CD36 tango in cancer: signaling pathways and functions

Bioinformatics analysis reveals lipid metabolism may play an important role in the SiO2-stimulated rat model

Silicosis is a progressive and irreversible common occupational disease caused by long-term inhalation of a large amount of free silica dust. Its pathogenesis is complex, and the existing prevention and treatment methods can not effectively improve silicosis injury. To uncover potential differential genes in silicosis, SiO₂-stimulated rats and their control original transcriptomic data sets GSE49144, GSE32147 and GSE30178 were downloaded for further bioinformatics analysis. We used R packages to extract and standardize transcriptome profiles, then screened differential genes, and enriched GO and KEGG pathways through clusterProfiler packages. In addition, we investigated the role of lipid metabolism in the progression of silicosis by qRT-PCR validation and transfection with si-CD36. A total of 426 differential genes were identified in this study. Based on GO and KEGG enrichment analysis, it was found that lipid and atherosclerosis were significantly enriched. qRT-PCR was used to detect the relative expression level of differential genes in this signaling pathway of silicosis rat models. mRNA levels of Abcg1, Il1b, Sod2, Cyba, Cd14, Cxcl2, Ccl3, Cxcl1, Ccl2 and CD36 increased, mRNA levels of Ccl5, Cybb and Il18 decreased. In addition, at the cellular level, SiO₂-stimulated lead to lipid metabolism disorder in NR8383, and silencing CD36 inhibited SiO₂-induced lipid metabolism disorder. These results indicate that lipid metabolism plays an important role in the progression of silicosis, and the genes and pathways reported in this study may provide new ideas for the pathogenesis of silicosis.

Spatial Transcriptomics Depict Ligand-Receptor Cross-talk Heterogeneity at the Tumor-Stroma Interface in Long-Term Ovarian Cancer Survivors

Advanced high-grade serous ovarian cancer (HGSC) is an aggressive disease that accounts for 70% of all ovarian cancer deaths. Nevertheless, 15% of patients diagnosed with advanced HGSC survive more than 10 years. The elucidation of predictive markers of these long-term survivors (LTS) could help identify therapeutic targets for the disease, and thus improve patient survival rates. To investigate the stromal heterogeneity of the tumor microenvironment (TME) in ovarian cancer, we used spatial transcriptomics to generate spatially resolved transcript profiles in treatment-naïve advanced HGSC from LTS and short-term survivors (STS) and determined the association between cancer-associated fibroblasts (CAF) heterogeneity and survival in patients with advanced HGSC. Spatial transcriptomics and single-cell RNA-sequencing data were integrated to distinguish tumor and stroma regions, and a computational method was developed to investigate spatially resolved ligand-receptor interactions between various tumor and CAF subtypes in the TME. A specific subtype of CAFs and its spatial location relative to a particular ovarian cancer cell subtype in the TME correlated with long-term survival in patients with advanced HGSC. Also, increased APOE-LRP5 cross-talk occurred at the stroma-tumor interface in tumor tissues from STS compared with LTS. These findings were validated using multiplex IHC. Overall, this spatial transcriptomics analysis revealed spatially resolved CAF-tumor cross-talk signaling networks in the ovarian TME that are associated with long-term survival of patients with HGSC. Further studies to confirm whether such cross-talk plays a role in modulating the malignant phenotype of HGSC and could serve as a predictive biomarker of patient survival are warranted.

SIGNIFICANCE

Generation of spatially resolved gene expression patterns in tumors from patients with ovarian cancer surviving more than 10 years allows the identification of novel predictive biomarkers and therapeutic targets for better patient management. See related commentary by Kelliher and Lengyel, p. 1383.

[Research Progress and New Immunotherapy Strategies of Tumor Microenvironment Metabolism]

The tumor microenvironment (TME), the environment of tumorigenesis and tumor progression, incorporates multiple types of cells and non-cellular components. TME plays an important role in tumorigenesis and tumor progression. Due to the abnormal proliferation of tumors, the TME has a unique chemophysiology environment and complex metabolic patterns, which subsequently affects the role of immune cells. Understanding the metabolic patterns of TME can help us develop immunotherapy regimens that target TME. Microbial metabolism and lipid metabolism, the key metabolic processes of TME, have emerged as important foci of research. The metabolites released by the microbiome and the reprogramming of cellular lipid metabolism affect the subsistence of tumor and immune cells. In this review, we summarized the composition and metabolic characteristics of TME and discussed the latest research progress in microbial metabolism and lipid metabolism in TME. We also provided an update on relevant metabolic regulatory targets and immunotherapy strategies, stressing that identifying highly effective therapeutic targets, in spite of the apparent difficulty, is what future research should be focused on.

Tumor-infiltrating CD36+CD8+T cells determine exhausted tumor microenvironment and correlate with inferior response to chemotherapy in non-small cell lung cancer

BACKGROUND

The scavenger receptor CD36 was reported to be highly expressed on tumor-infiltrating CD8⁺ T cells, but the clinical role remains obscure. This study aims to explore the infiltration and clinical value of CD36⁺CD8⁺ T cells in NSCLC.

METHODS

Immunohistochemistry and immunofluorescence were conducted for survival analyses and immunological evaluation in 232 NSCLC patients in Zhongshan Hospital. Flow cytometry analyses were carried out to assess the immune cells from fresh tumor samples, non-tumor tissues and peripheral blood. In vitro tumor infiltrating lymphocytes cultures were conducted to test the effect of CD36 blockage.

RESULTS

Accumulation of CD36⁺CD8⁺ T cells in tumor tissues was correlated with more advanced stage (p < 0.001), larger tumor size (p < 0.01), and lymph node metastasis (p < 0.0001) in NSCLC. Moreover, high infiltration of CD36⁺CD8⁺ T cells indicated poor prognosis in terms of both overall survival (OS) and recurrence-free survival (RFS) and inferior chemotherapy response. CD36⁺CD8⁺ T cells showed decreased GZMB (p < 0.0001) and IFN-γ (p < 0.001) with elevated PD-1 (p < 0.0001) and TIGIT (p < 0.0001). Analysis of tumor-infiltrating immune cell landscape revealed a positive correlation between CD36⁺CD8⁺ T cells and Tregs (p < 0.01) and M2-polarized macrophages (p < 0.01) but a negative correlation with Th1 (p < 0.05). Notably, inhibition of CD36 partially restored the cytotoxic function of CD8⁺ T cells by producing more GZMB and IFN-γ.

CONCLUSION

CD36⁺CD8⁺ T cells exhibit impaired immune function and high infiltration of CD36⁺CD8⁺ T cells indicated poor prognosis and inferior chemotherapy response in NSCLC patients. CD36 could be a therapeutic target in combination with chemotherapy in NSCLC patients.

The role of lipid metabolism in cancer radioresistance

Radiotherapy is one of the main therapies for cancer. The process leading to radioresistance is still not fully understood. Cancer radiosensitivity is related to the DNA reparation of cancer cells and the tumor microenvironment (TME), which supports cancer cell survival. Factors that affect DNA reparation and the TME can directly or indirectly affect the radiosensitivity of cancer. Recent studies have shown that lipid metabolism in cancer cells, which is involved in the stability of cell membrane structure, energy supply and signal transduction of cancer cells, can also affect the phenotype and function of immune cells and stromal cells in the TME. In this review, we discussed the effects of lipid metabolism on the radiobiological characteristics of cancer cells and the TME. We also summarized recent advances in targeted lipid metabolism as a radiosensitizer and discussed how these scientific findings could be translated into clinical practice to improve the radiosensitivity of cancer.

A new strategy for searching determinants in colorectal cancer progression through whole-part relationship combined with multi-omics

The high incidence and mortality of colorectal cancer (CRC) and the lack of adequate diagnostic molecules have led to poor treatment outcomes for colorectal cancer, making it particularly important to develop methods to obtain molecular with significant diagnostic effects. Here, we proposed a whole and part study strategy (early-stage colorectal cancer as "part" and colorectal cancer as "whole") to identify specific and co-pathways of change in early-stage and colorectal cancers and to discover the determinants of colorectal cancer development. Metabolite biomarkers discovered in plasma may not necessarily reflect the pathological status of tumor tissue. To explore the determinant biomarkers associated with plasma and tumor tissue in the CRC progression, multi-omics were performed on three phases of biomarker discovery studies (discovery, identification and validation) including 128 plasma metabolomes and 84 tissue transcriptomes. Importantly, we observe that the metabolic levels of oleic acid and FA (18:2) in patients with colorectal cancer were much higher than in healthy people. Finally, biofunctional verification confirmed that oleic acid and FA (18:2) can promote the growth of colorectal cancer tumor cells and be used as plasma biomarkers for early-stage colorectal cancer. We propose a novel research strategy to discover co-pathways and important biomarkers that may be targeted for a potential role in early colorectal cancer, and our work provides a promising tool for the clinical diagnosis of colorectal cancer.

Deficiency of Carbamoyl Phosphate Synthetase 1 Engenders Radioresistance in Hepatocellular Carcinoma via Deubiquitinating c-Myc

PURPOSE

Tumor radiation resistance is the main obstacle to effective radiation therapy for patients with hepatocellular carcinoma (HCC). We identified the role of urea cycle key enzyme carbamoyl phosphate synthetase 1 (CPS1) in radioresistance of HCC and explored its mechanism, aiming to provide a novel radiosensitization strategy for the CPS1-deficiency HCC subtype.

METHODS AND MATERIALS

The expression of CPS1 was measured by western blot and immunohistochemistry. Cell growth assay, EdU assay, cell apoptosis assay, cell cycle assay, clone formation assay, and subcutaneous tumor assay were performed to explore the relationship between CPS1 and radioresistance of HCC cells. Lipid metabonomic analysis was used for investigating the effects of CPS1 on lipid synthesis of HCC cells. RNA sequencing and coimmunoprecipitation assay were carried out to reveal the mechanism of CPS1 participating in the regulation of HCC radiation therapy resistance. Furthermore, 10074-G5, the specific inhibitor of c-Myc, was administered to HCC cells to investigate the role of c-Myc in CPS1-deficiency HCC cells.

RESULTS

We found that urea cycle key enzyme CPS1 was frequently lower in human HCC samples and positively associated with the patient's prognosis. Functionally, the present study proved that CPS1 depletion could accelerate the development of HCC and induce radiation resistance of HCC in vitro and in vivo, and deficiency of CPS1 promoted the synthesis of some lipid molecules. Regarding the mechanism, we uncovered that inhibition of CPS1 upregulated CyclinA2 and CyclinD1 by stabilizing oncoprotein c-Myc at the posttranscriptional level and generated radioresistance of HCC cells. Moreover, inactivation of c-Myc using 10074-G5, a specific c-Myc inhibitor, could partially attenuate the proliferation and radioresistance induced by depletion of CPS1.

CONCLUSIONS

Our results recapitulated that silencing CPS1 could promote HCC progression and radioresistance via c-Myc stability mediated by the ubiquitin-proteasome system, suggesting that targeting c-Myc in CPS1-deficiency HCC subtype may be a valuable radiosensitization strategy in the treatment of HCC.

Ferroptosis, Acyl Starvation, and Breast Cancer

To maintain their growth rate, cancer cells must secure a supply of fatty acids, which are necessary for building cell membranes and maintaining energy processes. This is one of the reasons why tissues with intensive fatty acid metabolism, such as the mammary gland, are more likely to develop tumors. One natural or induced defense process against cancer is ferroptosis, which interferes with normal fatty acid metabolism. This leads to the oxidation of polyunsaturated fatty acids, which causes a rearrangement of the metabolism and damages cell membranes. As a consequence of this oxidation, there is a shortage of normal polyunsaturated fatty acids, which disturbs the complicated metabolism of fatty acids. This imbalance in metabolism, resulting from the deficiency of properly structured fatty acids, is called, by these authors, "acyl starvation." When cancer cells are exposed to alternating hypoxia and reoxygenation, they often develop resistance to neoadjuvant therapies. Blocking the stearoyl-CoA desaturase - fatty acid-binding protein 4 - fatty acid translocase axis appears to be a promising pathway in the treatment of breast cancer. On the one hand, the inhibition of desaturase leads to the formation of toxic phospholipid hydroperoxides in ferroptosis, whereas on the other hand, the inhibition of fatty acid-binding protein 4 and translocase leads to a reduced uptake of fatty acids and disruption of the cellular transport of fatty acids, resulting in intracellular acyl starvation. The disruption in the metabolism of fatty acids in cancer cells may augment the effectiveness of neoadjuvant therapy. SIGNIFICANCE STATEMENT: Regulation of the metabolism of fatty acids in cancer cells seems to be a promising therapeutic direction. Studies show that the induction of ferroptosis in cancer cells, combined with use of neoadjuvant therapies, effectively inhibits the proliferation of these cells. We link the process of ferroptosis with apoptosis and SCD1-FABP4-CD36 axis and propose the term "acyl starvation" for the processes leading to FA deficiency, dysregulation of FA metabolism in cancer cells, and, most importantly, the appearance of incorrect proportions FAs.

Crosstalk between fatty acid metabolism and tumour-associated macrophages in cancer progression

Over the last few decades, cancer has been regarded as an independent and self sustaining progression. The earliest hallmarks of cancer comprise of sustaining proliferative signalling, avoiding growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, and activating invasion and metastasis. Nonetheless, two emerging hallmarks are being described: aberrant metabolic pathways and evasion of immune destruction. Changes in tumour cell metabolism are not restricted to tumour cells alone; the products of the altered metabolism have a direct impact on the activity of immune cells inside the tumour microenvironment, particularly tumour-associated macrophages (TAMs). The complicated process of cancer growth is orchestrated by metabolic changes dictating the tight mutual connection between these cells. Here, we discuss approaches to exploit the interaction of cancer cells' abnormal metabolic activity and TAMs. We also describe ways to exploit it by reprogramming fatty acid metabolism via TAMs.

2,3,7,8-Tetrachlorodibenzo-p-dioxin induces liver lipid metabolism disorder via the ROS/AMPK/CD36 signaling pathway

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is widely considered as the most toxic and common carcinogen in the world. Exposure to TCDD causes liver lipid metabolism disorder and steatosis. However, the molecular mechanism of TCDD-induced liver lipid accumulation is not completely clear. Here, we found that a 5 μg/kg TCDD exposure for 3 weeks induced hepatocyte lipid deposition, increased CD36 expression, and promoted AMP-activated protein kinase (AMPK) ɑ phosphorylation in the liver of C57BL/6J mice. Furthermore, sulfo-N-succinimidyl oleate, a CD36 inhibiter, blunted TCDD-induced lipid deposition in Huh7 cells, confirming the critical role of CD36 in TCDD-induced hepatic steatosis. In terms of molecular mechanisms, we found that TCDD exposure increased reactive oxygen species (ROS) levels in Huh7 cells, which activated AMPK. Moreover, the activated AMPK upregulated CD36 expression. Therefore, we can see that the increase in CD36 expression induced by TCDD was regulated by ROS/AMPK/CD36 signaling pathway. Our results help to clarify the molecular mechanism of TCDD-induced hepatic steatosis.

Hodgkin Lymphoma Cell Lines and Tissues Express mGluR5: A Potential Link to Ophelia Syndrome and Paraneoplastic Neurological Disease

Ophelia syndrome is characterized by the coincidence of severe neuropsychiatric symptoms, classical Hodgkin lymphoma, and the presence of antibodies to the metabotropic glutamate 5 receptor (mGluR5). Little is known about the pathogenetic link between these symptoms and the role that anti-mGluR5-antibodies play. We investigated lymphoma tissue from patients with Ophelia syndrome and with isolated classical Hodgkin lymphoma by quantitative immunocytochemistry for mGluR5-expression. Further, we studied the L-1236, L-428, L-540, SUP-HD1, KM-H2, and HDLM-2 classical Hodgkin lymphoma cell lines by FACS and Western blot for mGluR5-expression, and by transcriptome analysis. mGluR5 surface expression differed significantly in terms of receptor density, distribution pattern, and percentage of positive cells. The highest expression levels were found in the L-1236 line. RNA-sequencing revealed more than 800 genes that were higher expressed in the L-1236 line in comparison to the other classical Hodgkin lymphoma cell lines. High mGluR5-expression was associated with upregulation of PI3K/AKT and MAPK pathways and of downstream targets (e.g., EGR1) known to be involved in classical Hodgkin lymphoma progression. Finally, mGluR5 expression was increased in the classical Hodgkin lymphoma-tissue of our Ophelia syndrome patient in contrast to five classical Hodgkin lymphoma-patients without autoimmune encephalitis. Given the association of encephalitis and classical Hodgkin lymphoma in Ophelia syndrome, it is possible that mGluR5-expression in classical Hodgkin lymphoma cells not only drives tumor progression but also triggers anti-mGluR5 encephalitis even before classical Hodgkin lymphoma becomes manifest.

Targeting lipid metabolism in metastatic prostate cancer

Despite key advances in the treatment of prostate cancer (PCa), a proportion of men have de novo resistance, and all will develop resistance to current therapeutics over time. Aberrant lipid metabolism has long been associated with prostate carcinogenesis and progression, but more recently there has been an explosion of preclinical and clinical data which is informing new clinical trials. This review explores the epidemiological links between obesity and metabolic syndrome and PCa, the evidence for altered circulating lipids in PCa and their potential role as biomarkers, as well as novel therapeutic strategies for targeting lipids in men with PCa, including therapies widely used in cardiovascular disease such as statins, metformin and lifestyle modification, as well as novel targeted agents such as sphingosine kinase inhibitors, DES1 inhibitors and agents targeting FASN and beta oxidation.

Coexpression of PD-L1/PD-1 with CXCR3/CD36 and IL-19 Increase in Extranodal Lymphoma

Many studies have demonstrated that PD-L1/PD-1 signaling is an immune evasion mechanism in tumors. PD-L1/PD-1 coexpression with CXCR3/CD36 in peripheral lymphocytes in lymphoma still needs to be clarified. The current study investigated PD-L1/PD-1 coexpression with CXCR3/CD36 in circulating lymphocytes, serum IL-19 levels, and their correlation with clinical outcome and extranodal involvement in lymphoma. Subjects and Methods. The coexpression of PD-L1/PD-1 with CXCR3/CD36 on circulating lymphocytes was analyzed by flow cytometry in 78 lymphoma patients before and after therapy and in 50 healthy controls. The concentration levels of IL-19 in serum were assessed by an ELISA. Results. PD-L1 and PD-1 were expressed on circulating CXCR3+ and CD36+ lymphocytes in lymphoma and were significantly higher in patients with extranodal involvement than in lymphoma patients without extranodal involvement (P < 0.001). Elevated IL-19 levels were observed in lymphoma patients and increased significantly in extranodal involvement (P < 0.001). High percentages of PD-L1+CXCR3+ and PD-1+CXCR3+ lymphocytes were associated with high LDH levels, hepatomegaly, lymphedema, advanced tumor stage, and recurrence. Furthermore, patients with splenomegaly and generalized lymphadenopathy had high percentages of PD-L1+CXCR3+ lymphocytes. In addition, levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 were significantly associated with bone marrow, lung, and lymph vessel involvement. Further analysis revealed that high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes were associated with lung and bone marrow involvement. Patients with high levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 had inferior event-free survival (EFS) compared with that in lymphoma patients with low levels. EFS was decreased in patients with high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes. When using the receiver operating characteristic (ROC) curve, the superiority of IL-19 (area under the curve (AUC): 0.993) and PD-L1+CXCR3+% (AUC: 0.961) to PD-1+CXCR3+% (AUC: 0.805), PD-L1+CD36+% (AUC: 0.694), and PD-1+CD36+% (AUC 0.769) was evident in the diagnosis of extranodal involvement, identifying lymphoma patients with extranodal involvement from patients without extranodal involvement. Conclusions. Coexpression of PD-L1/PD-1 with CXCR3/CD36 in circulating lymphocytes and serum IL-19 levels contributes to poor prognosis and might be potential markers for extranodal involvement in lymphoma.

Modified lipidomic profile of cancer-associated small extracellular vesicles facilitates tumorigenic behaviours and contributes to disease progression

Metabolic rewiring is a key feature of cancer cells, which involves the alteration of amino acids, glucose and lipids to support aggressive cancer phenotypes. Changes in lipid metabolism alter cancer growth characteristics, membrane integrity and signalling pathways. Small extracellular vesicles (sEVs) are membrane-bound vesicles secreted by cells into the extracellular environment, where they participate in cell-to-cell communication. Lipids are involved in the formation and cargo assortment of sEVs, resulting in their selective packaging in these vesicles. Further, sEVs participate in different aspects of cancer development, such as proliferation, migration and angiogenesis. Various lipidomic studies have indicated the enrichment of specific lipids in sEVs derived from tumour cells, which aid in their pathological functioning. This paper summarises how the modified lipid profile of sEVs contributes to carcinogenesis and disease progression.

Metabolic hallmarks of natural killer cells in the tumor microenvironment and implications in cancer immunotherapy

Natural killer (NK) cells belong to the early responder group against cancerous cells and viral infection. Emerging evidence reveals that distinct metabolic reprogramming occurs concurrently with activation and memory formation of NK cells. However, metabolism of NK cells is disturbed in the tumor immune microenvironment, which may promote tumor progression while limiting immunotherapy responses. In this review, we highlight how cell metabolism influences NK cell activity, the key molecular regulators of NK cell metabolism, and emerging strategies to alter metabolism to improve cytotoxicity of NK cells to kill tumor cells for cancer patients.

The role of lipid metabolic reprogramming in tumor microenvironment

Metabolic reprogramming is one of the most important hallmarks of malignant tumors. Specifically, lipid metabolic reprogramming has marked impacts on cancer progression and therapeutic response by remodeling the tumor microenvironment (TME). In the past few decades, immunotherapy has revolutionized the treatment landscape for advanced cancers. Lipid metabolic reprogramming plays pivotal role in regulating the immune microenvironment and response to cancer immunotherapy. Here, we systematically reviewed the characteristics, mechanism, and role of lipid metabolic reprogramming in tumor and immune cells in the TME, appraised the effects of various cell death modes (specifically ferroptosis) on lipid metabolism, and summarized the antitumor therapies targeting lipid metabolism. Overall, lipid metabolic reprogramming has profound effects on cancer immunotherapy by regulating the immune microenvironment; therefore, targeting lipid metabolic reprogramming may lead to the development of innovative clinical applications including sensitizing immunotherapy.

Fatty acid metabolism reprogramming in ccRCC: mechanisms and potential targets

Lipid droplet formation is a defining histological feature in clear-cell renal cell carcinoma (ccRCC) but the underlying mechanisms and importance of this biological behaviour have remained enigmatic. De novo fatty acid (FA) synthesis, uptake and suppression of FA oxidation have all been shown to contribute to lipid storage, which is a necessary tumour adaptation rather than a bystander effect. Clinical studies and mechanistic investigations into the roles of different enzymes in FA metabolism pathways have revealed new metabolic vulnerabilities that hold promise for clinical effect. Several metabolic alterations are associated with worse clinical outcomes in patients with ccRCC, as lipogenic genes drive tumorigenesis. Enzymes involved in the intrinsic FA metabolism pathway include FA synthase, acetyl-CoA carboxylase, ATP citrate lyase, stearoyl-CoA desaturase 1, cluster of differentiation 36, carnitine palmitoyltransferase 1A and the perilipin family, and each might be potential therapeutic targets in ccRCC owing to the link between lipid deposition and ccRCC risk. Adipokines and lipid species are potential biomarkers for diagnosis and treatment monitoring in patients with ccRCC. FA metabolism could potentially be targeted for therapeutic intervention in ccRCC as small-molecule inhibitors targeting the pathway have shown promising results in preclinical models.

Lipid metabolism marker CD36 is associated with 18FDG-PET/CT false negative lymph nodes in head and neck squamous cell carcinoma

Background

Lymph node metastasis frequently occurs in head and neck squamous cell carcinoma (HNSCC) patients, and [¹⁸F] fluorodeoxyglucose positron emission tomography with computed tomography (¹⁸FDG-PET/CT) examination for lymph node metastasis could result in false negativity and delay following treatment. However, the mechanism and resolution for ¹⁸FDG-PET/CT false negatives remain unclear. Our study was aim to found biomarkers for false negativity and true positivity from a metabolic perspective.

Methods

Ninety-two patients diagnosed with HNSCC who underwent preoperative ¹⁸FDG-PET/CT and subsequent surgery in our institution were reviewed. Immunohistochemistry (IHC) examinations of glucose metabolism (GLUT1 and GLUT5), amino acid metabolism4 (GLS and SLC1A5), and lipid metabolism (CPT1A and CD36) markers were conducted on their primary lesion and lymph node sections.

Results

We identified specific metabolic patterns of the false-negative group. Significantly, CD36 IHC score of primary lesions was higher in false-negative group than true-positive group. Moreover, we validated pro-invasive biological effects of CD36 by bioinformatics analysis as well as experiments. Conclusion: IHC examination of CD36 expression, which is a lipid metabolism marker, in primary lesions could distinguish HNSCC patients' lymph nodes false negatives in ¹⁸FDG-PET/CT.

Small-interfering RNA targeting proprotein convertase subtilisin/kexin type 9 might promote fatty liver disease and hepatocellular carcinoma through upregulation of CD36

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low-density lipoprotein (LDL) receptor and fatty acid translocase CD36, inducing lysosomal degradation of these two receptors in the liver cells. Both monoclonal antibody (mAb) and small-interfering RNA (siRNA) targeting PCSK9 have been designed for treatment of familial hypercholesterolemia recently, with elevating LDL receptors on the liver cell surface and increasing LDL uptake as the main beneficial mechanism. However, given that the binding domains of PCSK9 for LDL receptor and CD36 are different, and PCSK9 mAb only attacks the domain for LDL receptor, CD36 expression remains partially controlled under PCSK9 mAb treatment. In contrast, PCSK9 siRNA brings on complete loss of PCSK9, resulting in overexpression of CD36. Based on the fact that CD36 is a key factor in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and subsequent hepatocellular carcinoma (HCC), the risk of developing NAFLD and HCC on long-term use of PCSK9 siRNA is thus raised as a hypothesis. Additionally, because CD36 is also involved in the promotion of malignant diseases other than HCC, such as acute myeloid leukemia, gastric cancer, breast cancer, and colorectal cancer, the speculative danger of flourishing these malignancies by PCSK9 siRNA is discussed as well.

Progress of potential drugs targeted in lipid metabolism research

Lipids are a class of complex hydrophobic molecules derived from fatty acids that not only form the structural basis of biological membranes but also regulate metabolism and maintain energy balance. The role of lipids in obesity and other metabolic diseases has recently received much attention, making lipid metabolism one of the attractive research areas. Several metabolic diseases are linked to lipid metabolism, including diabetes, obesity, and atherosclerosis. Additionally, lipid metabolism contributes to the rapid growth of cancer cells as abnormal lipid synthesis or uptake enhances the growth of cancer cells. This review introduces the potential drug targets in lipid metabolism and summarizes the important potential drug targets with recent research progress on the corresponding small molecule inhibitor drugs. The significance of this review is to provide a reference for the clinical treatment of metabolic diseases related to lipid metabolism and the treatment of tumors, hoping to deepen the understanding of lipid metabolism and health.

Immune-related gene-based prognostic index for predicting survival and immunotherapy outcomes in colorectal carcinoma

Introduction

Colorectal cancer shows high incidence and mortality rates. Immune checkpoint blockade can be used to treat colorectal carcinoma (CRC); however, it shows limited effectiveness in most patients.

Methods

To identify patients who may benefit from immunotherapy using immune checkpoint inhibitors, we constructed an immune-related gene prognostic index (IRGPI) for predicting the efficacy of immunotherapy in patients with CRC. Transcriptome datasets and clinical information of patients with CRC were used to identify differential immune-related genes between tumor and para-carcinoma tissue. Using weighted correlation network analysis and Cox regression analysis, the IRGPI was constructed, and Kaplan-Meier analysis was used to evaluate its predictive ability. We also analyzed the molecular and immune characteristics between IRGPI high-and low-risk subgroups, performed sensitivity analysis of ICI treatment, and constructed overall survival-related receiver operating characteristic curves to validate the IRGPI. Finally, IRGPI genes and tumor immune cell infiltration in CRC model mice with orthotopic metastases were analyzed to verify the results.

Results

The IRGPI was constructed based on the following 11 hub genes: ADIPOQ, CD36, CCL24, INHBE, UCN, IL1RL2, TRIM58, RBCK1, MC1R, PPARGC1A, and LGALS2. Patients with CRC in the high-risk subgroup showed longer overall survival than those in the low-risk subgroup, which was confirmed by GEO database. Clinicopathological features associated with cancer progression significantly differed between the high- and low-risk subgroups. Furthermore, Kaplan-Meier analysis of immune infiltration showed that the increased infiltration of naïve B cells, macrophages M1, and regulatory T cells and reduced infiltration of resting dendritic cells and mast cells led to a worse overall survival in patients with CRC. The ORC curves revealed that IRGPI predicted patient survival more sensitive than the published tumor immune dysfunction and rejection and tumor inflammatory signature.

Discussion

Thus, the low-risk subgroup is more likely to benefit from ICIs than the high-risk subgroup. CRC model mice showed higher proportions of Tregs, M1 macrophages, M2 macrophages and lower proportions of B cells, memory B cell immune cell infiltration, which is consistent with the IRGPI results. The IRGPI can predict the prognosis of patients with CRC, reflect the CRC immune microenvironment, and distinguish patients who are likely to benefit from ICI therapy.

tRNA-like Transcripts from the NEAT1-MALAT1 Genomic Region Critically Influence Human Innate Immunity and Macrophage Functions

The evolutionary conserved NEAT1-MALAT1 gene cluster generates large noncoding transcripts remaining nuclear, while tRNA-like transcripts (mascRNA, menRNA) enzymatically generated from these precursors translocate to the cytosol. Whereas functions have been assigned to the nuclear transcripts, data on biological functions of the small cytosolic transcripts are sparse. We previously found NEAT1^-/- and MALAT1^-/- mice to display massive atherosclerosis and vascular inflammation. Here, employing selective targeted disruption of menRNA or mascRNA, we investigate the tRNA-like molecules as critical components of innate immunity. CRISPR-generated human ΔmascRNA and ΔmenRNA monocytes/macrophages display defective innate immune sensing, loss of cytokine control, imbalance of growth/angiogenic factor expression impacting upon angiogenesis, and altered cell-cell interaction systems. Antiviral response, foam cell formation/oxLDL uptake, and M1/M2 polarization are defective in ΔmascRNA/ΔmenRNA macrophages, defining first biological functions of menRNA and describing new functions of mascRNA. menRNA and mascRNA represent novel components of innate immunity arising from the noncoding genome. They appear as prototypes of a new class of noncoding RNAs distinct from others (miRNAs, siRNAs) by biosynthetic pathway and intracellular kinetics. Their NEAT1-MALAT1 region of origin appears as archetype of a functionally highly integrated RNA processing system.

PPARα at the crossroad of metabolic-immune regulation in cancer

Rewiring metabolism to sustain cell growth, division, and survival is the most prominent feature of cancer cells. In particular, dysregulated lipid metabolism in cancer has received accumulating interest, since lipid molecules serve as cell membrane structure components, secondary signaling messengers, and energy sources. Given the critical role of immune cells in host defense against cancer, recent studies have revealed that immune cells compete for nutrients with cancer cells in the tumor microenvironment and accordingly develop adaptive metabolic strategies for survival at the expense of compromised immune functions. Among these strategies, lipid metabolism reprogramming toward fatty acid oxidation is closely related to the immunosuppressive phenotype of tumor-infiltrated immune cells, including macrophages and dendritic cells. Therefore, it is important to understand the lipid-mediated crosstalk between cancer cells and immune cells in the tumor microenvironment. Peroxisome proliferator-activated receptors (PPARs) consist of a nuclear receptor family for lipid sensing, and one of the family members PPARα is responsible for fatty acid oxidation, energy homeostasis, and regulation of immune cell functions. In this review, we discuss the emerging role of PPARα-associated metabolic-immune regulation in tumor-infiltrated immune cells, and key metabolic events and pathways involved, as well as their influences on antitumor immunity.

Metabolism-dependent ferroptosis promotes mitochondrial dysfunction and inflammation in CD4+ T lymphocytes in HIV-infected immune non-responders

BACKGROUND

HIV immune non-responders (INRs) are described as a failure to reestablish a pool of CD4⁺ T lymphocytes (CD4 cells) after antiretroviral therapy (ART), which is related to poor clinical results. Ferroptosis is a newly discovered form of cell death characterised by iron-dependent lipid peroxidation and the accumulation of reactive oxygen species (ROS). The mechanism of unrecoverable CD4 cells in INRs and whether ferroptosis plays a role are not fully understood.

METHODS

Ninety-two people living with HIV (PLHIVs) who experienced four-year ART with sustained viral suppression, including 27 INRs, 34 partial responders (PRs), and 31 complete responders (CRs); and 26 uninfected control participants (UCs) were analysed for 16 immune parameters with flow cytometry. Then plasma lipid, iron and oxidation, and antioxidant indicators were detected by ELISA, and CD4 cells were sorted out and visualised under transmission electron microscopy. Finally, ferroptosis inhibitors were added, and alterations in CD4 cell phenotype and function were observed.

FINDINGS

We found decreased recent thymic emigrants (RTE), over-activation and over-proliferation phenotypes, diminished killing function, decreased IL-7R and more severe inflammation; increased lipid peroxidation in the mitochondria and disruptions of the mitochondrial structure, showing typical features of ferroptosis in CD4 cells in INRs. Additionally, ferroptosis inhibitors could reduce inflammation and repair mitochondrial damage. Meanwhile, ELISA results showed increased plasma free fatty acids (FFA) and an imbalance of oxidative and antioxidant systems in INRs. Flow cytometry results displayed alterations of both transferrin receptor (CD71) and lipid transporter (CD36) expressions on the surface of CD4 cells. Mechanistically, there was a stronger correlation between CD36 expression and mitochondrial lipid peroxidation production, ferroptosis makers, and inflammation indicators; while amino acid transporter (CD98) was more related to killing functions; and CD71 was more closely related to activation status in CD4 cells.

INTERPRETATION

Cellular metabolism was closely correlated with its diverse functions in INRs. Ferroptosis was observed in CD4 cells of INRs, and inhibiting ferroptosis through modulating mitochondrial disorders and inflammation may offer an alternative immunological strategy for reinvigorating CD4 cells in INRs.

FUNDING

This research was supported by the 13th Five-year Plan, Ministry of Science and Technology of China (2018ZX10302-102), Beijing Municipal Administration of Hospitals' Ascent Plan (DFL20191802), and Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support (ZYLX202126).

CD36 and Its Role in Regulating the Tumor Microenvironment

CD36 is a transmembrane glycoprotein that binds to a wide range of ligands, including fatty acids (FAs), cholesterol, thrombospondin-1 (TSP-1) and thrombospondin-2 (TSP-2), and plays an important role in lipid metabolism, immune response, and angiogenesis. Recent studies have highlighted the role of CD36 in mediating lipid uptake by tumor-associated immune cells and in promoting tumor cell progression. In cancer-associated fibroblasts (CAFs), CD36 regulates lipid uptake and matrix protein production to promote tumor proliferation. In addition, CD36 can promote tumor cell adhesion to the extracellular matrix (ECM) and induce epithelial mesenchymal transition (EMT). In terms of tumor angiogenesis, CD36 binding to TSP-1 and TSP-2 can both inhibit tumor angiogenesis and promote tumor migration and invasion. CD36 can promote tumor angiogenesis through vascular mimicry (VM). Overall, we found that CD36 exhibits diverse functions in tumors. Here, we summarize the recent research findings highlighting the novel roles of CD36 in the context of tumors.

Lipid metabolic features of T cells in the Tumor Microenvironment

The tumor microenvironment (TME) is characterized by discrete changes in metabolic features of cancer and immune cells, with various implications. Cancer cells take up most of the available glucose to support their growth, thereby leaving immune cells with insufficient nutrients to expand. In the relative absence of glucose, T cells switch the metabolic program to lipid-based sources, which is pivotal to T-cell differentiation and activation in nutrient-stressed TME. Although consumption of lipids should provide an alternative energy source to starving T cells, a literature survey has revealed that it may not necessarily lead to antitumor responses. Different subtypes of T cells behave differently in various lipid overload states, which widely depends upon the kind of free fatty acids (FFA) engulfed. Key lipid metabolic genes provide cytotoxic T cells with necessary nutrients for proliferation in the absence of glucose, thereby favoring antitumor immunity, but the same genes cause immune evasion in T_mem and T_reg. This review aims to detail the complexity of differential lipid metabolism in distinct subtypes of T cells that drive the antitumor or pro-tumor immunity in specific TME states. We have identified key drug targets related to lipid metabolic rewiring in TME.

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.

Macrophage-mediated immune suppression contributes to poor outcome in liver metastasis. Here the authors show that CD36-expressing metastasis associated macrophages engulf tumor cell-derived extracellular vesicles enriched in long-chain fatty acids, acquiring a pro-tumorigenic phenotype in a preclinical liver metastasis model.

CD36 accelerates the progression of hepatocellular carcinoma by promoting FAs absorption

CD36 is emerging as a potential strategy for cancer treatment because of its function of regulating fatty acid intake. The purpose of this study was to clarify the molecular mechanism of CD36 in the progression of HCC. TCGA database was used to analyze the relationship of CD36 with HCC. The expression of CD36 in HCC clinical samples and cell lines was detected by qRT-PCR and western blot. Huh7 cells and HCCLM3 cells were transfected and treated into different group. CCK-8 and clone formation assay were used to detect the cell proliferation ability. Wound healing and transwell experiment were used to detect the metastatic ability. HCC xenografts were constructed in nude mice by subcutaneous injection of stably transfected Huh7 cells. The expression of CD36 in HCC was detected by immunohistochemistry (IHC). The contents of phospholipids and triglycerides in HCC cells were detected by ELISA. And the content of neutral lipids in HCC cells was detected by staining with BODIPY 493/503 and DAPI dye. Then transcriptional sequencing was used to determine the downstream mechanism of CD36 in HCC, and the differentially expressed genes (DEGs) were analyzed. CD36 was upregulated in HCC. Knockdown of CD36 could suppress the proliferation and metastasis of HCC in vitro and in vivo by regulating FAs intake in HCC. In addition, the expression of AKR1C2 was suppressed by sh-CD36, and which was also involved in the regulation of FAs intake. The molecular mechanism by which CD36 accelerated the progression of HCC was to promote the expression of AKR1C2 and thus enhance fatty acids (FAs) intake.

Bioinformatics analysis reveals the potential target of rosiglitazone as an antiangiogenic agent for breast cancer therapy

Background

Several studies have demonstrated the antitumor activity of rosiglitazone (RGZ) in cancer cells, including breast cancer cells. However, the molecular targets of RGZ in the inhibition of angiogenesis in breast cancer cells remain unclear. This study aimed to explore the potential targets of RGZ in inhibiting breast cancer angiogenesis using bioinformatics-based analysis.

Results

Venn diagram analysis revealed 29 TR proteins. KEGG pathway enrichment analysis demonstrated that TR regulated the adipocytokine, AMPK, and PPAR signaling pathways. Oncoprint analysis showed genetic alterations in FABP4 (14%), ADIPOQ (2.9%), PPARG (2.8%), PPARGC1A (1.5%), CD36 (1.7%), and CREBBP (11%) in patients with breast cancer in a TCGA study. The mRNA levels of FABP4, ADIPOQ, PPARG, CD36, and PPARGC1A were significantly lower in patients with breast cancer than in those without breast cancer. Analysis of gene expression using bc-GenExMiner showed that the mRNA levels of FABP, ADIPOQ, PPARG, CD36, PPARGC1A, and CREBBP were significantly lower in basal-like and triple-negative breast cancer (TNBC) cells than in non-basal-like and non-TNBC cells. In general, the protein levels of these genes were low, except for that of CREBBP. Patients with breast cancer who had low mRNA levels of FABP4, ADIPOQ, PPARG, and PPARGC1A had lower overall survival rates than those with high mRNA levels, which was supported by the overall survival related to DNA methylation. Correlation analysis of immune cell infiltration with TR showed a correlation between TR and immune cell infiltration, highlighting the potential of RGZ for immunotherapy.

Conclusion

This study explored the potential targets of RGZ as antiangiogenic agents in breast cancer therapy and highlighted FABP4, ADIPOQ, PPARG, PPARGC1A, CD36, and CREBBP as potential targets of RGZ. These findings require further validation to explore the potential of RGZ as an antiangiogenic agent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12863-022-01086-2.

Recent studies have focused on the development of indirect angiogenesis inhibitors.

Bioinformatics-based identification of potential rosiglitazone target genes to inhibit breast cancer angiogenesis.

FABP4, ADIPOQ, PPARG, PPARGC1A, CD36, and CREBBP are potential targets of rosiglitazone.

Lipid metabolism in pancreatic cancer: emerging roles and potential targets

Pancreatic cancer is one of the most serious health issues in developed and developing countries, with a 5-year overall survival rate currently <9%. Patients typically present with advanced disease due to vague symptoms or lack of screening for early cancer detection. Surgical resection represents the only chance for cure, but treatment options are limited for advanced diseases, such as distant metastatic or locally progressive tumors. Although adjuvant chemotherapy has improved long-term outcomes in advanced cancer patients, its response rate is low. So, exploring other new treatments is urgent. In recent years, increasing evidence has shown that lipid metabolism can support tumorigenesis and disease progression as well as treatment resistance through enhanced lipid synthesis, storage, and catabolism. Therefore, a better understanding of lipid metabolism networks may provide novel and promising strategies for early diagnosis, prognosis estimation, and targeted therapy for pancreatic cancer patients. In this review, we first enumerate and discuss current knowledge about the advances made in understanding the regulation of lipid metabolism in pancreatic cancer. In addition, we summarize preclinical studies and clinical trials with drugs targeting lipid metabolic systems in pancreatic cancer. Finally, we highlight the challenges and opportunities for targeting lipid metabolism pathways through precision therapies in pancreatic cancer.

The role of Platinum(IV)-based antitumor drugs and the anticancer immune response in medicinal inorganic chemistry. A systematic review from 2017 to 2022

Platinum-based antitumor drugs have been used in many types of tumors due to its broad antitumor spectrum in clinic. Encouraged by the cisplatin's (CDDP) worldwide success in cancer chemotherapy, the research in platinum-based antitumor drugs has evolved from traditional platinum drug to multi-ligand and multifunctional platinum prodrugs over half a century. With the rapid development of metal drugs and the anticancer immune response, challenges and opportunities in platinum drug research have been shifted from traditional platinum-based drugs to platinum-based hybrids and the direction of development is tending toward photodynamic therapy, nano-delivery therapy, drug combination, targeted therapy, diagnostic therapy, immune-combination therapy and tumor stem cell therapy. In this review, we first exhaustively overviewed the role of platinum-based antitumor prodrugs and the anticancer immune response in medicinal inorganic chemistry based on the special nanomaterials, the modification of specific ligands, and the multiple functions obtained that are beneficial for tumor therapy in the last five years. We also categorized them according to drug potency and function. There hasn't been a comprehensive evaluation of precursor platinum drugs in prior articles. And a multifarious approach to distinguish and detail the variety of alterations of platinum-based precursors in various valence states also hasn't been summarized. In addition, this review points out the main problems at the interface of chemistry, biology, and medicine from their action mechanisms for current platinum drug development, and provides up-to-date potential strategies from drug design perspectives to circumvent those drawbacks. And a promising idea is also enlightened for researchers in the development and discovery of platinum prodrugs.

EMAP II Expression Is Increased on Peripheral Blood Cells from Non-Hodgkin Lymphoma

Tumor immune evasion is a lineament of cancer. Endothelial monocyte activating polypeptide-II (EMAP II) has been assumed to impact tumor immune escape significantly. EMAP II was first reported in the murine methylcholanthrene A-induced fibrosarcoma supernatant and identified as a tumor-derived cytokine. This study evaluated EMAP II expression in peripheral blood cells and its association with treatment outcome, lactate dehydrogenase (LDH) levels, and clinical criteria in non-Hodgkin's lymphoma (NHL) patients. EMAP II expression on different blood cells obtained from the peripheral blood of 80 NHL patients was evaluated by two-color flow cytometry. The study reported that EMAP II expression was significantly increased in peripheral blood cells in patients with NHL compared to normal volunteers (P < 0.001). Additionally, EMAP II expression levels on blood cells decreased in complete remission (CR) while they increased in relapse. This study showed coexpression of EMAP II and CD36 on peripheral lymphocytes in NHL patients but not in healthy controls (P < 0.001). EMAP II expression on blood cells was associated with increased serum LDH levels. Furthermore, the percentages of EMAP II+/CD36+ peripheral lymphocytes were significantly higher in relapse than in CR and healthy controls. Analyses revealed that higher percentages of EMAP II+CD36+ cells were positively correlated with hepatomegaly, splenomegaly, and an advanced (intermediate and high risk) NHL stage. The results assume that EMAP II might be involved in NHL development and pathogenesis.

From Bowen disease to cutaneous squamous cell carcinoma: eight markers were verified from transcriptomic and proteomic analyses

Background

Bowen's disease is a cutaneous squamous cell carcinoma (CSCC) in situ. If left untreated, BD may progress to invasive CSCC. CSCC is one of the most common cutaneous carcinoma in the elderly and the advanced, metastasis CSCC usually have a poor outcomes. However, the mechanisms of invasion and metastasis from Bowen’s disease to CSCC is complicated and still unclear.

Objectives

The aim of this study was to explore the biomarkers and molecular alterations in Bowen’s disease development process via analyzing the proteomics changes in tissues of CSCC, Bowen disease and healthy skin.

Methods

A total of 7 individuals with CSCC (5 for proteomics study and 2 for validation), 7 individuals with Bowen disease (5 for proteomics study and 2 for validation) and 7 healthy controls (5 for proteomics study and 2 for validation) presented to the Department of Dermatology, Yijishan Hospital, the First Affiliated Hospital of Wannan Medical College between January 2021 and December 2021 were enrolled. The proteomics analysis was performed to screen differentially expressed proteins/gens (DEPs/DEGs) in the lesions of CSCC, Bowen disease and healthy skin tissues. The transcriptomic data (GSE32628) of CSCC was selected and downloaded from the GEO database. The common DEGs in our proteomics results and GSE32628 between CSCC and healthy skin tissues were selected. And then, the common DEGs which significantly up or down-regulated between CSCC and Bowen disease in our proteomics results were further screened to identify using Western blot methods in the validation group. CSCC A431 cells were transfected with SERPINB1 small interfering RNA (si-SERPINB1) or small interfering RNA negative control (si-NC). To explore the effect of SERPINB1 silencing on migration and invasion ability of A431 cells.

Results

A total of 501 proteins were differentially expressed between the CSCC and healthy skin tissues, with 332 up-regulated and 169 down-regulated at least 1.5-fold with a P value < 0.05. These DEPs involved multiple biological functions such as protein binding process, immune, inflammation, ribosome, protein digestion and absorption, ECM-receptor interaction, focal adhesion, PI3K-Akt signaling pathway and others. A total of 20 common DEGs (COL3A1, LUM, TNC, COL1A1, ALDH3A2, FSCN1, SERPINB4, SERPINB1, CD36, COL4A1, CSTB, GPX3, S100A7, ACTN1, SERPINB3, S100A8, RAB31, STAT1, SPRR1B, S100A9) between CSCC and healthy skin tissues in GSE32628 and our proteomics results were found. Besides, the proteins of TNC, FSCN1, SERPINB1, ACTN1 and RAB31 in CSCC were significantly up-regulated, while COL3A1, COL1A1 and CD36 were significantly down-regulated relative to Bowen disease in proteomics results. These proteins were mainly involved in multiple pathways, including Focal adhesion, ECM-receptor interaction, Human papillomavirus infection, PI3K-Akt signaling pathway, PPAR signaling pathway, AMPK signaling pathway and others. These eight proteins were selected for further validation. According to the Western blotting analysis, when compared with the Bowen disease and healthy skin tissues, we found that the relative expression levels of TNC, FSCN1, SERPINB1, ACTN1 and RAB31 in the CSCC were significantly increased, while COL1A1 and CD36 were significantly decreased, and the differences were statistically significant (P < 0.05). Furthermore, the relative expression levels of TNC, FSCN1, SERPINB1 in the Bowen disease were also significantly increased, while the COL3A1 were also significantly decreased relative to the healthy control. SERPINB1 siRNA inhibited the expression of SERPINB1 at mRNA and protein levels in the A431 cells. After interfering with the expression of SERPINB1, the migration and invasion ability in the A431 cells were significantly decreased (P < 0.05).

Conclusions

This study highlights that eight proteins, TNC, FSCN1, SERPINB1, ACTN1, RAB31, COL3A1, COL1A1, CD36, were significantly associated with the mechanisms of invasion and metastasis in Bowen’s disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03622-1.

Identification of a novel lipid metabolism-related gene signature for predicting colorectal cancer survival

Colorectal cancer (CRC) is a common malignant tumor worldwide. Lipid metabolism is a prerequisite for the growth, proliferation and invasion of cancer cells. However, the lipid metabolism-related gene signature and its underlying molecular mechanisms remain unclear. The aim of this study was to establish a lipid metabolism signature risk model for survival prediction in CRC and to investigate the effect of gene signature on the immune microenvironment. Lipid metabolism-mediated genes (LMGs) were obtained from the Molecular Signatures Database. The consensus molecular subtypes were established using "ConsensusClusterPlus" based on LMGs and the cancer genome atlas (TCGA) data. The risk model was established using univariate and multivariate Cox regression with TCGA database and independently validated in the international cancer genome consortium (ICGC) datasets. Immune infiltration in the risk model was developed using CIBERSORT and xCell analyses. A total of 267 differentially expressed genes (DEGs) were identified between subtype 1 and subtype 2 from consensus molecular subtypes, including 153 upregulated DEGs and 114 downregulated DEGs. 21 DEGs associated with overall survival (OS) were selected using univariate Cox regression analysis. Furthermore, a prognostic risk model was constructed using the risk coefficients and gene expression of eleven-gene signature. Patients with a high-risk score had poorer OS compared with patients in the low-risk score group (p = 3.36e-07) in the TCGA cohort and the validationdatasets (p = 4.03e-05). Analysis of immune infiltration identified multiple T cells were associated with better prognosis in the low-risk group, including Th2 cells (p = 0.0208), regulatory T cells (p = 0.0425), and gammadelta T cells (p = 0.0112). A nomogram integrating the risk model and clinical characteristics was further developed to predict the prognosis of patients with CRC. In conclusion, our study revealed that the expression of lipid-metabolism genes were correlated with the immune microenvironment. The eleven-gene signature might be useful for prediction the prognosis of CRC patients.

Targeting Strategies for Aberrant Lipid Metabolism Reprogramming and the Immune Microenvironment in Esophageal Cancer: A Review

Esophageal cancer is of high importance to occurrence, development, and treatment resistance. As evidenced by recent studies, pathways (e.g., Wnt/β-catenin, AMPK, and Hippo) are critical to the proliferation, differentiation, and self-renewal of esophageal cancer. In addition, the above pathways play a certain role in regulating esophageal cancer and act as potential therapeutic targets. Over the past few years, the function of lipid metabolism in controlling tumor cells and immune cells has aroused extensive attention. It has been reported that there are intricate interactions between lipid metabolism reprogramming between immune and esophageal cancer cells, whereas molecular mechanisms should be studied in depth. Immune cells have been commonly recognized as a vital player in the esophageal cancer microenvironment, having complex crosstalk with cancer cells. It is increasingly evidenced that the function of immune cells in the tumor microenvironment (TME) is significantly correlated with abnormal lipid metabolism. In this review, the latest findings in lipid metabolism reprogramming in TME are summarized, and the above findings are linked to esophageal cancer progression. Aberrant lipid metabolism and associated signaling pathways are likely to serve as a novel strategy to treat esophageal cancer through lipid metabolism reprogramming.

Energy Substrate Transporters in High-Grade Ovarian Cancer: Gene Expression and Clinical Implications

Ovarian cancer is a non-homogenous malignancy. High-grade serous carcinoma (HGSC) is the most common subtype, and its drug resistance mechanisms remain unclear. Despite the advantages of modern pharmacotherapy, high-grade ovarian cancer is associated with a poor prognosis and research into targeted therapies is in progress. The aim of the study was to assess the dominant energy substrate transport mechanism in ovarian cancer cells and to verify whether genomic aberrations could predict clinical outcomes using the Cancer Genome Atlas (TCGA) dataset. Total RNA was extracted from HGSC frozen tissues, and the expression of selected genes was compared to respective controls. GLUT1, FABPpm, MCT4 and SNAT1 genes were significantly overexpressed in carcinomas compared with controls, while expression of CD36/SR-B2, FATP1, FABP4, GLUT4, ASCT2 and LPL was decreased. No differences were found in FATP4, LAT1, MCT1 and FASN. The transcript content of mitochondrial genes such as PGC-1α, TFAM and COX4/1 was similar between groups, while the β-HAD level declined in ovarian cancer. Additionally, the MCT4 level was reduced and PGC-1α was elevated in cancer tissue from patients with ‘small’ primary tumor and omental invasion accompanied by ascites as compared to patients that exhibited greater tendencies to metastasize to lymph nodes with clear omentum. Based on TCGA, higher FABP4 and LPL and lower TFAM expression indicated poorer overall survival in patients with ovarian cancer. In conclusion, the presented data show that there is no exclusive energy substrate in HGSC. However, this study indicates the advantage of glucose and lactate transport over fatty acids, thereby suggesting potential therapeutic intervention targets to impede ovarian cancer growth.

Inhibition of PCSK9 enhances the antitumor effect of PD-1 inhibitor in colorectal cancer by promoting the infiltration of CD8+ T cells and the exclusion of Treg cells

Immunotherapy especially immune checkpoint inhibitors (ICIs) has brought favorable clinical results for numerous cancer patients. However, the efficacy of ICIs in colorectal cancer (CRC) is still unsatisfactory due to the poor median progression-free survival and overall survival. Here, based on the CRC models, we tried to elucidate novel relapse mechanisms during anti-PD-1 therapy. We found that PD-1 blockade elicited a mild antitumor effect in these tumor models with both increased CD8⁺ T cells and Treg cells. Gene mapping analysis indicated that proprotein convertase subtilisin/kexin type 9 (PCSK9), low-density lipoprotein receptor, transforming growth factor-β (TGF-β), and CD36 were unexpectedly upregulated during PD-1 blockade. To investigate the critical role of these proteins especially PCSK9 in tumor growth, anti-PCSK9 antibody in combination with anti-PD-1 antibody was employed to block PCSK9 and PD-1 simultaneously in CRC. Data showed that neutralizing PCSK9 during anti-PD-1 therapy elicited a synergetic antitumor effect with increased CD8⁺ T-cell infiltration and inflammatory cytokine releases. Moreover, the proportion of Treg cells was significantly reduced by co-inhibiting PCSK9 and PD-1. Overall, inhibiting PCSK9 can further enhance the antitumor effect of anti-PD-1 therapy in CRC, indicating that targeting PCSK9 could be a promising approach to potentiate ICI efficacy.

CD47: Beyond an immune checkpoint in cancer treatment

The transmembrane protein, CD47, is recognized as an important innate immune checkpoint, and CD47-targeted drugs have been in development with the aim of inhibiting the interaction between CD47 and the regulatory glycoprotein SIRPα, for antitumor immunotherapy. Further, CD47 mediates other essential functions such as cell proliferation, caspase-independent cell death (CICD), angiogenesis and other integrin-activation-dependent cell phenotypic responses when bound to thrombospondin-1 (TSP-1) or other ligands. Mounting strategies that target CD47 have been developed in pre-clinical and clinical trials, including antibodies, small molecules, siRNAs, and peptides, and some of them have shown great promise in cancer treatment. Herein, the authors endeavor to provide a retrospective of ligand-mediated CD47 regulatory mechanisms, their roles in controlling antitumor intercellular and intracellular signal transduction, and an overview of CD47-targetd drug design.

Transcriptome profile of spleen tissues from locally-adapted Kenyan pigs (Sus scrofa) experimentally infected with three varying doses of a highly virulent African swine fever virus genotype IX isolate: Ken12/busia.1 (ken-1033)

Background

African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs resulting in up to 100% mortality rates caused by the ASF virus (ASFV). The locally-adapted pigs in South-western Kenya have been reported to be resilient to disease and harsh climatic conditions and tolerate ASF; however, the mechanisms by which this tolerance is sustained remain largely unknown. We evaluated the gene expression patterns in spleen tissues of these locally-adapted pigs in response to varying infective doses of ASFV to elucidate the virus-host interaction dynamics.

Methods

Locally adapted pigs (n = 14) were experimentally infected with a high dose (1x10⁶HAD₅₀), medium dose (1x10⁴HAD₅₀), and low dose (1x10²HAD₅₀) of the highly virulent genotype IX ASFV Ken12/busia.1 (Ken-1033) isolate diluted in PBS and followed through the course of infection for 29 days. The in vivo pig host and ASFV pathogen gene expression in spleen tissues from 10 pigs (including three from each infective group and one uninfected control) were analyzed in a dual-RNASeq fashion. We compared gene expression between three varying doses in the host and pathogen by contrasting experiment groups against the naïve control.

Results

A total of 4954 differentially expressed genes (DEGs) were detected after ASFV Ken12/1 infection, including 3055, 1771, and 128 DEGs in the high, medium, and low doses, respectively. Gene ontology and KEGG pathway analysis showed that the DEGs were enriched for genes involved in the innate immune response, inflammatory response, autophagy, and apoptosis in lethal dose groups. The surviving low dose group suppressed genes in pathways of physiopathological importance. We found a strong association between severe ASF pathogenesis in the high and medium dose groups with upregulation of proinflammatory cytokines and immunomodulation of cytokine expression possibly induced by overproduction of prostaglandin E synthase (4-fold; p < 0.05) or through downregulation of expression of M1-activating receptors, signal transductors, and transcription factors. The host-pathogen interaction resulted in induction of expression of immune-suppressive cytokines (IL-27), inactivation of autophagy and apoptosis through up-regulation of NUPR1 [5.7-fold (high dose) and 5.1-fold (medium dose) [p < 0.05] and IL7R expression. We detected repression of genes involved in MHC class II antigen processing and presentation, such as cathepsins, SLA-DQB1, SLA-DOB, SLA-DMB, SLA-DRA, and SLA-DQA in the medium and high dose groups. Additionally, the host-pathogen interaction activated the CD8⁺ cytotoxicity and neutrophil machinery by increasing the expression of neutrophils/CD8⁺ T effector cell-recruiting chemokines (CCL2, CXCL2, CXCL10, CCL23, CCL4, CXCL8, and CXCL13) in the lethal high and medium dose groups. The recovered pigs infected with ASFV at a low dose significantly repressed the expression of CXCL10, averting induction of T lymphocyte apoptosis and FUNDC1 that suppressed neutrophilia.

Conclusions

We provide the first in vivo gene expression profile data from locally-adapted pigs from south-western Kenya following experimental infection with a highly virulent ASFV genotype IX isolate at varying doses that mimic acute and mild disease. Our study showed that the locally-adapted pigs induced the expression of genes associated with tolerance to infection and repression of genes involved in inflammation at varying levels depending upon the ASFV dose administered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08754-8.

Connecting Metabolic Rewiring With Phenotype Switching in Melanoma

Melanoma is a complex and aggressive cancer type that contains different cell subpopulations displaying distinct phenotypes within the same tumor. Metabolic reprogramming, a hallmark of cell transformation, is essential for melanoma cells to adopt different phenotypic states necessary for adaptation to changes arising from a dynamic milieu and oncogenic mutations. Increasing evidence demonstrates how melanoma cells can exhibit distinct metabolic profiles depending on their specific phenotype, allowing adaptation to hostile microenvironmental conditions, such as hypoxia or nutrient depletion. For instance, increased glucose consumption and lipid anabolism are associated with proliferation, while a dependency on exogenous fatty acids and an oxidative state are linked to invasion and metastatic dissemination. How these different metabolic dependencies are integrated with specific cell phenotypes is poorly understood and little is known about metabolic changes underpinning melanoma metastasis. Recent evidence suggests that metabolic rewiring engaging transitions to invasion and metastatic progression may be dependent on several factors, such as specific oncogenic programs or lineage-restricted mechanisms controlling cell metabolism, intra-tumor microenvironmental cues and anatomical location of metastasis. In this review we highlight how the main molecular events supporting melanoma metabolic rewiring and phenotype-switching are parallel and interconnected events that dictate tumor progression and metastatic dissemination through interplay with the tumor microenvironment.

Roles of Palmitoleic Acid and Its Positional Isomers, Hypogeic and Sapienic Acids, in Inflammation, Metabolic Diseases and Cancer

In the last few years, the monounsaturated hexadecenoic fatty acids are being increasingly considered as biomarkers of health with key functions in physiology and pathophysiology. Palmitoleic acid (16:1n-7) and sapienic acid (16:1n-10) are synthesized from palmitic acid by the action of stearoyl-CoA desaturase-1 and fatty acid desaturase 2, respectively. A third positional isomer, hypogeic acid (16:1n-9) is produced from the partial β-oxidation of oleic acid. In this review, we discuss the current knowledge of the effects of palmitoleic acid and, where available, sapienic acid and hypogeic acid, on metabolic diseases such as diabetes, cardiovascular disease, and nonalcoholic fatty liver disease, and cancer. The results have shown diverse effects among studies in cell lines, animal models and humans. Palmitoleic acid was described as a lipokine able to regulate different metabolic processes such as an increase in insulin sensitivity in muscle, β cell proliferation, prevention of endoplasmic reticulum stress and lipogenic activity in white adipocytes. Numerous beneficial effects have been attributed to palmitoleic acid, both in mouse models and in cell lines. However, its role in humans is not fully understood, and is sometimes controversial. Regarding sapienic acid and hypogeic acid, studies on their biological effects are still scarce, but accumulating evidence suggests that they also play important roles in metabolic regulation. The multiplicity of effects reported for palmitoleic acid and the compartmentalized manner in which they often occur, may suggest the overlapping actions of multiple isomers being present at the same or neighboring locations.

Fatty acid translocase: a culprit of lipid metabolism dysfunction in disease

Dysregulation of lipid deposition into and mobilization from white adipose tissue (WAT) underlies various diseases. Long-chain fatty acids (LCFA) and cholesterol trafficking in and out of adipocytes is a process relying on transporters shuttling lipids from the plasma membrane (PM) to lipid droplets (LD). CD36 is the fatty acid translocase (FAT) that transports LCFA and cholesterol across the PM. Interactions of CD36 with proteins PHB1, ANX2, and CAV1 mediate intercellular lipid transport between adipocytes, hematopoietic, epithelial, and endothelial cells. Intracellularly, the FAT complex has been found to regulate LCFA trafficking between the PM and LD. This process is regulated by CD36 glycosylation and S-acylation, as well as by post-translational modifications of PHB1 and ANX2, which determine both protein–protein interactions and the cellular localization of the complex. Changes in extracellular and intracellular LCFA levels have been found to induce the post-translational modifications and the function of the FAT complex in lipid uptake and mobilization. The role of the CD36/PHB1/ANX2 complex may span beyond lipid trafficking. The requirement of PHB1 for mitochondrial oxidative metabolism in brown adipocytes has been revealed. Cancer cells which take advantage of lipids mobilized by adipocytes and oxidized in leukocytes are indirectly affected by the function of FAT complex in other tissues. The direct importance of CD36 interaction with PHB1/and ANX2 in cancer cells remains to be established. This review highlights the multifaceted roles of the FAT complex in systemic lipid trafficking and discuss it as a potential target in metabolic disease and cancer.

Metabolic Reprogramming in Cancer Cells: Emerging Molecular Mechanisms and Novel Therapeutic Approaches

The constant changes in cancer cell bioenergetics are widely known as metabolic reprogramming. Reprogramming is a process mediated by multiple factors, including oncogenes, growth factors, hypoxia-induced factors, and the loss of suppressor gene function, which support malignant transformation and tumor development in addition to cell heterogeneity. Consequently, this hallmark promotes resistance to conventional anti-tumor therapies by adapting to the drastic changes in the nutrient microenvironment that these therapies entail. Therefore, it represents a revolutionary landscape during cancer progression that could be useful for developing new and improved therapeutic strategies targeting alterations in cancer cell metabolism, such as the deregulated mTOR and PI3K pathways. Understanding the complex interactions of the underlying mechanisms of metabolic reprogramming during cancer initiation and progression is an active study field. Recently, novel approaches are being used to effectively battle and eliminate malignant cells. These include biguanides, mTOR inhibitors, glutaminase inhibition, and ion channels as drug targets. This review aims to provide a general overview of metabolic reprogramming, summarise recent progress in this field, and emphasize its use as an effective therapeutic target against cancer.

Adipocytes contribute to tumor progression and invasion of peritoneal metastasis by interacting with gastric cancer cells as cancer associated fibroblasts

BACKGROUND

Peritoneal metastasis (PM) is one of the most common causes of noncurative surgery and the most frequent recurrence pattern in gastric cancer (GC). During the process of PM, GC cells detached from primary tumor interact with human peritoneal mesothelial cells (HPMC) overlapped with adipose tissues such as the omentum or mesentery. Although the interaction with HPMC promotes the malignancy of GC, the role of adipose tissues remains unclear.

AIMS

We aimed to clarify how adipose tissue are affected by adjacent primary tumors during the expression of adipokines and to elucidate whether GC cells transform adipocytes into CAFs in vitro. In addition, we investigated whether GC cells are affected by adipocytes in their ability to infiltrate.

METHODS

We investigated the phenotypic conversion of adipocytes during the malignant process of GC cells in vivo and in vitro. We evaluated the expression levels of adiponectin in the omental adipose tissue of gastric cancer patients by western blotting. Following adipocytes/gastric cancer cells coculture, adipocyte markers, adiponectin receptors, and inflammatory cytokine markers were detected by real-time PCR and/or western blotting in the single-cultured and co-cultured adipocytes; cancer-associated fibroblast (CAF) markers were detected by immunofluorescence and western blotting in the single-cultured and co-cultured adipocytes; invasion assays were performed in single cultured and co-cultured MKN45 and OCUM.

RESULTS

In omental adipose tissues that are situated close to the primary tumors, the expression of adiponectin tended to decrease in patients with subserosal or serosal invasion. By co-culturing with GC cells, adipocytes were dedifferentiated and the expression levels of CAF marker FSP1 and inflammatory cytokines, PAI-1 and IL-6, significantly increased (p < 0.05). Furthermore, GC cells co-cultured with adipocytes showed enhanced invasion ability.

CONCLUSION

Our findings suggest that the phenotypic conversion of adipocytes may promote the malignancy of GC in the construction of the cancer microenvironment of PM.

Whole-exome sequencing reveals damaging gene variants associated with hypoalphalipoproteinemia

Low levels of high density lipoprotein-cholesterol (HDL-C) are associated with an elevated risk of arteriosclerotic coronary heart disease. Heritability of HDL-C levels is high. In this research discovery study, we used whole-exome sequencing to identify damaging gene variants that may play significant roles in determining HDL-C levels. We studied 204 individuals with a mean HDL-C level of 27.8 ± 6.4 mg/dl (range: 4-36 mg/dl). Data were analyzed by statistical gene burden testing and by filtering against candidate gene lists. We found 120 occurrences of probably damaging variants (116 heterozygous; four homozygous) among 45 of 104 recognized HDL candidate genes. Those with the highest prevalence of damaging variants were ABCA1 (n = 20), STAB1 (n = 9), OSBPL1A (n = 8), CPS1 (n = 8), CD36 (n = 7), LRP1 (n = 6), ABCA8 (n = 6), GOT2 (n = 5), AMPD3 (n = 5), WWOX (n = 4), and IRS1 (n = 4). Binomial analysis for damaging missense or loss-of-function variants identified the ABCA1 and LDLR genes at genome-wide significance. In conclusion, whole-exome sequencing of individuals with low HDL-C showed the burden of damaging rare variants in the ABCA1 and LDLR genes is particularly high and revealed numerous occurrences in HDL candidate genes, including many genes identified in genome-wide association study reports. Many of these genes are involved in cancer biology, which accords with epidemiologic findings of the association of HDL deficiency with increased risk of cancer, thus presenting a new area of interest in HDL genomics.

Mechanisms of Natural Extracts of Andrographis paniculata That Target Lipid-Dependent Cancer Pathways: A View from the Signaling Pathway

Andrographis paniculata is a local medicinal plant that is widely cultivated in Malaysia. It is comprised of numerous bioactive compounds that can be isolated using water, ethanol or methanol. Among these compounds, andrographolide has been found to be the major compound and it exhibits varieties of pharmacological activities, including anti-cancer properties, particularly in the lipid-dependent cancer pathway. Lipids act as crucial membrane-building elements, fuel for energy-demanding activities, signaling molecules, and regulators of several cellular functions. Studies have shown that alterations in lipid composition assist cancer cells in changing microenvironments. Thus, compounds that target the lipid pathway might serve as potential anti-cancer therapeutic agents. The purpose of this review is to provide an overview of the medicinal chemistry and pharmacology of A. paniculata and its active compounds in terms of anti-cancer activity, primary mechanism of action, and cellular targets, particularly in the lipid-dependent cancer pathway.

Key Molecules of Fatty Acid Metabolism in Gastric Cancer

Fatty acid metabolism is closely linked to the progression of gastric cancer (GC), a very aggressive and life-threatening tumor. This study examines linked molecules, such as Sterol Regulatory Element-Binding Protein 1 (SREBP1), ATP Citrate Lyase (ACLY), Acetyl-CoA Synthases (ACSs), Acetyl-CoA Carboxylase (ACC), Fatty Acid Synthase (FASN), Stearoyl-CoA Desaturase 1 (SCD1), CD36, Fatty Acid Binding Proteins (FABPs), and Carnitine palmitoyltransferase 1 (CPT1), as well as their latest studies and findings in gastric cancer to unveil its core mechanism. The major enzymes of fatty acid de novo synthesis are ACLY, ACSs, ACC, FASN, and SCD1, while SREBP1 is the upstream molecule of fatty acid anabolism. Fatty acid absorption is mediated by CD36 and FABPs, and fatty acid catabolism is mediated by CPT1. If at all possible, we will discover novel links between fatty acid metabolism and a prospective gastric cancer target.

Fatty acid synthase: A druggable driver of breast cancer brain metastasis

INTRODUCTION

Brain metastasis (BrM) is a key contributor to morbidity and mortality in breast cancer patients, especially among high-risk epidermal growth factor receptor 2-positive (HER2+) and triple-negative/basal-like molecular subtypes. Optimal management of BrM is focused on characterizing a "BrM dependency map" to prioritize targetable therapeutic vulnerabilities.

AREAS COVERED

We review recent studies addressing the targeting of BrM in the lipid-deprived brain environment, which selects for brain-tropic breast cancer cells capable of cell-autonomously generating fatty acids by upregulating de novo lipogenesis via fatty acid synthase (FASN). Disruption of FASN activity impairs breast cancer growth in the brain, but not extracranially, and mapping of the molecular causes of organ-specific patterns of metastasis has uncovered an enrichment of lipid metabolism signatures in brain metastasizing cells. Targeting SREBP1-the master regulator of lipogenic gene transcription-curtails the ability of breast cancer cells to survive in the brain microenvironment.

EXPERT OPINION

Targeting FASN represents a new therapeutic opportunity for patients with breast cancer and BrM. Delivery of brain-permeable FASN inhibitors and identifying strategies to target metabolic plasticity that might compensate for impaired brain FASN activity are two potential roadblocks that may hinder FASN-centered strategies against BrM.