Dysregulated ceramides metabolism by fatty acid 2-hydroxylase exposes a metabolic vulnerability to target cancer metastasis

The bioenergetic landscape of cancer

BACKGROUND

Bioenergetic remodeling of core energy metabolism is essential to the initiation, survival, and progression of cancer cells through exergonic supply of adenosine triphosphate (ATP) and metabolic intermediates, as well as control of redox homeostasis. Mitochondria are evolutionarily conserved organelles that mediate cell survival by conferring energetic plasticity and adaptive potential. Mitochondrial ATP synthesis is coupled to the oxidation of a variety of substrates generated through diverse metabolic pathways. As such, inhibition of the mitochondrial bioenergetic system by restricting metabolite availability, direct inhibition of the respiratory Complexes, altering organelle structure, or coupling efficiency may restrict carcinogenic potential and cancer progression.

SCOPE OF REVIEW

Here, we review the role of bioenergetics as the principal conductor of energetic functions and carcinogenesis while highlighting the therapeutic potential of targeting mitochondrial functions.

MAJOR CONCLUSIONS

Mitochondrial bioenergetics significantly contribute to cancer initiation and survival. As a result, therapies designed to limit oxidative efficiency may reduce tumor burden and enhance the efficacy of currently available antineoplastic agents.

Tumor-associated macrophage (TAM)-secreted CCL22 confers cisplatin resistance of esophageal squamous cell carcinoma (ESCC) cells via regulating the activity of diacylglycerol kinase α (DGKα)/NOX4 axis

Tumor-associated macrophages (TAMs) are often associated with chemoresistance and resultant poor clinical outcome in solid tumors. Here, we demonstrated that TAMs-released chemokine-C-C motif chemokine 22 (CCL22) in esophageal squamous cell carcinoma (ESCC) stroma was tightly correlated with the chemoresistance of ESCC patients. TAMs-secreted CCL22 was able to block the growth inhibitory and apoptosis-promoting effects of cisplatin on ESCC cells. Mechanistically, CCL22 stimulated intratumoral diacylglycerol kinase α (DGKα) to produce phosphatidic acid (PA), which suppressed the activity of NADPH oxidase 4 (NOX4) and then blocked the overproduction of intratumoral reactive species oxygen (ROS) induced by cisplatin. CCL22 activated DGKα/nuclear factor-κB (NF-κB) axis to upregulate the level of several members of ATP binding cassette (ABC) transporter superfamily, including ABC sub-family G member 4 (ABCG4), ABC sub-family A member 3 (ABCA3), and ABC sub-family A member 5 (ABCA5), to lower the intratumoral concentration of cisplatin. Consequently, these processes induced the cisplatin resistance in ESCC cells. In xenografted models, targeting DGKα with 5'-cholesterol-conjugated small-interfering (si) RNA enhanced the chemosensitivity of cisplatin in ESCC treatment, especially in the context of TAMs. Our data establish the correlation between the TAMs-induced intratumoral metabolic product/ROS axis and chemotherapy efficacy in ESCC treatment and reveal relevant molecular mechanisms.

Identification of a lipid homeostasis-related gene signature for predicting prognosis, immunity, and chemotherapeutic effect in patients with gastric cancer

Gastric cancer (GC) is one of the most common and deadliest cancers worldwide. Lipid homeostasis is essential for tumour development because lipid metabolism is one of the most important metabolic reprogramming pathways within tumours. Elucidating the mechanism of lipid homeostasis in GC might significantly improve treatment strategies and patient prognosis. GSE62254 was applied to construct a lipid homeostasis-related gene signature score (HGSscore) by multiple bioinformatic algorithms including weighted gene coexpression network analysis (WGCNA) and LASSO-Cox regression. A nomogram based on HGSscore and relevant clinical characteristics was constructed to predict the survival of patients with GC. TIMER and xCell were used to evaluate immune and stromal cell infiltration in the tumour microenvironment. Correlations between lipid homeostasis-related genes and chemotherapeutic efficacy were analysed in GSCAlite. RT‒qPCR and cell viability assays were applied to verify the findings in this study. HGSscore was constructed based on eighteen lipid homeostasis-related genes that were selected by WGCNA and LASSO-Cox regression. HGSscore was strongly associated with advanced TNM stage and showed satisfactory value in predicting GC prognosis in three independent cohorts. Furthermore, we found that HGSscore was associated with the tumour mutation burden (TMB) and immune/stromal cell infiltration, which are related to GC prognosis, indicating that lipid homeostasis impacts the formation of the tumour microenvironment (TME). With respect to the GSCAlite platform, PLOD2 and TGFB2 were shown to be positively related to chemotherapeutic resistance, while SLC10A7 was a favourable factor for chemotherapy efficacy. Cell viability assays showed that disrupted lipid homeostasis could attenuate GC cell viability. Moreover, RT‒qPCR revealed that lipid homeostasis could influence expression of specific genes. We identified a lipid homeostasis-related gene signature that correlated with survival, clinical characteristics, the TME, and chemotherapeutic efficacy in GC patients. This research provides a new perspective for improving prognosis and guiding individualized chemotherapy for patients with GC.

Targeting lipid metabolism in cancer metastasis

This review delves into the most recent research on the metabolic adaptability of cancer cells and examines how their metabolic functions can impact their progression into metastatic forms. We emphasize the growing significance of lipid metabolism and dietary lipids within the tumor microenvironment, underscoring their influence on tumor progression. Additionally, we present an outline of the interplay between metabolic processes and the epigenome of cancer cells, underscoring the importance regarding the metastatic process. Lastly, we examine the potential of targeting metabolism as a therapeutic approach in combating cancer progression, shedding light on innovative drugs/targets currently undergoing preclinical evaluation.

Lipid metabolism analysis in esophageal cancer and associated drug discovery

Esophageal cancer is an upper gastrointestinal malignancy with a bleak prognosis. It is still being explored in depth due to its complex molecular mechanisms of occurrence and development. Lipids play a crucial role in cells by participating in energy supply, biofilm formation, and signal transduction processes, and lipid metabolic reprogramming also constitutes a significant characteristic of malignant tumors. More and more studies have found esophageal cancer has obvious lipid metabolism abnormalities throughout its beginning, progress, and treatment resistance. The inhibition of tumor growth and the enhancement of antitumor therapy efficacy can be achieved through the regulation of lipid metabolism. Therefore, we reviewed and analyzed the research results and latest findings for lipid metabolism and associated analysis techniques in esophageal cancer, and comprehensively proved the value of lipid metabolic reprogramming in the evolution and treatment resistance of esophageal cancer, as well as its significance in exploring potential therapeutic targets and biomarkers.

Detection, mechanisms, and therapeutic implications of oncometabolites

Metabolic abnormalities are a hallmark of cancer cells and are essential to tumor progression. Oncometabolites have pleiotropic effects on cancer biology and affect a plethora of processes, from oncogenesis and metabolism to therapeutic resistance. Targeting oncometabolites, therefore, could offer promising therapeutic avenues against tumor growth and resistance to treatments. Recent advances in characterizing the metabolic profiles of cancer cells are shedding light on the underlying mechanisms and associated metabolic networks. This review summarizes the diverse detection methods, molecular mechanisms, and therapeutic targets of oncometabolites, which may lead to targeting oncometabolism for cancer therapy.

Risk for Esophageal Cancer Based on Lifestyle Factors-Smoking, Alcohol Consumption, and Body Mass Index: Insight from a South Korean Population Study in a Low-Incidence Area

Esophageal cancer constitutes a global public health challenge. However, South Korean population-specific information on the association of lifestyle (smoking, alcohol consumption, and obesity status) with esophageal cancer risk is sparse. This nested case-control study analyzed the Korean national health screening cohort data (2002-2019) of 1114 patients with esophageal cancer and 4456 controls (1:4 propensity-score matched for sex, age, income, and residential region). Conditional and unconditional logistic regression analyses, after adjustment for multiple covariates, determined the effects of lifestyle factors on esophageal cancer risk. Smoking and alcohol consumption increased the esophageal cancer risk (adjusted odds ratio [95% confidence interval]: 1.37 [1.15-1.63] and 1.89 [1.60-2.23], respectively). Overweight (body mass index [BMI] ≥ 23 to <25 kg/m2), obese I (BMI ≥ 25 to <30 kg/m2), or obese II (BMI ≥ 30 kg/m2) categories had reduced odds of esophageal cancer (0.76 [0.62-0.92], 0.59 [0.48-0.72], and 0.47 [0.26-0.85], respectively). In the subgroup analyses, the association of incident esophageal cancer with smoking and alcohol consumption persisted, particularly in men or those aged ≥55 years, whereas higher BMI scores remained consistently associated with a reduced esophageal cancer likelihood across all age groups, in both sexes, and alcohol users or current smokers. Underweight current smokers exhibited a higher propensity for esophageal cancer. In conclusion, smoking and alcohol drinking may potentially increase the risk, whereas weight maintenance, with BMI ≥ 23 kg/m2, may potentially decrease the risk, for esophageal cancer in the South Korean population. Lifestyle modification in the specific subgroups may be a potential strategy for preventing esophageal cancer.

Identification of a Prognostic Gene Signature Based on Lipid Metabolism-Related Genes in Esophageal Squamous Cell Carcinoma

Background

Dysregulation of lipid metabolism is common in cancer. However, the molecular mechanism underlying lipid metabolism in esophageal squamous cell carcinoma (ESCC) and its effect on patient prognosis are not well understood. The objective of our study was to construct a lipid metabolism-related prognostic model to improve prognosis prediction in ESCC.

Methods

We downloaded the mRNA expression profiles and corresponding survival data of patients with ESCC from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. We performed differential expression analysis to identify differentially expressed lipid metabolism-related genes (DELMGs). We used Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses to establish a risk model in the GEO cohort and used data of patients with ESCC from the TCGA cohort for validation. We also explored the relationship between the risk model and the immune microenvironment via infiltrated immune cells and immune checkpoints.

Results

The result showed that 132 unique DELMGs distinguished patients with ESCC from the controls. We identified four genes (ACAA1, ACOT11, B4GALNT1, and DDHD1) as prognostic gene expression signatures to construct a risk model. Patients were classified into high- and low-risk groups as per the signature-based risk score. We used the receiver operating characteristic (ROC) curve and the Kaplan-Meier (KM) survival analysis to validate the predictive performance of the 4-gene signature in both the training and validation sets. Infiltrated immune cells and immune checkpoints indicated a difference in the immune status between the two risk groups.

Conclusion

The results of our study indicated that a prognostic model based on the 4-gene signature related to lipid metabolism was useful for the prediction of prognosis in patients with ESCC.

Exosome-mediated metabolic reprogramming: Implications in esophageal carcinoma progression and tumor microenvironment remodeling

Esophageal carcinoma is among the most fatal malignancies with increasing incidence globally. Tumor onset and progression can be driven by metabolic reprogramming, especially during esophageal carcinoma development. Exosomes, a subset of extracellular vesicles, display an average size of ∼100 nanometers, containing multifarious components (nucleic acids, proteins, lipids, etc.). An increasing number of studies have shown that exosomes are capable of transferring molecules with biological functions into recipient cells, which play crucial roles in esophageal carcinoma progression and tumor microenvironment that is a highly heterogeneous ecosystem through rewriting the metabolic processes in tumor cells and environmental stromal cells. The review introduces the reprogramming of glucose, lipid, amino acid, mitochondrial metabolism in esophageal carcinoma, and summarize current pharmaceutical agents targeting such aberrant metabolism rewiring. We also comprehensively overview the biogenesis and release of exosomes, and recent advances of exosomal cargoes and functions in esophageal carcinoma and their promising clinical application. Moreover, we discuss how exosomes trigger tumor growth, metastasis, drug resistance, and immunosuppression as well as tumor microenvironment remodeling through focusing on their capacity to transfer materials between cells or between cells and tissues and modulate metabolic reprogramming, thus providing a theoretical reference for the design potential pharmaceutical agents targeting these mechanisms. Altogether, our review attempts to fully understand the significance of exosome-based metabolic rewriting in esophageal carcinoma progression and remodeling of the tumor microenvironment, bringing novel insights into the prevention and treatment of esophageal carcinoma in the future.

PLCD3 promotes malignant cell behaviors in esophageal squamous cell carcinoma via the PI3K/AKT/P21 signaling

BACKGROUND

Phospholipase C Delta 3 (PLCD3) is a member of phospholipase C(PLC) Protein and PLCD3 protein plays a prominent role in many cancers. However, little is known about the role of PLCD3 in esophageal squamous cell carcinoma (ESCC).

MATERIAL AND METHODS

We analyzed PLCD3 mRNA and protein expression in ESCC tissues and cell lines by immunohistochemistry, quantitative real-time PCR, and western blot. The correlation between PLCD3 expression and clinicopathological characteristics was also analyzed. CCK8, colony formation, wound-healing, and transwell assays were conducted to measure cell functional alternations. Flow cytometry was performed to assess the apoptosis rate and cell cycle caused by PLCD3 knockdown. Xenograft models in nude mice to clarify the role of PLCD3 in ESCC. Key proteins in the PI3K / AKT signaling pathway after treatment of ECA109 and KYSE150 cells with the AKT inhibitor MK2206 were analyzed by western blot.

RESULTS

PLCD3 was highly expressed in ESCC tissues and cell lines. PLCD3 expression levels correlated with pathologic stage and lymphatic metastasis. PLCD3 knockdown inhibited cell proliferation, migration, invasion, promoted apoptosis, and caused the cell cycle arrest in the G1 phase. PLCD3 overexpression promoted cell proliferation, migration, and invasion. In vivo experiments with xenografts demonstrated that PLCD3 promoted ESCC tumorigenesis. Finally, Overexpression of PLCD3 activated the PI3K / AKT / P21 signaling.

CONCLUSION

PLCD3 promotes malignant cell behaviors in esophageal squamous cell carcinoma via the PI3K/AKT/P21 signaling and could serve as a potential target for ESCC treatment.

Ceramides and ceramide synthases in cancer: Focus on apoptosis and autophagy

Different studies corroborate a role for ceramide synthases and their downstream products, ceramides, in modulation of apoptosis and autophagy in the context of cancer. These mechanisms of regulation, however, appear to be context dependent in terms of ceramides' fatty acid chain length, subcellular localization, and the presence or absence of their downstream targets. Our current understanding of the role of ceramide synthases and ceramides in regulation of apoptosis and autophagy could be harnessed to pioneer the development of new treatments to activate or inhibit a single type of ceramide synthase, thereby regulating the apoptosis induction or cross talk of apoptosis and autophagy in cancer cells. Moreover, the apoptotic function of ceramide suggests that ceramide analogues can pave the way for the development of novel cancer treatments. Therefore, in the current review paper we discuss the impact of ceramide synthases and ceramides in regulation of apoptosis and autophagy in context of different types of cancers. We also briefly introduce the latest information on ceramide synthase inhibitors, their application in diseases including cancer therapy, and discuss approaches for drug discovery in the field of ceramide synthase inhibitors. We finally discussed strategies for developing strategies to use lipids and ceramides analysis in biological fluids for developing early biomarkers for cancer.

Integrated spatial transcriptomics and lipidomics of precursor lesions of pancreatic cancer identifies enrichment of long chain sulfatide biosynthesis as an early metabolic alteration

Background

The development of diverse spatial profiling technologies has provided an unprecedented insight into molecular mechanisms driving cancer pathogenesis. Here, we conducted the first integrated cross-species assessment of spatial transcriptomics and spatial metabolomics alterations associated with progression of intraductal papillary mucinous neoplasms (IPMN), bona fide cystic precursors of pancreatic ductal adenocarcinoma (PDAC).

Methods

Matrix Assisted Laster Desorption/Ionization (MALDI) mass spectrometry (MS)-based spatial imaging and Visium spatial transcriptomics (ST) (10X Genomics) was performed on human resected IPMN tissues (N= 23) as well as pancreata from a mutant Kras;Gnas mouse model of IPMN. Findings were further compared with lipidomic analyses of cystic fluid from 89 patients with histologically confirmed IPMNs, as well as single-cell and bulk transcriptomic data of PDAC and normal tissues.

Results

MALDI-MS analyses of IPMN tissues revealed long-chain hydroxylated sulfatides, particularly the C24:0(OH) and C24:1(OH) species, to be selectively enriched in the IPMN and PDAC neoplastic epithelium. Integrated ST analyses confirmed that the cognate transcripts engaged in sulfatide biosynthesis, including UGT8, Gal3St1 , and FA2H , were co-localized with areas of sulfatide enrichment. Lipidomic analyses of cystic fluid identified several sulfatide species, including the C24:0(OH) and C24:1(OH) species, to be significantly elevated in patients with IPMN/PDAC compared to those with low-grade IPMN. Targeting of sulfatide metabolism via the selective galactosylceramide synthase inhibitor, UGT8-IN-1, resulted in ceramide-induced lethal mitophagy and subsequent cancer cell death in vitro , and attenuated tumor growth of mutant Kras;Gnas allografts. Transcript levels of UGT8 and FA2H were also selectively enriched in PDAC transcriptomic datasets compared to non-cancerous areas, and elevated tumoral UGT8 was prognostic for poor overall survival.

Conclusion

Enhanced sulfatide metabolism is an early metabolic alteration in cystic pre-cancerous lesions of the pancreas that persists through invasive neoplasia. Targeting sulfatide biosynthesis might represent an actionable vulnerability for cancer interception.

Prognostic prediction and immunotherapy response analysis of the fatty acid metabolism-related genes in clear cell renal cell carcinoma

Background

Clear cell renal cell carcinoma (ccRCC) is a common urinary cancer. Although diagnostic and therapeutic approaches for ccRCC have been improved, the survival outcomes of patients with advanced ccRCC remain unsatisfactory. Fatty acid metabolism (FAM) has been increasingly recognized as a critical modulator of cancer development. However, the significance of the FAM in ccRCC remains unclear. Herein, we explored the function of a FAM-related risk score in the stratification and prediction of treatment responses in patients with ccRCC.

Methods

First, we applied an unsupervised clustering method to categorize patients from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) datasets into subtypes and retrieved FAM-related genes from the MSigDB database. We discern differentially expressed genes (DEGs) among different subtypes. Then, we applied univariate Cox regression analysis followed by least absolute shrinkage and selection operator (LASSO) linear regression based on DEGs expression to establish a FAM-related risk score for ccRCC.

Results

We stratified the three ccRCC subtypes based on FAM-related genes with distinct overall survival (OS), clinical features, immune infiltration patterns, and treatment sensitivities. We screened nine genes from the FAM-related DEGs in the three subtypes to establish a risk prediction model for ccRCC. Nine FAM-related genes were differentially expressed in the ccRCC cell line ACHN compared to the normal kidney cell line HK2. High-risk patients had worse OS, higher genomic heterogeneity, a more complex tumor microenvironment (TME), and elevated expression of immune checkpoints. This phenomenon was validated in the ICGC cohort.

Conclusion

We constructed a FAM-related risk score that predicts the prognosis and therapeutic response of ccRCC. The close association between FAM and ccRCC progression lays a foundation for further exploring FAM-related functions in ccRCC.

Activation of ACLY by SEC63 deploys metabolic reprogramming to facilitate hepatocellular carcinoma metastasis upon endoplasmic reticulum stress

BACKGROUND

Tumor cells display augmented capability to maintain endoplasmic reticulum (ER) homeostasis and hijack ER stress pathway for malignant phenotypes under microenvironmental stimuli. Metabolic reprogramming is a well-known hallmark for tumor cells to provide specific adaptive traits to the microenvironmental alterations. However, it's unknown how tumor cells orchestrate metabolic reprogramming and tumor progression in response to ER stress. Herein, we aimed to explore the pivotal roles of SEC63-mediated metabolic remodeling in hepatocellular carcinoma (HCC) cell metastasis after ER stress.

METHODS

The expression levels of SEC63 in HCC tissues and adjacent non-cancerous tissues were determined by immunohistochemistry and western blot. The regulatory roles of SEC63 in HCC metastasis were investigated both in vitro and in vivo by RNA-sequencing, metabolites detection, immunofluorescence, and transwell migration/invasion analyses. GST pull-down, immunoprecipitation/mass spectrometry and in vivo ubiquitination/phosphorylation assay were conducted to elucidate the underlying molecular mechanisms.

RESULTS

We identified SEC63 as a new regulator of HCC cell metabolism. Upon ER stress, the phosphorylation of SEC63 at T537 by IRE1α pathway contributed to SEC63 activation. Then, the stability of ACLY was upregulated by SEC63 to increase the supply of acetyl-CoA and lipid biosynthesis, which are beneficial for improving ER capacity. Meanwhile, SEC63 also entered into nucleus for increasing nuclear acetyl-CoA production to upregulate unfolded protein response targets to improve ER homeostasis. Importantly, SEC63 coordinated with ACLY to epigenetically modulate expression of Snail1 in the nucleus. Consequently, SEC63 promoted HCC cell metastasis and these effects were reversed by ACLY inhibition. Clinically, SEC63 expression was significantly upregulated in HCC tissue specimens and was positively correlated with ACLY expression. Importantly, high expression of SEC63 predicted unfavorable prognosis of HCC patients.

CONCLUSIONS

Our findings revealed that SEC63-mediated metabolic reprogramming plays important roles in keeping ER homeostasis upon stimuli in HCC cells. Meanwhile, SEC63 coordinates with ACLY to upregulate the expression of Snail1, which further promotes HCC metastasis. Metastasis is crucial for helping cancer cells seek new settlements upon microenvironmental stimuli. Taken together, our findings highlight a cancer selective adaption to ER stress as well as reveal the potential roles of the IRE1α-SEC63-ACLY axis in HCC treatment.

Fatty Acid 2-Hydroxylase and 2-Hydroxylated Sphingolipids: Metabolism and Function in Health and Diseases

Sphingolipids containing acyl residues that are hydroxylated at C-2 are found in most, if not all, eukaryotes and certain bacteria. 2-hydroxylated sphingolipids are present in many organs and cell types, though they are especially abundant in myelin and skin. The enzyme fatty acid 2-hydroxylase (FA2H) is involved in the synthesis of many but not all 2-hydroxylated sphingolipids. Deficiency in FA2H causes a neurodegenerative disease known as hereditary spastic paraplegia 35 (HSP35/SPG35) or fatty acid hydroxylase-associated neurodegeneration (FAHN). FA2H likely also plays a role in other diseases. A low expression level of FA2H correlates with a poor prognosis in many cancers. This review presents an updated overview of the metabolism and function of 2-hydroxylated sphingolipids and the FA2H enzyme under physiological conditions and in diseases.

Anti-PAI-1 Monoclonal Antibody Inhibits the Metastasis and Growth of Esophageal Squamous Cell Carcinoma

Plasminogen activator inhibitor (PAI-1) is highly expressed in esophageal squamous cell carcinoma (ESCC) and strongly contributes to metastasis, making it a potential target for ESCC therapy. However, the antibodies and inhibitors targeting PAI-1 have not shown good therapeutic effect in the in vivo experiments yet. Here, we generated a panel of novel monoclonal antibodies (mAbs) against PAI-1. Analysis of PAI-1 expression in 90 tissue specimens and 128 serum specimens from ESCC patients with these mAbs confirmed that PAI-1 levels was significantly correlated with metastasis and poor survival. In addition, we found that high PAI-1 expression contributed to the enhanced motility and invasiveness of two ESCC cell lines. Next, mAb-1E2 and mAb-2E3, which have highest affinity with PAI-1, were shown to possess strong inhibitory effects on ESCC migration and invasion. Anti-tumor and anti-metastatic effects of mAb-2E3 were further demonstrated in the experimental animal models. Finally, LRP1 was identified as key factor mediating the pro-invasive function of PAI-1 and the anti-invasive capacity of mAb-2E3 in ESCC cells. The mAb-2E3 markedly decreased STAT1 phosphorylation levels and blocked the binding between PAI-1 and LRP1-ClusterII domain. Collectively, mAb-2E3 developed by our lab may be an effective antibody drug which can be used for anti-metastatic therapy in ESCC.