Abstract P4-10-07: Breastfeeding experience among breast cancer patients in the modern era

Introduction: In recent years, the uptake of breastfeeding has become more common as it is regarded as healthy and beneficial for both mother and infant. The process of parturition and lactation plays a role in the normal differentiation and development of breast tissue, and multiparity has been associated with a decreased risk for breast cancer. The current study sought to describe the breastfeeding experience of a modern cohort of women with newly diagnosed BC, and to examine the clinicopathologic characteristics of their disease.

Methods: A retrospective review of our institutional Breast Cancer Database from 2009-2017 was performed to identify women with at least one full term pregnancy (FTP). Clinicopathologic and demographic information was recorded, including breastfeeding experience and cumulative duration of nursing. Women were grouped by self-reported breastfeeding experience and duration of breastfeeding for analysis. Pearson's chi-square tests were performed.

Results: Of 1919 patients, 1053 (54.9%) reporting breastfeeding. Breastfeeding increased from a low of 30.4% among women with first FTP (FFTP) in the 1950's to 84.6% with FFTP in the 2010's. There were no significant differences between those who did and did not breast feed with regards to race, family history, BRCA status, pathologic stage, grade, tumor histology, lymphovascular invasion (LVI), multifocality, tumor size or receptor status. When stratified by duration of breastfeeding, the most striking finding was that women who breastfed for >12 months were more likely to have tumors associated with LVI (p = 0.028).

Table– Breastfeeding Experience Among Parous Women with Breast CancerVariableNo Breastfeeding (n=866)Breastfeeding (n=1053)p-valueRace  0.432White648 (74.8%)767 (72.8%) Black73 (8.5%)112 (10.6%) Asian78 (9%)102 (9.7%) Hispanic64 (7.4%)67 (6.4%) Other3 (0.3%)5 (0.5%) Family history272 (31.4%)311 (29.6%)0.397BRCA 1,2 positive23 (2.7%)42 (4.0%)0.108Final Pathology Stage  0.2240190 (21.9%)222 (21.1%) I426 (49.2%)507 (48.1%) II197 (22.8%)229 (21.7%) III40 (4.6%)63 (6.0%) IV1 (0.1%)3 (0.3%) No residual (neoadjuvant)12 (1.4%)29 (34.1%) Invasive Grade  0.127Low92 (14.1%)120 (15.3%) Intermediate371 (56.7%)398 (50.6%) High191 (29.2%)268 (34.1%) Histology  0.130DCIS189 (21.8%)223 (21.2%) IDC531 (61.3%)688 (65.3%) ILC113 (13.1%)99 (9.4%) Other33 (3.8%)43 (4.1%) LVI127 (14.7%)174 (16.5%) Multifocality147 (17%)183 (17.4%) Median tumor size (cm; range)1.4 (0-9.5)1.3 (0-12.5)0.489Estrogen Receptor  0.206Positive726 (84.7%)861 (82.6%) Negative131 (15.3%)182 (17.4%) Progesterone Receptor  0.275Positive621 (72.5%)732 (70.2%) Negative236 (27.5%)311 (29.8%) HER2/neu Receptor  0.068Positive78 (12%)121 (15.4%) Negative571 (88%)667 (84.6%) 

Conclusions: Breastfeeding experience was not generally associated with significant differences in tumor or patient characteristics. However, breastfeeding for longer than 12 months was associated with LVI. It is possible that changes in the breast tissue that occur during the process of pregnancy and prolonged lactation may influence future tumor development. These findings are hypothesis generating and suggest that the relationship of prolonged breastfeeding and breast cancer development should be investigated further.

Citation Format: Gooch JC, Chun J, Jubas T, Guth A, Schnabel F. Breastfeeding experience among breast cancer patients in the modern era [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-07.

Abstract P5-02-01: The relationship of breast density in mammography and magnetic resonance imaging (MRI) in women with triple negative breast cancer (TNBC)

Introduction:

TNBC represent 10%–20% of invasive breast cancers. Previous studies showed that TNBC usually present with benign features on mammography, ultrasound and MRI. However, there is a dearth of information on the relationship of mammographic breast density (MBD), background parenchymal enhancement (BPE) and fibroglandular tissue (FGT) on MRI with TNBC. The purpose of this study was to evaluate the relationship between BD, BPE, and FGT in women with TNBC compared to non-TNBC in a contemporary cohort of women with breast cancer.

Methods:

The Institutional Breast Cancer Database was queried for women who had invasive breast cancer and underwent mammography and MRI between (2010-2017). Variables of interest included clinical, pathologic, and imaging characteristics. Statistical analyses included Pearson's Chi Square and logistic regression.

Results:

Of 2224 women, 210 (9%) had TNBC. The median age was 59 years (22-95) and median follow up was 4 years. When we looked at the clinical characteristics of women with TNBC compared to non-TNBC, race, BRCA1,2 status, method of presentation, palpability, histology, grade, and Ki67 were statistically different (Table 1). When we looked at the correlation of MBD, FGT, and BPE for women with TNBC, MBD was correlated with FGT (r=0.64) but weakly correlated with BPE (r=0.22). We found a significant association of low BPE and TNBC compared to the non-TNBCs (p=0.021) (Table 1). In a short period of time, only 8 women with TNBC had a recurrence with no significant association with MBD, BPE, or FGT (Table 1).

Table 1.Imaging Characteristics among TNBC compared to non-TNBCVariableTNBC (N=210)%Non-TNBC (N=2014)%P-valueRace    0.001White13665153376 Black35171749 Hispanic1261156 Asian23111739 Other42191 BRCA1/2    <0.001Positive3025425 Negative897579195 Method of Presentation    <0.001Breast exam1125475738 Mammography7737105753 Ultrasound731106 MRI126553 Palpable    <0.001Yes1185783342 No9144115258 Histology    <0.001DCIS with Microinvasion21382 IDC19693159079 ILC5226913 Invasive Other731176 Invasive Grade    <0.001Grade 11131016 Grade 22714111858 Grade 31688650126 ER    <0.001Positive00189194 Negative2101001226 PR    <0.001Positive00160080 Negative21010041221 Ki67    <0.001Median (range)60 (0-99) 10 (0-99)  Mammographic Density    0.165Less dense82417846 More dense11959103454 MRI BPE    0.021Low BPE707655564 High BPE222431236 MRI FGT    0.370Less dense475440449 More dense404642151 

Conclusions:

In our study population, MBD and FGT did not differ between patients with TNBC compared to non-TNBC. Interestingly, we found a higher proportion of women with lower BPE in the TNBC compared to the non-TNBC group. BPE refers to the amount of enhancing fibroglandular tissue and has been demonstrated to reflect variations in estrogen-mediated vascular permeability. Lower BPE in TNBC may reflect the fact that these tumors are not hormonally sensitive. This may also have implications for radiogenomics, which aims to correlate imaging characteristics with gene expression and genome-related characteristics in tumor biology. Further studies are warranted in looking at these imaging biomarkers and TNBC.

Citation Format: Chun J, Schnabel F, Gooch J, Lee J, Jubas T, Goodgal J, Guth A, Moy L. The relationship of breast density in mammography and magnetic resonance imaging (MRI) in women with triple negative breast cancer (TNBC) [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-02-01.

Lysophosphatidic acid receptor type 2 activation contributes to secondary damage after spinal cord injury in mice

Lysophosphatidic acid (LPA) is an extracellular lipid mediator involved in many physiological functions by signaling through six known G-protein-coupled receptors (LPA₁-LPA₆). In the central nervous system (CNS), LPA mediates a wide range of effects, including neural progenitor cell physiology, astrocyte and microglia activation, neuronal cell death, axonal retraction, and contributions to pain, schizophrenia and hydrocephalus. We recently reported that LPA-LPA₁ signaling mediates functional deficits and myelin loss after spinal cord injury (SCI). Here, we provide clear evidence on the deleterious contribution of another LPA receptor, LPA₂, to myelin loss after SCI. We found that LPA₂ is constitutively expressed in the spinal cord parenchyma and its transcripts were up-regulated after contusion injury, in part, by microglial cells. We also found that the demyelinating lesion triggered by intraspinal injection of LPA into the undamaged spinal cord was markedly reduced in the lack of LPA₂. Similarly, LPA₂ deficient mice showed enhanced motor skills and myelin sparing after SCI. To gain insights into the detrimental actions of LPA₂ in spinal cord we performed cell culture studies. These experiments revealed that, similar to LPA₁, activation of microglia LPA₂ led to oligodendrocyte cell death. Moreover, we also found that the cytotoxic effects underlaying microglial LPA-LPA₂ axis were mediated by the release of purines by microglia and the activation of P₂X₇ receptor on oligodendrocytes. Overall, this study provides new mechanistic insights into how LPA contributes to SCI physiopathology, and suggest that targeting LPA₂ could be a novel therapeutic approach for the treatment of acute SCI.

Publisher Correction: Somatic APP gene recombination in Alzheimer's disease and normal neurons

In this Article, the top label in Fig. 5d should read 'DISH 3/16' instead of 'DISH 3/17'. This error has been corrected online.

Lysophospholipid G protein-coupled receptor binding parameters as determined by backscattering interferometry

Lysophosphatidic acid (LPA) activates cognate G protein-coupled receptors (GPCRs) to initiate biological signaling cascades. Lysophospholipid (LP) receptor binding properties remain incompletely assessed because of difficulties with ligand lipophilicity and lipid "stickiness." These inherent attributes produce high levels of nonspecific binding within cell-membrane preparations used to assess GPCRs, as has been shown in classical binding assays using radiolabeled ligands, making accurate measurements of lipid binding kinetics difficult to achieve. Backscattering interferometry (BSI) is an optical technology that measures molecular binding interactions by reporting changes in the refractive index of a solution after binding events. Here, we report the use of BSI to assess LPA1 for its ability to bind to naturally occurring lipids and a synthetic LPA1 antagonist (ONO-9780307), under both primary- and competition-binding conditions. Assessment of 12 different lipids demonstrated that the known LP ligand, 1-oleoyl-LPA, as well as an endocannabinoid metabolite, anandamide phosphate, are specific ligands for LPA1, whereas other LPs tested were not. Newly determined dissociation constants (Kd values) for orthosteric lipid ligands approximated 10-9 M, substantially lower (i.e., with higher affinity) than measured Kd values in classical binding or cell-based assays. These results demonstrate that BSI may have particular utility in assessing binding interactions between lipid receptors and their lipid ligands and could provide new screening approaches for lipid receptor identification and drug discovery.

Effects of Ionic Strength, Salt, and pH on Aggregation of Boehmite Nanocrystals: Tumbler Small-Angle Neutron and X-ray Scattering and Imaging Analysis

The US government currently spends significant resources managing the legacies of the Cold War, including 300 million liters of highly radioactive wastes stored in hundreds of tanks at the Hanford (WA) and Savannah River (SC) sites. The materials in these tanks consist of highly radioactive slurries and sludges at very high pH and salt concentrations. The solid particles primarily consist of aluminum hydroxides and oxyhydroxides (gibbsite and boehmite), although many other materials are present. These form complex aggregates that dramatically affect the rheology of the solutions and, therefore, efforts to recover and treat these wastes. In this paper, we have used a combination of transmission and cryo-transmission electron microscopy, dynamic light scattering, and X-ray and neutron small and ultrasmall-angle scattering to study the aggregation of synthetic nanoboehmite particles at pH 9 (approximately the point of zero charge) and 12, and sodium nitrate and calcium nitrate concentrations up to 1 m. Although the initial particles form individual rhombohedral platelets, once placed in solution they quickly form well-bonded stacks, primary aggregates, up to ∼1500 Å long. These are more prevalent at pH = 12. Addition of calcium nitrate or sodium nitrate has a similar effect as lowering pH, but approximately 100 times less calcium than sodium is needed to observe this effect. These aggregates have fractal dimension between 2.5 and 2.6 that are relatively unaffected by salt concentration for calcium nitrate at high pH. Larger aggregates (>∼4000 Å) are also formed, but their size distributions are discrete rather than continuous. The fractal dimensions of these aggregates are strongly pH-dependent, but only become dependent on solute at high concentrations.

Somatic APP gene recombination in Alzheimer's disease and normal neurons

The diversity and complexity of the human brain are widely assumed to be encoded within a constant genome. Somatic gene recombination, which changes germline DNA sequences to increase molecular diversity, could theoretically alter this code but has not been documented in the brain, to our knowledge. Here we describe recombination of the Alzheimer's disease-related gene APP, which encodes amyloid precursor protein, in human neurons, occurring mosaically as thousands of variant 'genomic cDNAs' (gencDNAs). gencDNAs lacked introns and ranged from full-length cDNA copies of expressed, brain-specific RNA splice variants to myriad smaller forms that contained intra-exonic junctions, insertions, deletions, and/or single nucleotide variations. DNA in situ hybridization identified gencDNAs within single neurons that were distinct from wild-type loci and absent from non-neuronal cells. Mechanistic studies supported neuronal 'retro-insertion' of RNA to produce gencDNAs; this process involved transcription, DNA breaks, reverse transcriptase activity, and age. Neurons from individuals with sporadic Alzheimer's disease showed increased gencDNA diversity, including eleven mutations known to be associated with familial Alzheimer's disease that were absent from healthy neurons. Neuronal gene recombination may allow 'recording' of neural activity for selective 'playback' of preferred gene variants whose expression bypasses splicing; this has implications for cellular diversity, learning and memory, plasticity, and diseases of the human brain.

Genomic mosaicism in the developing and adult brain

Since the discovery of DNA, the normal developing and functioning brain has been assumed to be composed of cells with identical genomes, which remains the dominant view even today. However, this pervasive assumption is incorrect, as proven by increasing numbers of reports within the last 20 years that have identified multiple forms of somatically produced genomic mosaicism (GM), wherein brain cells-especially neurons-from a single individual show diverse alterations in DNA, distinct from the germline. Critically, these changes alter the actual DNA nucleotide sequences-in contrast to epigenetic mechanisms-and almost certainly contribute to the remarkably diverse phenotypes of single brain cells, including single-cell transcriptomic profiles. Here, we review the history of GM within the normal brain, including its major forms, initiating mechanisms, and possible functions. GM forms include aneuploidies and aneusomies, smaller copy number variations (CNVs), long interspersed nuclear element type 1 (LINE1) repeat elements, and single nucleotide variations (SNVs), as well as DNA content variation (DCV) that reflects all forms of GM with greatest coverage of large, brain cell populations. In addition, technical considerations are examined, along with relationships among GM forms and multiple brain diseases. GM affecting genes and loci within the brain contrast with current neural discovery approaches that rely on sequencing nonbrain DNA (e.g., genome-wide association studies (GWAS)). Increasing knowledge of neural GM has implications for mechanisms of development, diversity, and function, as well as understanding diseases, particularly considering the overwhelming prevalence of sporadic brain diseases that are unlinked to germline mutations. © 2018 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol, 2018.

'Crystal' Clear? Lysophospholipid Receptor Structure Insights and Controversies

Lysophospholipids (LPLs), particularly sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA), are bioactive lipid modulators of cellular homeostasis and pathology. The discovery and characterization of five S1P- and six LPA-specific G protein-coupled receptors (GPCRs), S1P1-5 and LPA1-6, have expanded their known involvement in all mammalian physiological systems. Resolution of the S1P1, LPA1, and LPA6 crystal structures has fueled the growing interest in these receptors and their ligands as targets for pharmacological manipulation. In this review, we have attempted to provide an integrated overview of the three crystallized LPL GPCRs with biochemical and physiological structure-function data. Finally, we provide a novel discussion of how chaperones for LPLs may be considered when extrapolating crystallographic and computational data toward understanding actual biological interactions and phenotypes.

Effects of genetic deletion versus pharmacological blockade of the LPA1 receptor on depression-like behaviour and related brain functional activity

Animal models of psychopathology are particularly useful for studying the neurobiology of depression and characterising the subtypes. Recently, our group was the first to identify a possible relationship between the LPA₁ receptor and a mixed anxiety-depression phenotype. Specifically, maLPA₁-null mice exhibited a phenotype characterised by depressive and anxious features. However, the constitutive lack of the gene encoding the LPA₁ receptor (Lpar1) can induce compensatory mechanisms that might have resulted in the observed deficits. Therefore, in the present study, we have compared the impact of permanent loss and acute pharmacological inhibition of the LPA₁ receptor on despair-like behaviours and on the functional brain map associated with these behaviours, as well as on the degree of functional connectivity among structures. Although the antagonist (intracerebroventricularly administered Ki16425) mimicked some, but not all, effects of genetic deletion of the LPA₁ receptor on the results of behavioural tests and engaged different brain circuits, both treatments induced depression-like behaviours with an agitation component that was linked to functional changes in key brain regions involved in the stress response and emotional regulation. In addition, both Ki16425 treatment and LPA₁ receptor deletion modified the functional brain maps in a way similar to the changes observed in depressed patients. In summary, the pharmacological and genetic approaches could ultimately assist in dissecting the function of the LPA₁ receptor in emotional regulation and brain responses, and a combination of those approaches might provide researchers with an opportunity to develop useful drugs that target the LPA₁ receptor as treatments for depression, mainly the anxious subtype.

This article has an associated First Person interview with the first author of the paper.

Summary: Animal models of psychopathology are useful for studying the neurobiology of depression. Here, we have assessed by pharmacological approach and knockout models the contribution of the LPA-LPA₁ signalling pathway to anxious depression.

Abstract 404: Sphingosine-1-phosphate Receptor 1 Inhibits Pathological Cardiac Remodeling Through Histone Deacetylases

Sphingosine-1-phosphate receptor 1 (S1P 1 , encoded by S1pr1 ) is a G protein-coupled receptor that signals in multiple cell types including endothelium and cardiomyocytes. We observed decreased cardiac S1PR1 mRNA in humans with nonischemic cardiomyopathy; these patterns were also observed in mice after cardiac stress. To assess the importance of reduced S1pr1 expression, we exposed S1pr1 heterozygous mice to isoproterenol or angiotensin II. Subsequently, hearts from S1pr1+/- mice displayed significantly higher markers of hypertrophy, inflammation, fibrosis, and oxidative stress than wild-type littermates. Cardiomyocyte-specific deletion of S1pr1 caused pronounced increases in the same markers. In wild-type mice, co-administration of the S1P 1 -specific agonist SEW2871 rescued the pathologic effects of angiotensin II. Because class I histone deacetylases (HDACs) contribute to pathological remodeling, we investigated interactions between S1P 1 and HDAC activities as a potential mechanism. In cultured mouse cardiomyocytes, angiotensin II increased expression of histone deacetylases 1 and 2, as well as other markers of pathological remodeling; co-treatment with SEW2871 inhibited these responses. Moreover, HDAC inhibition in S1pr1+/- mice blunted the pathological response to angiotensin II. These results indicate that S1P 1 protects by modulating HDAC1/2 during cardiac stress and support S1P 1 agonism as a therapeutic strategy for pathological cardiac remodeling in humans.

The Autotaxin-Lysophosphatidic Acid Axis Promotes Lung Carcinogenesis

Pathogenesis and progression of lung cancer are governed by complex interactions between the environment and host genetic susceptibility, which is further modulated by genetic and epigenetic changes. Autotaxin (ATX, ENPP2) is a secreted glycoprotein that catalyzes the extracellular production of lysophosphatidic acid (LPA), a growth-factor-like phospholipid that is further regulated by phospholipid phosphatases (PLPP). LPA's pleiotropic effects in almost all cell types are mediated through at least six G-protein coupled LPA receptors (LPAR) that exhibit overlapping specificities, widespread distribution, and differential expression profiles. Here we use both preclinical models of lung cancer and clinical samples (from patients and healthy controls) to investigate the expression levels, activity, and biological role of the above components of the ATX/LPA axis in lung cancer. ENPP2 was genetically altered in 8% of patients with lung cancer, whereas increased ATX staining and activity were detected in patient biopsies and sera, respectively. Moreover, PLPP3 expression was consistently downregulated in patients with lung cancer. Comparable observations were made in the two most widely used animal models of lung cancer, the carcinogen urethane-induced and the genetically engineered K-ras^G12D -driven models, where genetic deletion of Enpp2 or Lpar1 resulted in disease attenuation, thus confirming a procarcinogenic role of LPA signaling in the lung. Expression profiling data analysis suggested that metabolic rewiring may be implicated in the procarcinogenic effects of the ATX/LPA axis in K-ras- ^G12D -driven lung cancer pathogenesis.Significance: These findings establish the role of ATX/LPA in lung carcinogenesis, thus expanding the mechanistic links between pulmonary fibrosis and cancer. Cancer Res; 78(13); 3634-44. ©2018 AACR.

Abstract P5-23-03: Gene expression profiling in male breast cancer

Background:

Tumor gene expression profiling tests are widely used to quantify risk of recurrence of breast cancer and guide systemic therapy in early stage breast cancer. These assays have not been well validated in a male cohort. The purpose of this study was to determine the current rates of genomic testing in male breast cancer (MBC), the distribution of risk of recurrence scores (RRS) in early stage MBC, and the effect of RRS on systemic treatment patterns.

Methods:

The National Cancer Database was queried and found to include 6,227 cases of pathologic T1/T2 and N0/N1 MBC from 2008-2014 with known genomic testing status. Of the 1478 (23.74%) male patients who had gene expression profiling performed, variables of interest included age at diagnosis, stage, estrogen receptor status (ER), RRS, and treatment. We compared the treatment patterns of the 1,343 patients who had RRS available and the 4,527 patients who were not tested. A similar analysis was performed in female breast cancer (FBC) patients to serve as a point of reference. Statistical analysis included multivariate logistic regression and Pearson's chi-square test.

Results:

Of the 1,478 (23.74%) cases of MBC who had gene expression profiling, the most significant variables included: younger age, non-Black race, diagnosis after 2010, tumor Grade II, Estrogen Receptor (ER) positivity, and N0 or N1mi disease. Of those who had results, the distribution of RRS was 59.3% low, 27.4% intermediate, and 13.3% high. A similar distribution was found in 154,705 women who were tested during the same study period. Risk scores in men were significantly associated with tumor grade and size, but not nodal status. 83.4% of men with a low RRS were treated with hormone therapy alone, with an adjusted odds ratio (AOR) of 7.18 (CI 5.78-8.91, p<0.001). Also, 61.8% of men with a high RRS received combination chemotherapy and hormone therapy, with an AOR of 5.16 (CI 3.60-740, p<0.001).

Conclusion:

Although there is limited literature supporting the use of genomic assays in MBC, our study found similar rates of testing in men and women with early stage breast cancer. Treatment patterns varied significantly based on risk stratification, implying that physicians are using gene profiling assays to help guide treatment in MBC. Understanding the role for genomic profiling in MBC is particularly important as these results will be incorporated into the new AJCC 8th edition staging system. Long term follow up is needed to determine whether these tests accurately predict prognosis and recurrence in a male cohort.

Citation Format: Dubrovsky E, Raymond S, Chun J, Schnabel F. Gene expression profiling in male breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-23-03.

Synaptic Phospholipid Signaling Modulates Axon Outgrowth via Glutamate-dependent Ca2+-mediated Molecular Pathways

Altered synaptic bioactive lipid signaling has been recently shown to augment neuronal excitation in the hippocampus of adult animals by activation of presynaptic LPA₂-receptors leading to increased presynaptic glutamate release. Here, we show that this results in higher postsynaptic Ca²⁺ levels and in premature onset of spontaneous neuronal activity in the developing entorhinal cortex. Interestingly, increased synchronized neuronal activity led to reduced axon growth velocity of entorhinal neurons which project via the perforant path to the hippocampus. This was due to Ca²⁺-dependent molecular signaling to the axon affecting stabilization of the actin cytoskeleton. The spontaneous activity affected the entire entorhinal cortical network and thus led to reduced overall axon fiber numbers in the mature perforant path that is known to be important for specific memory functions. Our data show that precise regulation of early cortical activity by bioactive lipids is of critical importance for proper circuit formation.

CD14 is a key mediator of both lysophosphatidic acid and lipopolysaccharide induction of foam cell formation

Macrophage uptake of oxidized low-density lipoprotein (oxLDL) plays an important role in foam cell formation and the pathogenesis of atherosclerosis. We report here that lysophosphatidic acid (LPA) enhances lipopolysaccharide (LPS)-induced oxLDL uptake in macrophages. Our data revealed that both LPA and LPS highly induce the CD14 expression at messenger RNA and protein levels in macrophages. The role of CD14, one component of the LPS receptor cluster, in LPA-induced biological functions has been unknown. We took several steps to examine the role of CD14 in LPA signaling pathways. Knockdown of CD14 expression nearly completely blocked LPA/LPS-induced oxLDL uptake in macrophages, demonstrating for the first time that CD14 is a key mediator responsible for both LPA- and LPS-induced oxLDL uptake/foam cell formation. To determine the molecular mechanism mediating CD14 function, we demonstrated that both LPA and LPS significantly induce the expression of scavenger receptor class A type I (SR-AI), which has been implicated in lipid uptake process, and depletion of CD14 levels blocked LPA/LPS-induced SR-AI expression. We further showed that the SR-AI-specific antibody, which quenches SR-AI function, blocked LPA- and LPS-induced foam cell formation. Thus, SR-AI is the downstream mediator of CD14 in regulating LPA-, LPS-, and LPA/LPS-induced foam cell formation. Taken together, our results provide the first experimental evidence that CD14 is a novel connecting molecule linking both LPA and LPS pathways and is a key mediator responsible for LPA/LPS-induced foam cell formation. The LPA/LPS-CD14-SR-AI nexus might be the new convergent pathway, contributing to the worsening of atherosclerosis.

Phosphorylation-mediated activation of LDHA promotes cancer cell invasion and tumour metastasis

Metastases remain the major cause of death from cancer. Recent molecular advances have highlighted the importance of metabolic alterations in cancer cells, including the Warburg effect that describes an increased glycolysis in cancer cells. However, how this altered metabolism contributes to tumour metastasis remains elusive. Here, we report that phosphorylation-induced activation of lactate dehydrogenase A (LDHA), an enzyme that catalyses the interconversion of pyruvate and lactate, promotes cancer cell invasion, anoikis resistance and tumour metastasis. We demonstrate that LDHA is phosphorylated at tyrosine 10 by upstream kinases, HER2 and Src. Targeting HER2 or Src attenuated LDH activity as well as invasive potential in head and neck cancer and breast cancer cells. Inhibition of LDH activity by small hairpin ribonucleic acid or expression of phospho-deficient LDHA Y10F sensitized the cancer cells to anoikis induction and resulted in attenuated cell invasion and elevated reactive oxygen species, whereas such phenotypes were reversed by its product lactate or antioxidant N-acetylcysteine, suggesting that Y10 phosphorylation-mediated LDHA activity promotes cancer cell invasion and anoikis resistance through redox homeostasis. In addition, LDHA knockdown or LDHA Y10F rescue expression in human cancer cells resulted in decreased tumour metastasis in xenograft mice. Furthermore, LDHA phosphorylation at Y10 positively correlated with progression of metastatic breast cancer in clinical patient tumour samples. Our findings demonstrate that LDHA phosphorylation and activation provide pro-invasive, anti-anoikis and pro-metastatic advantages to cancer cells, suggesting that Y10 phosphorylation of LDHA may represent a promising therapeutic target and a prognostic marker for metastatic human cancers.

Lysophosphatidic Acid Signaling through the Lysophosphatidic Acid-1 Receptor Is Required for Alveolarization

Lysophosphatidic acid (LPA) signaling through one of its receptors, LPA1, contributes to both the development and the pathological remodeling after injury of many organs. Because we found previously that LPA-LPA1 signaling contributes to pulmonary fibrosis, here we investigated whether this pathway is also involved in lung development. Quantitative assessment of lung architecture of LPA1-deficient knock-out (KO) and wild-type (WT) mice at 3, 12, and 24 weeks of age using design-based stereology suggested the presence of an alveolarization defect in LPA1 KO mice at 3 weeks, which persisted as alveolar numbers increased in WT mice into adulthood. Across the ages examined, the lungs of LPA1 KO mice exhibited decreased alveolar numbers, septal tissue volumes, and surface areas, and increased volumes of the distal airspaces. Elastic fibers, critical to the development of alveolar septa, appeared less organized and condensed and more discontinuous in KO alveoli starting at P4. Tropoelastin messenger RNA expression was decreased in KO lungs, whereas expression of matrix metalloproteinases degrading elastic fibers was either decreased or unchanged. These results are consistent with the abnormal lung phenotype of LPA1 KO mice, being attributable to reduced alveolar septal formation during development, rather than to increased septal destruction as occurs in the emphysema of chronic obstructive pulmonary disease. Peripheral septal fibroblasts and myofibroblasts, which direct septation in late alveolarization, demonstrated reduced production of tropoelastin and matrix metalloproteinases, and diminished LPA-induced migration, when isolated from LPA1 KO mice. Taken together, our data suggest that LPA-LPA1 signaling is critically required for septation during alveolarization.

Autotaxin-lysophosphatidic acid-LPA3 signaling at the embryo-epithelial boundary controls decidualization pathways

During pregnancy, up-regulation of heparin-binding (HB-) EGF and cyclooxygenase-2 (COX-2) in the uterine epithelium contributes to decidualization, a series of uterine morphological changes required for placental formation and fetal development. Here, we report a key role for the lipid mediator lysophosphatidic acid (LPA) in decidualization, acting through its G-protein-coupled receptor LPA₃ in the uterine epithelium. Knockout of Lpar3 or inhibition of the LPA-producing enzyme autotaxin (ATX) in pregnant mice leads to HB-EGF and COX-2 down-regulation near embryos and attenuates decidual reactions. Conversely, selective pharmacological activation of LPA₃ induces decidualization via up-regulation of HB-EGF and COX-2. ATX and its substrate lysophosphatidylcholine can be detected in the uterine epithelium and in pre-implantation-stage embryos, respectively. Our results indicate that ATX-LPA-LPA₃ signaling at the embryo-epithelial boundary induces decidualization via the canonical HB-EGF and COX-2 pathways.

Dysregulation of lysophosphatidic acids in multiple sclerosis and autoimmune encephalomyelitis

Abstract

Bioactive lipids contribute to the pathophysiology of multiple sclerosis. Here, we show that lysophosphatidic acids (LPAs) are dysregulated in multiple sclerosis (MS) and are functionally relevant in this disease. LPAs and autotaxin, the major enzyme producing extracellular LPAs, were analyzed in serum and cerebrospinal fluid in a cross-sectional population of MS patients and were compared with respective data from mice in the experimental autoimmune encephalomyelitis (EAE) model, spontaneous EAE in TCR¹⁶⁴⁰ mice, and EAE in Lpar2^-/- mice. Serum LPAs were reduced in MS and EAE whereas spinal cord LPAs in TCR¹⁶⁴⁰ mice increased during the ‘symptom-free’ intervals, i.e. on resolution of inflammation during recovery hence possibly pointing to positive effects of brain LPAs during remyelination as suggested in previous studies. Peripheral LPAs mildly re-raised during relapses but further dropped in refractory relapses. The peripheral loss led to a redistribution of immune cells from the spleen to the spinal cord, suggesting defects of lymphocyte homing. In support, LPAR2 positive T-cells were reduced in EAE and the disease was intensified in Lpar2 deficient mice. Further, treatment with an LPAR2 agonist reduced clinical signs of relapsing-remitting EAE suggesting that the LPAR2 agonist partially compensated the endogenous loss of LPAs and implicating LPA signaling as a novel treatment approach.

Graphical abstract

Graphical summary of lysophosphatidic signaling in multiple sclerosis

Electronic supplementary material

The online version of this article (doi:10.1186/s40478-017-0446-4) contains supplementary material, which is available to authorized users.

Sphingosine 1-phosphate receptor 3 and RhoA signaling mediate inflammatory gene expression in astrocytes

Background

Sphingosine 1-phosphate (S1P) signals through G protein-coupled receptors to elicit a wide range of cellular responses. In CNS injury and disease, the blood-brain barrier is compromised, causing leakage of S1P from blood into the brain. S1P can also be locally generated through the enzyme sphingosine kinase-1 (Sphk1). Our previous studies demonstrated that S1P activates inflammation in murine astrocytes. The S1P₁ receptor subtype has been most associated with CNS disease, particularly multiple sclerosis. S1P₃ is most highly expressed and upregulated on astrocytes, however, thus we explored the involvement of this receptor in inflammatory astrocytic responses.

Methods

Astrocytes isolated from wild-type (WT) or S1P₃ knockout (KO) mice were treated with S1P₃ selective drugs or transfected with short interfering RNA to determine which receptor subtypes mediate S1P-stimulated inflammatory responses. Interleukin-6 (IL-6), and vascular endothelial growth factor A (VEGFa) messenger RNA (mRNA) and cyclooxygenase-2 (COX-2) mRNA and protein were assessed by q-PCR and Western blotting. Activation of RhoA was measured using SRE.L luciferase and RhoA implicated in S1P signaling by knockdown of Gα_12/13 proteins or by inhibiting RhoA activation with C3 exoenzyme. Inflammation was simulated by in vitro scratch injury of cultured astrocytes.

Results

S1P₃ was highly expressed in astrocytes and further upregulated in response to simulated inflammation. Studies using S1P₃ knockdown and S1P₃ KO astrocytes demonstrated that S1P₃ mediates activation of RhoA and induction of COX-2, IL-6, and VEGFa mRNA, with some contribution from S1P₂. S1P induces expression of all of these genes through coupling to the Gα_12/13 proteins which activate RhoA. Studies using S1P₃ selective agonists/antagonists as well as Fingolimod (FTY720) confirmed that stimulation of S1P₃ induces COX-2 expression in astrocytes. Simulated inflammation increased expression of Sphk1 and consequently activated S1P₃, demonstrating an autocrine pathway through which S1P is formed and released from astrocytes to regulate COX-2 expression.

Conclusions

S1P₃, through its ability to activate RhoA and its upregulation in astrocytes, plays a unique role in inducing inflammatory responses and should be considered as a potentially important therapeutic target for CNS disease progression.