Integrated lipidomics and proteomics reveal cardiolipin alterations, upregulation of HADHA and long chain fatty acids in pancreatic cancer stem cells

Triphenylphosphonium-Conjugated Palmitic Acid for Mitochondrial Targeting of Pancreatic Cancer Cells: Proteomic and Molecular Evidence

Pancreatic ductal adenocarcinoma (PDAC)'s resistance to therapies is mainly attributed to pancreatic cancer stem cells (PCSCs). Mitochondria-impairing agents can be used to hamper PCSC propagation and reduce PDAC progression. Therefore, to develop an efficient vector for delivering drugs to the mitochondria, we synthesized tris(3,5-dimethylphenyl)phosphonium-conjugated palmitic acid. Triphenylphosphonium (TPP) is a lipophilic cationic moiety that promotes the accumulation of conjugated agents in the mitochondrion. Palmitic acid (PA), the most common saturated fatty acid, has pro-apoptotic activity in different types of cancer cells. TPP-PA was prepared by the reaction of 16-bromopalmitic acid with TPP, and its structure was characterized by 1H and 13C NMR and HRMS. We compared the proteomes of TPP-PA-treated and untreated PDAC cells and PCSCs, identifying dysregulated proteins and pathways. Furthermore, assessments of mitochondrial membrane potential, intracellular ROS, cardiolipin content and lipid peroxidation, ER stress, and autophagy markers provided information on the mechanism of action of TPP-PA. The findings showed that TPP-PA reduces PDAC cell proliferation through mitochondrial disruption that leads to increased ROS, activation of ER stress, and autophagy. Hence, TPP-PA might offer a new approach for eliminating both the primary population of cancer cells and PCSCs, which highlights the promise of TPP-derived compounds as anticancer agents for PDAC.

The involvement of the mitochondrial membrane in drug delivery

Treatment effectiveness and biosafety are critical for disease therapy. Bio-membrane modification facilitates the homologous targeting of drugs in vivo by exploiting unique antibodies or antigens, thereby enhancing therapeutic efficacy while ensuring biosafety. To further enhance the precision of disease treatment, future research should shift focus from targeted cellular delivery to targeted subcellular delivery. As the cellular powerhouses, mitochondria play an indispensable role in cell growth and regulation and are closely involved in many diseases (e.g., cancer, cardiovascular, and neurodegenerative diseases). The double-layer membrane wrapped on the surface of mitochondria not only maintains the stability of their internal environment but also plays a crucial role in fundamental biological processes, such as energy generation, metabolite transport, and information communication. A growing body of evidence suggests that various diseases are tightly related to mitochondrial imbalance. Moreover, mitochondria-targeted strategies hold great potential to decrease therapeutic threshold dosage, minimize side effects, and promote the development of precision medicine. Herein, we introduce the structure and function of mitochondrial membranes, summarize and discuss the important role of mitochondrial membrane-targeting materials in disease diagnosis/treatment, and expound the advantages of mitochondrial membrane-assisted drug delivery for disease diagnosis, treatment, and biosafety. This review helps readers understand mitochondria-targeted therapies and promotes the application of mitochondrial membranes in drug delivery. STATEMENT OF SIGNIFICANCE: Bio-membrane modification facilitates the homologous targeting of drugs in vivo by exploiting unique antibodies or antigens, thereby enhancing therapeutic efficacy while ensuring biosafety. Compared to cell-targeted treatment, targeting of mitochondria for drug delivery offers higher efficiency and improved biosafety and will promote the development of precision medicine. As a natural material, the mitochondrial membrane exhibits excellent biocompatibility and can serve as a carrier for mitochondria-targeted delivery. This review provides an overview of the structure and function of mitochondrial membranes and explores the potential benefits of utilizing mitochondrial membrane-assisted drug delivery for disease treatment and biosafety. The aim of this review is to enhance readers' comprehension of mitochondrial targeted therapy and to advance the utilization of mitochondrial membrane in drug delivery.

Novel Antineoplastic Inducers of Mitochondrial Apoptosis in Human Cancer Cells

I propose a new strategy to suppress human cancer completely with two entirely new drug compounds exploiting cancer's Warburg effect characterized by a defective mitochondrial aerobic respiration, substituted by cytosolic aerobic fermentation/glycolysis of D-(+)-glucose into L-(+)-lactic acid. The two essentially new drugs, compound 1 [P(op)T(est)162] and compound 3 (PT167), represent new highly symmetric, four-bladed propeller-shaped polyammonium cations. The in vitro antineoplastic highly efficacious drug compound 3 represents a covalent combination of compound 1 and compound 2 (PT166). The intermediate drug compound 2 is an entirely new colchic(in)oid derivative synthesized from colchicine. Compound 2's structure was determined using X-ray crystallography. Compound 1 and compound 3 were active in vitro versus 60 human cancer cell lines of the National Cancer Institute (NCI) Developmental Therapeutics Program (DTP) 60-cancer cell testing. Compound 1 and compound 3 not only stop the growth of cancer cells to ±0% (cancerostatic effect) but completely kill nearly all 60 cancer cells to a level of almost -100% (tumoricidal effect). Compound 1 and compound 3 induce mitochondrial apoptosis (under cytochrome c release) in all cancer cells tested by (re)activating (in most cancers impaired) p53 function, which results in a decrease in cancer's dysregulated cyclin D1 and an induction of the cell cycle-halting cyclin-dependent kinase inhibitor p21Waf1/p21Cip1.

High-Throughput Microbore LC-MS Lipidomics to Investigate APOE Phenotypes

Microflow liquid chromatography interfaced with mass spectrometry (μLC-MS/MS) is increasingly applied for high-throughput profiling of biological samples and has been proven to have an acceptable trade-off between sensitivity and reproducibility. However, lipidomics applications are scarce. We optimized a μLC-MS/MS system utilizing a 1 mm inner diameter × 100 mm column coupled to a triple quadrupole mass spectrometer to establish a sensitive, high-throughput, and robust single-shot lipidomics workflow. Compared to conventional lipidomics methods, we achieve a ∼4-fold increase in response, facilitating quantification of 351 lipid species from a single iPSC-derived cerebral organoid during a 15 min LC-MS analysis. Consecutively, we injected 303 samples over ∼75 h to prove the robustness and reproducibility of the microflow separation. As a proof of concept, μLC-MS/MS analysis of Alzheimer's disease patient-derived iPSC cerebral organoid reveals differential lipid metabolism depending on APOE phenotype (E3/3 vs E4/4). Microflow separation proves to be an environmentally friendly and cost-effective method as it reduces the consumption of harmful solvents. Also, the data demonstrate robust, in-depth, high-throughput performance to enable routine clinical or biomedical applications.

Transcriptome and Lipidomic Analysis Suggests Lipid Metabolism Reprogramming and Upregulating SPHK1 Promotes Stemness in Pancreatic Ductal Adenocarcinoma Stem-like Cells

Cancer stem cells (CSCs) are considered to play a key role in the development and progression of pancreatic ductal adenocarcinoma (PDAC). However, little is known about lipid metabolism reprogramming in PDAC CSCs. Here, we assigned stemness indices, which were used to describe and quantify CSCs, to every patient from the Cancer Genome Atlas (TCGA-PAAD) database and observed differences in lipid metabolism between patients with high and low stemness indices. Then, tumor-repopulating cells (TRCs) cultured in soft 3D (three-dimensional) fibrin gels were demonstrated to be an available PDAC cancer stem-like cell (CSLCs) model. Comprehensive transcriptome and lipidomic analysis results suggested that fatty acid metabolism, glycerophospholipid metabolism, and, especially, the sphingolipid metabolism pathway were mostly associated with CSLCs properties. SPHK1 (sphingosine kinases 1), one of the genes involved in sphingolipid metabolism and encoding the key enzyme to catalyze sphingosine to generate S1P (sphingosine-1-phosphate), was identified to be the key gene in promoting the stemness of PDAC. In summary, we explored the characteristics of lipid metabolism both in patients with high stemness indices and in novel CSLCs models, and unraveled a molecular mechanism via which sphingolipid metabolism maintained tumor stemness. These findings may contribute to the development of a strategy for targeting lipid metabolism to inhibit CSCs in PDAC treatment.

Fecal Proteome Profile in Dogs Suffering from Different Hepatobiliary Disorders and Comparison with Controls

In the present study, the fecal proteomes of clinically healthy dogs (HD = n. 10), of dogs showing clinical, ultrasonographic, and/or laboratory evidence of different hepatobiliary dysfunction (DHD = n. 10), and of dogs suffering from chronic hepatitis (CHD = n. 10) were investigated with an Ultimate 3000 nanoUPLC system, coupled to an Orbitrap Fusion Lumos Tribrid mass spectrometer. Fifty-two different proteins of canine origin were identified qualitatively in the three study groups, and quantitative differences were found in 55 proteins when comparing groups. Quantitatively, a total of 41 and 36 proteins were found differentially abundant in the DHD and CHD groups compared to the control HD, and 38 proteins resulted dysregulated in the CHD group as compared to the DHD group. Among the various proteins, differently abundant fecal fibronectin and haptoglobin were more present in the feces of healthy and DHD dogs than in chronic ones, leading us to hypothesize its possible diagnostic/monitoring role in canine chronic hepatitis. On the other hand, the trefoil factor 2 was increased in DHD dogs. Our results show that the analysis of the fecal proteome is a very promising field of study, and in the case of dogs suffering from different hepatobiliary disorders, it was able to highlight both qualitative and quantitative differences among the three groups included. Results need to be confirmed with western blotting and in further studies.

Metabolic Rewiring and Stemness: A Critical Attribute of Pancreatic Cancer Progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive diseases with a poor 5-year survival rate. PDAC cells rely on various metabolic pathways to fuel their unlimited proliferation and metastasis. Reprogramming glucose, fatty acid, amino acid, and nucleic acid metabolisms contributes to PDAC cell growth. Cancer stem cells are the primary cell types that play a critical role in the progression and aggressiveness of PDAC. Emerging studies indicate that the cancer stem cells in PDAC tumors are heterogeneous and show specific metabolic dependencies. In addition, understanding specific metabolic signatures and factors that regulate these metabolic alterations in the cancer stem cells of PDAC paves the way for developing novel therapeutic strategies targeting CSCs. In this review, we discuss the current understanding of PDAC metabolism by specifically exploring the metabolic dependencies of cancer stem cells. We also review the current knowledge of targeting these metabolic factors that regulate CSC maintenance and PDAC progression.

Tumor microenvironment interactions with cancer stem cells in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer in the United States. Additionally, the low survival rate makes PDAC the third-leading cause of cancer-related mortality in the United States, and it is projected that by 2030, it will become the second-leading cause of cancer mortality. Several biological factors contribute to PDAC aggressiveness, and their understanding will narrow the gap from biology to clinical care of PDAC, leading to earlier diagnoses and the development of better treatment options. In this review, we describe the origins of PDAC highlighting the role of cancer stem cells (CSC). CSC, also known as tumor initiating cells, which exhibit a unique metabolism that allows them to maintain a highly plastic, quiescent, immune- and therapy-evasive state. However, CSCs can exit quiescence during proliferation and differentiation, with the capacity to form tumors while constituting a small population in tumor tissues. Tumorigenesis depends on the interactions between CSCs and other cellular and non-cellular components in the microenvironment. These interactions are fundamental to support CSC stemness and are maintained throughout tumor development and metastasis. PDAC is characterized by a massive desmoplastic reaction, which result from the deposition of high amounts of extracellular matrix components by stromal cells. Here we review how this generates a favorable environment for tumor growth by protecting tumor cells from immune responses and chemotherapy and inducing tumor cell proliferation and migration, leading to metastasis formation ultimately leading to death. We emphasize the interactions between CSCs and the tumor microenvironment leading to metastasis formation and posit that better understanding and targeting of these interactions will improve patient outcomes.

Identification of CEACAM5 as a stemness-related inhibitory immune checkpoint in pancreatic cancer

BACKGROUND

Immunotherapy has emerged as a new cancer treatment modality. However, tumour heterogeneity can diminish checkpoint blockade response and shorten patient survival. As a source of tumour heterogeneity, cancer stem cells act as an indispensable reservoir for local recurrence and distant metastasis. Thus, precision immunotherapy targeting tumour heterogeneity requires a comprehensive understanding of cancer stem cell immunology. Our study aimed to identify stemness-related inhibitory immune checkpoints and relevant regulatory pathways in pancreatic cancer.

METHODS

Pancreatic cancer-specific datasets in The Cancer Genome Atlas and the Cancer Therapeutics Response Portal were collected for in-depth bioinformatic analysis. Differentially expressed genes between pancreatic cancers with high and low stemness index (mRNAsi) scores were compared to screen out inhibitory immune checkpoints. Survival analysis was used to predict the prognostic value of immune checkpoint plus immune infiltrate in patients with pancreatic cancer. The expression of stemness-related immune checkpoint across immune subtypes of pancreatic cancer was detected and gene set enrichment analysis was performed to figure out the relevant regulatory signallings.

RESULTS

The abundance of cancer stemness predicted a low immunotherapy response to pancreatic cancer. The inhibitory immune checkpoint CEACAM5 that was enriched in pancreatic cancers with high mRNAsi scores also exhibited a strong correlation with invasive cell-enriched signature and Msi⁺ tumour-initiating cell-enriched signature. Levels of CEACAM5 expression were higher in the interferon-γ dominant immune subtype of pancreatic cancers that are characterized by high M1 macrophage infiltration. The patient group with high levels of CEACAM5 expression had a high risk of poor overall survival, even if accompanied by high infiltration of M1 macrophages. Furthermore, prostanoid and long-chain unsaturated fatty acid metabolic processes showed a significant association with cancer stemness and CEACAM5 expression.

CONCLUSIONS

Our findings suggest that CEACAM5 is a candidate stemness-related innate immune checkpoint in pancreatic cancer, and is potentially regulated by prostanoid and long-chain unsaturated fatty acid metabolic processes. Immune checkpoint blockade of CEACAM5, which synergizes with inhibition of those regulatory pathways, may improve the efficacy of precision immunotherapy targeting tumour heterogeneity caused by cancer stem cells.

Abnormal expression of HADH, an enzyme of fatty acid oxidation, affects tumor development and prognosis (Review)

Tumor occurrence and progression are closely associated with abnormal energy metabolism and energy metabolism associated with glucose, proteins and lipids. The reprogramming of energy metabolism is one of the hallmarks of cancer. As a form of energy metabolism, fatty acid metabolism includes fatty acid uptake, de novo synthesis and β‑oxidation. In recent years, the role of abnormal fatty acid β‑oxidation in tumors has gradually been recognized. Mitochondrial trifunctional protein (MTP) serves an important role in fatty acid β‑oxidation and HADH (two subtypes: α subunit, HADHA and β subunit, HADHB) are important subunits of MTP. HADH participates in the steps of 2, 3 and 4 fatty acid β‑oxidation. However, there is no review summarizing the specific role of HADH in tumors. Therefore, the present study focused on HADH as the main indicator to explore the changes in fatty acid β‑oxidation in several types of tumors. The present review summarized the changes in HADH in 11 organs (cerebrum, oral cavity, esophagus, liver, pancreas, stomach, colorectum, lymph, lung, breast, kidney), the effect of up‑ and downregulation and the relationship of HADH with prognosis. In summary, HADH can be either a suppressor or a promoter depending on where the tumor is located, which is closely associated with prognostic assessment. HADHA and HADHB have similar prognostic roles in known and comparable tumors.

High Throughput LC-MS Platform for Large Scale Screening of Bioactive Polar Lipids in Human Plasma and Serum

Lipids play a key role in many biological processes, and their accurate measurement is critical to unraveling the biology of diseases and human health. A high throughput HILIC-based (LC-MS) method for the semiquantitative screening of over 2000 lipids, based on over 4000 MRM transitions, was devised to produce an accessible and robust lipidomic screen for phospholipids in human plasma/serum. This methodology integrates many of the advantages of global lipid analysis with those of targeted approaches. Having used the method as an initial "wide class" screen, it can then be easily adapted for a more targeted analysis and quantification of key, dysregulated lipids. Robustness was assessed using 1550 continuous injections of plasma extracts onto a single column and via the evaluation of columns from 5 different batches of stationary phase. Initial screens in positive (239 lipids, 431 MRM transitions) and negative electrospray ionization (ESI) mode (232 lipids, 446 MRM transitions) were assessed for reproducibility, sensitivity, and dynamic range using analysis times of 8 min. The total number of lipids monitored using these screening methods was 433 with an overlap of 38 lipids in both modes. A polarity switching method for accurate quantification, using the same LC conditions, was assessed for intra- and interday reproducibility, accuracy, dynamic range, stability, carryover, dilution integrity, and matrix interferences and found to be acceptable. This polarity switching method was then applied to lipids important in the stratification of human prostate cancer samples.

The Effect of a Pex3 Mutation on Hearing and Lipid Content of the Inner Ear

Peroxisome biogenesis disorders (due to PEX gene mutations) are associated with symptoms that range in severity and can lead to early childhood death, but a common feature is hearing impairment. In this study, mice carrying Pex3 mutations were found to show normal auditory development followed by an early-onset progressive increase in auditory response thresholds. The only structural defect detected in the cochlea at four weeks old was the disruption of synapses below inner hair cells. A conditional approach was used to establish that Pex3 expression is required locally within the cochlea for normal hearing, rather than hearing loss being due to systemic effects. A lipidomics analysis of the inner ear revealed a local reduction in plasmalogens in the Pex3 mouse mutants, comparable to the systemic plasmalogen reduction reported in human peroxisome biogenesis disorders. Thus, mice with Pex3 mutations may be a useful tool to understand the physiological basis of peroxisome biogenesis disorders.

Mass spectrometry imaging discriminates glioblastoma tumor cell subpopulations and different microvascular formations based on their lipid profiles

Glioblastoma is a prevalent malignant brain tumor and despite clinical intervention, tumor recurrence is frequent and usually fatal. Genomic investigations have provided a greater understanding of molecular heterogeneity in glioblastoma, yet there are still no curative treatments, and the prognosis has remained unchanged. The aggressive nature of glioblastoma is attributed to the heterogeneity in tumor cell subpopulations and aberrant microvascular proliferation. Ganglioside-directed immunotherapy and membrane lipid therapy have shown efficacy in the treatment of glioblastoma. To truly harness these novel therapeutics and develop a regimen that improves clinical outcome, a greater understanding of the altered lipidomic profiles within the glioblastoma tumor microenvironment is urgently needed. In this work, high resolution mass spectrometry imaging was utilized to investigate lipid heterogeneity in human glioblastoma samples. Data presented offers the first insight into the histology-specific accumulation of lipids involved in cell metabolism and signaling. Cardiolipins, phosphatidylinositol, ceramide-1-phosphate, and gangliosides, including the glioblastoma stem cell marker, GD3, were shown to differentially accumulate in tumor and endothelial cell subpopulations. Conversely, a reduction in sphingomyelins and sulfatides were detected in tumor cell regions. Cellular accumulation for each lipid class was dependent upon their fatty acid residue composition, highlighting the importance of understanding lipid structure-function relationships. Discriminating ions were identified and correlated to histopathology and Ki67 proliferation index. These results identified multiple lipids within the glioblastoma microenvironment that warrant further investigation for the development of predictive biomarkers and lipid-based therapeutics.

Metabolic Pathways as a Novel Landscape in Pancreatic Ductal Adenocarcinoma

Metabolism plays a fundamental role in both human physiology and pathology, including pancreatic ductal adenocarcinoma (PDAC) and other tumors. Anabolic and catabolic processes do not only have energetic implications but are tightly associated with other cellular activities, such as DNA duplication, redox reactions, and cell homeostasis. PDAC displays a marked metabolic phenotype and the observed reduction in tumor growth induced by calorie restriction with in vivo models supports the crucial role of metabolism in this cancer type. The aggressiveness of PDAC might, therefore, be reduced by interventions on bioenergetic circuits. In this review, we describe the main metabolic mechanisms involved in PDAC growth and the biological features that may favor its onset and progression within an immunometabolic context. We also discuss the need to bridge the gap between basic research and clinical practice in order to offer alternative therapeutic approaches for PDAC patients in the more immediate future.

3-Bromo-Isoxazoline Derivatives Inhibit GAPDH Enzyme in PDAC Cells Triggering Autophagy and Apoptotic Cell Death

A growing interest in the study of aerobic glycolysis as a key pathway for cancer-cell energetic metabolism, favouring tumour progression and invasion, has led to consider GAPDH as an effective drug target to specifically hit cancer cells. In this study, we have investigated a panel of 3-bromo-isoxazoline derivatives based on previously identified inhibitors of Plasmodium falciparum GAPDH (PfGAPDH). The compounds are active, to a different extent, as inhibitors of human-recombinant GAPDH. They showed an antiproliferative effect on pancreatic ductal-adenocarcinoma cells (PDAC) and pancreatic-cancer stem cells (CSCs), and among them two promising compounds were selected to be tested in vivo. Interestingly, these compounds were not effective in fibroblasts. The AXP-3019 derivative was able to block PDAC-cell growth in mice xenograft without apparent toxicity. The overall results support the assumption that selective inhibition of the glycolytic pathway, by targeting GAPDH, is an effective therapy for pancreatic cancer and that 3-bromo-isoxazoline derivatives represent a new class of anti-cancer compounds targeting glycolysis.

Application of Mass Spectrometry in Pancreatic Cancer Translational Research

Pancreatic cancer (PC) is one of the most common malignant tumors in the digestive tract worldwide, with increased morbidity and mortality. In recent years, with the development of surgery, chemotherapy, radiotherapy, targeted therapy, and immunotherapy, and the change of the medical thinking model, remarkable progress has been made in researching comprehensive diagnosis and treatment of PC. However, the present situation of diagnostic and treatment of PC is still unsatisfactory. There is an urgent need for academia to fully integrate the basic research and clinical data from PC to form a research model conducive to clinical translation and promote the proper treatment of PC. This paper summarized the translation progress of mass spectrometry (MS) in the pathogenesis, diagnosis, prognosis, and PC treatment to promote the basic research results of PC into clinical diagnosis and treatment.

Mechanisms of Cancer Cell Death: Therapeutic Implications for Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a type of cancer that is strongly associated with poor prognosis and short median survival times. In stark contrast to the progress seen in other cancer types in recent decades, discoveries of new treatments in PDAC have been few and far between and there has been little improvement in overall survival (OS). The difficulty in treating this disease is multifactorial, contributed to by late presentation, difficult access to primary tumour sites, an 'immunologically cold' phenotype, and a strong tendency of recurrence likely driven by cancer stem cell (CSC) populations. Furthermore, apparently contrasting roles of tumour components (such as fibrotic stroma) and intracellular pathways (such as autophagy and TGFβ) have made it difficult to distinguish beneficial from detrimental drug targets. Despite this, progress has been made in the field, including the determination of mFOLFIRINOX as the standard-of-care adjuvant therapy and the discovery of KRASG12C mutant inhibitors. Moreover, new research, as outlined in this review, has highlighted promising new approaches including the targeting of the tumour microenvironment, enhancement of immunotherapies, epigenetic modulation, and destruction of CSCs.