and provide proof-of-concept evidence that targeting CD36 in tumors could unleash antitumor immunity and synergize with checkpoint blockade treatment. Citation Format: Haiping Wang, Ping-Chih Ho. CD36-mediated metabolic adaptation guides regulatory T-cells in tumors [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A223.