Roles of cPLA2alpha and arachidonic acid in cancer

A novel necroptosis-related gene signature in acute myeloid leukemia

OBJECTIVE

Necroptosis has been reported to play an important role in different cancers, including leukemia. However, biomarkers of necroptosis-related genes (NRGs) that help predict the prognosis of AML are still lacking. Our research aims to build a novel signature of NRGs that could enhance our understanding of the molecular heterogeneity in leukemia.

METHOD

Gene expression profiles as well as clinical features were downloaded from TCGA and GEO databases. Data analysis were executed using R software version 4.2.1 and GraphPad Prism version 9.0.0.

RESULT

Univariate cox regression and lasso regression were applied to identify survival-specific genes. Four genes including FADD, PLA2G4A, PYCARD and ZBP1 were considered as independent risk factors that affect the prognosis of patients. Risk scores were calculated according to the coefficient of four genes. Then clinical characteristics and risk scores were enrolled to construct a nomogram. CellMiner was also used to screen potential drugs and analyze the correlations between genes and drug sensitivity.

CONCLUSION

In general, we established a signature of four genes related to necroptosis that could be helpful for future risk stratification in patients with AML.

Dynamics of Docosahexaenoic Acid Utilization by Mouse Peritoneal Macrophages

In this work, the incorporation of docosahexaenoic acid (DHA) in mouse resident peritoneal macrophages and its redistribution within the various phospholipid classes were investigated. Choline glycerophospholipids (PC) behaved as the major initial acceptors of DHA. Prolonged incubation with the fatty acid resulted in the transfer of DHA from PC to ethanolamine glycerophospholipids (PE), reflecting phospholipid remodeling. This process resulted in the cells containing similar amounts of DHA in PC and PE in the resting state. Mass spectrometry-based lipidomic analyses of phospholipid molecular species indicated a marked abundance of DHA in ether phospholipids. Stimulation of the macrophages with yeast-derived zymosan resulted in significant decreases in the levels of all DHA-containing PC and PI species; however, no PE or PS molecular species were found to decrease. In contrast, the levels of an unusual DHA-containing species, namely PI(20:4/22:6), which was barely present in resting cells, were found to markedly increase under zymosan stimulation. The levels of this phospholipid also significantly increased when the calcium-ionophore A23187 or platelet-activating factor were used instead of zymosan to stimulate the macrophages. The study of the route involved in the synthesis of PI(20:4/22:6) suggested that this species is produced through deacylation/reacylation reactions. These results define the increases in PI(20:4/22:6) as a novel lipid metabolic marker of mouse macrophage activation, and provide novel information to understand the regulation of phospholipid fatty acid turnover in activated macrophages.

Role of Orai3 in the Pathophysiology of Cancer

The mammalian exclusive Orai3 channel participates in the generation and/or modulation of two independent Ca²⁺ currents, the store-operated current, I_crac, involving functional interactions between the stromal interaction molecules (STIM), STIM1/STIM2, and Orai1/Orai2/Orai3, as well as the store-independent arachidonic acid (AA) (or leukotriene C4)-regulated current I_arc, which involves Orai1, Orai3 and STIM1. Overexpression of functional Orai3 has been described in different neoplastic cells and cancer tissue samples as compared to non-tumor cells or normal adjacent tissue. In these cells, Orai3 exhibits a cell-specific relevance in Ca²⁺ influx. In estrogen receptor-positive breast cancer cells and non-small cell lung cancer (NSCLC) cells store-operated Ca²⁺ entry (SOCE) is strongly dependent on Orai3 expression while in colorectal cancer and pancreatic adenocarcinoma cells Orai3 predominantly modulates SOCE. On the other hand, in prostate cancer cells Orai3 expression has been associated with the formation of Orai1/Orai3 heteromeric channels regulated by AA and reduction in SOCE, thus leading to enhanced proliferation. Orai3 overexpression is associated with supporting several cancer hallmarks, including cell cycle progression, proliferation, migration, and apoptosis resistance. This review summarizes the current knowledge concerning the functional role of Orai3 in the pathogenesis of cancer.

A Multiplex CRISPR-Screen Identifies PLA2G4A as Prognostic Marker and Druggable Target for HOXA9 and MEIS1 Dependent AML

HOXA9 and MEIS1 are frequently upregulated in acute myeloid leukemia (AML), including those with MLL-rearrangement. Because of their pivotal role in hemostasis, HOXA9 and MEIS1 appear non-druggable. We, thus, interrogated gene expression data of pre-leukemic (overexpressing Hoxa9) and leukemogenic (overexpressing Hoxa9 and Meis1; H9M) murine cell lines to identify cancer vulnerabilities. Through gene expression analysis and gene set enrichment analyses, we compiled a list of 15 candidates for functional validation. Using a novel lentiviral multiplexing approach, we selected and tested highly active sgRNAs to knockout candidate genes by CRISPR/Cas9, and subsequently identified a H9M cell growth dependency on the cytosolic phospholipase A2 (PLA2G4A). Similar results were obtained by shRNA-mediated suppression of Pla2g4a. Remarkably, pharmacologic inhibition of PLA2G4A with arachidonyl trifluoromethyl ketone (AACOCF3) accelerated the loss of H9M cells in bulk cultures. Additionally, AACOCF3 treatment of H9M cells reduced colony numbers and colony sizes in methylcellulose. Moreover, AACOCF3 was highly active in human AML with MLL rearrangement, in which PLA2G4A was significantly higher expressed than in AML patients without MLL rearrangement, and is sufficient as an independent prognostic marker. Our work, thus, identifies PLA2G4A as a prognostic marker and potential therapeutic target for H9M-dependent AML with MLL-rearrangement.

The Involvement of Lactosylceramide in Central Nervous System Inflammation Related to Neurodegenerative Disease

Neurodegenerative diseases are a class of slow-progressing terminal illnesses characterized by neuronal lesions, such as multiple sclerosis [MS, Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS)]. Their incidence increases with age, and the associated burden on families and society will become increasingly more prominent with aging of the general population. In recent years, there is growing studies have shown that lactosylceramide (LacCer) plays a crucial role in the progression of neurodegeneration, although these diseases have different pathogenic mechanisms and etiological characteristics. Based on latest research progress, this study expounds the pathogenic role of LacCer in driving central nervous system (CNS) inflammation, as well as the role of membrane microstructure domain (lipid rafts) and metabolite gangliosides, and discusses in detail their links with the pathogenesis of neurodegenerative diseases, with a view to providing new strategies and ideas for the study of pathological mechanisms and drug development for neurodegenerative diseases in the future.

Targeting cPLA2α inhibits gastric cancer and augments chemotherapy efficacy via suppressing Ras/MEK/ERK and Akt/β-catenin pathways

BACKGROUND

Cytosolic phospholipase A2alpha (cPLA2α), an enzyme that is responsible for the hydrolysis of membrane phospholipids, is a key mediator of tumor transformation, progression and metastasis. The role of cPLA2α in gastric cancer has not been revealed.

METHODS

cPLA2α expression was analyzed using RT-PCR and immunohistochemistry approaches in gastric cancer patient samples (n = 26) and multiple cell lines (n = 7). cPLA2α function was studied using plasmid overexpression and siRNA knockdown approaches in SNU-1, MKN-74 and MKN-45 cell lines. The downstream effectors of cPLA2α were determined using biochemical assays.

RESULTS

cPLA2α upregulation is a common feature in gastric cancer patients, particularly those with metastasis. cPLA2α overexpression is sufficient to promote gastric cancer cell growth and migration, and confer chemo-resistance. cPLA2α depletion is active against gastric cancer via inhibiting growth and migration, and inducing apoptosis in gastric cancer cells. Of note, cPLA2α depletion augments efficacy of chemotherapy. Mechanistic studies confirm that cPLA2α regulates gastric cancer biological activities via mainly regulating Ras/MEK/ERK and possibly Akt/β-catenin pathways. Pearson correlation coefficient analysis also suggests a moderate positive correlation between cPLA2α and RAS in gastric cancer.

CONCLUSIONS

Our work demonstrates cPLA2α inhibition as a therapeutic strategy to overcome chemo-resistance and highlights the association of cPLA2α and Ras in gastric cancer.

Phospholipase Signaling in Breast Cancer

Breast cancer progression results from subversion of multiple intra- or intercellular signaling pathways in normal mammary tissues and their microenvironment, which have an impact on cell differentiation, proliferation, migration, and angiogenesis. Phospholipases (PLC, PLD and PLA) are essential mediators of intra- and intercellular signaling. They hydrolyze phospholipids, which are major components of cell membrane that can generate many bioactive lipid mediators, such as diacylglycerol, phosphatidic acid, lysophosphatidic acid, and arachidonic acid. Enzymatic processing of phospholipids by phospholipases converts these molecules into lipid mediators that regulate multiple cellular processes, which in turn can promote breast cancer progression. Thus, dysregulation of phospholipases contributes to a number of human diseases, including cancer. This review describes how phospholipases regulate multiple cancer-associated cellular processes, and the interplay among different phospholipases in breast cancer. A thorough understanding of the breast cancer-associated signaling networks of phospholipases is necessary to determine whether these enzymes are potential targets for innovative therapeutic strategies.

Therapeutic Effects of Curcumin against Bladder Cancer: A Review of Possible Molecular Pathways

There are concerns about the increased incidence of cancer both in developing and developed countries. In spite of recent progress in cancer therapy, this disease is still one of the leading causes of death worldwide. Consequently, there have been rigorous attempts to improve cancer therapy by looking at nature as a rich source of naturally occurring anti-tumor drugs. Curcumin is a well-known plant-derived polyphenol found in turmeric. This compound has numerous pharmacological effects such as antioxidant, anti-inflammatory, antidiabetic and anti-tumor properties. Curcumin is capable of suppressing the growth of a variety of cancer cells including those of bladder cancer. Given the involvement of various signaling pathways such as PI3K, Akt, mTOR and VEGF in the progression and malignancy of bladder cancer, and considering the potential of curcumin in targeting signaling pathways, it seems that curcumin can be considered as a promising candidate in bladder cancer therapy. In the present review, we describe the molecular signaling pathways through which curcumin inhibits invasion and metastasis of bladder cancer cells.

Biological and physical approaches on the role of piplartine (piperlongumine) in cancer

Chronic inflammation provides a favorable microenvironment for tumorigenesis, which opens opportunities for targeting cancer development and progression. Piplartine (PL) is a biologically active alkaloid from long peppers that exhibits anti-inflammatory and antitumor activity. In the present study, we investigated the physical and chemical interactions of PL with anti-inflammatory compounds and their effects on cell proliferation and migration and on the gene expression of inflammatory mediators. Molecular docking data and physicochemical analysis suggested that PL shows potential interactions with a peptide of annexin A1 (ANXA1), an endogenous anti-inflammatory mediator with therapeutic potential in cancer. Treatment of neoplastic cells with PL alone or with annexin A1 mimic peptide reduced cell proliferation and viability and modulated the expression of MCP-1 chemokine, IL-8 cytokine and genes involved in inflammatory processes. The results also suggested an inhibitory effect of PL on tubulin expression. In addition, PL apparently had no influence on cell migration and invasion at the concentration tested. Considering the role of inflammation in the context of promoting tumor initiation, the present study shows the potential of piplartine as a therapeutic immunomodulator for cancer prevention and progression.

Eicosanoids in Cancer: New Roles in Immunoregulation

Eicosanoids represent a family of active biolipids derived from arachidonic acid primarily through the action of cytosolic phospholipase A2-α. Three major downstream pathways have been defined: the cyclooxygenase (COX) pathway which produces prostaglandins and thromboxanes; the 5-lipoxygenase pathway (5-LO), which produces leukotrienes, lipoxins and hydroxyeicosatetraenoic acids, and the cytochrome P450 pathway which produces epoxygenated fatty acids. In general, these lipid mediators are released and act in an autocrine or paracrine fashion through binding to cell surface receptors. The pattern of eicosanoid production is cell specific, and is determined by cell-specific expression of downstream synthases. Increased eicosanoid production is associated with inflammation and a panel of specific inhibitors have been developed designated non-steroidal anti-inflammatory drugs. In cancer, eicosanoids are produced both by tumor cells as well as cells of the tumor microenvironment. Earlier studies demonstrated that prostaglandin E2, produced through the action of COX-2, promoted cancer cell proliferation and metastasis in multiple cancers. This resulted in the development of COX-2 inhibitors as potential therapeutic agents. However, cardiac toxicities associated with these agents limited their use as therapeutic agents. The advent of immunotherapy, especially the use of immune checkpoint inhibitors has revolutionized cancer treatment in multiple malignancies. However, the majority of patients do not respond to these agents as monotherapy, leading to intense investigation of other pathways mediating immunosuppression in order to develop rational combination therapies. Recent data have indicated that PGE2 has immunosuppressive activity, leading to renewed interest in targeting this pathway. However, little is known regarding the role of other eicosanoids in modulating the tumor microenvironment, and regulating anti-tumor immunity. This article reviews the role of eicosanoids in cancer, with a focus on their role in modulating the tumor microenvironment. While the role of PGE2 will be discussed, data implicating other eicosanoids, especially products produced through the lipoxygenase and cytochrome P450 pathway will be examined. The existence of small molecular inhibitors and activators of eicosanoid pathways such as specific receptor blockers make them attractive candidates for therapeutic trials, especially in combination with novel immunotherapies such as immune checkpoint inhibitors.

cPLA2α Enzyme Inhibition Attenuates Inflammation and Keratinocyte Proliferation

As a regulator of cellular inflammation and proliferation, cytosolic phospholipase A₂ α (cPLA₂α) is a promising therapeutic target for psoriasis; indeed, the cPLA₂α inhibitor AVX001 has shown efficacy against plaque psoriasis in a phase I/IIa clinical trial. To improve our understanding of the anti-psoriatic properties of AVX001, we sought to determine how the compound modulates inflammation and keratinocyte hyperproliferation, key characteristics of the psoriatic epidermis. We measured eicosanoid release from human peripheral blood mononuclear cells (PBMC) and immortalized keratinocytes (HaCaT) and studied proliferation in HaCaT grown as monolayers and stratified cultures. We demonstrated that inhibition of cPLA₂α using AVX001 produced a balanced reduction of prostaglandins and leukotrienes; significantly limited prostaglandin E₂ (PGE₂) release from both PBMC and HaCaT in response to pro-inflammatory stimuli; attenuated growth factor-induced arachidonic acid and PGE₂ release from HaCaT; and inhibited keratinocyte proliferation in the absence and presence of exogenous growth factors, as well as in stratified cultures. These data suggest that the anti-psoriatic properties of AVX001 could result from a combination of anti-inflammatory and anti-proliferative effects, probably due to reduced local eicosanoid availability.

Exposure to growth hormone is associated with hepatic up-regulation of cPLA2α and COX

Continuously elevated levels of growth hormone (GH) during life in mice are associated with hepatomegaly due to hepatocytes hypertrophy and hyperplasia, chronic liver inflammation, elevated levels of arachidonic acid (AA) at young ages and liver tumors development at old ages. In this work, the hepatic expression of enzymes involved in AA metabolism, cPLA2α, COX1 and COX2 enzymes, was evaluated in young and old GH-transgenic mice. Mice overexpressing GH exhibited higher hepatic expression of cPLA2α, COX1 and COX2 in comparison to controls at young and old ages and in both sexes. In old mice, when tumoral and non-tumoral tissue were compared, elevated expression of COX2 was observed in tumors. In contrast, exposure to continuous lower levels of hormone for a short period affected COX1 expression only in males. Considering the role of inflammation during liver tumorigenesis, these findings support a role of alterations in AA metabolism in GH-driven liver tumorigenesis.

Focus on the glycerophosphocholine pathway in choline phospholipid metabolism of cancer

Activated choline metabolism is a hallmark of carcinogenesis and tumor progression, which leads to elevated levels of phosphocholine and glycerophosphocholine in all types of cancer tested so far. Magnetic resonance spectroscopy applications have played a key role in detecting these elevated choline phospholipid metabolites. To date, the majority of cancer-related studies have focused on phosphocholine and the Kennedy pathway, which constitutes the biosynthesis pathway for membrane phosphatidylcholine. Fewer and more recent studies have reported on the importance of glycerophosphocholine in cancer. In this review article, we summarize the recent literature on glycerophosphocholine metabolism with respect to its cancer biology and its detection by magnetic resonance spectroscopy applications.

Cytosolic Phospholipase A2 Alpha Regulates TLR Signaling and Migration in Metastatic 4T1 Cells

Metastatic disease is the leading cause of death in breast cancer patients. Disrupting the cancer cell’s ability to migrate may be a strategy for hindering metastasis. Cytosolic phospholipase A2 α (cPLA2α), along with downstream proinflammatory and promigratory metabolites, has been implicated in several aspects of tumorigenesis, as well as metastasis, in various types of cancer. In this study, we aim to characterize the response to reduced cPLA2α activity in metastatic versus non-metastatic cells. We employ an isogenic murine cell line pair displaying metastatic (4T1) and non-metastatic (67NR) phenotype to investigate the role of cPLA2α on migration. Furthermore, we elucidate the effect of reduced cPLA2α activity on global gene expression in the metastatic cell line. Enzyme inhibition is achieved by using a competitive pharmacological inhibitor, cPLA2α inhibitor X (CIX). Our data show that 4T1 expresses significantly higher cPLA2α levels as compared to 67NR, and the two cell lines show different sensitivity to the CIX treatment with regards to metabolism and proliferation. Inhibition of cPLA2α at nontoxic concentrations attenuates migration of highly metastatic 4T1 cells, but not non-metastatic 67NR cells. Gene expression analysis indicates that processes such as interferon type I (IFN-I) signaling and cell cycle regulation are key processes regulated by cPLA2a in metastatic 4T1 cells, supporting the findings from the biological assays. This study demonstrates that two isogenic cancer cell lines with different metastatic potential respond differently to reduced cPLA2α activity. In conclusion, we argue that cPLA2α is a potential therapeutic target in cancer and that enzyme inhibition may inhibit metastasis through an anti-migratory mechanism, possibly involving Toll-like receptor signaling and type I interferons.

Annexin A2 interacting with ELMO1 regulates HCC chemotaxis and metastasis

AIMS

SDF-1α induced chemotaxis plays an important role in hepatocellular carcinoma metastasis. CXCR4 stimulated by SDF-1α/CXCL12 triggers heterotrimeric G proteins activation, which regulate migration and chemotaxis of hepatocellular carcinoma cells. The pathways linking the chemokine GPCR/Gi signaling to actin polymerization for migration of cancer cells are not known.

MATERIALS AND METHODS

Through would healing assay, chemotaxis assay, F-actin polymerization assay, confocal assay, immunohistochemical assay, protein identification and coimmunoprecipitation assay, we detected the role and mechanisms of Annexin A2 in hepatocellular carcinoma.

KEY FINDINGS

In the present study, we firstly investigated the role of Annexin A2 in HepG2 cell chemotaxis and metastasis. Immunohistochemical analysis showed that Annexin A2 was highly expressed in hepatocellular carcinoma tissues. Its expression was closely associated with lymph node and distant metastasis. Knockdown Annexin A2 impaired cancer cell chemotaxis. Co-immunoprecipitation results showed an interaction between Annexin A2 and ELMO1. CXCL12 triggers an ELMO1-dependent membrane translocation of Annexin A2.

SIGNIFICANCE

Taken together, our results indicated an important role of Annexin A2 in hepatocellular carcinoma tissues metastasis and revealed a novel molecular mechanism of its activation.

Inhibition of cytosolic phospholipase A2 alpha increases chemosensitivity in cervical carcinoma through suppressing β-catenin signaling

Cytosolic phospholipase A2alpha (cPLA2α) is a key mediator of tumorigenesis. In this study, by using a combination of pharmacological and genetic approaches in cell models and patient samples, we identify cPLA2α as a selective target to increase chemosensitivity in cervical cancer. We found that transcript and protein levels of cPLA2α but not other forms of cPLA2 (e.g., cPLA2β and cPLA2αδ) were consistently increased in all tested malignant cervical cancer cells and tissues compared to normal counterparts, suggesting that cPLA2α upregulation is a common feature in cervical cancer. We further found that promoting growth and survival rather than invasion were the predominant roles of cPLA2α on cervical cancer. In addition, chemotherapeutic agents achieved ~100% inhibition efficacy in cPLA2α-depleted cervical cancer cells, demonstrating the important role of cPLA2α in chemoresistance. Importantly, we identify that β-catenin is critically involved in the molecular mechanism of cPLA2α's action in cervical cancer. In summary, our work demonstrates the multiple essential roles of cPLA2α in cervical cancer, particularly in chemoresistance, via a β-catenin-dependent manner. Our work also suggests that targeting cPLA2α has a therapeutic value in overcoming chemoresistance in cervical cancer or other cPLA2α-regulated cancers.

Inhibition of PLA2G4A Reduces the Expression of Lung Cancer-Related Cytokines

Phospholipase A2-IVA (PLA2G4A) is the most abundant subtype of cytoplasmic phospholipase A2 (cPLA2) and is an important enzyme in tumor development. Our study aimed to explore the role of PLA2G4A in the regulation of lung cancer. The contents of cell-related cytokines (microsomal prostaglandin E synthase-1 [mPGES], PGE2, and prostacyclin [PGI2]) in A549 cells were analyzed by ELISA kits. Cell counting kit-8 (CCK8) was used to detect the effects of inhibitor of cPLA2 (arachidonyl trifluoromethyl ketone [AACOCF3]) on the proliferation of A549 cells. The migration and invasion of A549 cells were tested by cell scratch wound healing assay and transwell assay, respectively. Real-time quantitative PCR and Western blotting were used to detect the effect of inhibitor AACOCF3 on the expression of related mRNA and protein in A549 cells. ELISA result showed that the levels of mPGES, PGE2, and PGI2 in control group were significantly higher than those in the AACOCF3 group. Cell inhibition rate in the control group was significantly lower than that in the AACOCF3 group. The percentage of wound healing in the control group was significantly higher than that in the AACOCF3 group. Meanwhile, the relative invasive number of cells in the control group was significantly higher than those in the AACOCF3 group. The expression levels of related mRNA of PLA2G4A and cyclooxygenase-2 (COX-2) and the expression levels of mPGES, COX-1, and COX-2 protein in the control group were significantly higher than those in the AACOCF3 group. Our research showed that PLA2G4A was involved in migration and invasion of lung cancer cells.

Identification of the transgenic integration site in 2C T cell receptor transgenic mice

2C T cell receptor (TCR) transgenic mice have been long used to study the molecular basis of TCR binding to peptide/major compatibility complexes and the cytotoxicity mechanism of cytotoxic T lymphocytes (CTLs). To study the role of variable gene promoters in allelic exclusion, we previously constructed mutant mice in which the Vβ13 promoter was deleted (P13 mice). Introduction of 2C transgene into P13 mice accelerated the onset of systemic CD8 T cell lymphoma between 14 and 27 weeks of age, although parental P13 mice appeared to be normal. This observation suggests that the lymphoma development may be linked to features of 2C transgene. To identify the integration site of 2C transgene, Southern blotting identified a 2C-specific DNA fragment by 3' region probe of 2C TCR α transgene, and digestion-circularization-polymerase chain reaction (DC-PCR) amplified the 2C-specific DNA fragment with inverse primers specific to the southern probe. Sequence analysis revealed that DC-PCR product contained the probe sequences and the junction sequences of integration site, indicating that 2C TCR α transgene is integrated into chromosome 1. Further genomic analysis revealed cytosolic phospholipase A2 group IVA (cPLA2) as the nearest gene to the integration site. cPLA2 expression was upregulated in the normal thymi and T cell lymphomas from 2C transgenic mice, although it was not altered in the lymph nodes of 2C transgenic mice. The result is the first report demonstrating the integration site of 2C TCR transgene, and will facilitate the proper use of 2C transgenic mice in studies of CTLs.

A rare eicosanoid precursor analogue, sciadonic acid (5Z,11Z,14Z-20:3), detected in vivo in hormone positive breast cancer tissue

Numerous genetic alterations of HSA 11q13 are found frequently in several cancer types, including breast cancer (BC). The 11q13 locus harbors FADS2 encoding Δ6 desaturation which is not functional in several cancer cell lines, including hormone positive MCF7 BC cells. In vitro, the non-functional FADS2 activity unmasks 18:2n-6 elongation to 20:2n-6 and Δ5 desaturation by FADS1 to yield 5Z,11Z,14Z-20:3 (sciadonic acid) rather than 5Z,8Z,11Z,14Z-20:4 (arachidonic acid). In this pilot study we aimed to determine whether 5,11,14-20:3 appears in vivo in hormone positive human BC tissue. Fatty acids were profiled in surgically removed human breast tumor and adjacent normal tissue (n = 9). Sciadonic acid was detected in three of nine breast tumor samples and was below detect limits in normal breast tissue. The internal Δ8 double bond of arachidonic acid is required for normal eicosanoid synthesis but is missing in sciadonic acid. This pilot study demonstrates for the first time in vivo sciadonic acid in hormone positive BC tissue, warranting a larger survey study to further evaluate its appearance and the functional implications.

Melatonin potentiates the antitumor effect of curcumin by inhibiting IKKβ/NF-κB/COX-2 signaling pathway

Curcumin, a natural polyphenolic compound, has commonly been used as a food additive or in many traditional medicine remedies for over 2,000 years in many Asian countries. Melatonin is a hormone secreted from pineal glands of mammals and possesses diverse physiological functions. Both curcumin and melatonin have the effective potential to inhibit proliferation of various types of cancers, but there is no report on their combination for bladder cancer treatment, and the underlying mechanism remains poorly understood. In the present study, we investigated whether the combination of curcumin and melatonin leads to an enhanced inhibition of cell proliferation in bladder cancer cells. Our results showed that the combinational treatment enhanced the repression of nuclear translocation of NF-κB and their binding on COX-2 promoter via inhibiting IKKβ activity, resulting in inhibition of COX-2 expression. In addition, combined treatment with curcumin and melatonin induced cell apoptosis in bladder cancer through enhancing the release of cytochrome c from the mitochondrial intermembrane space into the cytosol. These results, therefore, indicated that melatonin synergized the inhibitory effect of curcumin against the growth of bladder cancer by enhancing the anti-proliferation, anti-migration, and pro-apoptotic activities, and provide strong evidence that combined treatment with curcumin and melatonin might exhibit an effective therapeutic option in bladder cancer therapy.

Dehydrocostus lactone, a natural sesquiterpene lactone, suppresses the biological characteristics of glioma, through inhibition of the NF-κB/COX-2 signaling pathway by targeting IKKβ

Dehydrocostus lactone (DHE), a natural sesquiterpene lactone, has been used for treatment of various diseases with its anti-inflammatory activity. Recently, it has caused extensive interest in researchers due to it has anti-cancer abilities in some types of carcinomas. However, the anti-cancer effect and mechanism of DHE in glioma remains unclear. The present study conducted to determine the biological effects of DHE on the glioblastoma cells, as well as the mechanisms underlying these effects. After treatment with DHE, the glioblastoma (U118, U251 or U87) cells were significantly inhibited in their viability, proliferation and migration. At the meantime, DHE also induced mitochondria-mediated apoptosis by promoting the release of cytochrome c into cytosol, which activating caspase signaling pathway. Furthermore, our results fully demonstrate that DHE significantly suppressed COX-2 expression by inhibiting the phosphorylation of IKKβ via targeting the ATP-binding site, thereby abrogating NF-κB binding and p300 recruitment to COX-2 promoter. Moreover, the current study firstly demonstrated that DHE can cross blood-brain barrier (BBB). In addition, treatment with DHE markedly inhibited neoplastic weight and volume without the notable adverse effects in the xenograft nude mice model, and these effects may be mediated through inhibition of the IKKβ/NF-κB/COX-2 signaling pathway. These findings provide the pharmacological evidence for development of DHE as a potential agent against glioma.

Biphasic activation of extracellular signal-regulated kinase (ERK) 1/2 in epidermal growth factor (EGF)-stimulated SW480 colorectal cancer cells

Cancer cells have different characteristics due to the genetic differences where these unique features may strongly influence the effectiveness of therapeutic interventions. Here, we show that the spontaneous reactivation of extracellular signalregulated kinase (ERK), distinct from conventional ERK activation, represents a potent mechanism for cancer cell survival. We studied ERK1/2 activation in vitro in SW480 colorectal cancer cells. Although ERK signaling tends to be transiently activated, we observed the delayed reactivation of ERK1/2 in epidermal growth factor (EGF)-stimulated SW480 cells. This effect was observed even after EGF withdrawal. While phosphorylated ERK1/2 translocated into the nucleus following its primary activation, it remained in the cytoplasm during late-phase activation. The inhibition of primary ERK1/2 activation or protein trafficking, blocked reactivation and concurrently increased caspase 3 activity. Our results suggest that the biphasic activation of ERK1/2 plays a role in cancer cell survival; thus, regulation of ERK1/2 activation may improve the efficacy of cancer therapies that target ERK signaling. [BMB Reports 2016; 49(4): 220-225]

Expression of Ovol2 is related to epithelial characteristics and shows a favorable clinical outcome in hepatocellular carcinoma

Metastasis involves epithelial–mesenchymal transition (EMT) and mesenchymal–epithelial transition. Ovol2 belongs to the Ovo-like family (Ovol) of evolutionarily conserved zinc-finger transcription factors that regulate gene expression in various differentiation processes. Recent studies have demonstrated that Ovols affect mesenchymal–epithelial transition by inducing the expression of miR-200 in a range of human cancers. Downregulated Ovol2 expression is involved in the invasion and metastasis of breast and prostate cancers, but little is known about its expression and prognostic value in other cancers, including hepatocellular carcinoma (HCC). This study was designed to explore the clinical and prognostic significance of Ovol2 in patients with HCC. The expression of Ovol2 in tumor samples from patients with HCC and HCC cell lines was examined using Western blotting, real-time polymerase chain reaction, and immunohistochemistry. The expression levels of EMT-related markers, including E-cadherin, N-cadherin, and vimentin, were detected in relation to Ovol2 expression. The prognostic significance of Ovol2 in patients with HCC was statistically analyzed by Kaplan–Meier and Cox regression analyses. Ovol2 expression was significantly lower in HCC tissues than in adjacent noncancerous tissues. Low expression of Ovol2 was detected in HCC tissues with poor histological differentiation, microvascular invasion, and cirrhosis. A significant relationship was observed between Ovol2 and EMT marker expression levels. Kaplan–Meier analysis showed that overall survival was significantly worse in patients with HCC with low Ovol2 expression, indicating that Ovol2 deletion was an independent predictor of unfavorable prognosis in patients with HCC. Elevated Ovol2 expression may suppress HCC cell invasion and metastasis via restricting EMT.

Cytosolic phospholipase A2α increases proliferation and de-differentiation of human renal tubular epithelial cells

The group IVA calcium-dependent cytosolic phospholipase A₂ (cPLA₂α) enzyme controls the release of arachidonic acid from membrane bound phospholipids and is the rate-limiting step in production of eicosanoids. A variety of different kidney injuries activate cPLA₂α, therefore we hypothesized that cPLA₂α activity would regulate pathologic processes in HK-2 cells, a human renal tubular epithelial cell line, by regulating cell phenotype and proliferation. In two lentiviral cPLA₂α-silenced knockdowns, we observed decreased proliferation and increased apoptosis compared to control HK-2 cells. cPLA₂α-silenced cells also demonstrated an altered morphology, had increased expression E-cadherin, and decreased expression of Ncadherin. Increased levels of E-cadherin were associated with increased promoter activity and decreased levels of SNAIL1, SNAIL2, and ZEB1, transcriptional repressors of E-cadherin expression. Addition of exogenous arachidonic acid, but not PGE2, reversed the phenotypic changes in cPLA₂α-silenced cells. These data suggest that cPLA₂α may play a key role in renal repair after injury through a PGE₂-independent mechanism.

Targeting of cytosolic phospholipase A2α impedes cell cycle re-entry of quiescent prostate cancer cells

Cell cycle re-entry of quiescent cancer cells has been proposed to be involved in cancer progression and recurrence. Cytosolic phospholipase A₂α (cPLA₂α) is an enzyme that hydrolyzes membrane glycerophospholipids to release arachidonic acid and lysophospholipids that are implicated in cancer cell proliferation. The aim of this study was to determine the role of cPLA₂α in cell cycle re-entry of quiescent prostate cancer cells. When PC-3 and LNCaP cells were rendered to a quiescent state, the active form of cPLA₂α with a phosphorylation at Ser⁵⁰⁵ was lower compared to their proliferating state. Conversely, the phospho-cPLA₂α levels were resurgent during the induction of cell cycle re-entry. Pharmacological inhibition of cPLA₂α with Efipladib upon induction of cell cycle re-entry inhibited the re-entry process, as manifested by refrained DNA synthesis, persistent high proportion of cells in G₀/G₁ and low percentage of cells in S and G₂/M phases, together with a stagnant recovery of Ki-67 expression. Simultaneously, Efipladib prohibited the emergence of Skp2 while maintained p27 at a high level in the nuclear compartment during cell cycle re-entry. Inhibition of cPLA₂α also prevented an accumulation of cyclin D1/CDK4, cyclin E/CDK2, phospho-pRb, pre-replicative complex proteins CDC6, MCM7, ORC6 and DNA synthesis-related protein PCNA during induction of cell cycle re-entry. Moreover, a pre-treatment of the prostate cancer cells with Efipladib during induction of cell cycle re-entry subsequently compromised their tumorigenic capacity in vivo. Hence, cPLA₂α plays an important role in cell cycle re-entry by quiescent prostate cancer cells.

Biological activity and binding properties of [Ru(II)(dcbpy)2Cl2] complex to bovine serum albumin, phospholipase A2 and glutathione

Ruthenium compounds are highly regarded as metallo-drug candidates. Many studies have focused their attention on the interaction between ruthenium complexes with their possible biological targets. The interaction of ruthenium complexes with transport proteins, enzymes and peptides is of great importance for understanding their biodistribution and mechanism of action, therefore, the development of an anti-cancer therapy involving ruthenium complexes has recently shifted from DNA targeting towards protein targeting. With the aim of gaining insight into possible interactions between ruthenium complexes with biologically relevant proteins, we have studied the interaction of cis-dichlorobis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) complex [Ru(II)(dcbpy)2Cl2], which previously showed good potency in photo-dynamic chemotherapy, with bovine serum albumin (BSA), phospholipase A2 (PLA2) and glutathione (GSH). Binding constants and possible number of binding sites to mentioned proteins and peptide are investigated by ultraviolet-visible spectroscopy and Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (MALDI TOF MS). The complex binding affinities were in the following order: PLA2 > BSA > GSH. Moreover, genotoxic profile of the complex, tested on peripheral blood lymphocytes as a model system, was also promising.

Annexin A1 localization and its relevance to cancer

Annexin A1 (ANXA1) is a Ca(2+)-regulated phospholipid-binding protein involved in various cell processes. ANXA1 was initially widely studied in inflammation resolution, but its overexpression was later reported in a large number of cancers. Further in-depth investigations have revealed that this protein could have many roles in cancer progression and act at different levels (from cancer initiation to metastasis). This is partly due to the location of ANXA1 in different cell compartments. ANXA1 can be nuclear, cytoplasmic and/or membrane associated. This last location allows ANXA1 to be proteolytically cleaved and/or to become accessible to its cognate partners, the formyl-peptide receptors. Indeed, in some cancers, ANXA1 is found at the cell surface, where it stimulates formyl-peptide receptors to trigger oncogenic pathways. In the present review, we look at the different locations of ANXA1 and their association with the deregulated pathways often observed in cancers. We have specifically detailed the non-classic pathways of ANXA1 externalization, the significance of its cleavage and the role of the ANXA1-formyl-peptide receptor complex in cancer progression.

Structure of Human GIVD Cytosolic Phospholipase A2 Reveals Insights into Substrate Recognition

Cytosolic phospholipases A2 (cPLA2s) consist of a family of calcium-sensitive enzymes that function to generate lipid second messengers through hydrolysis of membrane-associated glycerophospholipids. The GIVD cPLA2 (cPLA2δ) is a potential drug target for developing a selective therapeutic agent for the treatment of psoriasis. Here, we present two X-ray structures of human cPLA2δ, capturing an apo state, and in complex with a substrate-like inhibitor. Comparison of the apo and inhibitor-bound structures reveals conformational changes in a flexible cap that allows the substrate to access the relatively buried active site, providing new insight into the mechanism for substrate recognition. The cPLA2δ structure reveals an unexpected second C2 domain that was previously unrecognized from sequence alignments, placing cPLA2δ into the class of membrane-associated proteins that contain a tandem pair of C2 domains. Furthermore, our structures elucidate novel inter-domain interactions and define three potential calcium-binding sites that are likely important for regulation and activation of enzymatic activity. These findings provide novel insights into the molecular mechanisms governing cPLA2's function in signal transduction.

Tudor staphylococcal nuclease drives chemoresistance of non-small cell lung carcinoma cells by regulating S100A11

Lung cancer is the leading cause of cancer-related deaths worldwide. Non-small cell lung cancer (NSCLC), the major lung cancer subtype, is characterized by high resistance to chemotherapy. Here we demonstrate that Tudor staphylococcal nuclease (SND1 or TSN) is overexpressed in NSCLC cell lines and tissues, and is important for maintaining NSCLC chemoresistance. Downregulation of TSN by RNAi in NSCLC cells led to strong potentiation of cell death in response to cisplatin. Silencing of TSN was accompanied by a significant decrease in S100A11 expression at both mRNA and protein level. Downregulation of S100A11 by RNAi resulted in enhanced sensitivity of NSCLC cells to cisplatin, oxaliplatin and 5-fluouracil. AACOCF₃, a phospholipase A₂ (PLA₂) inhibitor, strongly abrogated chemosensitization upon silencing of S100A11 suggesting that PLA₂ inhibition by S100A11 governs the chemoresistance of NSCLC. Moreover, silencing of S100A11 stimulated mitochondrial superoxide production, which was decreased by AACOCF₃, as well as N-acetyl-L-cysteine, which also mimicked the effect of PLA₂ inhibitor on NSCLC chemosensitization upon S100A11 silencing. Thus, we present the novel TSN-S100A11-PLA₂ axis regulating superoxide-dependent apoptosis, triggered by platinum-based chemotherapeutic agents in NSCLC that may be targeted by innovative cancer therapies.

Anti-vascular effects of the cytosolic phospholipase A2 inhibitor AVX235 in a patient-derived basal-like breast cancer model

BACKGROUND

Group IVA cytosolic phospholipase A2 (cPLA2α) plays an important role in tumorigenesis and angiogenesis. It is overexpressed in basal-like breast cancer (BLBC), which is aggressive and usually triple-negative, making it unresponsive to current targeted therapies. Here, we evaluated the anti-angiogenic effects of a specific cPLA2α inhibitor, AVX235, in a patient-derived triple-negative BLBC model.

METHODS

Mice bearing orthotopic xenografts received i.p. injections of AVX235 or DMSO vehicle daily for 1 week and then every other day for up to 19 days. Six treated and six control mice were terminated after 2 days of treatment, and the tumors excised for high resolution magic angle spinning magnetic resonance spectroscopy (HR MAS MRS) and prostaglandin E2 (PGE2) enzyme immunoassay (EIA) analysis. A 1-week imaging study was performed on a separate cohort of mice. Longitudinal dynamic contrast enhanced (DCE)-MRI was performed before, after 4 days, and after 1 week of treatment. The mice were then perfused with a radiopaque vascular casting agent, and the tumors excised for micro-CT angiography. Subsequently, tumors were sectioned and stained with lectin and for Ki67 or α-smooth muscle actin to quantify endothelial cell proliferation and vessel maturity, respectively. Partial least squares discriminant analysis was performed on the multivariate HR MAS MRS data, and non-parametric univariate analyses using Mann-Whitney U tests (α = 0.05) were performed on all other data.

RESULTS

Glycerophosphocholine and PGE2 levels, measured by HR MAS MRS and EIA, respectively, were lower in treated tumors after 2 days of treatment. These molecular changes are expected downstream effects of cPLA2α inhibition and were followed by significant tumor growth inhibition after 8 days of treatment. DCE-MRI revealed that AVX235 treatment caused a decrease in tumor perfusion. Concordantly, micro-CT angiography showed that vessel volume fraction, density, and caliber were reduced in treated tumors. Moreover, histology showed decreased endothelial cell proliferation and fewer immature vessels in treated tumors.

CONCLUSIONS

These results demonstrate that cPLA2α inhibition with AVX235 resulted in decreased vascularization and perfusion and subsequent inhibition of tumor growth. Thus, cPLA2α inhibition may be a potential new therapeutic option for triple-negative basal-like breast cancer.

Pharmacological inhibition of lipid droplet formation enhances the effectiveness of curcumin in glioblastoma

Increased lipid droplet number and fatty acid synthesis allow glioblastoma multiforme, the most common and aggressive type of brain cancer, to withstand accelerated metabolic rates and resist therapeutic treatments. Lipid droplets are postulated to sequester hydrophobic therapeutic agents, thereby reducing drug effectiveness. We hypothesized that the inhibition of lipid droplet accumulation in glioblastoma cells using pyrrolidine-2, a cytoplasmic phospholipase A2 alpha inhibitor, can sensitize cancer cells to the killing effect of curcumin, a promising anticancer agent isolated from the turmeric spice. We observed that curcumin localized in the lipid droplets of human U251N glioblastoma cells. Reduction of lipid droplet number using pyrrolidine-2 drastically enhanced the therapeutic effect of curcumin in both 2D and 3D glioblastoma cell models. The mode of cell death involved was found to be mediated by caspase-3. Comparatively, the current clinical chemotherapeutic standard, temozolomide, was significantly less effective in inducing glioblastoma cell death. Together, our results suggest that the inhibition of lipid droplet accumulation is an effective way to enhance the chemotherapeutic effect of curcumin against glioblastoma multiforme.

Membrane and inhibitor interactions of intracellular phospholipases A2

Studying phospholipases A2 (PLA2s) is a challenging task since they act on membrane-like aggregated substrates and not on monomeric phospholipids. Multidisciplinary approaches that include hydrogen/deuterium exchange mass spectrometry (DXMS) and computational techniques have been employed with great success in order to address important questions about the mode of interactions of PLA2 enzymes with membranes, phospholipid substrates and inhibitors. Understanding the interactions of PLA2s is crucial since these enzymes are the upstream regulators of the eicosanoid pathway liberating free arachidonic acid (AA) and other polyunsaturated fatty acids (PUFA). The liberation of AA by PLA2 enzymes sets off a cascade of molecular events that involves downstream regulators such as cyclooxygenase (COX) and lipoxygenase (LOX) metabolites leading to inflammation. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) work by inhibiting COX, while Zileuton inhibits LOX and both rely on PLA2 enzymes to provide them with AA. That means PLA2 enzymes can potentially also be targeted to diminish inflammation at an earlier point in the process. In this review we describe extensive efforts reported in the past to define the interactions of PLA2 enzymes with membranes, substrate phospholipids and inhibitors using DXMS, molecular docking, and molecular dynamics (MD) simulations.

Chemopreventive Action of Anthocyanin-rich Black Soybean Fraction in APC (Min/+) Intestinal Polyposis Model

BACKGROUND

Anthocyanins have been shown to inhibit cancer cell growth by suppressing oxidative stress and inflammatory responses. The purpose of this study was to investigate the effects of an anthocyanin-rich extract (AE) from black soybean coat on intestinal carcinogenesis.

METHODS

Apc (Min/+) mice were fed a diet of 0.2% or 0.5% AE for 7 weeks. We analyzed the number of intestinal tumors, oxidative stress and inflammatory markers associated with β-catenin and cytosolic phospholipase A2 (cPLA2) signals. The number of intestinal tumors, and cellular expression of β-catenin were determined.

RESULTS

The number of intestinal tumors was significantly lower in mice fed a 0.5% AE diet compared to those of the other groups. Cytosolic β-catenin expression was significantly decreased in the AE supplemented groups compared to that of the control animals. In addition, mucosa expression of cyclooxygenase-2 and cPLA2 were also significantly decreased in the 0.5% AE group, by 32% and 62%, respectively, compared to the control group.

CONCLUSIONS

These results suggest that dietary AE reduced the development of intestinal tumors, possibly through the ability to suppress oxidative stresses, decreasing inflammatory responses mediated by β-catenin associated signals.

Saturated and mono-unsaturated lysophosphatidylcholine metabolism in tumour cells: a potential therapeutic target for preventing metastases

Background

Metastasis is the leading cause of mortality in malignant diseases. Patients with metastasis often show reduced Lysophosphatidylcholine (LysoPC) plasma levels and treatment of metastatic tumour cells with saturated LysoPC species reduced their metastatic potential in vivo in mouse experiments. To provide a first insight into the interplay of tumour cells and LysoPC, the interactions of ten solid epithelial tumour cell lines and six leukaemic cell lines with saturated and mono-unsaturated LysoPC species were explored.

Methods

LysoPC metabolism by the different tumour cells was investigated by a combination of cell culture assays, GC and MS techniques. Functional consequences of changed membrane properties were followed microscopically by detecting lateral lipid diffusion or cellular migration. Experimental metastasis studies in mice were performed after pretreatment of B16.F10 melanoma cells with LysoPC and FFA, respectively.

Results

In contrast to the leukaemic cells, all solid tumour cells show a very fast extracellular degradation of the LysoPC species to free fatty acids (FFA) and glycerophosphocholine. We provide evidence that the formerly LysoPC bound FFA were rapidly incorporated into the cellular phospholipids, thereby changing the FA-compositions accordingly. A massive increase of the neutral lipid amount was observed, inducing the formation of lipid droplets. Saturated LysoPC and to a lesser extent also mono-unsaturated LysoPC increased the cell membrane rigidity, which is assumed to alter cellular functions involved in metastasis. According to that, saturated and mono-unsaturated LysoPC as well as the respective FFA reduced the metastatic potential of B16.F10 cells in mice. Application of high doses of liposomes mainly consisting of saturated PC was shown to be a suitable way to strongly increase the plasma level of saturated LysoPC in mice.

Conclusion

These data show that solid tumours display a high activity to hydrolyse LysoPC followed by a very rapid uptake of the resulting FFA; a mechanistic model is provided. In contrast to the physiological mix of LysoPC species, saturated and mono-unsaturated LysoPC alone apparently attenuate the metastatic activity of tumours and the artificial increase of saturated and mono-unsaturated LysoPC in plasma appears as novel therapeutic approach to interfere with metastasis.

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.

N-3 polyunsaturated fatty acids inhibit IFN-γ-induced IL-18 binding protein production by prostate cancer cells

Prostate cancer cells can produce IL-18 binding protein (IL-18BP) in response to interferon-γ (IFN-γ), which may function to neutralize IL-18, an anti-tumor factor formerly known as IFN-γ inducing factor. The consumption of n-3 polyunsaturated fatty acids (PUFAs) has been associated with a lower risk of certain types of cancer including prostate cancer, although the precise mechanisms of this effect are poorly understood. We hypothesized that n-3 PUFAs could modify IL-18BP production by prostate cancer cells by altering IFN-γ receptor-mediated signal transduction. Here, we demonstrate that n-3 PUFA treatment significantly reduced IFN-γ-induced IL-18BP production by DU-145 and PC-3 prostate cancer cells by inhibiting IL-18BP mRNA expression and was associated with a reduction in IFN-γ receptor expression. Furthermore, IFN-γ-induced phosphorylation of Janus kinase 1 (JAK1), signal transducers and activators of transcription 1 (STAT1), extracellular signal-regulated kinases 1/2 (ERK1/2), and P38 were suppressed by n-3 PUFA treatment. By contrast, n-6 PUFA had no effect on IFN-γ receptor expression, but decreased IFN-γ-induced IL-18BP production and IFN-γ stimulation of JAK1, STAT1, ERK1/2, and JNK phosphorylation. These data indicate that both n-3 and n-6 PUFAs may be beneficial in prostate cancer by altering IFN-γ signaling, thus inhibiting IL-18BP production and thereby rendering prostate cancer cells more sensitive to IL-18-mediated immune responses.

Gamabufotalin, a bufadienolide compound from toad venom, suppresses COX-2 expression through targeting IKKβ/NF-κB signaling pathway in lung cancer cells

BACKGROUND

Gamabufotalin (CS-6), a major bufadienolide of Chansu, has been used for cancer therapy due to its desirable metabolic stability and less adverse effect. However, the underlying mechanism of CS-6 involved in anti-tumor activity remains poorly understood.

METHODS

The biological functions of gamabufotalin (CS-6) were investigated by migration, colony formation and apoptosis assays in NSCLC cells. The nuclear localization and interaction between transcriptional co-activator p300 and NF-κB p50/p65 and their binding to COX-2 promoter were analyzed after treatment with CS-6. Molecular docking study was used to simulate the interaction of CS-6 with IKKβ. The in vivo anti-tumor efficacy of CS-6 was also analyzed in xenografts nude mice. Western blot was used to detect the protein expression level.

RESULTS

Gamabufotalin (CS-6) strongly suppressed COX-2 expression by inhibiting the phosphorylation of IKKβ via targeting the ATP-binding site, thereby abrogating NF-κB binding and p300 recruitment to COX-2 promoter. In addition, CS-6 induced apoptosis by activating the cytochrome c and caspase-dependent apoptotic pathway. Moreover, CS-6 markedly down-regulated the protein levels of COX-2 and phosphorylated p65 NF-κB in tumor tissues of the xenograft mice, and inhibited tumor weight and size.

CONCLUSIONS

Our study provides pharmacological evidence that CS-6 exhibits potential use in the treatment of COX-2-mediated diseases such as lung cancer.

Remodeling of channel-forming ORAI proteins determines an oncogenic switch in prostate cancer

ORAI family channels have emerged as important players in malignant transformation, yet the way in which they reprogram cancer cells remains elusive. Here we show that the relative expression levels of ORAI proteins in prostate cancer are different from that in noncancerous tissue. By mimicking ORAI protein remodeling observed in primary tumors, we demonstrate in in vitro models that enhanced ORAI3 expression favors heteromerization with ORAI1 to form a novel channel. These channels support store-independent Ca(2+) entry, thereby promoting cell proliferation and a smaller number of functional homomeric ORAI1-based store-operated channels, which are important in supporting susceptibility to apoptosis. Thus, our findings highlight disrupted dynamic equilibrium of channel-forming proteins as an oncogenic mechanism.

Metabolomic Analysis of Liver Tissue from the VX2 Rabbit Model of Secondary Liver Tumors

Purpose. The incidence of liver neoplasms is rising in USA. The purpose of this study was to determine metabolic profiles of liver tissue during early cancer development. Methods. We used the rabbit VX2 model of liver tumors (LT) and a control group consisting of sham animals implanted with Gelfoam into their livers (LG). After two weeks from implantation, liver tissue from lobes with and without tumor was obtained from experimental animals (LT+/LT−) as well as liver tissue from controls (LG+/LG−). Peaks obtained by Gas Chromatography-Mass Spectrometry were subjected to identification. 56 metabolites were identified and their profiles compared between groups using principal component analysis (PCA) and a mixed-effect two-way ANOVA model. Results. Animals recovered from surgery uneventfully. Analyses identified a metabolite profile that significantly differs in experimental conditions after controlling the False Discovery Rate (FDR). 16 metabolites concentrations differed significantly when comparing samples from (LT+/LT−) to samples from (LG+/LG−) livers. A significant difference was also shown in 20 metabolites when comparing samples from (LT+) liver lobes to samples from (LT−) liver lobes. Conclusion. Normal liver tissue harboring malignancy had a distinct metabolic signature. The role of metabolic profiles on liver biopsies for the detection of early liver cancer remains to be determined.

Eicosanoid profiling in an orthotopic model of lung cancer progression by mass spectrometry demonstrates selective production of leukotrienes by inflammatory cells of the microenvironment

Eicosanoids are bioactive lipid mediators derived from arachidonic acid¹ (AA), which is released by cytosolic phospholipase A₂ (cPLA₂). AA is metabolized through three major pathways, cyclooxygenase (COX), lipoxygenase (LO) and cytochrome P450, to produce a family of eicosanoids, which individually have been shown to have pro- or anti-tumorigenic activities in cancer. However, cancer progression likely depends on complex changes in multiple eicosanoids produced by cancer cells and by tumor microenvironment and a systematic examination of the spectrum of eicosanoids in cancer has not been performed. We used liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) to quantitate eicosanoids produced during lung tumor progression in an orthotopic immunocompetent mouse model of lung cancer, in which Lewis lung carcinoma (LLC) cells are injected into lungs of syngeneic mice. The presence of tumor increased products of both the cyclooxygenase and the lipoxygenase pathways in a time-dependent fashion. Comparing tumors grown in cPLA₂ knockout vs wild-type mice, we demonstrated that prostaglandins (PGE₂, PGD₂ and PGF_2a) were produced by both cancer cells and the tumor microenvironment (TME), but leukotriene (LTB₄, LTC₄, LTD₄, LTE₄) production required cPLA₂ expression in the TME. Using flow cytometry, we recovered tumor-associated neutrophils and 2 types of tumor-associated macrophages from tumor-bearing lungs and we defined their distinct eicosanoid profiles by LC/MS/MS. The combination of flow cytometry and LC/MS/MS unravels the complexity of eicosanoid production in lung cancer and provides a rationale to develop therapeutic strategies that target select cell populations to inhibit specific classes of eicosanoids.

Cytosolic phospholipaseA2 inhibition with PLA-695 radiosensitizes tumors in lung cancer animal models

Lung cancer remains the leading cause of cancer deaths in the United States and the rest of the world. The advent of molecularly directed therapies holds promise for improvement in therapeutic efficacy. Cytosolic phospholipase A2 (cPLA₂) is associated with tumor progression and radioresistance in mouse tumor models. Utilizing the cPLA₂ specific inhibitor PLA-695, we determined if cPLA2 inhibition radiosensitizes non small cell lung cancer (NSCLC) cells and tumors. Treatment with PLA-695 attenuated radiation induced increases of phospho-ERK and phospho-Akt in endothelial cells. NSCLC cells (LLC and A549) co-cultured with endothelial cells (bEND3 and HUVEC) and pre-treated with PLA-695 showed radiosensitization. PLA-695 in combination with irradiation (IR) significantly reduced migration and proliferation in endothelial cells (HUVEC & bEND3) and induced cell death and attenuated invasion by tumor cells (LLC &A549). In a heterotopic tumor model, the combination of PLA-695 and radiation delayed growth in both LLC and A549 tumors. LLC and A549 tumors treated with a combination of PLA-695 and radiation displayed reduced tumor vasculature. In a dorsal skin fold model of LLC tumors, inhibition of cPLA₂ in combination with radiation led to enhanced destruction of tumor blood vessels. The anti-angiogenic effects of PLA-695 and its enhancement of the efficacy of radiotherapy in mouse models of NSCLC suggest that clinical trials for its capacity to improve radiotherapy outcomes are warranted.

cPLA2α knockout mice exhibit abnormalities in the architecture and synapses of cortical neurons

Cytosolic phospholipase A2α (cPLA2α) affects membrane fluidity and permeability by catalyzing the hydrolysis of membrane phospholipids. We hypothesize that cPLA2α deficiency induces rigidity and architectural changes in cell membranes, especially in large cortical neurons. These membrane changes are discernible using light and electron microscopy. Through careful comparison with wild-type counterparts, we observed significant morphological changes in cortical neurons of cPLA2α knockout mice. These changes included the following: (1) increased numbers of nucleoli and enlarged nuclei, (2) narrower spaces between the inner and outer nuclear membranes, (3) reduced numbers of nuclear pores and altered nuclear pore structure, and (4) morphological changes in synaptic clefts. These results further suggest that cPLA2α and its cleaved arachidonic acids play important roles in cortical neuronal maturation and in normal neurochemical processes.

HERV-E-mediated modulation of PLA2G4A transcription in urothelial carcinoma

Human endogenous retroviruses (HERV) and related elements account for more than 8% of the human genome and significantly contribute to the human transcriptome by long terminal repeat (LTR) promoter activity. In this context, HERVs are thought to intervene in the expression of adjacent genes by providing regulatory sequences (cis-effect) or via noncoding RNA including natural antisense transcripts. To address the potential impact of HERV activity in urothelial carcinoma, we comparatively analyzed the HERV transcription profiles in paired samples of non-malignant urothelium and urothelial carcinoma derived from 13 patients with bladder cancer by means of a retrovirus-specific microarray (RetroArray). We established a characteristic HERV signature consisting of six ubiquitously active HERV subgroups (E4-1, HERV-Rb, ERV9, HERV-K-T47D, NMWV3, HERV-KC4). The transcription pattern is largely identical in human urothelial carcinoma, non-malignant urothelial tissue, four tumor-derived cell lines and in a non-malignant urothelial cell line (UROtsa). Quantitative reverse transcriptase PCR (qRT-PCR) of HERV-E4-1, HERV-K(HML-6) and HERV-T(S71-TK1) revealed a bias to lower HERV activity in carcinoma samples compared to non-malignant tissue. Determination of active HERV-E4-1 loci by cloning and sequencing revealed six HERV-E4-1 proviral loci that are differentially regulated in urothelial carcinoma cells and normal tissue. Two full-length HERV-E4-1 proviruses, HERV-Ec1 and HERV-Ec6, are located in antisense orientation in introns of the genes PLA2G4A and RNGTT, respectively. PLA2G4A encodes a cytosolic phospholipase A2 (cPLA2) that is dysregulated in many human tumors. PLA2G4A and HERV-Ec1 displayed reciprocal transcript levels in 7 of 11 urothelial carcinoma patients. Moreover, reciprocal shifts were observed after treatment of UROtsa cells with HERV-Ec1 and PLA2G4A-directed siRNAs or 5-aza-2′-deoxycytidine (aza-dC) pointing to an antagonistic regulation of PLA2G4A and HERV-Ec1 transcription in human urothelial cells. We suggest that transcription of HERV-Ec1 contributes to fine tuning of cPLA2 expression, thereby facilitating tumorigenesis.

[Botulinum toxin type-A toxin activity on prostate cancer cell lines]

AIM OF THE STUDY

Botulinum toxin A (BoNT/A) has been recently used in the treatment of benign prostatic hyperplasia due to its apoptotic activity on prostatic epithelium but few data exist on this issue in prostate cancer. Also no information exist on the eventual modulation exerted by the neurotoxin on Phospholipase A2 (PLA2) expression in prostate cancer. The aim of this study was to evaluate the activity of BoNT/A on cell growth and expression of PLA2 in prostate cancer lines.

MATERIALS AND METHODS

PC-3 and LNCaP cell lines were exposed to BoNT/A (Xeomin®), different doses and time of exposure. Presence of SV2 receptors (SV2-A and SV2-B) for the neurotoxin was also investigated. The expression of P-Ser505-cPLA2-α (phosphorylated enzyme) was performed immunofluorescence.

RESULTS

After 96 hours of BoNT/A administration a 20% reduction of cell growth in LNCaP and 25% in PC-3 were observed. SV-2 receptors were expressed in both cell lines. No cPLA2-α total expression was found in LnCaP. In PC-3 there was a high expression of cPLA2-α total which was not modified after BoNT/A treatment. In both LNCap and PC-3 the expression of P-Ser505-cPLA2-α (phosphorylated enzyme) increases significantly after treatment with [10 U/ml] of BoNT/A.

CONCLUSIONS

LNCaP and PC-3 cell lines are sensitive to treatment with BoNT/A which probably enters the cells by SV2 receptors. The increase in the phosphorylated form of cPLA2-a, induced by BoNT/A may represent one mechanism by which the toxin reduces cell growth and proliferation.

The gene expression profiles of induced pluripotent stem cells from individuals with childhood cerebral adrenoleukodystrophy are consistent with proposed mechanisms of pathogenesis

Introduction

X-linked adrenoleukodystrophy (X-ALD) is a complex disorder with variable expressivity that affects the nervous, adrenocortical and male reproductive systems. Although ABCD1 mutations are known to provide the genetic basis for X-ALD, its pathogenesis is not fully elucidated. While elevated very long chain fatty acid (VLCFA) levels in blood and reduced VLCFA catabolic activity in cultured fibroblasts are biomarkers used to identify ABCD1 mutation carriers, the roles peroxisomal lipid metabolism play in disease etiology are unknown.

Methods

Primary skin fibroblasts from two male patients with the childhood cerebral form of the disease (CCALD) caused by ABCD1 frameshift or missense mutations and three healthy donors were transduced with retroviral vectors expressing the OCT4, SOX2, KLF4 and c-MYC factors. Candidate induced pluripotent stem cells (iPSCs) were subject to global gene expression, DNA methylation, DNA copy number variation, and genotyping analysis and tested for pluripotency through in vitro differentiation and teratoma formation. Saturated VLCFA (sVLCFA) and plasmalogen levels in primary fibroblasts and iPSCs from healthy donors as well as CCALD patients were determined through mass spectroscopy.

Results

Skin fibroblasts from CCALD patients and healthy donors were reprogrammed into validated iPSCs. Unlike fibroblasts, CCALD patient iPSCs show differentially expressed genes (DEGs) relevant to both peroxisome abundance and neuroinflammation. Also, in contrast to fibroblasts, iPSCs from patients showed no significant difference in sVLCFA levels relative to those from controls. In all cell types, the plasmalogen levels tested did not correlate with ABCD1 mutation status.

Conclusion

Normal ABCD1 gene function is not required for reprogramming skin fibroblasts into iPSCs or maintaining pluripotency. Relative to DEGs found in fibroblasts, DEGs uncovered in comparisons of CCALD patient and control iPSCs are more consistent with major hypotheses regarding disease pathogenesis. These DEGs were independent of differences in sVLCFA levels, which did not vary according to ABCD1 mutation status. The highlighted genes provide new leads for pathogenic mechanisms that can be explored in animal models and human tissue specimens. We suggest that these iPSC resources will have applications that include assisting efforts to identify genetic and environmental modifiers and screening for therapeutic interventions tailored towards affected cell populations and patient genotypes.