Ceramide species are elevated in human breast cancer and are associated with less aggressiveness

Integration of network pharmacology, metabolomics and lipidomics for clarifying the role of sphingolipid metabolism in the treatment of liver cancer by regorafenib

AIMS

Regorafenib, an FDA-approved drug for advanced primary liver cancer (PLC), could provide survival benefits for patients. However, markers for its therapeutic sensitivity are lacking. This study seeks to identify sensitive targets of regorafenib in PLC from the perspective of small molecular metabolites.

MATERIALS AND METHODS

Initiated with network pharmacology (NP) to map regorafenib's target landscape and metabolic regulatory network in liver cancer. Subsequently, regorafenib's impact on hepatoma cells was evaluated by flow cytometry, western blotting (WB) and cell viability assay. Advanced metabolomics and lipidomics were employed to elucidate regorafenib's metabolic reprogramming effects in liver cancer. Metabolic enzyme expression was assessed by WB, immunohistochemical and immunofluorescence assays. Ultimately, mendelian randomization (MR) analysis was utilized to investigate the potential causality of sphingolipid metabolism in hepatic cancer.

KEY FINDINGS

Regorafenib was observed to inhibit hepatoma cell proliferation and cell cycle progression at G0/G1 phase, resulting in significant alterations in sphingolipid levels. It promoted the significant accumulation of 16:0 dihydroceramide (16:0 dhCer) by upregulating ceramide synthase 6 (CERS6) expression and inhibiting dihydroceramide desaturase 1 (DEGS1) activity. The MR analysis revealed that DEGS1 was a risk factor for the development and progression of liver cancer, while cumulative 16:0 dhCer was a protective factor.

SIGNIFICANCE

Sphingolipids, particularly dhCer and regulatory enzymes, may be potential sensitive markers of regorafenib in the treatment of liver cancer, providing new insights for enhancing the treated efficacy of regorafenib in liver cancer.

Detection and Validation of Organic Metabolites in Urine for Clear Cell Renal Cell Carcinoma Diagnosis

BACKGROUND

Clear cell renal cell carcinoma (ccRCC) comprises the majority, approximately 70-80%, of renal cancer cases and often remains asymptomatic until incidentally detected during unrelated abdominal imaging or at advanced stages. Currently, standardized screening tests for renal cancer are lacking, which presents challenges in disease management and improving patient outcomes. This study aimed to identify ccRCC-specific volatile organic compounds (VOCs) in the urine of ccRCC-positive patients and develop a urinary VOC-based diagnostic model.

METHODS

This study involved 233 pretreatment ccRCC patients and 43 healthy individuals. VOC analysis utilized stir-bar sorptive extraction coupled with thermal desorption gas chromatography/mass spectrometry (SBSE-TD-GC/MS). A ccRCC diagnostic model was established via logistic regression, trained on 163 ccRCC cases versus 31 controls, and validated with 70 ccRCC cases versus 12 controls, resulting in a ccRCC diagnostic model involving 24 VOC markers.

RESULTS

The findings demonstrated promising diagnostic efficacy, with an Area Under the Curve (AUC) of 0.94, 86% sensitivity, and 92% specificity.

CONCLUSIONS

This study highlights the feasibility of using urine as a reliable biospecimen for identifying VOC biomarkers in ccRCC. While further validation in larger cohorts is necessary, this study's capability to differentiate between ccRCC and control groups, despite sample size limitations, holds significant promise.

The Interplay between Oxidative Stress and Sphingolipid Metabolism in Endometrial Cancer

Endometrial cancer is one of the most common malignancies in women. Sphingolipids, a group of lipids, play a key role in cancer biology. Cancer cells often exhibit abnormal redox homeostasis characterized by elevated levels of reactive oxygen species (ROS). Emerging evidence suggests that ceramides are involved in inhibiting proliferation and inducing apoptosis through ROS production. However, there is no data on the relationship between sphingolipid metabolism and oxidative status in endometrial cancer. The present study aims to assess the content of individual sphingolipids and oxidative status in healthy women and those with endometrial cancer. Sphingolipid analysis was performed using mass spectrometry. Total oxidative status (TOS) and total antioxidant capacity (TAC) were assessed colorimetrically. Our results showed a significant increase in the levels of all measured sphingolipids in cancer tissues compared to healthy endometrium. Additionally, a significant decrease in the S1P/ceramide ratio (sphingolipid rheostat) was observed in cancer patients, particularly for C14:0-Cer, C16:0-Cer, C18:1-Cer, C22:0-Cer, and C24:0-Cer. Furthermore, increased TOS and decreased TAC were found in cancer patients compared to healthy women. Significant correlations were observed between the levels of individual sphingolipids and oxidative status, with the strongest correlation noted between C22:0-Cer and TOS (r = 0.64). We conclude that endometrial cancer is characterized by profound changes in sphingolipid metabolism, contributing to oxidative dysregulation and tumor progression.

Mapping Spatiotemporal Heterogeneity in Multifocal Breast Tumor Progression by Noninvasive Ultrasound Elastography-Guided Mass Spectrometry Imaging Strategy

Spatiotemporal heterogeneity of tumors provides an escape mechanism for breast cancer cells, which can obstruct the investigation of tumor progression. While molecular profiling obtained from mass spectrometry imaging (MSI) is rich in biochemical information, it lacks the capacity for in vivo analysis. Ultrasound diagnosis has a high diagnostic accuracy but low chemical specificity. Here, we describe a noninvasive ultrasound elastography (UE)-guided MSI strategy (UEg-MSI) that integrates physical and biochemical characteristics of tumors acquired from both in vivo and in vitro imaging. Using UEg-MSI, both elasticity histopathology metabolism "fingerprints" and reciprocal crosstalk are revealed, indicating the intact, multifocal spatiotemporal heterogeneity of spontaneous tumorigenesis of the breast from early, middle, and late stages. Our results demonstrate a gradual increase in malignant degree of primary focus in cervical and thoracic mammary glands. This progression is characterized by increased stiffness according to elasticity scores, histopathological changes from hyperplasia to increased nests of neoplastic cells and necrotic areas, and regional metabolic heterogeneity and reprogramming at the spatiotemporal level. De novo fatty acid (FA) synthesis focused on independent (such as ω-9 FAs) and dependent (such as ω-6 FAs) dietary FA intake in the core cancerous nest areas in the middle and late stages of tumor or in the peripheral microareas in the early stage of the tumor. SM-Cer signaling pathway and GPs biosynthesis and degradation, as well as glycerophosphoinositol intensity, changed in multiple characteristic microareas. The UEg-MSI strategy holds the potential to expand MSI applications and enhance ultrasound-mediated cancer diagnosis. It offers new insight into early cancer discovery and the occurrence of metastasis.

Anti-cancer effectiveness of a novel ceramide analog on chemo-sensitive and chemo-resistant breast cancers

INTRODUCTION

Ceramides are known to show anti-cancer activity. A novel ceramide analog, (S,E)-3-hydroxy-2-(2-hydroxybenzylidene)amino-N-tetradecylpropanamide (analog 315) was developed as part of a larger study focused on finding more effective breast cancer treatments.

OBJECTIVE

To assess whether analog 315 shows any or a combination of the following effects in breast cancer cells in vitro: inhibiting proliferation, inducing apoptosis, and altering protein expression. Also, to determine whether it inhibits chemo-resistant breast cancer tumor growth in vivo mouse model.

METHODS

In vitro cell proliferation and apoptosis after treatment with analog 315 were assessed in three breast cancer cell lines (MCF-7, MCF-7TN-R, and MDA-MB-231) and reported. Protein expression was assessed by microarray assay. For the in vivo studies, chemo-resistant breast cancer cells were used for tumor development in two groups of mice (treated and control). Analog 315 (25 mg/kg/day) or control (dimethyl sulfoxide) was administered intraperitoneally for 7 days. Effects of analog 315 on inhibiting the growth of chemo-resistant breast cancer tumors after treatment are reported.

RESULTS

Analog 315 reduced MCF-7TN-R chemo-resistant tumor burden (volume and weight) in mice. Liver metastasis was observed in control mice, but not in the treated animals. Ki-67, a proliferation marker for breast cancer cells, increased significantly ( P  < 0.05) in control tumor tissue. In vitro studies showed that analog 315 inhibited cell proliferation, altered protein expression and induced apoptosis in all three breast cancer cell lines studied, of which the effects on MCF-7TN-R cells were the most significant.

CONCLUSION

Analog 315 reduced tumor growth in chemo-resistant breast cancer, inhibited cell proliferation, altered protein expression, and induced apoptosis in all three cell lines studied.

Oral Administration of Glucosylceramide Suppresses Tumor Growth by Affecting the Ceramide/Sphingosine-1-Phosphate Balance in Breast Cancer Tissue

Background

Ceramide and sphingosine-1-phosphate (S1P) play opposing roles in cell death and survival, and maintain a dynamic balance called the sphingolipid rheostat. Glucosylceramide is a substrate to generate ceramide but its effect on breast cancer by oral administration was never tested. The purpose of this study was to reveal the anticancer activity of glucosylceramide and its potential as a new therapeutic agent in breast cancer.

Methods

E0771 cells were inoculated into the breast tissue of female C57BL/6NJcl mice. Glucosylceramide was administered orally to the mice for nine consecutive days. The concentrations of sphingolipid mediators including ceramide, glucosylceramide, and S1P in tumor tissues and serum were determined by mass spectrometry.

Results

Oral administration of glucosylceramide significantly suppressed E0771 tumor growth compared with the control group (P = 0.006). There were no significant differences in the serum concentrations of sphingolipid mediators including ceramide and S1P between the mice treated with glucosylceramide and control-treated mice. The ceramide concentration was significantly lower in tumor tissues (P = 0.026), and the S1P concentration was significantly higher than that in paired non-tumor tissues (P = 0.009). The S1P concentration in tumor tissues was significantly lower in mice treated with glucosylceramide than in control-treated mice (P = 0.001). The ceramide-to-S1P concentration ratio in tumor tissues was significantly higher in mice treated with glucosylceramide than in control-treated mice (P = 0.034).

Conclusions

Breast tumors could enhance their survival by increasing S1P conversion from ceramide. Oral administration of glucosylceramide suppressed tumor growth by affecting the ceramide/S1P balance. Oral administration of glucosylceramide is a promising basis for a new therapeutic approach.

Natural Products and Small Molecules Targeting Cellular Ceramide Metabolism to Enhance Apoptosis in Cancer Cells

Molecular targeting strategies have been used for years in order to control cancer progression and are often based on targeting various enzymes involved in metabolic pathways. Keeping this in mind, it is essential to determine the role of each enzyme in a particular metabolic pathway. In this review, we provide in-depth information on various enzymes such as ceramidase, sphingosine kinase, sphingomyelin synthase, dihydroceramide desaturase, and ceramide synthase which are associated with various types of cancers. We also discuss the physicochemical properties of well-studied inhibitors with natural product origins and their related structures in terms of these enzymes. Targeting ceramide metabolism exhibited promising mono- and combination therapies at preclinical stages in preventing cancer progression and cemented the significance of sphingolipid metabolism in cancer treatments. Targeting ceramide-metabolizing enzymes will help medicinal chemists design potent and selective small molecules for treating cancer progression at various levels.

Diverse Sphingolipid Profiles in Rectal and Colon Cancer

Colorectal cancer is a heterogenous group of neoplasms showing a variety of clinical and pathological features depending on their anatomical location. Sphingolipids are involved in the formation and progression of cancers, and their changes are an important part of the abnormalities observed during carcinogenesis. Because the course of rectal and colonic cancer differs, the aim of the study was to assess whether the sphingolipid profile is also different in tumors of these two regions. Using a combination of ultra-high-performance liquid chromatography combined with triple quadrupole mass spectrometry, differences in the amounts of cellular sphingolipids were found in colorectal cancer. Sphingosine content was higher in rectal cancer than in adjacent healthy tissue, while the content of two ceramides (C18:0-Cer and C20:0-Cer) was lower. In colon cancer, a higher content of sphingosine, sphinganine, sphingosine-1-phosphate, and two ceramides (C14:0-Cer and C24:0-Cer) was found compared to healthy tissue, but there was no decrease in the amount of any of the assessed sphingolipids. In rectal cancer, the content of sphinganine and three ceramides (C16:0-Cer, C22:0-Cer, C24:0-Cer), as well as the entire pool of ceramides, was significantly lower compared to colon cancer. The S1P/Cer ratio in rectal cancer (S1P/C18:1-Cer, S1P/C20:0-Cer, S1P/C22:0-Cer, S1P/C24:1-Cer) and in colon cancer (S1P/C18:0-Cer, S1P/C18:1-Cer, S1P/C20:0-Cer) was higher than in adjacent healthy tissue and did not differ between the two sites (rectal cancer vs. colonic cancer). It seems that the development of colorectal cancer is accompanied by complex changes in the metabolism of sphingolipids, causing not only qualitative shifts in the ceramide pool of cancer tissue but also quantitative disturbances, depending on the location of the primary tumor.

Lipidomic Profiling Reveals Biological Differences between Tumors of Self-Identified African Americans and Non-Hispanic Whites with Cancer

In the US, the incidence and mortality of many cancers are disproportionately higher in African Americans (AA). Yet, AA remain poorly represented in molecular studies investigating the roles that biological factors might play in the development, progression, and outcomes of many cancers. Given that sphingolipids, key components of mammalian cellular membranes, have well-established roles in the etiology of cancer progression, malignancy, and responses to therapy, we conducted a robust mass spectrometry analysis of sphingolipids in normal adjacent uninvolved tissues and tumors of self-identified AA and non-Hispanic White (NHW) males with cancers of the lung, colon, liver, and head and neck and of self-identified AA and NHW females with endometrial cancer. In these cancers, AA have worse outcomes than NHW. The goal of our study was to identify biological candidates to be evaluated in future preclinical studies targeting race-specific alterations in the cancers of AA. We have identified that various sphingolipids are altered in race-specific patterns, but more importantly, the ratios of 24- to 16-carbon fatty acyl chain-length ceramides and glucosylceramides are higher in the tumors of AA. As there is evidence that ceramides with 24-carbon fatty acid chain length promote cellular survival and proliferation, whereas 16-carbon chain length promote apoptosis, these results provide important support for future studies tailored to evaluate the potential roles these differences may play in the outcomes of AA with cancer.

Sphingosine Kinase 2 in Stromal Fibroblasts Creates a Hospitable Tumor Microenvironment in Breast Cancer

Reciprocal interactions between breast cancer cells and the tumor microenvironment (TME) are important for cancer progression and metastasis. We report here that the deletion or inhibition of sphingosine kinase 2 (SphK2), which produces sphingosine-1-phosphate (S1P), markedly suppresses syngeneic breast tumor growth and lung metastasis in mice by creating a hostile microenvironment for tumor growth and invasion. SphK2 deficiency decreased S1P and concomitantly increased ceramides, including C16-ceramide, in stromal fibroblasts. Ceramide accumulation suppressed activation of cancer-associated fibroblasts (CAF) by upregulating stromal p53, which restrained production of tumor-promoting factors to reprogram the TME and to restrict breast cancer establishment. Ablation of p53 in SphK2-deficient fibroblasts reversed these effects, enabled CAF activation and promoted tumor growth and invasion. These data uncovered a novel role of SphK2 in regulating non-cell-autonomous functions of p53 in stromal fibroblasts and their transition to tumor-promoting CAFs, paving the way for the development of a strategy to target the TME and to enhance therapeutic efficacy.

SIGNIFICANCE

Sphingosine kinase 2 (SphK2) facilitates the activation of stromal fibroblasts to tumor-promoting cancer-associated fibroblasts by suppressing host p53 activity, revealing SphK2 as a potential target to reprogram the TME.

Exploring the role of sphingolipid-related genes in clinical outcomes of breast cancer

Background

Despite tremendous advances in cancer research, breast cancer (BC) remains a major health concern and is the most common cancer affecting women worldwide. Breast cancer is a highly heterogeneous cancer with potentially aggressive and complex biology, and precision treatment for specific subtypes may improve survival in breast cancer patients. Sphingolipids are important components of lipids that play a key role in the growth and death of tumor cells and are increasingly the subject of new anti-cancer therapies. Key enzymes and intermediates of sphingolipid metabolism (SM) play an important role in regulating tumor cells and further influencing clinical prognosis.

Methods

We downloaded BC data from the TCGA database and GEO database, on which we performed in depth single-cell sequencing analysis (scRNA-seq), weighted co-expression network analysis, and transcriptome differential expression analysis. Then seven sphingolipid-related genes (SRGs) were identified using Cox regression, least absolute shrinkage, and selection operator (Lasso) regression analysis to construct a prognostic model for BC patients. Finally, the expression and function of the key gene PGK1 in the model were verified by in vitro experiments.

Results

This prognostic model allows for the classification of BC patients into high-risk and low-risk groups, with a statistically significant difference in survival time between the two groups. The model is also able to show high prediction accuracy in both internal and external validation sets. After further analysis of the immune microenvironment and immunotherapy, it was found that this risk grouping could be used as a guide for the immunotherapy of BC. The proliferation, migration, and invasive ability of MDA-MB-231 and MCF-7 cell lines were dramatically reduced after knocking down the key gene PGK1 in the model through cellular experiments.

Conclusion

This study suggests that prognostic features based on genes related to SM are associated with clinical outcomes, tumor progression, and immune alterations in BC patients. Our findings may provide insights for the development of new strategies for early intervention and prognostic prediction in BC.

The Critical Impact of Sphingolipid Metabolism in Breast Cancer Progression and Drug Response

Breast cancer is the second leading cause of cancer-related death in women in the world, and its management includes a combination of surgery, radiation therapy, chemotherapy, and immunotherapy, whose effectiveness depends largely, but not exclusively, on the molecular subtype (Luminal A, Luminal B, HER2+ and Triple Negative). All breast cancer subtypes are accompanied by peculiar and substantial changes in sphingolipid metabolism. Alterations in sphingolipid metabolite levels, such as ceramides, dihydroceramide, sphingosine, sphingosine-1-phosphate, and sphingomyelin, as well as in their biosynthetic and catabolic enzymatic pathways, have emerged as molecular mechanisms by which breast cancer cells grow, respond to or escape therapeutic interventions and could take on diagnostic and prognostic value. In this review, we summarize the current landscape around two main themes: 1. sphingolipid metabolites, enzymes and transport proteins that have been found dysregulated in human breast cancer cells and/or tissues; 2. sphingolipid-driven mechanisms that allow breast cancer cells to respond to or evade therapies. Having a complete picture of the impact of the sphingolipid metabolism in the development and progression of breast cancer may provide an effective means to improve and personalize treatments and reduce associated drug resistance.

Tumor ratio of unsaturated to saturated sulfatide species is associated with disease-free survival in intrahepatic cholangiocarcinoma

PURPOSE

Cholangiocarcinoma (CCA) is a malignancy arising from the bile duct epithelium and has a poor outcome. Sulfatides are lipid components of lipid rafts, and are implicated in several cancer types. In the liver, sulfatides are specifically present in the bile ducts. Here, sulfatide abundance and composition were analyzed using mass spectrometry imaging in intrahepatic CCA (iCCA) tumor tissue, and correlated with tumor biology and clinical outcomes.

METHODS

Sulfatides were analyzed in iCCA (n = 17), hepatocellular carcinoma (HCC, n = 10) and colorectal liver metastasis (CRLM, n = 10) tumor samples, as well as tumor-distal samples (control, n = 16) using mass spectrometry imaging. Levels of sulfatides as well as the relative amount in structural classes were compared between groups, and were correlated with clinical outcomes for iCCA patients.

RESULTS

Sulfatide localization was limited to the respective tumor areas and the bile ducts. Sulfatide abundance was similar in iCCA and control tissue, while intensities were notably higher in CRLM in comparison with control (18-fold, P < 0.05) and HCC tissue (47-fold, P < 0.001). Considerable variation in sulfatide abundance was observed in iCCA tumors. A high ratio of unsaturated to saturated sulfatides was associated with reduced disease-free survival (10 vs. 20 months) in iCCA. The sulfatide pattern in HCC deviated from the other groups, with a higher relative abundance of odd- versus even-chain sulfatides.

CONCLUSION

Sulfatides were found in tumor tissue of patients with iCCA, with sulfatide abundance per pixel being similar to bile ducts. In this explorative study, sulfatide abundance was not related to overall survival of iCCA patients. A high ratio of unsaturated to saturated sulfatides was associated with earlier tumor recurrence in patients with iCCA.

Unique sphingolipid signature identifies luminal and triple-negative breast cancer subtypes

Breast cancer (luminal and triple-negative breast cancer [TNBC]) is the most common cancer among women in India and worldwide. Altered sphingolipid levels have emerged as a common phenomenon during cancer progression. However, these alterations are yet to be translated into robust diagnostic and prognostic markers for cancer. Here, we present the quantified sphingolipids of tumor and adjacent-normal tissues from patients of luminal (n = 70) and TNBC (n = 42) subtype from an Indian cohort using targeted liquid chromatography mass spectrometry. We recorded unique sphingolipid profiles that distinguished luminal and TNBC tumors in comparison to adjacent normal tissue by six-sphingolipid signatures. Moreover, systematic comparison of the profiles of luminal and TNBC tumors provided a unique five-sphingolipid signature distinguishing the two subtypes. We further identified key sphingolipids that can stratify grade II and grade III tumors of luminal and TNBC subtype as well as their lymphovascular invasion status. Therefore, we provide the right evidence to develop these candidate sphingolipids as widely acceptable marker/s capable of diagnosing luminal vs TNBC subtype of breast cancer, and predicting the disease severity by identifying the tumor grade.

Lipidomics-based tissue heterogeneity in specimens of luminal breast cancer revealed by clustering analysis of mass spectrometry imaging: A preliminary study

Cancer tissues reflect a greater number of pathological characteristics of cancer compared to cancer cells, so the evaluation of cancer tissues can be effective in determining cancer treatment strategies. Mass spectrometry imaging (MSI) can evaluate cancer tissues and even identify molecules while preserving spatial information. Cluster analysis of cancer tissues' MSI data is currently used to evaluate the phenotype heterogeneity of the tissues. Interestingly, it has been reported that phenotype heterogeneity does not always coincide with genotype heterogeneity in HER2-positive breast cancer. We thus investigated the phenotype heterogeneity of luminal breast cancer, which is generally known to have few gene mutations. As a result, we identified phenotype heterogeneity based on lipidomics in luminal breast cancer tissues. Clusters were composed of phosphatidylcholine (PC), triglycerides (TG), phosphatidylethanolamine, sphingomyelin, and ceramide. It was found that mainly the proportion of PC and TG correlated with the proportion of cancer and stroma on HE images. Furthermore, the number of carbons in these lipid class varied from cluster to cluster. This was consistent with the fact that enzymes that synthesize long-chain fatty acids are increased through cancer metabolism. It was then thought that clusters containing PCs with high carbon counts might reflect high malignancy. These results indicate that lipidomics-based phenotype heterogeneity could potentially be used to classify cancer for which genetic analysis alone is insufficient for classification.

Selection hub MicroRNAs as biomarkers in breast cancer stem cells in extracellular matrix using bioinformatics analyses

Background

Breast cancer is one of the most common cancers in women, and many people get it every year. The cancer stem cells are maybe crucial role to exacerbates and relapse the breast cancer. Therefore, finding biomarkers in human secretions can be an suitable solution for early detection and neo adjuvant therapy. This study aimed to investigate the molecular events related to the cancer stem cells in breast cancer, after which we nominated a suitable MicroRNAs participates in breast cancer pathogenesis.

Methods

In this study, we investigated the relationship between molecular pathways using a bioinformatics approach. First, we selected the appropriate RNA-Seq datasets from the GEO database. We used Enrichr, KEGG, and Shiny GO databases to evaluate the signal pathways and gene ontology after isolating the gene expression profiles. In the next step, we used the STRING database to assess the protein network, and we used the Targetscan database to nominate the MicroRNA.

Results

510 high-expression genes and 460 low-expression genes were associated with breast cancer and the cancer stem cells. Highly expressed genes were involved in the cell cycle and cellular aging pathways. On the other hand, low-expression genes were involved in the RNA transports, spliceosome, and apoptosis pathways. After evaluating the ontology of genes and the relationship between proteins, high-expression SPARC, INHBA, FN1, and GBA proteins were nominated. In the next section, the MicroRNAs related to these genes were hsa miR-9.5p, hsa miR-203.3p, and hsa miR-429.

Conclusion

In general, we examined more closely and more the relationship between the cancer stem cells pathway and breast cancer using a regular and accurate bioinformatics framework. Finally, we nominated suitable MicroRNAs that were involved in breast cancer stem cells.

Emerging Roles of Ceramides in Breast Cancer Biology and Therapy

One of the classic hallmarks of cancer is the imbalance between elevated cell proliferation and reduced cell death. Ceramide, a bioactive sphingolipid that can regulate this balance, has long been implicated in cancer. While the effects of ceramide on cell death and therapeutic efficacy are well established, emerging evidence indicates that ceramide turnover to downstream sphingolipids, such as sphingomyelin, hexosylceramides, sphingosine-1-phosphate, and ceramide-1-phosphate, is equally important in driving pro-tumorigenic phenotypes, such as proliferation, survival, migration, stemness, and therapy resistance. The complex and dynamic sphingolipid network has been extensively studied in several cancers, including breast cancer, to find key sphingolipidomic alterations that can be exploited to develop new therapeutic strategies to improve patient outcomes. Here, we review how the current literature shapes our understanding of how ceramide synthesis and turnover are altered in breast cancer and how these changes offer potential strategies to improve breast cancer therapy.

The Lard Works in Mysterious Ways: Ceramides in Nutrition-Linked Chronic Disease

Diet influences onset, progression, and severity of several chronic diseases, including heart failure, diabetes, steatohepatitis, and a subset of cancers. The prevalence and clinical burden of these obesity-linked diseases has risen over the past two decades. These metabolic disorders are driven by ectopic lipid deposition in tissues not suited for fat storage, leading to lipotoxic disruption of cell function and survival. Sphingolipids such as ceramides are among the most deleterious and bioactive metabolites that accrue, as they participate in selective insulin resistance, dyslipidemia, oxidative stress and apoptosis. This review discusses our current understanding of biochemical pathways controlling ceramide synthesis, production and action; influences of diet on ceramide levels; application of circulating ceramides as clinical biomarkers of metabolic disease; and molecular mechanisms linking ceramides to altered metabolism and survival of cells. Development of nutritional or pharmacological strategies to lower ceramides could have therapeutic value in a wide range of prevalent diseases.

UHPLC-HRMS–based serum lipisdomics reveals novel biomarkers to assist in the discrimination between colorectal adenoma and cancer

The development of a colorectal adenoma (CA) into carcinoma (CRC) is a long and stealthy process. There remains a lack of reliable biomarkers to distinguish CA from CRC. To effectively explore underlying molecular mechanisms and identify novel lipid biomarkers promising for early diagnosis of CRC, an ultrahigh-performance liquid chromatography tandem high-resolution mass spectrometry (UHPLC-HRMS) method was employed to comprehensively measure lipid species in human serum samples of patients with CA and CRC. Results showed significant differences in serum lipid profiles between CA and CRC groups, and 85 differential lipid species (P &lt; 0.05 and fold change &gt; 1.50 or &lt; 0.67) were discovered. These significantly altered lipid species were mainly involved in fatty acid (FA), phosphatidylcholine (PC), and triacylglycerol (TAG) metabolism with the constituent ratio &gt; 63.50%. After performance evaluation by the receiver operating characteristic (ROC) curve analysis, seven lipid species were ultimately proposed as potential biomarkers with the area under the curve (AUC) &gt; 0.800. Of particular value, a lipid panel containing docosanamide, SM d36:0, PC 36:1e, and triheptanoin was selected as a composite candidate biomarker with excellent performance (AUC = 0.971), and the highest selected frequency to distinguish patients with CA from patients with CRC based on the support vector machine (SVM) classification model. To our knowledge, this study was the first to undertake a lipidomics profile using serum intended to identify screening lipid biomarkers to discriminate between CA and CRC. The lipid panel could potentially serve as a composite biomarker aiding the early diagnosis of CRC. Metabolic dysregulation of FAs, PCs, and TAGs seems likely involved in malignant transformation of CA, which hopefully will provide new clues to understand its underlying mechanism.

Mass spectrometry imaging to explore molecular heterogeneity in cell culture

Molecular analysis on the single-cell level represents a rapidly growing field in the life sciences. While bulk analysis from a pool of cells provides a general molecular profile, it is blind to heterogeneities between individual cells. This heterogeneity, however, is an inherent property of every cell population. Its analysis is fundamental to understanding the development, function, and role of specific cells of the same genotype that display different phenotypical properties. Single-cell mass spectrometry (MS) aims to provide broad molecular information for a significantly large number of cells to help decipher cellular heterogeneity using statistical analysis. Here, we present a sensitive approach to single-cell MS based on high-resolution MALDI-2-MS imaging in combination with MALDI-compatible staining and use of optical microscopy. Our approach allowed analyzing large amounts of unperturbed cells directly from the growth chamber. Confident coregistration of both modalities enabled a reliable compilation of single-cell mass spectra and a straightforward inclusion of optical as well as mass spectrometric features in the interpretation of data. The resulting multimodal datasets permit the use of various statistical methods like machine learning-driven classification and multivariate analysis based on molecular profile and establish a direct connection of MS data with microscopy information of individual cells. Displaying data in the form of histograms for individual signal intensities helps to investigate heterogeneous expression of specific lipids within the cell culture and to identify subpopulations intuitively. Ultimately, t-MALDI-2-MSI measurements at 2-µm pixel sizes deliver a glimpse of intracellular lipid distributions and reveal molecular profiles for subcellular domains.

Involvement of Ceramide Signalling in Radiation-Induced Tumour Vascular Effects and Vascular-Targeted Therapy

Sphingolipids are well-recognized critical components in several biological processes. Ceramides constitute a class of sphingolipid metabolites that are involved in important signal transduction pathways that play key roles in determining the fate of cells to survive or die. Ceramide accumulated in cells causes apoptosis; however, ceramide metabolized to sphingosine promotes cell survival and angiogenesis. Studies suggest that vascular-targeted therapies increase endothelial cell ceramide resulting in apoptosis that leads to tumour cure. Specifically, ultrasound-stimulated microbubbles (USMB) used as vascular disrupting agents can perturb endothelial cells, eliciting acid sphingomyelinase (ASMase) activation accompanied by ceramide release. This phenomenon results in endothelial cell death and vascular collapse and is synergistic with other antitumour treatments such as radiation. In contrast, blocking the generation of ceramide using multiple approaches, including the conversion of ceramide to sphingosine-1-phosphate (S1P), abrogates this process. The ceramide-based cell survival "rheostat" between these opposing signalling metabolites is essential in the mechanotransductive vascular targeting following USMB treatment. In this review, we aim to summarize the past and latest findings on ceramide-based vascular-targeted strategies, including novel mechanotransductive methodologies.

High-throughput metabolomics reveals dysregulation of hydrophobic metabolomes in cancer cell lines by Eleusine indica

Eleusine indica, which is used in traditional medicine, exhibits antiproliferative activity against several cancer cell lines. However, metabolomic studies to evaluate the metabolite changes induced by E. indica in cancer cells are still lacking. The present study investigated the anticancer effects of a root fraction of E. indica (R-S5-C1-H1) on H1299, MCF-7, and SK-HEP-1 cell lines and analyzed metabolic changes in the treated cancer cells using ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS). Cell metabolic activity assays demonstrated that the cell viability of the three cancer cell lines was significantly reduced following treatment with R-S5-C1-H1, with half-maximal inhibitory concentrations values of 12.95 µg/mL, 15.99 µg/mL, and 13.69 µg/mL at 72 h, respectively. Microscopy analysis using Hoechst 33342 and Annexin V fluorescent dyes revealed that cells treated with R-S5-C1-H1 underwent apoptotic cell death, while chemometric analysis suggested that apoptosis was triggered 48 h after treatment with R-S5-C1-H1. Deconvoluted cellular metabolomics revealed that hydrophobic metabolites were significantly altered, including triacylglycerols, phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, and ceramide, suggesting that apoptosis induction by R-S5-C1-H1 potentially occurred through modulation of phospholipid synthesis and sphingolipid metabolism. These metabolomic profiling results provide new insights into the anticancer mechanisms of E. indica and facilitate the overall understanding of molecular events following therapeutic interventions.

Multifunctional Role of Lipids in Modulating the Tumorigenic Properties of 4T1 Breast Cancer Cells

Tumor growth and progression are linked to an altered lipid metabolism in the tumor microenvironment (TME), including tumor cells and tumor-associated macrophages (TAMs). A growing number of lipid metabolism targeting drugs have shown efficacy in anti-tumor therapy. In addition, exogenously applied lipids and lipid analogues have demonstrated anti-tumor activities in several cancers, including breast cancer. In this study, we investigated the anti-tumor efficacies of the natural lipids palmitic acid (PA), sphingomyelin (SM), ceramide (Cer) and docosahexaenoic acid (DHA) on breast cancer cells. All tested lipids reduced the malignancy of breast cancer cells in vitro by impairing cell proliferation, migration and invasiveness. PA showed superior anti-tumor properties, as it additionally impaired cancer cell viability by inducing apoptosis, without affecting healthy cells. Co-culture experiments further demonstrated that Cer and PA reduced the immunosuppressive phenotype of M2 macrophages and the M2 macrophage-promoted the epithelial–mesenchymal transition (EMT) and migration of breast cancer cells. At the molecular level, this coincided with the up-regulation of E-cadherin. Our results highlight a powerful role for exogenously applied PA and Cer in reducing breast cancer tumorigenicity by simultaneously targeting cancer cells and M2 macrophages. Our findings support the notion that lipids represent alternative biocompatible therapeutic agents for breast cancer.

Proteomic and metabolomic profiling combined with in vitro studies reveal the antiproliferative mechanism of silver nanoparticles in MDA-MB-231 breast carcinoma cells

Silver nanoparticles, shaped and stabilized by various means, are known to alter biological systems and promote cytotoxicity. However, the precise mechanism by which they induce toxic outcomes in cancer cells is poorly understood. Using a combination of cellular and biophysical assays and proteomic and metabolomic analyses, we report the cytotoxic mechanism of action of tryptone-stabilized silver nanoparticles (T-AgNPs). After their facile synthesis and characterization using an assortment of spectroscopic techniques and transmission electron microscopy, the mechanism of action of the particles was elucidated using MDA-MB-231 breast cancer cells as the cell model. The nanoparticles inhibited the proliferative (IC₅₀:100 ± 3 μg mL^-1) and clonogenic potential of the cells. Flow cytometry analyses revealed an absence of phase-specific cell cycle arrest but extensive cell death in the treated cells. The mechanism of action of the particles consisted of their direct binding to the microtubule-building protein tubulin and the disruption of its helical integrity, as confirmed via fluorometric analysis and far-UV spectropolarimetry, respectively. The binding hampered the assembly of microtubules, as confirmed via polymer mass analysis of in vitro assembled, purified tubulin and immunofluorescence imaging of cellular microtubules. Proteomic and metabolomic analyses revealed the downregulation of lipid metabolism to be a synergistic contributor to cell death. Taken together, we report a novel antiproliferative mechanism of action of T-AgNPs that involves tubulin disruption and the downregulation of lipid metabolism.

Plasma Sphingosine-1-Phosphate Levels Are Associated with Progression of Estrogen Receptor-Positive Breast Cancer

Although numerous experiments revealed an essential role of a lipid mediator, sphingosine-1-phosphate (S1P), in breast cancer (BC) progression, the clinical significance of S1P remains unclear due to the difficulty of measuring lipids in patients. The aim of this study was to determine the plasma concentration of S1P in estrogen receptor (ER)-positive BC patients, as well as to investigate its clinical significance. We further explored the possibility of a treatment strategy targeting S1P in ER-positive BC patients by examining the effect of FTY720, a functional antagonist of S1P receptors, on hormone therapy-resistant cells. Plasma S1P levels were significantly higher in patients negative for progesterone receptor (PgR) expression than in those positive for expression (p = 0.003). Plasma S1P levels were also significantly higher in patients with larger tumor size (p = 0.012), lymph node metastasis (p = 0.014), and advanced cancer stage (p = 0.003), suggesting that higher levels of plasma S1P are associated with cancer progression. FTY720 suppressed the viability of not only wildtype MCF-7 cells, but also hormone therapy-resistant MCF-7 cells. Targeting S1P signaling in ER-positive BC appears to be a possible new treatment strategy, even for hormone therapy-resistant patients.

Lipid metabolism in cancer progression and therapeutic strategies

Dysregulated lipid metabolism represents an important metabolic alteration in cancer. Fatty acids, cholesterol, and phospholipid are the three most prevalent lipids that act as energy producers, signaling molecules, and source material for the biogenesis of cell membranes. The enhanced synthesis, storage, and uptake of lipids contribute to cancer progression. The rewiring of lipid metabolism in cancer has been linked to the activation of oncogenic signaling pathways and cross talk with the tumor microenvironment. The resulting activity favors the survival and proliferation of tumor cells in the harsh conditions within the tumor. Lipid metabolism also plays a vital role in tumor immunogenicity via effects on the function of the noncancer cells within the tumor microenvironment, especially immune‐associated cells. Targeting altered lipid metabolism pathways has shown potential as a promising anticancer therapy. Here, we review recent evidence implicating the contribution of lipid metabolic reprogramming in cancer to cancer progression, and discuss the molecular mechanisms underlying lipid metabolism rewiring in cancer, and potential therapeutic strategies directed toward lipid metabolism in cancer. This review sheds new light to fully understanding of the role of lipid metabolic reprogramming in the context of cancer and provides valuable clues on therapeutic strategies targeting lipid metabolism in cancer.

Characterizing the breast cancer lipidome and its interaction with the tissue microbiota

Breast cancer is the most diagnosed cancer amongst women worldwide. We have previously shown that there is a breast microbiota which differs between women who have breast cancer and those who are disease-free. To better understand the local biochemical perturbations occurring with disease and the potential contribution of the breast microbiome, lipid profiling was performed on non-tumor breast tissue collected from 19 healthy women and 42 with breast cancer. Here we identified unique lipid signatures between the two groups with greater amounts of lysophosphatidylcholines and oxidized cholesteryl esters in the tissue from women with breast cancer and lower amounts of ceramides, diacylglycerols, phosphatidylcholines, and phosphatidylethanolamines. By integrating these lipid signatures with the breast bacterial profiles, we observed that Gammaproteobacteria and those from the class Bacillus, were negatively correlated with ceramides, lipids with antiproliferative properties. In the healthy tissues, diacylglyerols were positively associated with Acinetobacter, Lactococcus, Corynebacterium, Prevotella and Streptococcus. These bacterial groups were found to possess the genetic potential to synthesize these lipids. The cause-effect relationships of these observations and their contribution to disease patho-mechanisms warrants further investigation for a disease afflicting millions of women around the world.

Interaction of microRNAs with sphingosine kinases, sphingosine-1 phosphate, and sphingosine-1 phosphate receptors in cancer

Sphingosine-1-phosphate (S1P), a pleiotropic lipid mediator, participates in various cellular processes during tumorigenesis, including cell proliferation, survival, drug resistance, metastasis, and angiogenesis. S1P is formed by two sphingosine kinases (SphKs), SphK1 and SphK2. The intracellularly produced S1P is delivered to the extracellular space by ATP-binding cassette (ABC) transporters and spinster homolog 2 (SPNS2), where it binds to five transmembrane G protein-coupled receptors to mediate its oncogenic functions (S1PR1-S1PR5). MicroRNAs (miRNAs) are small non-coding RNAs, 21-25 nucleotides in length, that play numerous crucial roles in cancer, such as tumor initiation, progression, apoptosis, metastasis, and angiogenesis via binding to the 3'-untranslated region (3'-UTR) of the target mRNA. There is growing evidence that various miRNAs modulate tumorigenesis by regulating the expression of SphKs, and S1P receptors. We have reviewed various roles of miRNAs, SphKs, S1P, and S1P receptors (S1PRs) in malignancies and how notable miRNAs like miR-101, miR-125b, miR-128, and miR-506, miR-1246, miR-21, miR-126, miR499a, miR20a-5p, miR-140-5p, miR-224, miR-137, miR-183-5p, miR-194, miR181b, miR136, and miR-675-3p, modulate S1P signaling. These tumorigenesis modulating miRNAs are involved in different cancers including breast, gastric, hepatocellular carcinoma, prostate, colorectal, cervical, ovarian, and lung cancer via cell proliferation, invasion, angiogenesis, apoptosis, metastasis, immune evasion, chemoresistance, and chemosensitivity. Therefore, understanding the interaction of SphKs, S1P, and S1P receptors with miRNAs in human malignancies will lead to better insights for miRNA-based cancer therapy.

Sphingosine 1-phosphate (S1P) produced by sphingosine kinase 1 (SphK1) and exported via ABCC1 is related to hepatocellular carcinoma (HCC) progression

Sphingosine-1-Phosphate (S1P) is produced by Sphingosine Kinase 1 (SphK1) in the cell and is transported out of the cells by ABCC1 transporter. S1P induces inflammation, angiogenesis and modulates tumor immune microenvironment (TIME) in autocrine and paracrine manner. We hypothesized that high S1P export is associated with hepatocellular carcinoma (HCC) progression and worse survival. Transcriptome linked with clinical data were obtained from a total of 533 patients from TCGA (The Cancer Genome Atlas)-HCC (n = 350), GSE6764 (n = 75), and GSE89377 (n = 108) cohorts. Both SphK1 and ABCC1 were expressed higher in aggressive HCC than normal liver or cirrhosis and correlated with MKi67 expression. High S1P export by high expression of both SphK1 and ABCC1 enriched gene sets related with cell proliferation (E2F targets, G2M checkpoint, MYC targets), inflammation (Inflammatory response, TNFα, IL6), angiogenesis, metastasis (TGF-β, epithelial-mesenchymal transition), and immune response (allograft rejection, complement, interferon-gamma) in gene set enrichment analysis. High S1P export was associated with elevation of HGF, HSP90AA1, TRAF2, and AKR1B10. It was also associated with high intratumor heterogeneity, leucocyte fraction, macrophage regulation and lymphocyte infiltration, as well as T helper type2 cells, macrophages, dendritic cells, CD4⁺ T memory activated cells, B-cells and cytolytic activity score in TIME. High S1P export was associated with significantly worse disease specific survival (P = 0.034) and overall survival (P = 0.004) compared to low S1P export group. In conclusion, simultaneous high expression of SphK1 and ABCC1 that reflect S1P export is associated with enhancement of both HCC progression and immune response. Given that S1P export was also associated with worse survival, we cannot help but speculate that pro-cancer pathways activated by S1P may overwhelm the anti-cancer immune response mediated by S1P.

Acute toxicity evaluation of a novel ceramide analog for the treatment of breast cancer

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Novel ceramide drug for breast cancer.

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Toxicological profile was studied.

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Single dose of 80 mg/kg dose was safe.

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Single dose of 120 mg/kg caused minor liver and cardiac tissue damage.

We have previously reported that treating triple-negative tumor bearing nude mice with intraperitoneal (ip) 10 mg/kg body weight of (S,E)-3-hydroxy-2-(2-hydroxybenzylidene)amino-N-tetradecylpropanamide, a ceramide analog, 5 days per week for 3 weeks, was shown not only to suppress tumor growth but also to reduce metastasis. Studies reported here focus on determining the toxicity of this drug in the nude mice. During the first study, treated animals (single intraperitoneal (ip) injection, 0, 40, 80 and 120 mg/kg body weight) were closely monitored for 14 days for any signs of illness or death. No mice were lost in any animal groups; however, hepatic serum enzymes were elevated, and hepatic and heart tissue damages were found in the highest dosage group. The subsequent study was performed using a lower dosage range (single ip injection, 0, 25, 50 and 75 mg/kg body weight), which resulted in no significant toxicity. All tested parameters were within normal ranges, with no observed irregularities. Our findings show that a single ip dose of this ceramide analog induced liver and heart toxicity at 120 mg/kg but not at doses of 80 mg/kg body weight or lower.

Dysregulation of sphingolipid metabolic enzymes leads to high levels of sphingosine-1-phosphate and ceramide in human hepatocellular carcinoma

AIM

Sphingosine-1-phosphate (S1P) and ceramide are bioactive sphingolipids known to be important in regulating numerous processes involved in cancer progression. The aim of this study was to determine the absolute levels of sphingolipids in hepatocellular carcinoma (HCC) utilizing data obtained from surgical specimens. In addition, we explored the clinical significance of S1P in patients with HCC and the biological role of S1P in HCC cells.

METHODS

Tumors and normal liver tissues were collected from 20 patients with HCC, and sphingolipids were measured by mass spectrometry. The Cancer Genome Atlas (TCGA) cohort was utilized to evaluate gene expression of enzymes related to sphingolipid metabolism. Immunohistochemistry of phospho-sphingosine kinase 1 (SphK1), an S1P-producing enzyme, was performed for 61 surgical specimens. CRISPR/Cas9-mediated SphK1 knockout cells were used to examine HCC cell biology.

RESULTS

S1P levels were substantially higher in HCC tissue compared with normal liver tissue. Levels of other sphingolipids upstream of S1P in the metabolic cascade, such as sphingomyelin, monohexosylceramide and ceramide, were also considerably higher in HCC tissue. Enzymes involved in generating S1P and its precursor, ceramide, were found in higher levels in HCC compared with normal liver tissue. Immunohistochemical analysis found that phospho-SphK1 expression was associated with tumor size. Finally, in vitro assays indicated that S1P is involved in the aggressiveness of HCC cells.

CONCLUSIONS

Sphingolipid levels, including S1P and ceramide, were elevated in HCC compared with surrounding normal liver tissue. Our findings suggest S1P plays an important role in HCC tumor progression, and further examination is warranted.

The long chain base unsaturation has a stronger impact on 1-deoxy(methyl)-sphingolipids biophysical properties than the structure of its C1 functional group

1-deoxy-sphingolipids, also known as atypical sphingolipids, are directly implicated in the development and progression of hereditary sensory and autonomic neuropathy type 1 and diabetes type 2. The mechanisms underlying their patho-physiological actions are yet to be elucidated. Accumulating evidence suggests that the biological actions of canonical sphingolipids are triggered by changes promoted on membrane organization and biophysical properties. However, little is known regarding the biophysical implications of atypical sphingolipids. In this study, we performed a comprehensive characterization of the effects of the naturally occurring 1-deoxy-dihydroceramide, 1-deoxy-ceramide^Δ14Z and 1-deoxymethyl-ceramide^Δ3E in the properties of a fluid membrane. In addition, to better define which structural features determine sphingolipid ability to form ordered domains, the synthetic 1-O-methyl-ceramide^Δ4E and 1-deoxy-ceramide^Δ4E were also studied. Our results show that natural and synthetic 1-deoxy(methyl)-sphingolipids fail to laterally segregate into ordered domains as efficiently as the canonical C16-ceramide. The impaired ability of atypical sphingolipids to form ordered domains was more dependent on the presence, position, and configuration of the sphingoid base double bond than on the structure of its C1 functional group, due to packing constraints introduced by an unsaturated backbone. Nonetheless, absence of a hydrogen bond donor and acceptor group at the C1 position strongly reduced the capacity of atypical sphingolipids to form gel domains. Altogether, the results showed that 1-deoxy(methyl)-sphingolipids induce unique changes on the biophysical properties of the membranes, suggesting that these alterations might, in part, trigger the patho-biological actions of these lipids.

Untargeted metabolomics of newborn dried blood spots reveals sex-specific associations with pediatric acute myeloid leukemia

The etiology of pediatric acute myeloid leukemia (AML) is largely unknown, but evidence for mutations in utero and long latency periods suggests that environmental factors play a role. Therefore, we used untargeted metabolomics of archived newborn dried blood spots (DBS) to investigate neonatal exposures as potential causal risk factors for AML. Untargeted metabolomics profiling was performed on DBS punches from 48 pediatric patients with AML and 46 healthy controls as part of the California Childhood Leukemia Study (CCLS). Because sex disparities are suggested by differences in AML incidence rates, metabolite features associated with AML were identified in analyses stratified by sex. There was no overlap between the 16 predictors of AML in females and 15 predictors in males, suggesting that neonatal metabolomic profiles of pediatric AML risk are sex-specific. In females, four predictors of AML were putatively annotated as ceramides, a class of metabolites that has been linked with cancer cell proliferation. In females, two metabolite predictors of AML were strongly correlated with breastfeeding duration, indicating a possible biological link between this putative protective risk factor and childhood leukemia. In males, a heterogeneous metabolite profile of AML predictors was observed. Replication with larger participant numbers is required to validate findings.

Ceramide expression in relation to breast cancer molecular subtypes in Saudi women

Background/Introduction

Despite advances in the diagnosis and management of breast cancer (BC), it is still associated with high mortality rates. New biomarkers are being developed for the diagnosis, treatment, and prediction of responses of BC. Ceramide (CER), a bioactive sphingolipid, has emerged recently as a useful diagnostic tool in several types of tumors. In this study, we evaluated CER expression in invasive BC and assessed its relation to the molecular subtypes of BC.

Materials and methods

The clinical data and histopathological slides of 50 patients with invasive ductal carcinoma were retrieved and reviewed. The cases were then stained with a mouse monoclonal anti-ceramide antibody. Pearson correlation was used to assess the correlation between CER percentage and intensity and other clinical and pathological variables.

Results

CER expression showed a direct relationship with estrogen and progesterone receptors Allred scores. However, it showed an inverse relation with tumor grade, HER2/neu status and Ki-67 index.

Conclusions

CER expression is likely to be associated with luminal BC molecular subtypes. However, more research is needed to confirm these results and to explore its relation to the different clinical outcomes, including response to treatment and prognosis.

Discovery of novel ceramide analogs with favorable pharmacokinetic properties and combination with AKT inhibitor against colon cancer

Ceramides have emerged as potential therapeutic option with novel mechanism to affect the proliferation, differentiation, senescence, and apoptosis of cancer cells through regulation of multiple signal transduction. Aiming at the improvement of the apoptosis activity and pharmacokinetic profiles of ceramides, a novel series of ceramide analogs were developed through structure simplification and conformation restriction. Among them, compound 12 bearing an alkoxyl naphthyl motif, with favorable rat pharmacokinetic properties, showed better anti-proliferative activity against various colon cancer cells (IC50 ∼20 μM) than other ceramide analogues, as well as the synergistic effect combined with AKT inhibitor MK2206. Additionally, we demonstrated that this combination therapy promoted caspase 3-dependent apoptotic pathway and intensified cell cycle arrest in the G0/G1 phase. Furthermore, the combination of compound 12 and MK2206 displayed synergistic anti-tumor effect in vivo.

A circular network of coregulated sphingolipids dictates lung cancer growth and progression

Background

Sphingolipid metabolism is among the top dysregulated pathways in non-small cell lung carcinomas (NSCLC). However, the molecular control of sphingolipid metabolic reprogramming in cancer progression remains unclear.

Methods

We first determined the correlation between sphingolipid metabolic gene expression and patient prognosis. We then carried out sphingolipidomics analysis of health individual and NSCLC patient sera as well as B3GNT5 and GAL3ST1 genetically perturbed NSCLC cell lines. We used these cell lines to perform tumorigenesis study to determine the cellular role of B3GNT5 and GAL3ST1 in cancer growth and progression.

Findings

The expression of B3GNT5 and GAL3ST1 among sphingolipid metabolic enzymes is most significantly associated with patient prognosis, whilst sphingolipidomics analysis of healthy individual and NSCLC patient sera identifies their metabolites, lacto/neolacto-series glycosphingolipid and sulfatide species, as potential biomarkers that were more effective than current clinical biomarkers for staging patients. Further network analysis of the sphingolipidomes reveals a circular network of coregulated sphingolipids, indicating that the lacto/neolacto-series glycosphingolipid/sulfatide balance functions as a checkpoint to determine sphingolipid metabolic reprograming during patient progression. Sphingolipidomics analysis of B3GNT5/GAL3ST1 genetically perturbed NSCLC cell lines confirms their key regulatory role in sphingolipid metabolism, while B3GNT5 and GAL3ST1 expression has an opposite role on tumorigenesis.

Interpretation

Our results provide new insights whereby B3GNT5 and GAL3ST1 differentially regulate sphingolipid metabolism in lung cancer growth and progression.

Funding

This work was supported by the Natural Science Foundation of China (81872142, 81920108028); Guangzhou Science and Technology Program (201904020008); Guangdong Science and Technology Department (2020A0505100029, 2019A1515011802, 2020A1515011280, 2020B1212060018, 2020B1212030004); China Postdoctoral Science Foundation (2019M650226, 2019M650227).

Alternative splicing of ceramide synthase 2 alters levels of specific ceramides and modulates cancer cell proliferation and migration in Luminal B breast cancer subtype

Global dysregulation of RNA splicing and imbalanced sphingolipid metabolism has emerged as promoters of cancer cell transformation. Here, we present specific signature of alternative splicing (AS) events of sphingolipid genes for each breast cancer subtype from the TCGA-BRCA dataset. We show that ceramide synthase 2 (CERS2) undergoes a unique cassette exon event specifically in Luminal B subtype tumors. We validated this exon 8 skipping event in Luminal B cancer cells compared to normal epithelial cells, and in patient-derived tumor tissues compared to matched normal tissues. Differential AS-based survival analysis shows that this AS event of CERS2 is a poor prognostic factor for Luminal B patients. As Exon 8 corresponds to catalytic Lag1p domain, overexpression of AS transcript of CERS2 in Luminal B cancer cells leads to a reduction in the level of very-long-chain ceramides compared to overexpression of protein-coding (PC) transcript of CERS2. We further demonstrate that this AS event-mediated decrease of very-long-chain ceramides leads to enhanced cancer cell proliferation and migration. Therefore, our results show subtype-specific AS of sphingolipid genes as a regulatory mechanism that deregulates sphingolipids like ceramides in breast tumors, and can be explored further as a suitable therapeutic target.

Cholesterol and Sphingolipid Enriched Lipid Rafts as Therapeutic Targets in Cancer

Lipid rafts are critical cell membrane lipid platforms enriched in sphingolipid and cholesterol content involved in diverse cellular processes. They have been proposed to influence membrane properties and to accommodate receptors within themselves by facilitating their interaction with ligands. Over the past decade, technical advances have improved our understanding of lipid rafts as bioactive structures. In this review, we will cover the more recent findings about cholesterol, sphingolipids and lipid rafts located in cellular and nuclear membranes in cancer. Collectively, the data provide insights on the role of lipid rafts as biomolecular targets in cancer with good perspectives for the development of innovative therapeutic strategies.

Antitumor Efficacy of Ceranib-2 with Nano-Formulation of PEG and Rosin Esters

Ceranib-2 is a recently discovered, poorly water-soluble potent ceramidase inhibitor, with the ability to suppress cancer cell proliferation and delay tumor growth. However, its poor water solubility and weak cellular bioavailability hinder its use as a therapeutic agent for cancer. PEGylated rosin esters are an excellent platform as a natural polymer for drug delivery applications, especially for controlling drug release due to their degradability, biocompatibility, capability to improve solubility, and pharmacokinetics of potent drugs. In this study, stable aqueous amphiphilic submicron-sized PEG400-rosin ester-ceranib-2 (PREC-2) particles, ranging between 100 and 350 nm in a 1:1 mixture, were successfully synthesized by solvent evaporation mediated by sonication.Conclusion: Stable aqueous PEGylated rosin ester nanocarriers might present a significant solution to improve solubility, pharmacokinetic, and bioavailability of ceranib-2, and hold promises for use as an anticancer adjacent drug after further investigations.

Remodeling Lipids in the Transition from Chronic Liver Disease to Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC) has poor prognosis. We studied blood lipids by comparing healthy volunteers to patients with chronic liver disease (CLD), and to patients with HCC caused by viral infections. We contrasted our findings in blood to lipid alterations in liver tumor and nontumor tissue samples from HCC patients. In blood, most lipid species were found at increased levels in CLD patients compared to healthy volunteers. This trend was mostly reversed in HCC versus CLD patients. In liver tumor tissues, levels of many lipids were decreased compared to paired nontumor liver tissues. Differences in lipid levels were further defined by alterations in the degree of saturation in the fatty acyl chains. Some lipids, including free fatty acids, saturated lysophosphatidylcholines and saturated triacylglycerides, showed a continuous trend in the transition from the blood of healthy controls to CLD and HCC patients. For HCC patients, phosphatidylglycerides showed similar alterations in both blood and tissues.

Abstract

Hepatocellular carcinoma (HCC) is a worldwide health problem. HCC patients show a 50% mortality within two years of diagnosis. To better understand the molecular pathogenesis at the level of lipid metabolism, untargeted UPLC MS—QTOF lipidomics data were acquired from resected human HCC tissues and their paired nontumor hepatic tissues (n = 46). Blood samples of the same HCC subjects (n = 23) were compared to chronic liver disease (CLD) (n = 15) and healthy control (n = 15) blood samples. The participants were recruited from the National Liver Institute in Egypt. The lipidomics data yielded 604 identified lipids that were divided into six super classes. Five-hundred and twenty-four blood lipids were found as significantly differentiated (p < 0.05 and qFDR p < 0.1) between the three study groups. In the blood of CLD patients compared to healthy control subjects, almost all lipid classes were significantly upregulated. In CLD patients, triacylglycerides were found as the most significantly upregulated lipid class at qFDR p = 1.3 × 10⁻⁵⁶, followed by phosphatidylcholines at qFDR p = 3.3 × 10⁻⁵¹ and plasmalogens at qFDR p = 1.8 × 10^-46. In contrast, almost all blood lipids were significantly downregulated in HCC patients compared to CLD patients, and in HCC tissues compared to nontumor hepatic tissues. Ceramides were found as the most significant lipid class (qFDR p = 1 × 10⁻¹⁴) followed by phosphatidylglycerols (qFDR p = 3 × 10⁻⁹), phosphatidylcholines and plasmalogens. Despite these major differences, there were also common trends in the transitions between healthy controls, CLD and HCC patients. In blood, several mostly saturated triacylglycerides showed a continued increase in the trajectory towards HCC, accompanied by reduced levels of saturated free fatty acids and saturated lysophospatidylcholines. In contrast, the largest overlaps of lipid alterations that were found in both HCC tissue and blood comparisons were decreased levels of phosphatidylglycerols and sphingolipids. This study highlights the specific impact of HCC tumors on the circulating lipids. Such data may be used to target lipid metabolism for prevention, early detection and treatment of HCC in the background of viral-related CLD etiology.

High levels of modified ceramides are a defining feature of murine and human cancer cachexia

BACKGROUND

Cancer cachexia (CCx) is a multifactorial energy-wasting syndrome reducing the efficiency of anti-cancer therapies, quality of life, and survival of cancer patients. In the past years, most studies focused on the identification of tumour and host-derived proteins contributing to CCx. However, there is still a lack of studies addressing the changes in bioactive lipids. The aim of this study was to identify specific lipid species as a hallmark of CCx by performing a broad range lipid analysis of plasma from well-established CCx mouse models as well as cachectic and weight stable cancer patients.

METHODS

Plasma from non-cachectic (PBS-injected mice, NC26 tumour-bearing mice), pre-cachectic and cachectic mice (C26 and LLC tumour-bearing mice, Apc^Min/+ mutant mice), and plasma from weight stable and cachectic patients with gastrointestinal cancer, were analysed using the Lipidyzer™ platform. In total, 13 lipid classes and more than 1100 lipid species, including sphingolipids, neutral and polar glycerolipids, were covered by the analysis. Correlation analysis between specific lipid species and readouts of CCx were performed. Lipidomics data were confirmed by gene expression analysis of metabolic organs to analyse enzymes involved in sphingolipid synthesis and degradation.

RESULTS

A decrease in several lysophosphatidylcholine (LPC) species and an increase in numerous sphingolipids including sphingomyelins (SMs), ceramides (CERs), hexosyl-ceramides (HCERs) and lactosyl-ceramides (LCERs), were mutual features of CCx in both mice and cancer patients. Notably, sphingolipid levels gradually increased during cachexia development. Key enzymes involved in ceramide synthesis were elevated in liver but not in adipose, muscle, or tumour tissues, suggesting that ceramide turnover in the liver is a major contributor to elevated sphingolipid levels in CCx. LPC(16:1), LPC(20:3), SM(16:0), SM(24:1), CER(16:0), CER(24:1), HCER(16:0), and HCER(24:1) were the most consistently affected lipid species between mice and humans and correlated negatively (LPCs) or positively (SMs, CERs and HCERs) with the severity of body weight loss.

CONCLUSIONS

High levels of sphingolipids, specifically ceramides and modified ceramides, are a defining feature of murine and human CCx and may contribute to tissue wasting and skeletal muscle atrophy through the inhibition of anabolic signals. The progressive increase in sphingolipids during cachexia development supports their potential as early biomarkers for CCx.

Ceramide Pathway Regulators Predict Clinical Prognostic Risk and Affect the Tumor Immune Microenvironment in Lung Adenocarcinoma

Purpose

The ceramide pathway is strongly associated with the regulation of tumor proliferation, differentiation, senescence, and apoptosis. This study aimed to explore the gene signatures, prognostic value, and immune-related effects of ceramide-regulated genes in lung adenocarcinoma (LUAD).

Methods

Public datasets of LUAD from The Cancer Genome Atlas and Gene Expression Omnibus were selected. Consensus clustering was adopted to classify LUAD patients, and a least absolute shrinkage and selection operator (LASSO) regression model was employed to develop a prognostic risk signature. CIBERSORT algorithm was used to estimate the association between the risk signature and the tumor immune microenvironment.

Results

Most of the 22 ceramide-regulated genes were differentially expressed between LUAD and normal samples. LUAD patients were classified into two subgroups (cluster 1 and 2) and cluster 2 was associated with a poor prognosis. Furthermore, a prognostic risk signature was developed based on the three ceramide-regulated genes, Cytochrome C (CYCS), V-rel reticuloendotheliosis viral oncogene homolog A (RELA) and Fas-associated via death domain (FADD). LUAD patients with low- and high-risk scores differed concerning the subtypes of tumor-infiltrating immune cells. A moderate to weak correlation was observed between the risk score and tumor-infiltrating immune cells.

Conclusions

Ceramide-regulated genes could predict clinical prognostic risk and affect the tumor immune microenvironment in LUAD.

Identification of long-term survival-associated gene in breast cancer

Breast cancer patients at the same stage may show different clinical prognoses or different therapeutic effects of systemic therapy. Differentially expressed genes of breast cancer were identified from GSE42568. Through survival, receiver operating characteristic (ROC) curve, random forest, GSVA and a Cox regression model analyses, genes were identified that could be associated with survival time in breast cancer. The molecular mechanism was identified by enrichment, GSEA, methylation and SNV analyses. Then, the expression of a key gene was verified by the TCGA dataset and RT-qPCR, Western blot, and immunohistochemistry. We identified 784 genes related to the 5-year overall survival time of breast cancer. Through ROC curve and random forest analysis, 10 prognostic genes were screened. These were integrated into a complex by GSVA, and high expression of the complex significantly promoted the recurrence-free survival of patients. In addition, key genes were related to immune and metabolic-related functions. Importantly, we identified methylation of MEX3A and TBC1D 9 and mutations events. Finally, the expression of UGCG was verified by the TCGA dataset and by experimental methods in our own samples. These results indicate that 10 genes may be potential biomarkers and therapeutic targets for long-term survival in breast cancer, especially UGCG.

Ceramide synthase 6 predicts poor prognosis and activates the AKT/mTOR/4EBP1 pathway in high-grade serous ovarian cancer

Objective: Ovarian cancer is one of the most common gynecological malignancies worldwide, and its mortality rate ranks first among gynecologic cancers. Ceramide synthases are closely related to cancer development. In this study, we investigated the role of ceramide synthase 6 (CerS6) in the development of serous ovarian cancer. Methods: Expression of CerS6 in cancerous and healthy ovarian tissue was assessed by database analysis and immunohistochemistry. The biological role of CerS6 in serous ovarian cancer cells was assessed by CerS6 knockdown followed by cell counting, colony formation, transwell migration, wound healing, and flow cytometry assays and measurement of tumor proliferation in nude mice. Signaling pathway components were analyzed by Western blotting. Gene enrichment was analyzed by GSEA and R, and RNA sequencing was used to compare the transcriptomes of serous ovarian cancer cells with and without CerS6 knockdown. Results: High CerS6 expression in ovarian cancer tissues was closely related to poor prognosis. Knockdown of CerS6 inhibited serous ovarian cancer cell proliferation, invasion, and metastasis and promoted their apoptosis. In addition, CerS6 knockdown increased the proportion of serous ovarian cancer cells in G2/M phase. CerS6 regulates cell cycle through the AKT/mTOR/4EBP1 signaling pathway, which affects cell proliferation and metastasis. The GSEA, R, and RNA sequencing analyses showed that knocking down CerS6 significantly affects cell cycle in serous ovarian cancer cells. Conclusions: CerS6 may have an oncogenic role in ovarian cancer and may represent a new prognostic marker and therapeutic target for serous ovarian cancer.

Role of Sphingolipid Signaling in Glomerular Diseases: Focus on DKD and FSGS

Sphingolipids are well-recognized as major players in the pathogenesis of many human diseases, including chronic kidney disease. The kidney is a very sensitive organ to alterations in sphingolipid metabolism. The critical issues to be addressed in this review relate to the role of sphingolipids and enzymes involved in sphingolipid metabolism in the pathogenesis of glomerular diseases with a special focus on podocytes, a key cellular component of the glomerular filtration barrier. Among several sphingolipids, we will highlight the role of ceramide, sphingosine, sphingosine-1-phosphate and ceramide-1-phosphate. Additionally, we will summarize the current knowledge with regard to the use of sphingolipids as therapeutic agents for the treatment of podocyte injury in kidney disease.

Circulating sphingomyelins on estrogen receptor-positive and estrogen receptor-negative breast cancer-specific survival

Aim: This study aims to determine whether a causal relationship exists between circulating sphingomyelins and breast cancer-specific survival, since, if one does, sphingomyelins could be studied as a therapeutic target in the management of breast cancer. Patients/materials & methods: Mendelian randomization is used here to investigate whether higher levels of circulating sphingomyelins impact breast cancer-specific survival for estrogen receptor-negative (ER–) and estrogen receptor-positive (ER+) patients. Results: The results suggest a null effect of sphingomyelins for ER– breast cancer-specific survival and a protective effect for ER+ breast cancer-specific survival. Sensitivity analyses implicate low-density lipoprotein cholesterol as a potential confounder. Conclusion: Future studies should replicate and triangulate the present findings with other methods and tease out the roles of sphingomyelins and low-density lipoprotein cholesterol on breast cancer-specific survival.

Ether lipid and sphingolipid expression patterns are estrogen receptor-dependently altered in breast cancer cells

Identifying co-expression of lipid species is challenging, but indispensable to identify novel therapeutic targets for breast cancer treatment. Lipid metabolism is often dysregulated in cancer cells, and changes in lipid metabolism affect cellular processes such as proliferation, autophagy, and tumor development. In addition to mRNA analysis of sphingolipid metabolizing enzymes, we performed liquid chromatography time-of-flight mass spectrometry analysis in three breast cancer cell lines. These breast cancer cell lines differ in estrogen receptor and G-protein coupled estrogen receptor 1 status. Our data show that sphingolipids and non-sphingolipids are strongly increased in SKBr3 cells. SKBr3 cells are estrogen receptor negative and G-protein coupled estrogen receptor 1 positive. Treatment with G15, a G-protein coupled estrogen receptor 1 antagonist, abolishes the effect of increased sphingolipid and non-sphingolipid levels in SKBr3 cells. In particular, ether lipids are expressed at much higher levels in cancer compared to normal cells and are strongly increased in SKBr3 cells. Our analysis reveals that this is accompanied by increased sphingolipid levels such as ceramide, sphingadiene-ceramide and sphingomyelin. This shows the importance of focusing on more than one lipid class when investigating molecular mechanisms in breast cancer cells. Our analysis allows unbiased screening for different lipid classes leading to identification of co-expression patterns of lipids in the context of breast cancer. Co-expression of different lipid classes could influence tumorigenic potential of breast cancer cells. Identification of co-regulated lipid species is important to achieve improved breast cancer treatment outcome.

Large granular lymphocyte leukemia serum and corresponding hematological parameters reveal unique cytokine and sphingolipid biomarkers and associations with STAT3 mutations

Large granular lymphocyte (LGL) leukemia is a rare hematological disorder with expansion of the T-cell or natural killer (NK) cell lineage. Signal transducer and activator of transcription 3 (STAT3) exhibits somatic activating mutations in 30%-40% of LGL leukemia cases. Transcriptional targets of STAT3 include inflammatory cytokines, thus previous studies have measured cytokine levels of LGL leukemia patients compared to normal donors. Sphingolipid metabolism is a growing area of cancer research, with efforts focused on drug discovery. To date, no studies have examined serum sphingolipids in LGL leukemia patients, and only one study compared a subset of cytokines between the T-LGL and NK-LGL subtypes. Therefore, here, we included both LGL leukemia subtypes with the goals of (a) measuring serum sphingolipids for the first time, (b) measuring cytokines to find distinctions between the subtypes, and (c) establishing relationships with STAT3 mutations and clinical data. The serum analyses identified cytokines (EGF, IP-10, G-CSF) and sphingolipids (SMC22, SMC24, SMC20, LysoSM) significantly different in the LGL leukemia group compared to normal donors. In a mixed STAT3 mutation group, D661Y samples exhibited the highest mean corpuscular volume (MCV) values. We explored this further by expanding the cohort to include larger groups of single STAT3 mutations. Male D661Y STAT3 samples had lower Hgb and higher MCV compared to wild type (WT) or Y640F counterparts. This is the first report examining large groups of individual STAT3 mutations. Overall, our results revealed novel serum biomarkers and evidence that D661Y mutation may show different clinical manifestation compared to WT or Y640F STAT3.

Gene Pair Correlation Coefficients in Sphingolipid Metabolic Pathway as a Potential Prognostic Biomarker for Breast Cancer

Complex diseases such as cancer are usually governed by dynamic and simultaneous modifications of multiple genes. Since sphingolipids are potent bioactive molecules and regulate many important pathophysiological processes such as carcinogenesis, we studied the gene pair correlations of 36 genes (31 genes in the sphingolipid metabolic pathway and 5 genes encoding the sphingosine-1-phosphate receptors) between breast cancer patients and healthy controls. It is remarkable to observe that the gene expressions were widely and strongly correlated in healthy controls but in general lost in breast cancer patients. This study suggests that gene pair correlation coefficients could be applied as a systematic and novel method for the diagnosis and prognosis of breast cancer.