ATX-LPA receptor axis in inflammation and cancer

Discovery of a Novel Orally Active, Selective LPA Receptor Type 1 Antagonist, 4-(4-(2-Isopropylphenyl)-4-((2-methoxy-4-methylphenyl)carbamoyl)piperidin-1-yl)-4-oxobutanoic Acid, with a Distinct Molecular Scaffold

Lysophosphatidic acid receptor 1 (LPAR1) antagonists show promise as potentially novel antifibrotic treatments. In a human LPAR1 β-arrestin recruitment-based high-throughput screening campaign, we identified urea 19 as a hit with a LPAR1 IC50 value of 5.0 μM. Hit-to-lead activities revealed that one of the urea nitrogen atoms can be replaced by carbon and establish the corresponding phenylacetic amide as a lead structure for further optimization. Medicinal chemistry efforts led to the discovery of piperidine 18 as a potent and selective LPAR1 antagonist with oral activity in a mouse model of LPA-induced skin vascular leakage. The molecular scaffold of 18 shares no obvious structural similarity with any other LPAR1 antagonist disclosed so far.

Discovery of the Novel, Orally Active, and Selective LPA1 Receptor Antagonist ACT-1016-0707 as a Preclinical Candidate for the Treatment of Fibrotic Diseases

Piperidine 3 is a potent and selective lysophosphatidic acid receptor subtype 1 receptor (LPAR1) antagonist that has shown efficacy in a skin vascular leakage target engagement model in mice. However, compound 3 has very high human plasma protein binding and high clearance in rats, which could significantly hamper its clinical development. Continued lead optimization led to the potent, less protein bound, metabolically stable, and orally active azetidine 17. Rat pharmacokinetics (PK) studies revealed that 17 accumulated in the liver. In vitro studies indicated that 17 is an organic anion co-transporting polypeptide 1B1 (OATP1B1) substrate. Although analogue 24 was no longer a substrate of OATP1B1, PK studies suggested that the compound undergoes enterohepatic recirculation. Replacing the carboxylic acidic side chain by a non-acidic sulfamide moiety and further fine-tuning of the scaffold yielded the potent, orally active LPAR1 antagonist 49, which was selected for preclinical development for the treatment of fibrotic diseases.

Experimental autotaxin inhibitors for the treatment of idiopathic pulmonary fibrosis

INTRODUCTION

Idiopathic Pulmonary Fibrosis (IPF) is a progressive, irreversible, and fatal lung disease with unmet medical needs. Autotaxin (ATX) is an extracellular enzyme involved in the generation of lysophosphatidic acid (LPA). Preclinical and clinical data have suggested the ATX-LPAR signaling axis plays an important role in the pathogenesis and the progression of IPF.

AREAS COVERED

The aim of this review is to provide an update on the available evidence on autotaxin inhibitors in IPF and further details on the ongoing clinical studies involving these molecules.

EXPERT OPINION

The development of autotaxin inhibitors as a potential therapy for idiopathic pulmonary fibrosis has gained attention due to evidence of their involvement in the disease. Preclinical and early-phase clinical studies have explored these inhibitors' efficacy and safety, offering a novel approach in treating this disease. Combining autotaxin inhibitors with existing anti-fibrotic agents is considered for enhanced therapeutic effects. Large phase III trials assessed Ziritaxestat but yielded disappointing results, highlighting the importance of long-term observation and clinical outcomes in clinical research. Patient stratification and personalized medicine are crucial, as pulmonary fibrosis is a heterogeneous disease. Ongoing research and collaboration are essential for this advancement.

Infliximab, a Monoclonal Antibody against TNF-α, Inhibits NF-κB Activation, Autotaxin Expression and Breast Cancer Metastasis to Lungs

An inflammatory milieu in the tumor microenvironment leads to immune evasion, resistance to cell death, metastasis and poor prognosis in breast cancer patients. TNF-α is a proinflammatory cytokine that regulates multiple aspects of tumor biology from initiation to progression. TNF-α-induced NF-κB activation initiates inflammatory pathways, which determine cell survival, death and tumor progression. One candidate pathway involves the increased secretion of autotaxin, which produces lysophosphatidate that signals through six G-protein-coupled receptors. Significantly, autotaxin is one of the 40-50 most upregulated genes in metastatic tumors. In this study, we investigated the effects of TNF-α by blocking its action with a monoclonal antibody, Infliximab, and studied the effects on autotaxin secretion and tumor progression. Infliximab had little effect on tumor growth, but it decreased lung metastasis by 60% in a syngeneic BALB/c mouse model using 4T1 breast cancer cells. Infliximab-treated mice also showed a decrease in proliferation and metastatic markers like Ki-67 and vimentin in tumors. This was accompanied by decreases in NF-κB activation, autotaxin expression and the concentrations of plasma and tumor cytokines/chemokines which are involved in metastasis. We also demonstrated a positive correlation of TNF-α -NF-κB and ATX expression in breast cancer patients using cancer databases. Studies in vitro showed that TNF-α-induced NF-κB activation increases autotaxin expression and the clone forming ability of 4T1 breast cancer cells. This report highlights the potential role of Infliximab as an additional approach to attenuate signaling through the autotaxin-lysophosphatidate-inflammatory cycle and decrease mortality from metastatic cancer.

Revealing the Preventable Effects of Fu-Zheng-Qu-Xie Decoction against Recurrence and Metastasis of Postoperative Early-Stage Lung Adenocarcinoma Based on Network Pharmacology Coupled with Metabolomics Analysis

Fu-Zheng-Qu-Xie (FZQX) decoction is a traditional Chinese herbal prescription for the treatment of lung cancer and exerts proapoptotic and immunomodulatory effects. It has been clinically suggested to be effective in improving the survival of postoperative early-stage lung adenocarcinoma (LUAD), but the mechanism remains unclear. In this study, we used network pharmacology coupled with metabolomics approaches to explore the pharmacological action and effective mechanism of FZQX against the recurrence and metastasis of postoperative early-stage LUAD. Network pharmacology analysis showed that FZQX could prevent the recurrence and metastasis of postoperative early-stage LUAD by regulating a series of targets involving vascular endothelial growth factor receptor 2, estrogen receptor 1, sarcoma gene, epidermal growth factor receptor, and protein kinase B and by influencing the Ras, PI3K-Akt, and mitogen-activated protein kinase signaling pathways. In liquid chromatography-mass spectrometry analysis, 11 differentially expressed metabolites, including PA(12:0/18:4(6Z,9Z,12Z,15Z)), PC(16:0/0:0)[U], LysoPC(18:1(11Z)), and LysoPC(18:0), were discovered in the FZQX-treated group compared to those in the model group before treatment or normal group. They were enriched in cancer metabolism-related signaling pathways such as central carbon metabolism in cancer, choline metabolism, and glycerol phospholipid metabolism. Collectively, our results suggest that the multicomponent and multitarget interaction network of FZQX inhibits the recurrence and metastasis of postoperative early-stage LUAD by activating the receptor signal transduction pathway to inhibit proliferation, induce cell apoptosis, inhibit aerobic glycolysis, and reprogram tumor lipid metabolism.

Autotaxin production in the human breast cancer tumor microenvironment mitigates tumor progression in early breast cancers

Autotaxin (ATX) is a secreted enzyme that produces extracellular lysophosphatidate in physiological wound healing. ATX is overexpressed in many cancers to promote growth, metastasis, and treatment resistance. However, ATX expression is very low in breast cancer cells, and is instead secreted by the tumor microenvironment (TME). Paracrine ATX expression, and its effects on tumor progression, has not been robustly studied in human breast tumors. In this study, ATX expression was analyzed in over 5000 non-metastatic breast cancers from databases TCGA, METABRIC and GSE96058, dichotomized by the median. Gene set enrichment analysis (GSEA) and the xCell algorithm investigated biological functions of ATX and correlation to TME cell populations. TME ATX production was verified by single cell RNA sequencing. The highest ATX expression occurred in endothelial cells and cancer-associated fibroblasts (P<0.0001). High tumor ATX expression correlated to increased adipocyte, fibroblast, and endothelial cell fractions (P<0.01), and GSEA demonstrated enriched immune system, tumor suppressor, pro-survival, stemness, and pro-inflammatory signaling in multiple gene sets. Tumor mutational burden was decreased, Ki67 scores were decreased, tumor infiltrating immune cell populations increased, and immune cytolytic activity scores increased (all P<0.01) for ATX-high tumors. Overall survival trends favored ATX-high tumors (hazard ratios 0.75-0.80). In summary, in human breast cancers, ATX is produced by the TME, and in non-metastatic tumors, high levels correlate with an anti-tumor phenotype. Because pre-clinical models use aggressive pro-metastatic cell lines where ATX-mediated signaling promotes tumorigenesis, further research is required to verify an anti-to-pro-tumor phenotype switch with breast cancer progression and/or treatment resistance.

EMT activates exocytotic Rabs to coordinate invasion and immunosuppression in lung cancer

Epithelial-to-mesenchymal transition (EMT) underlies immunosuppression, drug resistance, and metastasis in epithelial malignancies. However, the way in which EMT orchestrates disparate biological processes remains unclear. Here, we identify an EMT-activated vesicular trafficking network that coordinates promigratory focal adhesion dynamics with an immunosuppressive secretory program in lung adenocarcinoma (LUAD). The EMT-activating transcription factor ZEB1 drives exocytotic vesicular trafficking by relieving Rab6A, Rab8A, and guanine nucleotide exchange factors from miR-148a-dependent silencing, thereby facilitating MMP14-dependent focal adhesion turnover in LUAD cells and autotaxin-mediated CD8+ T cell exhaustion, indicating that cell-intrinsic and extrinsic processes are linked through a microRNA that coordinates vesicular trafficking networks. Blockade of ZEB1-dependent secretion reactivates antitumor immunity and negates resistance to PD-L1 immune checkpoint blockade, an important clinical problem in LUAD. Thus, EMT activates exocytotic Rabs to drive a secretory program that promotes invasion and immunosuppression in LUAD.

Oleic Acid-Containing Phosphatidylinositol Is a Blood Biomarker Candidate for SPG28

Hereditary spastic paraplegia is a genetic neurological disorder characterized by spasticity of the lower limbs, and spastic paraplegia type 28 is one of its subtypes. Spastic paraplegia type 28 is a hereditary neurogenerative disorder with an autosomal recessive inheritance caused by loss of function of DDHD1. DDHD1 encodes phospholipase A1, which catalyzes phospholipids to lysophospholipids such as phosphatidic acids and phosphatidylinositols to lysophosphatidic acids and lysophoshatidylinositols. Quantitative changes in these phospholipids can be key to the pathogenesis of SPG28, even at subclinical levels. By lipidome analysis using plasma from mice, we globally examined phospholipids to identify molecules showing significant quantitative changes in Ddhd1 knockout mice. We then examined reproducibility of the quantitative changes in human sera including SPG28 patients. We identified nine kinds of phosphatidylinositols that show significant increases in Ddhd1 knockout mice. Of these, four kinds of phosphatidylinositols replicated the highest level in the SPG28 patient serum. All four kinds of phosphatidylinositols contained oleic acid. This observation suggests that the amount of oleic acid-containing PI was affected by loss of function of DDHD1. Our results also propose the possibility of using oleic acid-containing PI as a blood biomarker for SPG28.

Identification of Prognostic Markers of DNA Damage and Oxidative Stress in Diagnosing Papillary Renal Cell Carcinoma Based on High-Throughput Bioinformatics Screening

Purpose

Papillary renal cell carcinoma (pRCC) is the second most common histological subtype of adult kidney tumors, with a poor prognosis due to limited understanding of the disease mechanism. Herein, we have performed high-throughput bioinformatic screening to explore and identify potential biomarkers of DNA damage and oxidative stress for pRCC.

Methods

RNA sequencing data related to pRCC were downloaded from the TCGA database, and differentially expressed genes (DEG) were identified by a wide variety of clustering and classification algorithms, including self-organized maps (SOM), artificial neural networks (ANN), support vector machines (SVM), fuzzy logic, and hyphenated techniques such as neuro-fuzzy networks. Then DAVID and STRING online biological information tools were used to analyze functional enrichment of the regulatory networks of DEG and construct a protein-protein interaction (PPI) network, and then the Cytoscape software was used to identify hub genes. The importance of key genes was assessed by the analysis of the Kaplan-Meier survival curves using the R software. Lastly, we have analyzed the expression of hub genes of DNA damage and oxidative stress (BDKRB1, NMUR2, PMCH, and SAA1) in pRCC tissues and adjacent normal tissues, as well as the relationship between the expression of hub genes in pRCC tissues and pathological characteristics and prognosis of pRCC patients.

Results

A total of 1,992 DEGs for pRCC were identified, with 1,142 upregulated ones and 850 downregulated ones. The DEGs were significantly enriched in activities including DNA damage and oxidative stress, chemical synaptic transmission, an integral component of the membrane, calcium ion binding, and neuroactive ligand-receptor interaction. cytoHubba in the Cytoscape software was used to determine the top 10 hub genes in the PPI network as BDKRB2, NMUR2, NMU, BDKRB1, LPAR5, KNG1, LPAR3, SAA1, MCHR1, PMCH, and NCAPH. Furthermore, the expression level of hub genes BDKRB1, NMUR2, PMCH, and SAA1 in pRCC tissues was significantly higher than that in the adjacent normal tissues. Meanwhile, the expression level of hub genes BDKRB1, NMUR2, PMCH, and SAA1 in pRCC tissues was significantly positively correlated with tumor stage, lymph node metastasis, and the histopathology grade of pRCC. In addition, high expression levels of hub genes BDKRB1, NMUR2, PMCH, and SAA1 were associated with a poor prognosis for patients with pRCC. Univariate and multivariate analyses showed that the expression of hub genes BDKRB1, NMUR2, PMCH, and SAA1 were independent risk factors for the prognosis of patients with pRCC.

Conclusion

The results of this analysis suggested that BDKRB1, NMUR2, PMCH, and SAA1 might be potential prognostic biomarkers and novel therapeutic targets for pRCC.

The Autotaxin-LPA Axis Emerges as a Novel Regulator of Smooth Muscle Cell Phenotypic Modulation during Intimal Hyperplasia

Neointimal hyperplasia is characterized by a loss of the contractile phenotype of vascular smooth muscle cells (VSMCs). Our group has recently shown that VSMC proliferation and migration are mediated by lysophosphatidic acid (LPA) during restenosis, but the role of autotaxin (ATX; lysophospholipase D), which produces LPA, remains unclear. Endothelial denudation of the mouse carotid artery was performed to induce neointimal hyperplasia, and the extent of damage caused by the ATX-LPA axis was assessed in VSMCs. We observed the upregulation of ATX activity (p < 0.0002) in the injured carotid artery using an AR2 probe fluorescence assay. Further, the tissue carotid LPA levels were elevated 2.7-fold in carotid vessels, augmenting neointimal hyperplasia. We used an electrical cell-substrate impedance sensor (ECIS) to measure VSMC proliferation and migration. Treatment with an ATX inhibitor (PF8380) or LPA receptor inhibitor (Ki16425) attenuated VSMC proliferation (extracellular signal-regulated kinases) activity and migration in response to recombinant ATX. Indeed, PF8380 treatment rescued the aggravated post-wire injury neointima formation of carotid arteries. The upregulation of ATX following vessel injury leads to LPA production in VSMCs, favoring restenosis. Our observations suggest that inhibition of the ATX-LPA axis could be therapeutically targeted in restenosis to minimize VSMC phenotypic modulation and inflammation after vascular injury.

Circulating autotaxin levels in healthy teenagers: Data from the Vitados cohort

Autotaxin (ATX) is a secreted enzyme with a lysophospholipase D activity, mainly secreted by adipocytes and widely expressed. Its major function is to convert lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA), an essential bioactive lipid involved in multiple cell processes. The ATX-LPA axis is increasingly studied because of its involvement in numerous pathological conditions, more specifically in inflammatory or neoplastic diseases, and in obesity. Circulating ATX levels gradually increase with the stage of some pathologies, such as liver fibrosis, thus making them a potentially interesting non-invasive marker for fibrosis estimation. Normal circulating levels of ATX have been established in healthy adults, but no data exist at the pediatric age. The aim of our study is to describe the physiological concentrations of circulating ATX levels in healthy teenagers through a secondary analysis of the VITADOS cohort. Our study included 38 teenagers of Caucasian origin (12 males, 26 females). Their median age was 13 years for males and 14 years for females, ranging from Tanner 1 to 5. BMI was at the 25th percentile for males and 54th percentile for females, and median blood pressure was normal. ATX median levels were 1,049 (450-2201) ng/ml. There was no difference in ATX levels between sexes in teenagers, which was in contrast to the male and female differences described in the adult population. ATX levels significantly decreased with age and pubertal status, reaching adult levels at the end of puberty. Our study also suggested positive correlations between ATX levels and blood pressure (BP), lipid metabolism, and bone biomarkers. However, except for LDL cholesterol, these factors were also significantly correlated with age, which might be a confounding factor. Still, a correlation between ATX and diastolic BP was described in obese adult patients. No correlation was found between ATX levels and inflammatory marker C-reactive protein (CRP), Body Mass Index (BMI), and biomarkers of phosphate/calcium metabolism. In conclusion, our study is the first to describe the decline in ATX levels with puberty and the physiological concentrations of ATX levels in healthy teenagers. It will be of utmost importance when performing clinical studies in children with chronic diseases to keep these kinetics in mind, as circulating ATX might become a non-invasive prognostic biomarker in pediatric chronic diseases.

Autotaxin and Lysophosphatidic Acid Signalling: the Pleiotropic Regulatory Network in Cancer

Autotaxin, also known as ecto-nucleotide pyrophosphatase/phosphodiesterase family member 2, is a secreted glycoprotein that plays multiple roles in human physiology and cancer pathology. This protein, by converting lysophosphatidylcholine into lysophosphatidic acid, initiates a complex signalling cascade with significant biological implications. The article outlines the autotaxin gene and protein structure, expression regulation and physiological functions, but focuses mainly on the role of autotaxin in cancer development and progression. Autotaxin and lysophosphatidic acid signalling influence several aspects of cancer, including cell proliferation, migration, metastasis, therapy resistance, and interactions with the immune system. The potential of autotaxin as a diagnostic biomarker and promising drug target is also examined.

Non-Coding RNA Related to MAPK Signaling Pathway in Liver Cancer

The advancement in high-throughput sequencing analysis and the evaluation of chromatin state maps have revealed that eukaryotic cells produce many non-coding transcripts/RNAs. Further, a strong association was observed between some non-coding RNAs and cancer development. The mitogen-activated protein kinases (MAPK) belong to the serine–threonine kinase family and are the primary signaling pathways involved in cell proliferation from the cell surface to the nucleus. They play an important role in various human diseases. A few non-coding RNAs associated with the MAPK signaling pathway play a significant role in the development of several malignancies, including liver cancer. In this review, we summarize the molecular mechanisms and interactions of microRNA, lncRNA, and other non-coding RNAs in the development of liver cancer that are associated with the MAPK signaling pathway. Further, we briefly discuss the therapeutic strategies for liver cancer related to ncRNA and the MAPK signaling pathway.

A defective lysophosphatidic acid-autophagy axis increases miscarriage risk by restricting decidual macrophage residence

Massive infiltrated and enriched decidual macrophages (dMφ) have been widely regarded as important regulators of maternal-fetal immune tolerance and trophoblast invasion, contributing to normal pregnancy. However, the characteristics of metabolic profile and the underlying mechanism of dMφ residence remain largely unknown. Here, we observe that dMφ display an active glycerophospholipid metabolism. The activation of ENPP2-lysophosphatidic acid (LPA) facilitates the adhesion and retention, and M2 differentiation of dMφ during normal pregnancy. Mechanistically, this process is mediated through activation of the LPA receptors (LPAR1 and PPARG/PPARγ)-DDIT4-macroautophagy/autophagy axis, and further upregulation of multiple adhesion factors (e.g., cadherins and selectins) in a CLDN7 (claudin 7)-dependent manner. Additionally, poor trophoblast invasion and placenta development, and a high ratio of embryo loss are observed in Enpp2^±, lpar1^-/- or PPARG-blocked pregnant mice. Patients with unexplained spontaneous abortion display insufficient autophagy and cell residence of dMφ. In therapeutic studies, supplementation with LPA or the autophagy inducer rapamycin significantly promotes dMφ autophagy and cell residence, and improves embryo resorption in Enpp2^± and spontaneous abortion mouse models, which should be dependent on the activation of DDIT4-autophagy-CLDN7-adhesion molecules axis. This observation reveals that inactivation of ENPP2-LPA metabolism and insufficient autophagy of dMφ result in resident obstacle of dMφ and further increase the risk of spontaneous abortion, and provides potential therapeutic strategies to prevent spontaneous abortion.Abbreviations: ACTB: actin beta; ADGRE1/F4/80: adhesion G protein-coupled receptor E1; Atg5: autophagy related 5; ATG13: autophagy related 13; BECN1: beclin 1; CDH1/E-cadherin: cadherin 1; CDH5/VE-cadherin: cadherin 5; CFSE: carboxyfluorescein succinimidyl ester; CLDN7: claudin 7; CSF1/M-CSF: colony stimulating factor 1; CSF2/GM-CSF: colony stimulating factor 2; Ctrl: control; CXCL10/IP-10: chemokine (C-X-C) ligand 10; DDIT4: DNA damage inducible transcript 4; dMφ: decidual macrophage; DSC: decidual stromal cells; ENPP2/ATX: ectonucleotide pyrophosphatase/phosphodiesterase 2; Enpp2^±: Enpp2 heterozygous knockout mouse; ENPP2i/PF-8380: ENPP2 inhibitor; EPCAM: epithelial cell adhesion molecule; ESC: endometrial stromal cells; FGF2/b-FGF: fibroblast growth factor 2; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GPCPD1: glycerophosphocholine phosphodiesterase 1; HE: heterozygote; HIF1A: hypoxia inducible factor 1 subunit alpha; HNF4A: hepatocyte nuclear factor 4 alpha; HO: homozygote; ICAM2: intercellular adhesion molecule 2; IL: interleukin; ITGAV/CD51: integrin subunit alpha V; ITGAM/CD11b: integrin subunit alpha M; ITGAX/CD11b: integrin subunit alpha X; ITGB3/CD61: integrin subunit beta 3; KLRB1/NK1.1: killer cell lectin like receptor B1; KRT7/cytokeratin 7: keratin 7; LPA: lysophosphatidic acid; LPAR: lysophosphatidic acid receptor; lpar1^-/-: lpar1 homozygous knockout mouse; LPAR1i/AM966: LPAR1 inhibitor; LY6C: lymphocyte antigen 6 complex, locus C1; LYPLA1: lysophospholipase 1; LYPLA2: lysophospholipase 2; Lyz2: lysozyme 2; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MARVELD2: MARVEL domain containing 2; 3-MA: 3-methyladenine; MBOAT2: membrane bound O-acyltransferase domain containing 2; MGLL: monoglyceride lipase; MRC1/CD206: mannose receptor C-type 1; MTOR: mechanistic target of rapamycin kinase; NP: normal pregnancy; PDGF: platelet derived growth factor; PLA1A: phospholipase A1 member A; PLA2G4A: phospholipase A2 group IVA; PLPP1: phospholipid phosphatase 1; pMo: peripheral blood monocytes; p-MTOR: phosphorylated MTOR; PPAR: peroxisome proliferator activated receptor; PPARG/PPARγ: peroxisome proliferator activated receptor gamma; PPARGi/GW9662: PPARG inhibitor; PTPRC/CD45: protein tyrosine phosphatase receptor type, C; Rapa: rapamycin; RHEB: Ras homolog, mTORC1 binding; SA: spontaneous abortion; SELE: selectin E; SELL: selectin L; siCLDN7: CLDN7-silenced; STAT: signal transducer and activator of transcription; SQSTM1: sequestosome 1; TJP1: tight junction protein 1; VCAM1: vascular cell adhesion molecule 1; WT: wild type.

Lysophosphatidic Acid Signaling and microRNAs: New Roles in Various Cancers

A wide range of microRNAs (miRNAs) are coded for in the human genome and contribute to the regulation of gene expression. MiRNAs are able to degrade mRNAs and/or prevent the RNA transcript from being translated through complementary binding of the miRNA seed region (nucleotide 2-8) to the 3’-untranslated regions of many mRNAs. Although miRNAs are involved in almost all processes of normal human cells, they are also involved in the abnormal functions of cancer cells. MiRNAs can play dual regulatory roles in cancer, acting either as tumor suppressors or as tumor promoters, depending on the target, tumor type, and stage. In the current review, we discuss the present status of miRNA modulation in the setting of lysophosphatidic acid (LPA) signaling. LPA is produced from lysophosphatidylcholine by the enzyme autotaxin and signals via a range of G protein-coupled receptors to affect cellular processes, which ultimately causes changes in cell morphology, survival, proliferation, differentiation, migration, and adhesion. Several studies have identified miRNAs that are over-expressed in response to stimulation by LPA, but their functional roles have not yet been fully clarified. Since RNA-based treatments hold tremendous promise in the area of personalized medicne, many efforts have been made to bring miRNAs into clinical trials, and this field is evolving at an increasing pace.

Mast Cell–Tumor Interactions: Molecular Mechanisms of Recruitment, Intratumoral Communication and Potential Therapeutic Targets for Tumor Growth

Mast cells (MCs) are tissue-resident immune cells that are important players in diseases associated with chronic inflammation such as cancer. Since MCs can infiltrate solid tumors and promote or limit tumor growth, a possible polarization of MCs to pro-tumoral or anti-tumoral phenotypes has been proposed and remains as a challenging research field. Here, we review the recent evidence regarding the complex relationship between MCs and tumor cells. In particular, we consider: (1) the multifaceted role of MCs on tumor growth suggested by histological analysis of tumor biopsies and studies performed in MC-deficient animal models; (2) the signaling pathways triggered by tumor-derived chemotactic mediators and bioactive lipids that promote MC migration and modulate their function inside tumors; (3) the possible phenotypic changes on MCs triggered by prevalent conditions in the tumor microenvironment (TME) such as hypoxia; (4) the signaling pathways that specifically lead to the production of angiogenic factors, mainly VEGF; and (5) the possible role of MCs on tumor fibrosis and metastasis. Finally, we discuss the novel literature on the molecular mechanisms potentially related to phenotypic changes that MCs undergo into the TME and some therapeutic strategies targeting MC activation to limit tumor growth.

Discovery of Potent Selective Nonzinc Binding Autotaxin Inhibitor BIO-32546

Autotaxin (ATX) is a lysophospholipase D that is the main enzyme responsible for generating LPA in body fluids. Although ATX was isolated from a conditioned medium of melanoma cells, later it was discovered to play a critical role in vascular and neuronal development. ATX has also been implicated in primary brain tumor, fibrosis, and rheumatoid arthritis, as well as neurological diseases such as multiple sclerosis, Alzheimer's disease, and neuropathic pain. As ATX and LPA levels are increased upon neuronal injury, a selective ATX inhibitor could provide a new approach to treat neuropathic pain. Herein we describe the discovery of a novel series of nonzinc binding reversible ATX inhibitors, particularly a potent, selective, orally bioavailable, brain-penetrable tool compound BIO-32546, as well as its synthesis, X-ray cocrystal structure, pharmacokinetics, and in vivo efficacy.

Discoidin Domain Receptor 2 Mediates Lysophosphatidic Acid-Induced Ovarian Cancer Aggressiveness

Lysophosphatidic acid (LPA), a bioactive lipid produced extracellularly by autotaxin (ATX), has been known to induce various pathophysiological events, including cancer cell invasion and metastasis. Discoidin domain receptor 2 (DDR2) expression is upregulated in ovarian cancer tissues, and is closely associated with poor clinical outcomes in ovarian cancer patients. In the present study, we determined a critical role and signaling cascade for the expression of DDR2 in LPA-induced ovarian cancer cell invasion. We also found ectopic expression of ATX or stimulation of ovarian cancer cells with LPA-induced DDR2 expression. However, the silencing of DDR2 expression significantly inhibited ATX- and LPA-induced ovarian cancer cell invasion. In addition, treatment of the cells with pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and mTOR abrogated LPA-induced DDR2 expression. Moreover, we observed that HIF-1α, located downstream of the mTOR, is implicated in LPA-induced DDR2 expression and ovarian cancer cell invasion. Finally, we provide evidence that LPA-induced HIF-1α expression mediates Twist1 expression to upregulate DDR2 expression. Collectively, the present study demonstrates that ATX, and thereby LPA, induces DDR2 expression through the activation of the PI3K/Akt/mTOR/HIF-1α/Twist1 signaling axes, aggravating ovarian cancer cell invasion.

Loss of FOXF1 expression promotes human lung-resident mesenchymal stromal cell migration via ATX/LPA/LPA1 signaling axis

Forkhead box F1 (FOXF1) is a lung embryonic mesenchyme-associated transcription factor that demonstrates persistent expression into adulthood in mesenchymal stromal cells. However, its biologic function in human adult lung-resident mesenchymal stromal cells (LR-MSCs) remain to be elucidated. Here, we demonstrate that FOXF1 expression acts as a restraint on the migratory function of LR-MSCs via its role as a novel transcriptional repressor of autocrine motility-stimulating factor Autotaxin (ATX). Fibrotic human LR-MSCs demonstrated lower expression of FOXF1 mRNA and protein, compared to non-fibrotic controls. RNAi-mediated FOXF1 silencing in LR-MSCs was associated with upregulation of key genes regulating proliferation, migration, and inflammatory responses and significantly higher migration were confirmed in FOXF1-silenced LR-MSCs by Boyden chamber. ATX is a secreted lysophospholipase D largely responsible for extracellular lysophosphatidic acid (LPA) production, and was among the top ten upregulated genes upon Affymetrix analysis. FOXF1-silenced LR-MSCs demonstrated increased ATX activity, while mFoxf1 overexpression diminished ATX expression and activity. The FOXF1 silencing-induced increase in LR-MSC migration was abrogated by genetic and pharmacologic targeting of ATX and LPA1 receptor. Chromatin immunoprecipitation analyses identified three putative FOXF1 binding sites in the 1.5 kb ATX promoter which demonstrated transcriptional repression of ATX expression. Together these findings identify FOXF1 as a novel transcriptional repressor of ATX and demonstrate that loss of FOXF1 promotes LR-MSC migration via the ATX/LPA/LPA1 signaling axis.

ENPP4 overexpression is associated with no recovery from Barrett's esophagus

Early diagnosis and treatment of precancerous conditions of the esophagus is important to improve overall survival. Barrett's esophagus is the most common precancerous condition of the esophagus, and patients with Barrett's esophagus may develop tumor, maintain a precancerous condition, or recover. We analyzed miRNA and mRNA expression profiles from esophageal adenocarcinoma tissue and normal esophageal tissue in GEO database. We identified DEGs and DE_miRNAs from GEO2R online tools and used Venn software were used to detect the common DEGs and DE_miRNAs. We used Enrichr, an online bioinformatic tool, to perform the gene ontology (GO) analysis including BP, MF, and CC. We analyzed Mirdb.tsv, mirtarbase.tsv, and targetscan.tsv files and identified miRNA targeting genes. We analysed the data of RNA sequencing expression retrieved from the GEPIA website on the basis of thousands of samples from the GTEx projects and TCGA. There were three miRNA (has-mir-205, has-mir-203, has-mir-18) and one DEG (ENPP4) that were associated with the recovery from Barrett's esophagus. ENPP4 promotes coagulation, hemostasis, wound healing, and participates in neutrophil degranulation, neutrophil immune activation and its mediated immunity, contributes to the composition of some membrane particles and tertiary particles, and is related to nucleotide diphosphatase activity. ENPP4 overexpression was not conducive to Barrett's esophagus recovery.

Lysophosphatidic acid as a regulator of endometrial connective tissue growth factor and prostaglandin secretion during estrous cycle and endometrosis in the mare

Background

Equine endometrosis is a chronic degenerative condition, described as endometrial fibrosis that forms in the stroma, under the basement membrane and around the endometrial glands. The role of lysophosphatidic acid (LPA) in the development of tissue fibrosis varies depending on the organ, and its profibrotic role in mare endometrosis remains unclear. The study aimed to establish the endometrial presence of LPA and its receptors (LPAR1–4), together with its effects on connective tissue growth factor (CTGF) and prostaglandins (PG) secretion from equine endometrium under physiological (estrous cycle), or pathological conditions (endometrosis). Mare endometria in the mid-luteal phase (n = 5 for each category I, IIA, IIB, III of Kenney and Doig) and in the follicular phase (n = 5 for each category I, IIA, III and n = 4 for IIB) were used. In experiment 1, the levels of LPA, LPAR1–4 mRNA level and protein abundance were investigated in endometria at different stages of endometrosis. In experiment 2, the in vitro effect of LPA (10^− 9 M) on the secretion of CTGF and PGs from endometrial tissue explants at different stages of endometrosis were determined.

Results

Endometrial LPA concentration was higher in the mid-luteal phase compared to the follicular phase in category I endometrium (P < 0.01). There was an alteration in endometrial concentrations of LPA and LPAR1–4 protein abundance in the follicular phase at different stages of endometrosis (P < 0.05). Additionally, LPA increased the secretion of PGE₂ from category I endometrium in both phases of the estrous cycle (P < 0.05). The effect of LPA on the secretion of CTGF and PGF_2α from endometrial tissue was altered depending on different stages of endometrosis (P < 0.05).

Conclusion

Our data indicate that endometrosis disturbs proper endometrial function and is associated with altered endometrial LPA concentration, its receptor expression and protein abundance, PGE₂/PGF_2α ratio, and CTGF secretion in response to LPA. These changes could influence several physiological events occurring in endometrium in mare during estrous cycle and early pregnancy.

Identification of Potential Key Genes and Pathways in Enzalutamide-Resistant Prostate Cancer Cell Lines: A Bioinformatics Analysis with Data from the Gene Expression Omnibus (GEO) Database

Enzalutamide (ENZ) has been approved for the treatment of advanced prostate cancer (PCa), but some patients develop ENZ resistance initially or after long-term administration. Although a few key genes have been discovered by previous efforts, the complete mechanisms of ENZ resistance remain unsolved. To further identify more potential key genes and pathways in the development of ENZ resistance, we employed the GSE104935 dataset, including 5 ENZ-resistant (ENZ-R) and 5 ENZ-sensitive (ENZ-S) PCa cell lines, from the Gene Expression Omnibus (GEO) database. Integrated bioinformatics analyses were conducted, such as analysis of differentially expressed genes (DEGs), Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, protein-protein interaction (PPI) analysis, gene set enrichment analysis (GSEA), and survival analysis. From these, we identified 201 DEGs (93 upregulated and 108 downregulated) and 12 hub genes (AR, ACKR3, GPER1, CCR7, NMU, NDRG1, FKBP5, NKX3-1, GAL, LPAR3, F2RL1, and PTGFR) that are potentially associated with ENZ resistance. One upregulated pathway (hedgehog pathway) and seven downregulated pathways (pathways related to androgen response, p53, estrogen response, TNF-α, TGF-β, complement, and pancreas β cells) were identified as potential key pathways involved in the occurrence of ENZ resistance. Our findings may contribute to further understanding the molecular mechanisms of ENZ resistance and provide some clues for the prevention and treatment of ENZ resistance.

Autotaxin inhibition attenuates endothelial permeability after ischemia-reperfusion injury

BACKGROUND

Autotaxin (ATX-secretory lysophospholipase D) is the primary lysophosphatidic acid (LPA) producing enzyme. LPA promotes endothelial hyper-permeability and microvascular dysfunction following cellular stress.

OBJECTIVE

We sought to assess whether ATX inhibition would attenuate endothelial monolayer permeability after anoxia-reoxygenation (A-R) in vitro and attenuate the increase in hydraulic permeability observed after ischemia-reperfusion injury (IRI) in vivo.

METHODS

A permeability assay assessed bovine endothelial monolayer permeability during anoxia-reoxygenation with/without administration of pipedimic acid, a specific inhibitor of ATX, administered either pre-anoxia or post-anoxia. Hydraulic permeability (Lp) of rat mesenteric post-capillary venules was evaluated after IRI, with and without ATX inhibition. Lastly, Lp was evaluated after the administration of ATX alone.

RESULTS

Anoxia-reoxygenation increased monolayer permeability 4-fold (p < 0.01). Monolayer permeability was reduced to baseline similarly in both the pre-anoxia and post-anoxia ATX inhibition groups (each p < 0.01, respectively). Lp was attenuated by 24% with ATX inhibition (p < 0.01). ATX increased Lp from baseline in a dose dependent manner (p < 0.05).

CONCLUSIONS

Autotaxin inhibition attenuated increases in endothelial monolayer permeability during A-R in vitro and hydraulic permeability during IRI in vivo. Targeting ATX may be especially beneficial by limiting its downstream mediators that contribute to mechanisms associated with endothelial permeability. ATX inhibitors may therefore have potential for pharmacotherapy during IRI.

The Effect of the Tumor Microenvironment and Tumor-Derived Metabolites on Dendritic Cell Function

Dendritic cells (DCs) have a critical effect on the outcome of adaptive immune responses against growing tumors. Recent studies on the metabolism on DCs provide new insights on the functioning of these critical controllers of innate and adaptive immunity. DCs within the tumor microenvironment (TME) often exist in an inactive state, which is thought to limit the adaptive immune response elicited by the growing tumor. Tumor-derived factors in the TME are known to suppress DC activation and result in functional alterations in DC phenotype. We are now beginning to appreciate that many of these factors can also induce changes in immune cell metabolism. In this review, we discuss the functional alternation of DC phenotype by tumor metabolites.

Design, Synthesis, and Preliminary Bioactivity Evaluation of 2,7-Substituted Carbazole Derivatives as Potent Autotaxin Inhibitors and Antitumor Agents†

BACKGROUND

Autotaxin-LPA signaling has been implicated in cancer progression, and targeted for the discovery of cancer therapeutic agents.

OBJECTIVE

Potential ATX inhibitors were synthesized to develop novel leading compounds and effective anticancer agents.

METHODS

The present work designs and synthesizes a series of 2,7-subsitituted carbazole derivatives with different terminal groups R [R = -Cl (I), -COOH (II), -B(OH)2 (III), or -PO(OH)2 (I-IV)]. The inhibition of these compounds on the enzymatic activity of ATX was measured using FS-3 and Bis-pNpp as substrates, and the cytotoxicity of these compounds was evaluated using SW620, SW480, PANC-1, and SKOV-3 human carcinoma cells. Furthermore, the binding of leading compound with ATX was analyzed by molecular docking.

RESULTS

Compound III was shown to be a promising antitumor candidate by demonstrating both good inhibition of ATX enzymatic activity and high cytotoxicity against human cancer cell lines. Molecular docking study shows that compound III is located in a pocket, which mainly comprises amino acids 209 to 316 in domain 2 of ATX, and binds with these residues of ATX through van der Waals, conventional hydrogen bonds, and hydrophobic interactions.

CONCLUSION

Compound III with the terminal group R = -B(OH)2 has the most potent inhibitory effect with the greatest cytotoxicity to cancer cells. Moreover, the docking model provides a structural basis for the future optimization of promising antitumor compounds.

Targeting Lysophosphatidic Acid in Cancer: The Issues in Moving from Bench to Bedside

Since the clear demonstration of lysophosphatidic acid (LPA)'s pathological roles in cancer in the mid-1990s, more than 1000 papers relating LPA to various types of cancer were published. Through these studies, LPA was established as a target for cancer. Although LPA-related inhibitors entered clinical trials for fibrosis, the concept of targeting LPA is yet to be moved to clinical cancer treatment. The major challenges that we are facing in moving LPA application from bench to bedside include the intrinsic and complicated metabolic, functional, and signaling properties of LPA, as well as technical issues, which are discussed in this review. Potential strategies and perspectives to improve the translational progress are suggested. Despite these challenges, we are optimistic that LPA blockage, particularly in combination with other agents, is on the horizon to be incorporated into clinical applications.

MicroRNA Regulation of the Autotaxin-Lysophosphatidic Acid Signaling Axis

The revelation that microRNAs (miRNAs) exist within the human genome uncovered an underappreciated mechanism of gene expression. For cells to regulate expression of their genes, miRNA molecules and argonaute proteins bind to mRNAs and interfere with efficient translation of the RNA transcript. Although miRNAs have important roles in normal tissues, miRNAs may adopt aberrant functions in malignant cells depending on their classification as either a tumor suppressor or oncogenic miRNA. Within this review, the current status of miRNA regulation is described in the context of signaling through the lysophosphatidic acid receptors, including the lysophosphatidic acid-producing enzyme, autotaxin. Thus far, research has revealed miRNAs that increase in response to lysophosphatidic acid stimulation, such as miR-21, miR-30c-2-3p, and miR-122. Other miRNAs inhibit the translation of lysophosphatidic acid receptors, such as miR-15b, miR-23a, and miR200c, or proteins that are downstream of lysophosphatidic acid signaling, such as miR-146 and miR-21. With thousands of miRNAs still uncharacterized, it is anticipated that the complex regulation of lysophosphatidic acid signaling by miRNAs will continue to be elucidated. RNA-based therapeutics have entered the clinic with enormous potential in precision medicine. This exciting field is rapidly emerging and it will be fascinating to witness its expansion in scope.

Examining barbiturate scaffold for the synthesis of new agents with biological interest

Aim: Barbiturates have a long history of being used as drugs presenting wide varieties of biological activities (antimicrobial, anti-urease and antioxidant). Reactive oxygen species are associated with inflammation implicated in cancer, atherosclerosis and autoimmune diseases. Multitarget agents represent a powerful approach to the therapy of complicated inflammatory diseases. Results: A novel series of barbiturates has been synthesized and evaluated in several in vitro assays. Compound 16b (lipoxygenases inhibitor, 55.0 μM) was found to be a cyclooxygenase-2 inhibitor (27.5 μM). Compound 8b was profiled as a drug-like candidate. Conclusion: The barbiturate core represents a new scaffold for lipoxygenases inhibition, and the undertaken derivatives show promise as multiple-target agents to combat inflammatory diseases.

Mutant p53 regulates LPA signaling through lysophosphatidic acid phosphatase type 6

Emerging evidence has indicated that high-grade serous ovarian cancer (HGSOC) originates in the fallopian tube, where the earliest known genetic lesion is the mutation of TP53. In addition to such genetic changes, HGSOC is characterized by altered metabolism, including the production of oncogenic lipids such as lysophosphatidic acid (LPA). To understand the crosstalk between TP53 mutations and LPA signaling, we utilized primary fallopian tube epithelial cells (FTEC) engineered to overexpress mutant p53. We found that gain-of-function (GOF) p53 mutations downregulated the LPA-degrading enzyme lysophosphatidic acid phosphatase type 6 (ACP6), leading to upregulation of focal adhesion signaling in an LPA-dependent manner. Although highly expressed in normal fallopian tube epithelium, ACP6 expression was significantly reduced in ovarian cancer tumors and early in situ lesions. Downregulation of ACP6 in ovarian cancer cells was necessary and sufficient to support HGSOC proliferation, adhesion, migration, and invasion. Using mouse models of metastasis, we established that attenuation of ACP6 expression was associated with increased tumor burden. Conversely, overexpression of ACP6 suppressed invasive behavior. These data identify an involvement of oncogenic p53 mutations in LPA signaling and HGSOC progression through regulation of ACP6 expression.

Serum ATX as a novel biomarker for breast cancer

Recent accumulating evidence indicates the biological actions of Autotaxin-Lysophosphatidic acid (ATX-LPA) signaling axis in malignant tumors. However, the role of Autotaxin-Lysophosphatidic acid signaling axis in breast cancer has not been reported. The present study aims to examine the alterations of serum autotaxin in breast cancer and discuss whether serum autotaxin could be useful as a novel parameter of breast cancer.Serum autotaxin antigen was measured in 112 patients with breast cancer and 50 healthy volunteers by ELISA. The association of serum autotaxin antigen levels with clinicopathological parameters and outcomes of breast cancer was analyzed.Serum autotaxin antigen was significantly higher in breast cancer patients than healthy volunteers (291.32 ± 38.02 ng/ml vs 254.04 ± 21.03 ng/ml, respectively; P < .0001). Serum autotaxin measurement successfully discriminated breast cancer patients from normal and healthy controls (AUC = 0.798, 95% CI: 0.732-0.864) with an optimal cut-off value of 267.34 ng/ml (sensitivity = 0.741, specificity = 0.800). Increased serum autotaxin was associated with breast cancer nodal status (P = .007), Tumor-Node- Metastasis (TNM) stage (P = .009) and Ki-67 index (P = .004). Univariate and multivariate Cox regression analysis revealed that elevated serum autotaxin showed an independent prognostic value for poor Disease-free survival.Our present study confirmed the elevation, potential diagnostic, and independent prognostic value of serum autotaxin for breast cancer. Serum autotaxin could serve as a reliable novel biomarker for breast cancer.

Acute and chronic effect of bariatric surgery on circulating autotaxin levels

Autotaxin (ATX), an adipose tissue-derived lysophospholipase, has been involved in the pathophysiology of cardiometabolic diseases. The impact of bariatric surgery on circulating ATX levels is unknown. We examined the short- (24 h, 5 days) and longer-term (6 and 12 months) impact of bariatric surgery; as well as the short-term effect of caloric restriction (CR) on plasma ATX levels in patients with severe obesity. We measured ATX levels in 69 men and women (mean age: 41 ± 11 years, body mass index: 49.8 ± 7.1 kg/m2 ), before and after biliopancreatic diversion with duodenal switch surgery (BPD-DS) as well as in a control group (patients with severe obesity without surgery; n = 34). We also measured ATX levels in seven patients with severe obesity and type 2 diabetes who underwent a 3-day CR protocol before their BPD-DS. At baseline, ATX levels were positively associated with body mass index, fat mass, insulin resistance (HOMA-IR) as well as insulin and leptin levels and negatively with fat-free mass. ATX concentrations decreased 26.2% at 24 h after BPD-DS (342.9 ± 152.3 pg/mL to 253.2 ± 68.9 pg/mL, P < 0.0001) and by 16.4% at 12 months after BPD-DS (342.9 ± 152.3 pg/mL to 286.8 ± 182.6 pg/mL, P = 0.04). ATX concentrations were unchanged during follow-up in the control group (P = 0.4), and not influenced by short-term CR. In patients with severe obesity, bariatric surgery induced a rapid and sustained decrease in plasma ATX levels. Acute changes in ATX may not be explained by bariatric surgery-induced CR.

Links Between Iron and Lipids: Implications in Some Major Human Diseases

Maintenance of iron homeostasis is critical to cellular health as both its excess and insufficiency are detrimental. Likewise, lipids, which are essential components of cellular membranes and signaling mediators, must also be tightly regulated to hinder disease progression. Recent research, using a myriad of model organisms, as well as data from clinical studies, has revealed links between these two metabolic pathways, but the mechanisms behind these interactions and the role these have in the progression of human diseases remains unclear. In this review, we summarize literature describing cross-talk between iron and lipid pathways, including alterations in cholesterol, sphingolipid, and lipid droplet metabolism in response to changes in iron levels. We discuss human diseases correlating with both iron and lipid alterations, including neurodegenerative disorders, and the available evidence regarding the potential mechanisms underlying how iron may promote disease pathogenesis. Finally, we review research regarding iron reduction techniques and their therapeutic potential in treating patients with these debilitating conditions. We propose that iron-mediated alterations in lipid metabolic pathways are involved in the progression of these diseases, but further research is direly needed to elucidate the mechanisms involved.

Lysophosphatidic acid enhances breast cancer cells-mediated osteoclastogenesis

Lysophosphatidic acid (LPA) is known to play a critical role in breast cancer metastasis to bone. In this study, we tried to investigate any role of LPA in the regulation of osteoclastogenic cytokines from breast cancer cells and the possibility of these secretory factors in affecting osteoclastogenesis. Effect of secreted cytokines on osteoclastogenesis was analyzed by treating conditioned media from LPA-stimulated breast cancer cells to differentiating osteoclasts. Result demonstrated that IL-8 and IL-11 expression were upregulated in LPA-treated MDA-MB-231 cells. IL-8 was induced in both MDA-MB-231 and MDA-MB-468, however, IL-11 was induced only in MDA-MB-231, suggesting differential LPARs participation in the expression of these cytokines. Expression of IL-8 but not IL-11 was suppressed by inhibitors of PI3K, NFkB, ROCK and PKC pathways. In the case of PKC activation, it was observed that PKCδ and PKCμ might regulate LPA-induced expression of IL-11 and IL-8, respectively, by using specific PKC subtype inhibitors. Finally, conditioned Medium from LPA-stimulated breast cancer cells induced osteoclastogenesis. In conclusion, LPA induced the expression of osteolytic cytokines (IL-8 and IL-11) in breast cancer cells by involving different LPA receptors. Enhanced expression of IL-8 by LPA may be via ROCK, PKCu, PI3K, and NFkB signaling pathways, while enhanced expression of IL-11 might involve PKCδ signaling pathway. LPA has the ability to enhance breast cancer cells-mediated osteoclastogenesis by inducing the secretion of cytokines such as IL-8 and IL-11.

CARMA3 Is a Critical Mediator of G Protein-Coupled Receptor and Receptor Tyrosine Kinase-Driven Solid Tumor Pathogenesis

The CARMA–Bcl10–MALT1 (CBM) signalosome is an intracellular protein complex composed of a CARMA scaffolding protein, the Bcl10 linker protein, and the MALT1 protease. This complex was first recognized because the genes encoding its components are targeted by mutation and chromosomal translocation in lymphoid malignancy. We now know that the CBM signalosome plays a critical role in normal lymphocyte function by mediating antigen receptor-dependent activation of the pro-inflammatory, pro-survival NF-κB transcription factor, and that deregulation of this signaling complex promotes B-cell lymphomagenesis. More recently, we and others have demonstrated that a CBM signalosome also operates in cells outside of the immune system, including in several solid tumors. While CARMA1 (also referred to as CARD11) is expressed primarily within lymphoid tissues, the related scaffolding protein, CARMA3 (CARD10), is more widely expressed and participates in a CARMA3-containing CBM complex in a variety of cell types. The CARMA3-containing CBM complex operates downstream of specific G protein-coupled receptors (GPCRs) and/or growth factor receptor tyrosine kinases (RTKs). Since inappropriate expression and activation of GPCRs and/or RTKs underlies the pathogenesis of several solid tumors, there is now great interest in elucidating the contribution of CARMA3-mediated cellular signaling in these malignancies. Here, we summarize the key discoveries leading to our current understanding of the role of CARMA3 in solid tumor biology and highlight the current gaps in our knowledge.

Activity and clinical relevance of autotaxin and lysophosphatidic acid pathways in high-grade serous carcinoma

The aim of this study was to analyze the expression, biological role and clinical relevance of autotaxin (ATX), the enzyme synthetizing lysophosphatidic acid (LPA), and LPA receptors (LPAR) in high-grade serous carcinoma (HGSC). mRNA expression by qRT-PCR of LPAR1-6 was analyzed in 155 HGSC specimens (88 effusions, 67 solid lesions). ATX mRNA expression was analyzed in 97 specimens. ATX, ERK, and AKT protein expression was studied by Western blotting. LPAR2 mRNA was overexpressed in HGSC cells in effusions compared to solid lesions, with opposite findings for LPAR3 and LPAR6 mRNA and ATX protein. Higher LPAR1 levels were significantly related to longer overall survival (OS) in pre-chemotherapy effusions (p = 0.027). Conversely, higher expression of LPAR1, LPAR2, and LPAR5 in post-chemotherapy effusions was significantly associated with shorter OS (p = 0.037, p = 0.025 and p = 0.021, respectively) and progression-free survival (PFS) (p < 0.001, p = 0.007 and p < 0.001, respectively) in univariate survival analysis. LPAR1 mRNA expression was an independent prognosticator of OS in patients with pre-chemotherapy effusions and PFS in patients with post-chemotherapy effusions (p = 0.013 both). In conclusion, LPAR mRNA and ATX protein levels are anatomic site-dependent in HGSC and the former are informative of disease outcome.

Autotaxin exacerbates tumor progression by enhancing MEK1 and overriding the function of miR-489-3p

Upregulated expression of autotaxin, a secreted phospholipase and phosphodiesterase enzyme, appears in malignant disease. The identification of a circulating miRNA signature should distinguish autotaxin-mediated disease and also elucidate unknown molecular mechanisms that rationalize its malignant potential. Using female transgenic 'AT-ATX' mice, whereby human wild-type autotaxin is expressed in liver under the control of the alpha-1 antitrypsin promoter, transgenic animals express augmented autotaxin in circulation and a percentage develop tumors. Serum collected at necropsy had circulating miRNAs analyzed for statistical significance. The ensuing autotaxin-mediated miRNome differentiated between groups: healthy FVB/N mice versus AT-ATX mice with and without tumors. Intriguingly, miR-489-3p was sharply increased in AT-ATX tumor-bearing mice. Tissue analysis showed a correlation between miR-489-3p expression in tumors and surrounding milieu with autotaxin concentration in circulation. Sequence alignment suggested miR-489-3p targets MEK1, which was confirmed through in vitro studies. Exogenously added miR-489-3p, which decreases MEK1 in normal cells, dramatically increased MEK1 expression in cells stably expressing autotaxin. Taken together, this suggests that autotaxin overrides the normal regulatory function of miR-489-3p to inhibit MEK1 via coordinately increased miR-489-3p appearing in serum.

Microrna-139-5p inhibits epithelial-mesenchymal transition and fibrosis in post-menopausal women with interstitial cystitis by targeting LPAR4 via the PI3K/Akt signaling pathway

The study explores whether miR-139-5p targeting LPAR4 affects epithelial-mesenchymal transition (EMT) and fibrosis in post-menopausal women with interstitial cystitis (IC) via the PI3K/Akt signaling pathway. Bladder tissues of IC and normal bladder tissues were collected. The pathology of bladder tissues was observed by HE, Masson and Picrosirius red staining. LPAR4 positive expression rate were determined by IHC. ELISA was performed to detect the levels of IL-6, IL-8, IL-10, and TNF-α. Rat IC models were randomized into seven different groups. miR-139-5p, LPAR1, LPAR2, LPAR3, LPAR4, LPAR5, P13K, Akt, E-cadherin, N-cadherin, Vimentin, TGF-β1, and CTGF expression were determined by RT-qPCR and Western blotting. Dual luciferase reporter gene assay verified that LPAR4 is a target gene of miR-139-5p. Fibrosis was a pathological manifestation of IC. The IC group showed higher LPAR4, PI3K, Akt, p-PI3K, p-Akt, N-cadherin, Vimentin, TGF-β1, and CTGF expression but lower miR-139-5p and E-cadherin expression than the normal group. The levels of IL-6, IL-8, IL-10, and TNF-α expression decreased while HB-EGF increased in the IC group in comparison of the normal group. Compared with the blank and NC groups, E-cadherin expression was increased in the miR-139-5p mimic and siRNA-LPAR4 groups, while LPAR4, PI3K, Akt, p-P13K, p-Akt, N-cadherin, Vimentin, TGF-β1, and CTGF expression were decreased. An opposite trend was found in the miR-139-5p inhibitor group. The miR-139-5p decreased in the miR-139-5p inhibitor + siRNA-LPAR4 and miR-139-5p inhibitor + wortmannin groups. Conclusively, miR-139-5p targeting LPAR4 inhibits EMT and fibrosis in post-menopausal IC women through the PI3K/Akt signaling pathway.

Autotaxin-Lysophosphatidic Acid: From Inflammation to Cancer Development

Lysophosphatidic acid (LPA) is a ubiquitous lysophospholipid and one of the main membrane-derived lipid signaling molecules. LPA acts as an autocrine/paracrine messenger through at least six G protein-coupled receptors (GPCRs), known as LPA_1–6, to induce various cellular processes including wound healing, differentiation, proliferation, migration, and survival. LPA receptors and autotaxin (ATX), a secreted phosphodiesterase that produces this phospholipid, are overexpressed in many cancers and impact several features of the disease, including cancer-related inflammation, development, and progression. Many ongoing studies aim to understand ATX-LPA axis signaling in cancer and its potential as a therapeutic target. In this review, we discuss the evidence linking LPA signaling to cancer-related inflammation and its impact on cancer progression.

Lysophosphatidic acid via LPA-receptor 5/protein kinase D-dependent pathways induces a motile and pro-inflammatory microglial phenotype

BACKGROUND

Extracellular lysophosphatidic acid (LPA) species transmit signals via six different G protein-coupled receptors (LPAR1-6) and are indispensible for brain development and function of the nervous system. However, under neuroinflammatory conditions or brain damage, LPA levels increase, thereby inducing signaling cascades that counteract brain function. We describe a critical role for 1-oleyl-2-hydroxy-sn-glycero-3-phosphate (termed "LPA" throughout our study) in mediating a motile and pro-inflammatory microglial phenotype via LPAR5 that couples to protein kinase D (PKD)-mediated pathways.

METHODS

Using the xCELLigence system and time-lapse microscopy, we investigated the migrational response of microglial cells. Different M1 and M2 markers were analyzed by confocal microscopy, flow cytometry, and immunoblotting. Using qPCR and ELISA, we studied the expression of migratory genes and quantitated the secretion of pro-inflammatory cytokines and chemokines, respectively. Different transcription factors that promote the regulation of pro-inflammatory genes were analyzed by western blot. Reactive oxygen species (ROS) and nitric oxide (NO) production, phagocytosis, and microglial cytotoxicity were determined using commercially available assay kits.

RESULTS

LPA induces MAPK family and AKT activation and pro-inflammatory transcription factors' phosphorylation (NF-κB, c-Jun, STAT1, and STAT3) that were inhibited by both LPAR5 and PKD family antagonists. LPA increases migratory capacity, induces secretion of pro-inflammatory cytokines and chemokines and expression of M1 markers, enhances production of ROS and NO by microglia, and augments cytotoxicity of microglial cell-conditioned medium towards neurons. The PKD family inhibitor blunted all of these effects. We propose that interference with this signaling axis could aid in the development of new therapeutic approaches to control neuroinflammation under conditions of overshooting LPA production.

CONCLUSIONS

In the present study, we show that inflammatory LPA levels increased the migratory response of microglia and promoted a pro-inflammatory phenotype via the LPAR5/PKD axis. Interference with this signaling axis reduced microglial migration, blunted microglial cytotoxicity, and abrogated the expression and secretion of pro-inflammatory mediators.

A murine preclinical syngeneic transplantation model for breast cancer precision medicine

We previously demonstrated that altered activity of lysophosphatidic acid in murine mammary glands promotes tumorigenesis. We have now established and characterized a heterogeneous collection of mouse-derived syngeneic transplants (MDSTs) as preclinical platforms for the assessment of personalized pharmacological therapies. Detailed molecular and phenotypic analyses revealed that MDSTs are the most heterogeneous group of genetically engineered mouse models (GEMMs) of breast cancer yet observed. Response of MDSTs to trametinib, a mitogen-activated protein kinase (MAPK) kinase inhibitor, correlated with RAS/MAPK signaling activity, as expected from studies in xenografts and clinical trials providing validation of the utility of the model. Sensitivity of MDSTs to talazoparib, a poly(adenosine 5'-diphosphate-ribose) polymerase (PARP) inhibitor, was predicted by PARP1 protein levels and by a new PARP sensitivity predictor (PSP) score developed from integrated analysis of drug sensitivity data of human cell lines. PSP score-based classification of The Cancer Genome Atlas breast cancer suggested that a subset of patients with limited therapeutic options would be expected to benefit from PARP-targeted drugs. These results indicate that MDSTs are useful models for studies of targeted therapies, and propose novel potential biomarkers for identification of breast cancer patients likely to benefit from personalized pharmacological treatments.

Active YAP promotes pancreatic cancer cell motility, invasion and tumorigenesis in a mitotic phosphorylation-dependent manner through LPAR3

The transcriptional co-activator Yes-associated protein, YAP, is a main effector in the Hippo tumor suppressor pathway. We recently defined a mechanism for positive regulation of YAP through CDK1-mediated mitotic phosphorylation. Here, we show that active YAP promotes pancreatic cancer cell migration, invasion and anchorage-independent growth in a mitotic phosphorylation-dependent manner. Mitotic phosphorylation is essential for YAP-driven tumorigenesis in animals. YAP reduction significantly impairs cell migration and invasion. Immunohistochemistry shows significant upregulation and nuclear localization of YAP in metastases when compared with primary tumors and normal tissue in human. Mitotic phosphorylation of YAP controls a unique transcriptional program in pancreatic cells. Expression profiles reveal LPAR3 (lysophosphatidic acid receptor 3) as a mediator for mitotic phosphorylation-driven pancreatic cell motility and invasion. Together, this work identifies YAP as a novel regulator of pancreatic cancer cell motility, invasion and metastasis, and as a potential therapeutic target for invasive pancreatic cancer.

Near-Infrared Fluorogenic Probes with Polarity-Sensitive Emission for in Vivo Imaging of an Ovarian Cancer Biomarker

Lysophosphatidic acid (LPA, cutoff values ≥ 1.5 μM) is an effective biomarker for early stage ovarian cancer. The development of selective probes for LPA detection is therefore critical for early clinical diagnosis. Although current methods have been developed for the detection of LPA in solution, they cannot be used for tracking LPA in vivo. Here, we report a near-infrared (NIR) fluorescent probe that can selectively respond to LPA based on polarity-sensitive emission at a very low detection limit of 0.5 μM in situ. This probe exhibits a marked increase of fluorescence at 720 nm upon binding to LPA, allowing the direct visualization of LPA in vitro and in vivo without interference from other biomolecules. Moreover, the probe containing two arginine-glycine-aspartic acid units can be efficiently taken up by cancer cells based on an αvβ3 integrin receptor targeting mechanism. It also exhibits excellent biocompatibility and high pH stability in live cells and in vivo. Confocal laser scanning microscopy and flow cytometric imaging of SKOV-3 cells have confirmed that our probe can be used to image LPA in live cells. In particular, its NIR turn-on fluorescence can be used to effectively monitor LPA imaging in a SKOV-3 tumor-bearing mouse model. Our probe may pave the way for the detection of cancer-related biomarkers and even for early stage cancer diagnosis.

TRIP6 antagonizes the recruitment of A20 and CYLD to TRAF6 to promote the LPA2 receptor-mediated TRAF6 activation

The elevated lysophosphatidic acid signaling has been causally linked to cancer-associated inflammation and tumorigenesis through upregulation of nuclear factor-κB signaling. However, how this signaling event is regulated has not yet been fully understood. Here we demonstrate that TRIP6, an LPA2 receptor-interacting adaptor protein, functions as a positive regulator of nuclear factor-κB and JNK signaling through direct binding to and activation of the E3 ligase TRAF6. Upon lysophosphatidic acid stimulation, TRIP6 recruits TRAF6 to the LPA2 receptor and promotes lysophosphatidic acid-induced JNK and nuclear factor-κB activation in a TRAF6-dependent manner. TRIP6 antagonizes the recruitment of deubiquitinases A20 and CYLD to TRAF6, thus sustaining the E3 ligase activity of TRAF6 and augmenting lysophosphatidic acid-activated nuclear factor-κB signaling. In contrast, depletion of TRIP6 by TRIP6-specific shRNA or Cas9/sgRNA greatly enhances the association of TRAF6 with A20 and CYLD, and attenuates lysophosphatidic acid-induced muclear factor-κB and JNK/p38 activation in ovarian cancer cells. On the other hand, TRAF6 also regulates TRIP6 by facilitating its binding to nuclear factor-κB p65 and phosphorylation by c-Src. Together, TRIP6 cooperates with TRAF6 to regulate the LPA2 receptor signaling, which may ultimately contribute to chronic inflammation, apoptotic resistance and cell invasion.

Homology modeling and docking studies of ENPP4: a BCG activated tumoricidal macrophage protein

BACKGROUND

The 3D structure and functions of ENPP4, a protein expressed on the surface of Bacillus Calmette-Guerin (BCG)-activated macrophages, are unknown. In this study, we analyzed the 3D structure of ENPP4 and determined its tumoricidal effects on MCA207 cells.

RESULTS

Homology modeling showed that Arg305, Tyr341, Asn291, and Asn295 are important residues in substrate, adenosine triphosphate (ATP), binding. A molecular dynamics study was also carried out to study the stability of ENPP4 (including zinc atoms) as well as its ligand-enzyme complex. BCG increased ENPP4 expression in macrophages, and specific blocking of ENPP4 in BCG-activated macrophages (BAMs) significantly reduced their cytotoxicity against MCA207 cells.

CONCLUSIONS

These results indicate that zinc remains inside the ENPP4 protein, a BCG activated tumoricidal macrophage protein, throughout the simulation. Important information for the design of new inhibitors was obtained.

Higher plasma levels of lysophosphatidylcholine 18:0 are related to a lower risk of common cancers in a prospective metabolomics study

BACKGROUND

First metabolomics studies have indicated that metabolic fingerprints from accessible tissues might be useful to better understand the etiological links between metabolism and cancer. However, there is still a lack of prospective metabolomics studies on pre-diagnostic metabolic alterations and cancer risk.

METHODS

Associations between pre-diagnostic levels of 120 circulating metabolites (acylcarnitines, amino acids, biogenic amines, phosphatidylcholines, sphingolipids, and hexoses) and the risks of breast, prostate, and colorectal cancer were evaluated by Cox regression analyses using data of a prospective case-cohort study including 835 incident cancer cases.

RESULTS

The median follow-up duration was 8.3 years among non-cases and 6.5 years among incident cases of cancer. Higher levels of lysophosphatidylcholines (lysoPCs), and especially lysoPC a C18:0, were consistently related to lower risks of breast, prostate, and colorectal cancer, independent of background factors. In contrast, higher levels of phosphatidylcholine PC ae C30:0 were associated with increased cancer risk. There was no heterogeneity in the observed associations by lag time between blood draw and cancer diagnosis.

CONCLUSION

Changes in blood lipid composition precede the diagnosis of common malignancies by several years. Considering the consistency of the present results across three cancer types the observed alterations point to a global metabolic shift in phosphatidylcholine metabolism that may drive tumorigenesis.

Autotaxin, a lysophospholipase D with pleomorphic effects in oncogenesis and cancer progression

The ectonucleotide pyrophosphatase/phosphodiesterase type 2, more commonly known as autotaxin (ATX), is an ecto-lysophospholipase D encoded by the human ENNP2 gene. ATX is expressed in multiple tissues and participates in numerous key physiologic and pathologic processes, including neural development, obesity, inflammation, and oncogenesis, through the generation of the bioactive lipid, lysophosphatidic acid. Overwhelming evidence indicates that altered ATX activity leads to oncogenesis and cancer progression through the modulation of multiple hallmarks of cancer pathobiology. Here, we review the structural and catalytic characteristics of the ectoenzyme, how its expression and maturation processes are regulated, and how the systemic integration of its pleomorphic effects on cells and tissues may contribute to cancer initiation, progression, and therapy. Additionally, the up-to-date spectrum of the most frequent ATX genomic alterations from The Cancer Genome Atlas project is reported for a subset of cancers.