Phospholipase A2 as targets for anti-cancer drugs

Phospholipase A2 expression in prostate cancer as a biomarker of good prognosis: A comprehensive study in patients with long follow-up

BACKGROUND

Phospholipase A2 (PLA2) is a large family of enzymes involved in the inflammatory process that catalyzes the hydrolysis of membrane phospholipids, leading to the production of free fatty acids and lysophospholipids, starting the arachidonic acid cascade. Their expression has been related to the behavior of several cancers. Our objective is to search for PLA2 expression in prostate cancer (PCa) tissue that correlates with prognosis and survival.

METHODS

Using qRT-PCR, we analyzed the expression levels of PLA2G1B, PLA2G2A, PLA2G2D, PLA2G4A, PLA2G4B, PLA2G4C, PLA2G4D, PLA2G4E, PLA2G4F, PLA2G6, PLA2G7, PLA2G16, PNPLA1, and PNPLA2 in PCa tissue from 108 patients submitted to radical prostatectomy, followed by a mean time of 163 months.

RESULTS

All PLA2 was overexpressed in PCa compared to normal tissue. Interestingly, higher expression of some PLA2 was related to favorable prognostic factors: lower levels of PSA (PLA2G2A, PLA2G4D), lower rates of lymph node metastasis (PLA2G16 and PLA2G1B), and organ-confined disease (PLA2G4A). Most importantly, PLAG4B was independently related to longer disease-free survival.

CONCLUSION

This is the first study exploring comprehensively the expression levels of PLA2 in PCa, showing that the higher expression of some PLA2 should be used as biomarkers of good prognosis and longer disease-free survival.

Exploring the protein profile and biological activity of Crotalus molossus venom against E. coli, P. aeruginosa and S. aureus bacteria and T47D breast carcinoma cells

Mexico has the highest diversity of snake species in the world, following Australia when considering just venomous snakes. Specifically, in Sonora, the second largest state in the country, more than 15 highly venomous species occur, including the northern black-tailed rattlesnake (Crotalus molossus). This specie's venom has not been as thoroughly researched in contrast with other Mexican vipers, nevertheless some studies report its biological activity and even pharmacological potential with antibacterial and cytotoxic activity. In this study we identified the main protein components from a pool of C. molossus venom through a gel-free proteomics approach, reporting ∼140 proteins belonging to the SVMP (38.76%), PLA2 (28.75%), CTL (11.93%), SVSP (6.03%) and LAAO (5.67%) toxin families. To study its biological activities, we evaluated its hemolytic, antibacterial, and cytotoxic activity in red blood cells, Gram positive and negative bacteria and a luminal A breast carcinoma cell line (T47D), respectively, in vitro. We report that concentrations <100 μg/mL are potentially not hemolytic and reduced the bacteria viability of E. coli and S. aureus with an IC50 of 10.27 and 11.51 μg/mL, respectively. Finally, we determined the C. molossus venom as cytotoxic against the T47D breast carcinoma cell line, with an IC50 of 1.55 μg/mL. We suggest that the evaluated cytotoxicity was due to a high abundance of SVMPs and PLA2s, since it's been reported that they affect the extracellular matrix and membrane permeation. This may provide a useful tool for pharmaceutical screening in the future.

Advancements in the use of nanopharmaceuticals for cancer treatment

OBJECTIVE

Advances in nanotechnology make it possible to specifically target therapies to cancer cells and neoplasms, guide the surgical resection of tumors, and optimize the effectiveness of radiological treatments. This research article provides a concise synthesis of current knowledge in the field of galenic pharmacy focused on targeted drug delivery in oncology. This research article synthesizes current knowledge in galenic pharmacy, focusing on targeted drug delivery in oncology and reviewing recent advancements in nanopharmaceuticals for cancer treatment.

DATA SOURCE

The data for this review are derived from a comprehensive analysis of the most cited scientific literature (Pubmed). Recent studies, clinical trials, and technological breakthroughs related to nanopharmaceuticals have been rigorously examined. This diverse source ensures a comprehensive representation of the latest developments in the field.

SUMMARY OF DATA

The results highlight the emergence of nanopharmaceuticals as a promising approach to cancer treatment. The most common in oncology remain liposomes, nanopolymers, and nanocrystals. From a galenic point of view, these three forms offer a wide range of improvements compared to conventional forms such as improvement in solubility as well as stability. The same observation is in the clinic where treatment response rates are significantly improved. The most advantageous form will depend on the specific characteristics of each patient and each type of cancer. The precise design of nanocarriers allows for targeted drug delivery, enhancing therapeutic efficacy while reducing side effects. Concrete examples of clinical applications are presented, illustrating the practical potential of these advancements.

CONCLUSION

In conclusion, this review provides a holistic overview of recent developments in galenic pharmacy for targeted drug delivery in oncology. The stability of nanocarriers is a crucial challenge because it conditions the effectiveness and safety of the drugs transported. Environmental and biological variations encountered in the body can compromise this stability, jeopardizing the therapeutic effectiveness and safety of treatments. Likewise, personalized approaches are essential to address interindividual variations in treatment response, as well as patients' pharmacogenomic profiles, in order to optimize therapeutic effectiveness and minimize adverse effects.

Untargeted metabolomics of bladder tissue using liquid chromatography and quadrupole time-of-flight mass spectrometry for cancer biomarker detection

Bladder cancer (BC) ranks among the most common cancers globally, with an increasing occurrence, particularly in developed nations. Utilizing tissue metabolomics presents a promising strategy for identifying potential biomarkers for cancer detection. In this study, we utilized ultra-high-performance liquid chromatography coupled with ultra-high-resolution mass spectrometry (UHPLC-UHRMS), incorporating both C18-silica and HILIC columns, to comprehensively analyze both polar and non-polar metabolite profiles in tissue samples from 99 patients with bladder cancer. By utilizing an untargeted approach with external validation, we identified twenty-five tissue metabolites that hold promise as potential indicators of BC. Furthermore, twenty-five characteristic tissue metabolites that exhibit discriminatory potential across bladder cancer tumor grades, as well as thirty-nine metabolites that display correlations with tumor stages were presented. Receiver operating characteristics analysis demonstrated high predictive power for all types of metabolomics data, with area under the curve (AUC) values exceeding 0.966. Notably, this study represents the first report in which human bladder normal tissues adjacent to cancerous tissues were analyzed using UHPLC-UHRMS. These findings suggest that the metabolite markers identified in this investigation could serve as valuable tools for the detection and monitoring of bladder cancer stages and grades.

Research progress in nano-drug delivery systems based on the characteristics of the liver cancer microenvironment

The liver cancer has microenvironmental features such as low pH, M2 tumor-associated macrophage enrichment, low oxygen, rich blood supply and susceptibility to hematotropic metastasis, high chemokine expression, enzyme overexpression, high redox level, and strong immunosuppression, which not only promotes the progression of the disease, but also seriously affects the clinical effectiveness of traditional therapeutic approaches. However, nanotechnology, due to its unique advantages of size effect and functionalized modifiability, can be utilized to develop various responsive nano-drug delivery system (NDDS) by using these characteristic signals of the liver cancer microenvironment as a source of stimulation, which in turn can realize the intelligent release of the drug under the specific microenvironment, and significantly increase the concentration of the drug at the target site. Therefore, researchers have designed a series of stimuli-responsive NDDS based on the characteristics of the liver cancer microenvironment, such as hypoxia, weak acidity, and abnormal expression of proteases, and they have been widely investigated for improving anti-tumor therapeutic efficacy and reducing the related side effects. This paper provides a review of the current application and progress of NDDS developed based on the response and regulation of the microenvironment in the treatment of liver cancer, compares the effects of the microenvironment and the NDDS, and provides a reference for building more advanced NDDS.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Manoalide Induces Intrinsic Apoptosis by Oxidative Stress and Mitochondrial Dysfunction in Human Osteosarcoma Cells

Osteosarcoma (OS) is the most common primary malignant bone tumor that produces immature osteoid. Metastatic OS has a poor prognosis with a death rate of >70%. Manoalide is a natural sesterterpenoid isolated from marine sponges. It is a phospholipase A2 inhibitor with anti-inflammatory, analgesic, and anti-cancer properties. This study aimed to investigate the mechanism and effect of manoalide on OS cells. Our experiments showed that manoalide induced cytotoxicity in 143B and MG63 cells (human osteosarcoma). Treatment with manoalide at concentrations of 10, 20, and 40 µM for 24 and 48 h reduced MG63 cell viability to 45.13-4.40% (p < 0.01). Meanwhile, manoalide caused reactive oxygen species (ROS) overproduction and disrupted antioxidant proteins, activating the apoptotic proteins caspase-9/-3 and PARP (Poly (ADP-ribose) polymerase). Excessive levels of ROS in the mitochondria affected oxidative phosphorylation, ATP generation, and membrane potential (ΔΨ_m). Additionally, manoalide down-regulated mitochondrial fusion protein and up-regulated mitochondrial fission protein, resulting in mitochondrial fragmentation and impaired function. On the contrary, a pre-treatment with n-acetyl-l-cysteine ameliorated manoalide-induced apoptosis, ROS, and antioxidant proteins in OS cells. Overall, our findings show that manoalide induces oxidative stress, mitochondrial dysfunction, and apoptosis, causing the cell death of OS cells, showing potential as an innovative alternative treatment in human OS.

Relationship between tumor microbiota transcriptional activity and gene expression in breast cancer

BACKGROUND

A few studies have reported the distribution of the microbiota in breast cancer tissues, but few reports have compared the microbiota in different subtypes of breast cancer tissue. Moreover, no study has reported on the relationship between the microbiota and gene expression in breast tumor.

METHODS

Sections of formalin-fixed paraffin-embedded (FFPE) tissue were prepared from the breast tumors of 70 patients and were subjected to microarray analysis to identify gene expression profiles. The same total RNA samples were also used to analyze the microbiota activity in tumor tissues by performing 16 S rRNA sequencing and internal transcribed spacer (ITS) sequencing of reverse transcript cDNA with Illumina Miseq. Pearson's correlation coefficient was used for calculating the correlation between microbial relative activity and gene expression.

RESULTS

The microbiota transcriptional activity of 70 FFPE samples mainly consisted of the phyla Bacteroidetes, Firmicutes and Proteobacteria. Prevotella_9, Bacteroides and Alloprevotella were the most active genera in ER+/HER2-, ER+/HER2 + and ER-/HER2 + tumors, while triple-negative samples exhibited a higher activity of Lactobacillus. In ER-negative samples (triple-negative and ER-/HER2+), 479 genes, including the breast carcinogenesis genes phospholipase A2, histone cluster 2, Crk-like, and cyclin D1, were significantly positive associated with the activity of Lactobacillus.

CONCLUSION

This was the first study to clarify an association between the breast tumor microbiota transcriptional activity and the expression of carcinogenesis genes in ER-negative breast cancer. Changes in the microbiota of breast tissue induced by external factors might be one of the key causes of ER negative breast cancer.

Enzyme Inhibitors from Gorgonians and Soft Corals

For decades, gorgonians and soft corals have been considered promising sources of bioactive compounds, attracting the interest of scientists from different fields. As the most abundant bioactive compounds within these organisms, terpenoids, steroids, and alkaloids have received the highest coverage in the scientific literature. However, enzyme inhibitors, a functional class of bioactive compounds with high potential for industry and biomedicine, have received much less notoriety. Thus, we revised scientific literature (1974-2022) on the field of marine natural products searching for enzyme inhibitors isolated from these taxonomic groups. In this review, we present representative enzyme inhibitors from an enzymological perspective, highlighting, when available, data on specific targets, structures, potencies, mechanisms of inhibition, and physiological roles for these molecules. As most of the characterization studies for the new inhibitors remain incomplete, we also included a methodological section presenting a general strategy to face this goal by accomplishing STRENDA (Standards for Reporting Enzymology Data) project guidelines.

Multimodal regulation of the osteoclastogenesis process by secreted group IIA phospholipase A2

Increasing evidence points to the involvement of group IIA secreted phospholipase A₂ (sPLA₂-IIA) in pathologies characterized by abnormal osteoclast bone-resorption activity. Here, the role of this moonlighting protein has been deepened in the osteoclastogenesis process driven by the RANKL cytokine in RAW264.7 macrophages and bone-marrow derived precursor cells from BALB/cJ mice. Inhibitors with distinct selectivity toward sPLA₂-IIA activities and recombinant sPLA₂-IIA (wild-type or catalytically inactive forms, full-length or partial protein sequences) were instrumental to dissect out sPLA₂-IIA function, in conjunction with reduction of sPLA₂-IIA expression using small-interfering-RNAs and precursor cells from Pla2g2a knock-out mice. The reported data indicate sPLA₂-IIA participation in murine osteoclast maturation, control of syncytium formation and resorbing activity, by mechanisms that may be both catalytically dependent and independent. Of note, these studies provide a more complete understanding of the still enigmatic osteoclast multinucleation process, a crucial step for bone-resorbing activity, uncovering the role of sPLA₂-IIA interaction with a still unidentified receptor to regulate osteoclast fusion through p38 SAPK activation. This could pave the way for the design of specific inhibitors of sPLA₂-IIA binding to interacting partners implicated in osteoclast syncytium formation.

Purification, Characterization and Evaluation of the Antitumoral Activity of a Phospholipase A2 from the Snake Bothrops moojeni

Nature presents a wide range of biomolecules with pharmacological potential, including venomous animal proteins. Among the protein components from snake venoms, phospholipases (PLA₂) are of great importance for the development of new anticancer compounds. Thus, we aimed to evaluate the PLA₂ anticancer properties from Bothrops moojeni venom. The crude venom was purified through three chromatographic steps, monitored by enzymatic activity and SDS-PAGE (12%). The purified PLA₂ denominated BmPLA2 had its molecular mass and N-terminal sequence identified by mass spectrometry and Edman degradation, respectively. BmPLA2 was assayed against human epithelial colorectal adenocarcinoma cells (Caco-2), human rhabdomyosarcoma cells (RD) and mucoepidermoid carcinoma of the lung (NCI-H292), using human fibroblast cells (MRC-5) and microglia cells (BV-2) as a cytotoxicity control. BmPLA2 presented 13,836 Da and a 24 amino acid-residue homologue with snake PLA₂, which showed a 90% similarity with other Bothrops moojeni PLA₂. BmPLA2 displayed an IC₅₀ of 0.6 µM against Caco-2, and demonstrated a selectivity index of 1.85 (compared to MRC-5) and 6.33 (compared to BV-2), supporting its selectivity for cancer cells. In conclusion, we describe a new acidic phospholipase, which showed antitumor activity and is a potential candidate in the development of new biotechnological tools.

Qualitative Analysis of Proteins in Two Snake Venoms, Gloydius Blomhoffii and Agkistrodon Acutus

Objectives

Snake venom is a complex mixture of various pharmacologically active substances, such as small proteins, peptides, and organic and mineral components. This paper aims to identify and analyse the proteins in common venomous snakes, such as Gloydius blomhoffii (G. blomhoffii) and Agkistrodon acutus (A. acutus), in Korea.

Methods

We used mass spectrometry, electrophoresis, N-terminal sequencing and in-gel digestion to analyse the proteins in these two snake venoms.

Results

We identified eight proteins in G. blomhoffii venom and four proteins in A. acutus venom. The proteins detected in G. blomhoffii and A. acutus venoms were phospholipase A2, snake venom metalloproteinase and cysteine-rich secretory protein. Snake C-type lectin (snaclec) was unique to A. acutus venom.

Conclusion

These data will contribute to the current knowledge of proteins present in the venoms of viper snakes and provide useful information for investigating their therapeutic potential.

The Chemical Profiling, Docking Study, and Antimicrobial and Antibiofilm Activities of the Endophytic fungi Aspergillus sp. AP5

Growing data suggest that Aspergillus niger, an endophytic fungus, is a rich source of natural compounds with a wide range of biological properties. This study aimed to examine the antimicrobial and antibiofilm capabilities of the Phragmites australis-derived endophyte against a set of pathogenic bacteria and fungi. The endophytic fungus Aspergillus sp. AP5 was isolated from the leaves of P. australis. The chemical profile of the fungal crude extract was identified by spectroscopic analysis using LC-HRESIMS. The fungal-derived extract was evaluated for its antimicrobial activity towards a set of pathogenic bacterial and fungal strains including Staphylococcus aureus, Pseudomonas aeruginosa, Proteus vulgaris, Klebsiella sp., Candida albicans, and Aspergillus niger. Moreover, antibiofilm activity toward four resistant biofilm-forming bacteria was also evaluated. Additionally, a neural-networking pharmacophore-based visual screening predicted the most probable bioactive compounds in the obtained extract. The AP5-EtOAc extract was found to have potent antibacterial activities against S. aureus, E. coli, and Klebsiella sp., while it exhibited low antibacterial activity toward P. Vulgaris and P. aeruginosa and displayed anticandidal activity. The AP5-EtOAc extract had significant antibiofilm activity in S. aureus, followed by P. aeruginosa. The active metabolites' antifungal and/or antibacterial activities may be due to targeting the fungal CYP 51 and/or the bacterial Gyr-B.

Anti-HIV Activity of Snake Venom Phospholipase A2s: Updates for New Enzymes and Different Virus Strains

Since the beginning of the HIV epidemic, lasting more than 30 years, the main goal of scientists was to develop effective methods for the prevention and treatment of HIV infection. Modern medicines have reduced the death rate from AIDS by 80%. However, they still have side effects and are very expensive, dictating the need to search for new drugs. Earlier, it was shown that phospholipases A2 (PLA2s) from bee and snake venoms block HIV replication, the effect being independent on catalytic PLA2 activity. However, the antiviral activity of human PLA2s against Lentiviruses depended on catalytic function and was mediated through the destruction of the viral membrane. To clarify the role of phospholipolytic activity in antiviral effects, we analyzed the anti-HIV activity of several snake PLA2s and found that the mechanisms of their antiviral activity were similar to that of mammalian PLA2. Our results indicate that snake PLA2s are capable of inhibiting syncytium formation between chronically HIV-infected cells and healthy CD4-positive cells and block HIV binding to cells. However, only dimeric PLA2s had pronounced virucidal and anti-HIV activity, which depended on their catalytic activity. The ability of snake PLA2s to inactivate the virus may provide an additional barrier to HIV infection. Thus, snake PLA2s might be considered as candidates for lead molecules in anti-HIV drug development.

Mechanistic Insights into Biological Activities of Polyphenolic Compounds from Rosemary Obtained by Inverse Molecular Docking

Rosemary (Rosmarinus officinalis L.) represents a medicinal plant known for its various health-promoting properties. Its extracts and essential oils exhibit antioxidative, anti-inflammatory, anticarcinogenic, and antimicrobial activities. The main compounds responsible for these effects are the diterpenes carnosic acid, carnosol, and rosmanol, as well as the phenolic acid ester rosmarinic acid. However, surprisingly little is known about the molecular mechanisms responsible for the pharmacological activities of rosemary and its compounds. To discern these mechanisms, we performed a large-scale inverse molecular docking study to identify their potential protein targets. Listed compounds were separately docked into predicted binding sites of all non-redundant holo proteins from the Protein Data Bank and those with the top scores were further examined. We focused on proteins directly related to human health, including human and mammalian proteins as well as proteins from pathogenic bacteria, viruses, and parasites. The observed interactions of rosemary compounds indeed confirm the beforementioned activities, whereas we also identified their potential for anticoagulant and antiparasitic actions. The obtained results were carefully checked against the existing experimental findings from the scientific literature as well as further validated using both redocking procedures and retrospective metrics.

Human Group IIA Phospholipase A2-Three Decades on from Its Discovery

Phospholipase A₂ (PLA₂) enzymes were first recognized as an enzyme activity class in 1961. The secreted (sPLA₂) enzymes were the first of the five major classes of human PLA₂s to be identified and now number nine catalytically-active structurally homologous proteins. The best-studied of these, group IIA sPLA₂, has a clear role in the physiological response to infection and minor injury and acts as an amplifier of pathological inflammation. The enzyme has been a target for anti-inflammatory drug development in multiple disorders where chronic inflammation is a driver of pathology since its cloning in 1989. Despite intensive effort, no clinically approved medicines targeting the enzyme activity have yet been developed. This review catalogues the major discoveries in the human group IIA sPLA₂ field, focusing on features of enzyme function that may explain this lack of success and discusses future research that may assist in realizing the potential benefit of targeting this enzyme. Functionally-selective inhibitors together with isoform-selective inhibitors are necessary to limit the apparent toxicity of previous drugs. There is also a need to define the relevance of the catalytic function of hGIIA to human inflammatory pathology relative to its recently-discovered catalysis-independent function.

Cancer nanotechnology: current status and perspectives

Modern medicine has been waging a war on cancer for nearly a century with no tangible end in sight. Cancer treatments have significantly progressed, but the need to increase specificity and decrease systemic toxicities remains. Early diagnosis holds a key to improving prognostic outlook and patient quality of life, and diagnostic tools are on the cusp of a technological revolution. Nanotechnology has steadily expanded into the reaches of cancer chemotherapy, radiotherapy, diagnostics, and imaging, demonstrating the capacity to augment each and advance patient care. Nanomaterials provide an abundance of versatility, functionality, and applications to engineer specifically targeted cancer medicine, accurate early-detection devices, robust imaging modalities, and enhanced radiotherapy adjuvants. This review provides insights into the current clinical and pre-clinical nanotechnological applications for cancer drug therapy, diagnostics, imaging, and radiation therapy.

Anti-Cancer and Anti-Inflammatory Potential of the Green Synthesized Silver Nanoparticles of the Red Sea Sponge Phyllospongia lamellosa Supported by Metabolomics Analysis and Docking Study

BACKGROUND

The Red Sea sponges have been endorsed as a plentiful source of bioactive compounds with promising anti-cancer and anti-inflammatory activities; therefore, exploring their potential as a source of anti-cancer metabolites has stimulated a growing research interest.

PURPOSE

To investigate the anti-cancer and anti-inflammatory potential of the Red Sea sponges, in their bulk and silver nanostructure. Metabolomics analysis of the selected sponge followed by molecular docking studies, will be conducted to explore and predict the secondary metabolites that might provide its capability of inhibiting cancer.

MATERIALS AND METHODS

We prepared a chloroform extract (CE) and ethyl acetate extract (EE) of the Red Sea sponge Phyllospongia lamellosa synthesized silver nanoparticles. The prepared silver nanoparticles were characterized through UV-vis spectrophotometric, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR) analyses. Testing for their anti-cancer activities was performed against MCF-7, MDB-231, and MCF-10A cells. Anti-inflammatory activity against COX-1 and 2 was assessed. Furthermore, liquid chromatography-mass spectrometry (LC-MS)-based metabolomics analysis and molecular docking were also applied.

Enzyme-responsive smart nanocarriers for targeted chemotherapy: an overview

Nanocarriers play pivotal roles in the field of biomedical applications, particularly in anticancer therapy. One of the prominent strategies for the transport of anticancer drugs with site-specific release and improved therapeutic efficacy is the use of an enzyme-responsive drug delivery system. There is an emerging class of cancer therapeutics engineered to control the release of a drug via enzymatic degradation. Enzymes, being an essential component of bio-nanotechnology toolbox, hold exceptional biorecognition abilities as well as outstanding catalytic properties. Often, abnormal enzyme expression observed in cancer offers many opportunities in designing nanocarriers modified with enzyme-labile linkage. Through altered physical or chemical characteristics of these nanocarriers or cleavage of the drug in response to the bio-action of enzyme, an on-demand drug release can be obtained. In this review, several classes of enzymes performing critical roles in cancer such as hydrolases, lipases, and oxidoreductases are summarized. Insights on various approaches that interfere with the mechanism of these enzymes have also been included. Finally, various smart nanocarriers such as mesoporous silica nanoparticles, gold nanoparticles, carbon-nanotubes, micelles, liposomes, and dendrimers serving as excellent platforms for enzyme-responsive formulations have been discussed.

Non-coding RNAs and lipids mediate the function of extracellular vesicles in cancer cross-talk

Research on extracellular vesicles (EVs) has been expanded, especially in the field of cancer. The cargoes in EVs, especially those in small EVs such as exosomes include microRNAs (miRNAs), mRNA, proteins, and lipids, are assumed to work cooperatively in the tumor microenvironment. In 2007, it was reported that miRNAs were abundant among the non-coding RNAs present in exosomes. Since then, many studies have investigated the functions of miRNAs and have tried to apply these molecules to aid in the diagnosis of cancer. Accordingly, many reviews of non-coding RNAs in EVs have been published for miRNAs. This review focuses on relatively new cargoes, covering long noncoding (lnc) RNAs, circular RNAs, and repeat RNAs, among non-coding RNAs. These RNAs, regardless of EV or cell type, have newly emerged due to the innovation of sequencing technology. The poor conservation, low quantity, and technical difficulty in detecting these RNA types have made it difficult to elucidate their functions and expression patterns. We herein summarize a limited number of studies. Although lipids are major components of EVs, current research on EVs focuses on miRNA and protein biology, while the roles of lipids in exosomes have not drawn attention. However, several recent studies revealed that phospholipids, which are components of the EV membrane, play important roles in the intercommunication between cells and in the generation of lipid mediators. Here, we review the reported roles of these molecules, and describe their potential in cancer biology.

Rapid Screening and Identification of Antitumor Ingredients from the Mangrove Endophytic Fungus Using an Enzyme-Immobilized Magnetic Nanoparticulate System

As a consequence of recent progression in biomedicine and nanotechnology, nanoparticle-based systems have evolved as a new method with extensive applications in responsive therapy, multimodal imaging, drug delivery and natural product separation. Meanwhile, the magnetic nanoparticulate system has aroused great interest for separation and purification because of its excellent magnetic properties. Phospholipase A₂ (PLA₂) is a highly expressed regulator to promote the growth of various cancers and is an ideal target to treat cancers. In this study, a novel strategy based on ligand–receptor interactions to discover novel PLA₂ inhibitors was established, in which PLA₂-functionalized Fe₃O₄@PLGA-PEG-NH₂ magnetic nanoparticles were used as a supporting material combined with high-performance liquid chromatography–mass spectrometry, aiming to accelerate the discovery of novel PLA₂ inhibitors from natural sources such as mangrove endophytic fungi. Under the optimized ligand fishing conditions, six target compounds were ultimately fished and identified to be cyclic peptides (1–3) and sterols (4–6), which compounds 1, 2 and 4–6 have well-documented cytotoxicities. Compound 3 exerted better inhibitory effect on A549 cells by experiment. In conclusion, PLA₂-functionalized Fe₃O₄@PLGA-PEG-NH₂ magnetic nanoparticles-based ligand fishing provided a feasible, selective and effective platform for the efficient screening and identification of antitumor components from natural products.

An optimised MALDI-TOF assay for phosphatidylcholine-specific phospholipase C

The Bacillus cereus phosphatidylcholine-specific phospholipase C (PC-PLCBc) is an enzyme that catalyses the hydrolysis of phosphatidylcholines into phosphocholine and 1,2-diacylglycerols. PC-PLCBc has found applications in both the food industry and in medicinal chemistry. Herein, we report our work in the development and optimisation of a matrix assisted laser desorption ionisation time-of-flight (MALDI-TOF) mass spectrometry-based assay to monitor PC-PLCBc activity. The use of one-phase and two-phase reaction systems to assess the inhibition of PC-PLCBc with different structural classes of inhibitors was compared. We also highlighted the advantage of our assay over the commonly used commercially available Amplex Red assay. This method will also be applicable to work on the activity and inhibition of other phospholipases.

Biochemical and functional characterization of a new recombinant phospholipase A2 inhibitor from Crotalus durissus collilineatus snake serum

Phospholipase A₂ plays an important role in many diseases. Thus, the production of bioactive molecules, which can modulate PLA₂ activity, became an important target for the pharmaceutical industry. Previously, we demonstrated the inhibitory and anti-angiogenic effect of γCdcPLI, the natural PLA₂inhibitor from Crotalus durissus collilineatus. The aim of the present study was to recombinantly express the γCdcPLI inhibitor and analyze its biochemical and functional characteristics. Based on the amino acid sequence from the natural protein, we designed a synthetic gene for production of a non-tagged recombinant recγCdcPLI using the pHis-Parallel2 vector. To enable disulfide bond formation, protein expression was performed using E. coli Rosetta-gamiB. The protein was purified by anion and affinity chromatography with a yield of 5 mg/L. RecγCdcPLI showed similar secondary structure in CD and FTIR, revealing predominately β-strands. Analogous to the natural protein, recγCdcPLI was able to form oligomers of ~5.5 nm. The inhibitor was efficiently binding to PLA₂ from honeybee (Kd = 1.48 μM) and was able to inhibit the PLA₂ activity. Furthermore, it decreased the vessel formation in HUVEC cells, suggesting an anti-angiogenic potential. Heterologous production of recγCdcPLI is highly efficient and thus enables enhanced drug design for treatment of diseases triggered by PLA₂ activity.

Secretory Phospholipase A2 Inhibition Attenuates Adhesive Properties of Esophageal Barrett's Cells

BACKGROUND

Gastroesophageal reflux and Barrett's esophagus are significant risk factors for the development of esophageal adenocarcinoma. Group IIa secretory phospholipase A₂ (sPLA₂) catalyzes the production of various proinflammatory metabolites and plays a critical role in promoting reflux-induced inflammatory changes within the distal esophagus. We hypothesized that inhibition of sPLA₂ in human Barrett's cells would attenuate adhesion molecule expression via decreased activation of nuclear factor kappa B (NF-κB) and decrease cell proliferation, possibly mitigating the invasive potential of Barrett's esophagus.

MATERIALS AND METHODS

Normal human esophageal epithelial cells (HET1A) and Barrett's cells (CPB) were assayed for baseline sPLA₂ expression. CPB cells were treated with a specific inhibitor of sPLA₂ followed by tumor necrosis factor-α. Protein expression was evaluated using immunoblotting. Cell proliferation was assessed using an MTS cell proliferation assay kit. Statistical analysis was performed using the Student's t-test or analysis of variance, where appropriate.

RESULTS

CPB cells demonstrated higher baseline sPLA₂ expression than HET1A cells (P = 0.0005). Treatment with 30 μM sPLA₂ inhibitor significantly attenuated intercellular adhesion molecule-1 (P = 0.004) and vascular cell adhesion molecule-1 (P < 0.0001) expression as well as decreased NF-κB activation (P = 0.002). sPLA₂ inhibition decreased cell proliferation in a dose-dependent manner (P < 0.001 for 15, 20, and 30 μM doses).

CONCLUSIONS

sPLA₂ inhibition in human Barrett's cells decreases cellular adhesive properties and NF-κB activation as well as decreases cell proliferation, signifying downregulation of the inflammatory response and possible attenuation of cellular malignant potential. These findings identify sPLA₂ inhibition as a potential chemopreventive target for premalignant lesions of the esophagus.

Phospholipase A2 superfamily in cancer

Phospholipase A2 enzymes (PLA₂s) comprise a superfamily that is generally divided into six subfamilies known as cytosolic PLA₂s (cPLA₂s), calcium-independent PLA₂s (iPLA₂s), secreted PLA₂s (sPLA₂s), lysosomal PLA₂s, platelet-activating factor (PAF) acetylhydrolases, and adipose specific PLA₂s. Each subfamily consists of several isozymes that possess PLA₂ activity. The first three PLA₂ subfamilies play important roles in inflammation-related diseases and cancer. In this review, the roles of well-studied enzymes sPLA₂-IIA, cPLA₂α and iPLA₂β in carcinogenesis and cancer development were discussed. sPLA₂-IIA seems to play conflicting roles and can act as a tumor suppressor or a tumor promoter according to the cancer type, but cPLA₂α and iPLA₂β play protumorigenic role in most cancers. The mechanisms of PLA₂-mediated signal transduction and crosstalk between cancer cells and endothelial cells in the tumor microenvironment are described. Moreover, the mechanisms by which PLA₂s mediate lipid reprogramming and glycerophospholipid remodeling in cancer cells are illustrated. PLA₂s as the upstream regulators of the arachidonic acid cascade are generally high expressed and activated in various cancers. Therefore, they can be considered as potential pharmacological targets and biomarkers in cancer. The detailed information summarized in this review may aid in understanding the roles of PLA₂s in cancer, and provide new clues for the development of novel agents and strategies for tumor prevention and treatment.

Anticancer Drug Affects Metabolomic Profiles in Multicellular Spheroids: Studies Using Mass Spectrometry Imaging Combined with Machine Learning

Multicellular spheroids (hereinafter referred to as spheroids) are 3D biological models. The metabolomic profiles inside spheroids provide crucial information reflecting the molecular phenotypes and microenvironment of cells. To study the influence of an anticancer drug on the spatially resolved metabolites, spheroids were cultured using HCT-116 colorectal cancer cells, treated with the anticancer drug Irinotecan under a series of time- and concentration-dependent conditions. The Single-probe mass spectrometry imaging (MSI) technique was utilized to conduct the experiments. The MSI data were analyzed using advanced data analysis methods to efficiently extract metabolomic information. Multivariate curve resolution alternating least square (MCR-ALS) was used to decompose each MS image into different components with grouped species. To improve the efficiency of data analysis, both supervised (Random Forest) and unsupervised (cluster large applications (CLARA)) machine learning (ML) methods were employed to cluster MS images according to their metabolomic features. Our results indicate that anticancer drug significantly affected the abundances of a variety of metabolites in different regions of spheroids. This integrated experiment and data analysis approach can facilitate the studies of metabolites in different types of 3D tumor models and tissues and potentially benefit the drug discovery, therapeutic resistance, and other biological research fields.

Overexpression of the phospholipase A2 group V gene in glioma tumors is associated with poor patient prognosis

Purpose: Gliomas are the most common primary malignant neoplasms of the central nervous system. Secreted phospholipases A2 (sPLA2s) are known to play an important role in various physiological processes, including bioactive lipid production, defense mechanisms, and cell signaling. However, their roles and clinical importance in gliomas remain unclear. Patients and methods: In this study, we analyzed the association between the expression of various sPLA2-encoding genes and the clinicopathology of gliomas, using the data of 1047 patients obtained from a public database. Immunohistochemical analysis of 82 glioma tissues was also carried out to assess the relationship between phospholipase A2 group V (PLA2G5) protein expression and the World Health Organization (WHO) glioma grades. Results: We found that high PLA2G5 gene expression was associated with unfavorable prognosis in both low-grade and high-grade gliomas. The immunohistochemistry of the 82 glioma tissues further confirmed that PLA2G5 protein expression was dependent on the WHO glioma grade. In addition, we found a correlation between PLA2G5 gene expression and both epithelial-mesenchymal transition and the isocitrate dehydrogenase 1 mutation status in these tumors. Conclusion: Our results indicate that PLA2G5 could be a potential biomarker for predicting poor prognosis in patients with gliomas.

Recent advances in the metabolomic study of bladder cancer

INTRODUCTION

Metabolomics is a chemical process, involving the characterization of metabolites and cellular metabolism. Recent studies indicate that numerous metabolic pathways are altered in bladder cancer (BLCA), providing potential targets for improved detection and possible therapeutic intervention. We review recent advances in metabolomics related to BLCA and identify various metabolites that may serve as potential biomarkers for BLCA. Areas covered: In this review, we describe the latest advances in defining the BLCA metabolome and discuss the possible clinical utility of metabolic alterations in BLCA tissues, serum, and urine. In addition, we focus on the metabolic alterations associated with tobacco smoke and racial disparity in BLCA. Expert commentary: Metabolomics is a powerful tool which can shed new light on BLCA development and behavior. Key metabolites may serve as possible markers of BLCA. However, prospective validation will be needed to incorporate these markers into clinical care.

Cytotoxic and inflammatory potential of a phospholipase A2 from Bothrops jararaca snake venom

Background

Snake venom phospholipases A₂ (PLA₂s) have been reported to induce myotoxic, neurotoxic, hemolytic, edematogenic, cytotoxic and proinflammatory effects. This work aimed at the isolation and functional characterization of a PLA₂ isolated from Bothrops jararaca venom, named BJ-PLA₂-I.

Methods and Results

For its purification, three consecutive chromatographic steps were used (Sephacryl S-200, Source 15Q and Mono Q 5/50 GL). BJ-PLA₂-I showed acidic characteristics, with pI~ 4.4 and molecular mass of 14.2 kDa. Sequencing resulted in 60 amino acid residues that showed high similarity to other Bothrops PLA₂s, including 100% identity with BJ-PLA₂, an Asp49 PLA₂ previously isolated from B. jararaca venom. Being an Asp49 PLA₂, BJ-PLA₂-I showed high catalytic activity, and also inhibitory effects on the ADP-induced platelet aggregation. Its inflammatory characterization showed that BJ-PLA₂-I was able to promote leukocyte migration in mice at different concentrations (5, 10 and 20 μg/mL) and also at different response periods (2, 4 and 24 h), mainly by stimulating neutrophil infiltration. Furthermore, increased levels of total proteins, IL-6, IL-1β and PGE₂ were observed in the inflammatory exudate induced by BJ-PLA₂-I, while nitric oxide, TNF-α, IL-10 and LTB₄ levels were not significantly altered. This toxin was also evaluated for its cytotoxic potential on normal (PBMC) and tumor cell lines (HL-60 and HepG2). Overall, BJ-PLA₂-I (2.5–160 μg/mL) promoted low cytotoxicity, with cell viabilities mostly varying between 70 and 80% and significant values obtained for HL-60 and PBMC only at the highest concentrations of the toxin evaluated.

Conclusions

BJ-PLA₂-I was characterized as an acidic Asp49 PLA₂ that induces acute local inflammation and low cytotoxicity. These results should contribute to elucidate the action mechanisms of snake venom PLA₂s.

Liquid extraction surface analysis nanospray electrospray ionization based lipidomics for in situ analysis of tumor cells with multidrug resistance

RATIONALE

Multidrug resistance (MDR) occurs frequently and is a major challenge in tumor treatment. The lipid composition in the cell membrane and the redox balance are closely associated with the development of MDR. Liquid extraction surface analysis in combination with mass spectrometry (LESA-MS) has the characteristics of minimal sample preparation, rapid analysis, high sensitivity and high throughput, and has obtained wide applications.

METHODS

LESA-MS was employed to in situ determine the lipids and other specific metabolites of intact MCF-7/ADR cells (adriamycin-resistant breast cancer cells) and its parental MCF-7/S cells grown on a glass slide. In situ atomic force microscopy was used to observe the morphology of tumor cells before and after extraction. Multivariate statistical analysis was used to investigate the potential lipid biomarkers correlated with the MDR. Moreover, the cell membrane fluidity and potential were determined.

RESULTS

The changes in the level of the lipids were closely correlated with the multidrug resistance of MCF-7/S cells. Moreover, lower cell membrane fluidity and higher cell membrane potential were observed and thus demonstrated the changes in the cell membrane induced by multidrug resistance. Also, the ratios of GSH/GSSG, ATP/ADP and ATP/AMP were significantly higher in MCF-7/ADR cells relative to MCF-7/S cells.

CONCLUSIONS

Lower cell membrane fluidity and higher cell membrane potential caused by the changes in lipid compositions, enhanced anti-oxidative ability and energy generation were involved in the development of the MDR. The specific alterations identified in this study may provide more information for overcoming MDR.

Metabolomic identification of diagnostic serum-based biomarkers for advanced stage melanoma

INTRODUCTION

Melanoma is a highly aggressive malignancy and is currently one of the fastest growing cancers worldwide. While early stage (I and II) disease is highly curable with excellent prognosis, mortality rates rise dramatically after distant spread. We sought to identify differences in the metabolome of melanoma patients to further elucidate the pathophysiology of melanoma and identify potential biomarkers to aid in earlier detection of recurrence.

METHODS

Using ¹H NMR and DI-LC-MS/MS, we profiled serum samples from 26 patients with stage III (nodal metastasis) or stage IV (distant metastasis) melanoma and compared their biochemical profiles with 46 age- and gender-matched controls.

RESULTS

We accurately quantified 181 metabolites in serum using a combination of ¹H NMR and DI-LC-MS/MS. We observed significant separation between cases and controls in the PLS-DA scores plot (permutation test p-value = 0.002). Using the concentrations of PC-aa-C40:3, DL-carnitine, octanoyl-L-carnitine, ethanol, and methylmalonyl-L-carnitine we developed a diagnostic algorithm with an AUC (95% CI) = 0.822 (0.665-0.979) with sensitivity and specificity of 100 and 56%, respectively. Furthermore, we identified arginine, proline, tryptophan, glutamine, glutamate, glutathione and ornithine metabolism to be significantly perturbed due to disease (p < 0.05).

CONCLUSION

Targeted metabolomic analysis demonstrated significant differences in metabolic profiles of advanced stage (III and IV) melanoma patients as compared to controls. These differences may represent a potential avenue for the development of multi-marker serum-based assays for earlier detection of recurrences, allow for newer, more effective targeted therapy when tumor burden is less, and further elucidate the pathophysiologic changes that occur in melanoma.

Molecular Correlates of In Vitro Responses to Dacomitinib and Afatinib in Bladder Cancer

Background:

The HER family of proteins (EGFR, HER2, HER3 and HER4) have long been thought to be therapeutic targets for bladder cancer, but previous clinical trials targeting these proteins have been disappointing. Second generation agents may be more effective.

Objective:

The aim of this study was to evaluate responses to two second-generation irreversible tyrosine kinase inhibitors, dacomitinib and afatinib, in bladder cancer cell lines.

Methods:

Cell lines were characterized by targeted next generation DNA sequencing, RNA sequencing, western blotting and flow cytometry. Cell survival responses to dacomitinib or afatinib were determined using (3-[4,5-dimethylthioazol-2-yl]-2,5-diphenyl tetrazolium bromide) (MTT) or [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and phenazine methosylfate (PMS) cell survival assays.

Results:

Only two cell lines of 12 tested were sensitive to afatinib. Sensitivity to afatinib was significantly associated with mutation in either HER2 or HER3 (p < 0.05). The two cell lines sensitive to afatinib were also responsive to dacomitinib ralong with an additional 4 other cell lines out of 16 tested. No characteristic was associated with dacomitinib sensitivity. Molecular profiling demonstrated that only two genes were high in both afatinib and dacomitinib sensitive cells. Further rhigher expression of RAS pathway genes was noted for dacomitinib responsive cells.

Conclusions:

This study confirms that cell line screening can be useful in pre-clinical evaluation of targeted small molecule inhibitors and suggests that compounds with similar structure(s) and target(s) may have distinct sensitivity profiles. Further rcombinational targeting of additional molecularly relevant pathways may be important in enhancing responses to HER targeted agents in bladder cancer.

Reprogrammed lipid metabolism in bladder cancer with cisplatin resistance

Due to its tendency to recur and acquire chemoresistance quickly, bladder cancer (BC) remains to be an elusive and difficult disease. Patients with recurrent and chemoresistant BC have an extremely poor prognosis. One possible approach that may provide insightful and valuable information regarding resistance mechanisms is looking into the lipid metabolism of BC cells. Metabolism of lipids is essential for cancer cells and is associated with the regulation of a variety of key cellular processes and functions. This study conducted a comparative lipidomic profiling of two isogenic human T24 bladder cancer cell lines, one of which is clinically characterized as cisplatin-sensitive (T24S) and the other as cisplatin-resistant (T24R). Immunohistochemistry analysis revealed that expression of cytosolic acetyl-CoA synthetase 2 (ACSS2) is positively correlated with aggressive BC. Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) analysis profiled a total of 1,864 lipids and levels of differentially expressed lipids suspected of being associated with cisplatin resistance were determined. In addition, we found that ACSS2 inhibition greatly perturbed levels of metabolites, including CE(18:1), CE(22:6), TG(49:1), and TG(53:2). This study broadens our current knowledge on the links between cisplatin resistance and lipid metabolism in aggressive BC and suggests potential biomarkers for identifying higher-risk patients.

Plasma Lipidomic Signature of Rectal Adenocarcinoma Reveals Potential Biomarkers

Background

Rectal adenocarcinoma (RAC) is a common malignant tumor of the digestive tract and survival is highly dependent upon stage of disease at diagnosis. Lipidomic strategy can be used to identify potential biomarkers for establishing early diagnosis or therapeutic programs for RAC.

Objective

To evaluate the lipoperoxidation biomarkers and lipidomic signature in the plasma of patients with RAC (n = 23) and healthy controls (n = 18).

Methods

Lipoperoxidation was evaluated based on malondialdehyde (MDA) and F₂-isoprostane levels and the lipidomic profile obtained by gas chromatography and high resolution mass spectrometry (ESI-q-TOF) associated with a multivariate statistical technique.

Results

The most abundant ions identified in the RAC patients were those of protonated phosphatidylcholine and phosphatidylethanolamine. It was found that a lisophosphatidylcholine (LPC) plasmalogen containing palmitoleic acid [LPC (P-16:1)], with highest variable importance projection score, showed a tendency to be lower in the cancer patients. A reduction of n − 3 polyunsaturated fatty acids was observed in the plasma of these patients. MDA levels were higher in patients with advanced cancer (stages III/IV) than in the early stages groups and the healthy group (p < 0.05). No differences in F₂-isoprostane levels were observed among these groups.

Conclusion

This study shows that the reduction in plasma levels of LPC plasmalogens associated with an increase in MDA levels may indicate increased oxidative stress in these patients and identify the metabolite LPC (P-16:1) as a putatively novel lipid signature for RAC.

Laser desorption/ionization MS imaging of cancer kidney tissue on silver nanoparticle-enhanced target

Aim: Renal cell carcinoma is a very aggressive and often fatal disease for which there are no specific biomarkers found to date. The purpose of work was to find substances that differentiate the cancerous and healthy tissue by using laser desorption/ionization MS imaging combined with silver nanoparticle-enhanced target. Results: Ion images and comparative analysis of spectra revealed differences in intensities for several metabolites, for which their biochemical properties were discussed. Statistical analysis allowed to distinguish healthy and cancer tissue without the involvement of a pathologist. Conclusion: Laser desorption/ionization MS imaging technology combined with silver nanoparticle-enhanced target enabled rapid visualization of the differences between the clear cell renal cell carcinoma and the healthy part of the kidney tissue.

Phospholipases during membrane dynamics in malaria parasites

Plasmodium parasites, the causative agents of malaria, display a well-regulated lipid metabolism required to ensure their survival in the human host as well as in the mosquito vector. The fine-tuning of lipid metabolic pathways is particularly important for the parasites during the rapid erythrocytic infection cycles, and thus enzymes involved in lipid metabolic processes represent prime targets for malaria chemotherapeutics. While plasmodial enzymes involved in lipid synthesis and acquisition have been studied in the past, to date not much is known about the roles of phospholipases for proliferation and transmission of the malaria parasite. These phospholipid-hydrolyzing esterases are crucial for membrane dynamics during host cell infection and egress by the parasite as well as for replication and cell signaling, and thus they are considered important virulence factors. In this review, we provide a comprehensive bioinformatic analysis of plasmodial phospholipases identified to date. We further summarize previous findings on the lipid metabolism of Plasmodium, highlight the roles of phospholipases during parasite life-cycle progression, and discuss the plasmodial phospholipases as potential targets for malaria therapy.

Antitumoral effects of γCdcPLI, a PLA2 inhibitor from Crotalus durissus collilineatus via PI3K/Akt pathway on MDA-MB-231 breast cancer cell

Phospholipases A₂(PLA₂s) overexpression is closely associated with the malignant potential of breast cancers. Here, we showed for the first the antitumoral effects of γCdcPLI, a PLA₂ inhibitor from Crotalus durissus collilineatus via PI3K/Akt pathway on MDA-MB-231 cell. Firstly, γCdcPLI was more cytotoxic to MDA-MB-231 breast cancer cells than other cell lines (MCF-7, HeLa, PC3 and A549) and did not affect the viability of non-tumorigenic breast cell (MCF 10A). In addition, γCdcPLI induced modulation of important mediators of apoptosis pathways such as p53, MAPK-ERK, BIRC5 and MDM2. γCdcPLI decreased MDA-MB-231 adhesion, migration and invasion. Interestingly, the γCdcPLI also inhibited the adhesion and migration of endothelial cells and blocked angiogenesis by inhibiting tube formation by HUVECs in vitro and sprouting elongation on aortic ring assay ex vivo. Furthermore, γCdcPLI reduced the production of vascular endothelial growth factor (VEGF). γCdcPLI was also able to decrease PGE2 levels in MDA-MB-231 and inhibited gene and protein expression of the PI3K/Akt pathway. In conclusion, γCdcPLI showed in vitro antitumoral, antimestatatic and anti-angiogenic potential effects and could be an attractive approach for futures studies in cancer therapy.

Combination diagnosis of multi-slice spiral computed tomography and secretary phospholipase A2-IIa for solitary pulmonary nodules

INTRODUCTION

This study was aimed to compare the diagnostic value of multi-slice spiral computed tomography (CT) and secretary phospholipase A2-IIa (sPLA2-IIa) in differentiating between malignant and benign solitary pulmonary nodules (SPNs).

METHODS

A total of 223 patients with SPNs (91 patients with malignant SPNs and 132 patients with benign SPNs) were included from Weihai Central Hospital during October 2014 to December 2016. SPN diagnosis was confirmed in all patients using needle biopsy, surgery and bronchoscopy. The patients were managed with dynamic multi-slice CT scans, and their sPLA2-IIa levels were also detected. By selecting the area of interest of focus, the perfusion parameters of multi-slice CT targeting the focus were obtained.

RESULTS

The levels of MTT, PS, BV, BF and sPLA2-IIa significantly increased with increasing severity of SPNs (P<.05). Notably, BV (area under the ROC curve [AUC]=0.915; 95%CI: 0.88-0.95; sensitivity=91.21%; specificity=78.79%) showed a higher potential to discriminate patients with malignant SPNs from those with benign SPNs than did BF (AUC=0.712; 95%CI: 0.65-0.78; sensitivity=72.50%; specificity=59.10%), PS (AUC=0.772; 95%CI: 0.71-0.84; sensitivity=65.93%; specificity=82.58%) and MTT (AUC=0.600; 95%CI: 0.52-0.68; sensitivity=52.75%; specificity=78.03%). Finally, the combined diagnostic value of BV and sPLA2-IIa was quite ideal (AUC=0.947; 95%CI: 0.92-0.97; sensitivity=85.70%; specificity=92.70%) for malignant and benign SPNs.

CONCLUSIONS

The combined diagnostic value of BV and sPLA2-IIa appeared as a desirable detection method for malignant and benign SPNs.

Secretory phospholipase-A2 and fatty acid composition in oral reactive lesions: a cross-sectional study

Background

Oral reactive lesions are the most common lesions of oral cavity. Phospholipases and fatty acids play key roles in the creation of inflammation by change in metabolic activities and production of lipid mediators. The aim of this study was to investigate the amount of secretory phospholipase-A2 (sPLA2) and difference of fatty acid pattern in oral reactive hyperplasia and adjacent normal appearing tissues in patients with oral reactive lesions.

Methods

Paired samples of oral hyperplastic (OH) and adjacent normal-appearing tissue of 45 patients were investigated in this study. The collected samples were analyzed with enzymatic spectrophotometric method in terms of the amount of sPLA2 and composition of fatty acids by gas–liquid chromatography method.

Results

The amount of sPLA2 (1.8-fold, p < 0.001), stearic acid (1.2-fold, p < 0.001), oleic acid (1.1-fold, p = 0.01), arachidonic acid (1.5-fold, p < 0.001) and docosahexaenoic acid (1.3-fold, p = 0.02) were increased, while the amount of palmitoleic acid (−45%, p < 0.001) and linoleic acid (−19%, p < 0.001) were reduced in the OH tissue samples. Furthermore, the results demonstrated significant associations between the type and location of tissue samples with monounsaturated fatty acids (MUFAs) and n−3 polyunsaturated fatty acids. Tissue samples from patients with inflammatory fibroepithelial hyperplasia showed relatively higher MUFAs and lower n−3 polyunsaturated fatty acids than other type of lesions.

Conclusions

Localized changes in the sPLA2 activity and composition of fatty acid are associated with oral reactive hyperplasia and the type of pathological response. We suggest that sPLA2 activity and multiple type of fatty acids might be used as potential therapeutic target for oral reactive hyperplasia.

Overexpression of secretory phospholipase A2-IIa supports cancer stem cell phenotype via HER/ERBB-elicited signaling in lung and prostate cancer cells

Resistance to conventional chemotherapies remains a significant clinical challenge in treatment of cancer. The cancer stem cells (CSCs) have properties necessary for tumor initiation, resistance to therapy, and progression. HER/ERBB‑elicited signaling supports CSC properties. Our previous studies revealed that secretory phospholipase A2 group IIa (sPLA2‑IIa) is overexpressed in both prostate and lung cancer cells, leading to an aberrant high level in the interstitial fluid, i.e., tumor microenvironment and blood. HER/ERBB-PI3K-Akt-NF-κB signaling stimulates sPLA2‑IIa overexpression, and in turn, sPLA2‑IIa activates EGFR family receptors and HER/ERBB-elicited signaling and stimulates sPLA2‑IIa overexpression in a positive feedback manner. The present study determined the molecular mechanisms of sPLA2‑IIa in stimulating HER/ERBB-elicited signaling and supporting CSC properties. We found that sPLA2‑IIa binds both EGFR and HER3 demonstrated by co-immunoprecipitation experiments and also indirectly interacts with HER2, suggesting that sPLA2‑IIa functions as a ligand for both EGFR and HER3. Furthermore, both side population CSCs from non-small cell lung cancer (NSCLC) A549 and H1975 cells and ALDH1‑high CSCs from castration-resistant prostate cancer (CRPC) 22Rv1 cells overexpress sPLA2‑IIa and produce tumors when inoculated into subcutis of nude mice. Given an aberrant high level of sPLA2‑IIa in the tumor microenvironment that should be much higher than that in the blood, our findings support the notion that sPLA2‑IIa functions as a ligand for EGFR family receptors and supports CSC properties via HER/ERBB-elicited signaling, which may contribute to resistance to therapy and cancer progression.

Comparative metabolomic analysis of HPAC cells following the acquisition of erlotinib resistance

Pancreatic cancer is one of the most lethal types of cancer, due to difficulty in early detection and the limited efficacy of available treatments. Erlotinib is used to inhibit the epidermal growth factor receptor for the treatment of pancreatic cancer; however, erlotinib resistance is a major issue and the mechanisms underlying the development of erlotinib resistance remain unclear. To better understand the alterations in tumor metabolism by acquired resistance to erlotinib, an erlotinib-resistant pancreatic cancer cell line (HPAC-ER) was established, followed by a comparison of the metabolic characteristics between these cells and their erlotinib-sensitive parental cells (HPAC). This comparison was accomplished through mass spectrometry-based targeted metabolic profiling. Five metabolite groups (acylcarnitines, amino acids and biogenic amines, glycerophospholipids, sphingolipids and monosaccharides) were semi-quantified and compared statistically. These results revealed significant differences between the two groups of cells. A significant increase in the level of short-chain acylcarnitines and selected lysophosphatidylcholines, and a significant decrease in the level of acyl-alkyl-phosphatidylcholines and one sphingolipid, were observed in the HPAC-ER cells compared with the HPAC cells. The metabolic changes observed in the present study support the theory that there are increased metabolic demands in erlotinib-resistant cancer, reflecting the changes in acetyl-CoA-associated and choline phospholipid metabolism. These findings will aid in elucidating the changes that occur in pancreatic cancer metabolism through the acquired resistance to erlotinib, and in the identification of biomarkers for the early detection of pancreatic cancer.

Effect of the enzymatically modified supported dipalmitoylphosphatidylcholine (DPPC) bilayers on calcium carbonate formation

After an hour contact with a phospholipase A₂ (PLA₂) solution, only the outer leaflet of the dipalmitoylphosphatidylcholine (DPPC) bilayers supported on mica surface underwent hydrolysis whose products, i.e., palmitic acid and lysophospholipid, accumulated on the bilayer surface. Only calcite was present on the bare mica and enzymatically unmodified and modified supported DPPC bilayers soaked for 2 weeks at 25 and 37 °C in a solution of initial pH equals to 7.4 and 9.2 containing calcium and bicarbonate ions at their concentrations about those of human blood plasma. The DPPC bilayers accelerate the crystal growth at lower pH and favors CaCO₃ nucleation at higher pH. Enzymatic modification of bilayers does not affect crystal morphology and its organization on the examined surface but causes a slight crystal size increase at lower pH and significantly reduces crystal size at alkaline pH. The temperature increase leads to the formation of bigger crystals under physiological pH and has almost no effect on crystal size at alkaline pH. The obtained results are probably attributed to Ca²⁺ interaction with a specific polar site on the surface of the membrane and DPPC hydrolysis products acting as nucleation centers.

Interaction kinetics of serum proteins with liposomes and their effect on phospholipase-induced liposomal drug release

We used surface plasmon resonance (SPR) to measure the affinity and kinetics of the interaction between serum proteins and both conventional and PEGylated liposomes. The effect of the interactions on secretory phospholipase A2 (sPLA2)-induced release of a model drug from liposomes was also assessed. SPR analysis of 12 serum proteins revealed that the mode of interaction between serum proteins and liposomes greatly varies depending on the type of protein. For example, albumin bound to liposomes at slower association/dissociation rates with higher affinity and prevented sPLA2-induced drug release from PEGylated liposomes. Conversely, fibronectin bound at faster association/dissociation rates with lower affinity and demonstrated little impact on the drug release. These results indicate that the effect of serum proteins on sPLA2 phospholipid hydrolysis varies with the mode of interaction between proteins and liposomes. Understanding how the proteins interact with liposomes and impact sPLA2 phospholipid hydrolysis should aid the rational design of therapeutic liposomal formulations.

Prognostic significance of PLA2G4C gene polymorphism in patients with stage II colorectal cancer

BACKGROUND

Phospholipase A2 Group IV C (PLA2G4C) catalyzes the release of certain fatty acids from phospholipids and plays a role in a range of physiological functions, such as remodeling of cell membranes and the production of prostaglandins. Furthermore, it has been proposed that PLA2G4C plays an important role in breast cancer cell chemotaxis. This study aimed to investigate the effect of a single nucleotide polymorphism (SNP) rs1549637 (T>A) of the PLA2G4C gene on the prognosis of colorectal cancer (CRC).

MATERIAL AND METHODS

Whole blood DNA was extracted from 381 patients with CRC and 618 controls, and a TaqMan SNP genotyping assay was used to determine the distribution of the genotypes. Cancer-specific and disease-free survival was analyzed by Kaplan-Meier graphs and by uni- and multivariable Cox regression.

RESULTS

The cancer-specific survival differed between the genotypes (p = 0.019) and the carriers of the A allele were associated with the highest risk of CRC death, with a hazard ratio (HR) of 1.72 [95% confidence interval (CI) 1.17-2.53, p = 0.006] compared with homozygous carriers of the T allele. This increased mortality in the carriers with the allele A was especially marked in stage II with an HR of 3.84 (95% CI 1.51-9.78, p = 0.005).

CONCLUSION

The A allele in PLA2G4C SNP (rs1549637) is associated with a worse prognosis in patients with CRC, especially in stage II disease, and it could be a potential prognostic biomarker in the planning of individual adjuvant therapy in stage II patients.

Overexpression of phospholipase A2 Group IIA in esophageal squamous cell carcinoma and association with cyclooxygenase-2 expression

BACKGROUND

Esophageal cancer is one of the most frequently occurring malignancies and the seventh leading cause of cancer-related deaths in the world. The esophageal squamous cell carcinoma (ESCC) is the most common histological type of esophageal cancer worldwide.

MATERIALS AND METHODS

Our goal in this study was to detect phospholipase A2 Group IIA (PLA2G2A) and cyclooxygenase-2 (COX-2) immuno-expression in ESCC in a high- risk population in China.

RESULTS

Positive expression of PLA2G2A protein was observed in 57.2% (166/290) of the cases, while COX-2 was found in 257 of 290 samples (88.6%), both PLA2G2A and COX-2 being expressed in 153 cases (52.8%), with a significant agreement (Kappa=0.091, p=0.031).Overexpression of PLA2G2A was significantly correlated with the depth of invasion (p=0.001). Co-expression of PLA2G2A and COX-2 not only significantly correlated with the depth of invasion (p=0.004) but also with TNM stage (p=0.04).

CONCLUSIONS

Our results showed that in patients with ESCC, PLA2G2A overexpression and PLA2G2A co-expression with COX-2 is significantly correlated with advanced stage. The biological role and pathophysiologic regulation of PLA2G2A and COX-2 overexpression in ESCC deserve further investigation.

Deletion of phospholipase A2 group IVc induces apoptosis in rat mammary tumour cells by the nuclear factor-κB/lipocalin 2 pathway

Although some forms of phospholipase A2, the initiator of the arachidonic acid cascade, contribute to carcinogenesis in many organs, the contribution of phospholipase A2 group IVc (Pla2g4c) remains to be clarified and the function of the enzyme in cancer development is unknown. The Hirosaki hairless rat (HHR), a mutant rat strain with autosomal recessive inheritance, derived spontaneously from the Sprague-Dawley rat (SDR). The HHRs showed a lower incidence and much smaller volume of mammary tumours induced by 7,12-dimethylbenz[a]anthracene, and a markedly increased number of TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick-end labelling)-positive apoptotic cells was detected. Array comparative genomic hybridization and PCR analyses revealed the deletion of 50-kb genomic DNA on 1q21, including Pla2g4c, in HHRs. The Pla2g4c gene was expressed in the ductal carcinoma cells and myoepithelial cells in SDRs, but not in HHRs. The direct involvement of Pla2g4c in the prevention of cell death was demonstrated through the inhibition of its expression in rat mammary tumour RMT-1 cells using siRNA. This treatment also induced expression of lipocalin 2 (Lcn2) and other NF-κB (nuclear factor κB)-related genes. siRNA-induced apoptosis was inhibited by Lcn2 repression or NF-κB inhibitors. This is the first report on Pla2g4c gene-deficient rats and their low susceptibility to mammary carcinogenesis by enhancing NF-κB/Lcn2-induced apoptosis.

Mechanisms for proteinase-activated receptor 1-triggered prostaglandin E2 generation in mouse osteoblastic MC3T3-E1 cells

We analyzed signaling mechanisms for prostaglandin E2 (PGE2) production following activation of proteinase-activated receptor-1 (PAR1), a thrombin receptor, in preosteoblastic MC3T3-E1 cells. PAR1 stimulation caused PGE2 release, an effect suppressed by inhibitors of COX-1, COX-2, iPLA2, cPLA2, MAP kinases (MAPKs), Src, EGF receptor (EGFR) tyrosine kinase (EGFR-TK) and matrix metalloproteinase (MMP), but not by an intracellular Ca2+ chelator or inhibitors of PI3 kinase, protein kinase C (PKC) and NF-κB. PAR1 activation induced phosphorylation of MAPKs and upregulation of COX-2. The phosphorylation of p38 MAPK was suppressed by inhibitors of Src and EGFR-TK. The COX-2 upregulation was dependent on ERK, p38, EGFR-TK, Src, and COX-2 itself. PAR1 activation also induced MEK-dependent phosphorylation of cAMP response element binding protein (CREB). All inhibitors of EP1, EP2, EP3 and EP4 receptors suppressed the PAR1-triggered PGE2 release. Exogenously applied PGE2 facilitated PAR1-triggered COX-2 upregulation, but it alone had no effect. Together, the PAR1-mediated PGE2 production in MC3T3-E1 cells appears to involve iPLA2 and cPLA2 for arachidonic acid release, and the MEK/ERK/CREB and Src/MMP/EGFR/p38 pathways for COX-2 upregulation, which is facilitated by endogenous PGE2 formed by COX-2. These signaling mechanisms might underlie the role of the thrombin/PAR1/PGE2 system in the early stage of the bone healing.