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

2019 ◽  
Vol 20 (19) ◽  
pp. 4800 ◽  
Author(s):  
Hanna Maja Tunset ◽  
Astrid Jullumstrø Feuerherm ◽  
Linn-Karina Myrland Selvik ◽  
Berit Johansen ◽  
Siver Andreas Moestue
Keyword(s):  
Gene Expression ◽  
Phospholipase A2 ◽  
Cell Line ◽  
Enzyme Inhibition ◽  
Cell Lines ◽  
Cytosolic Phospholipase A2 ◽  
Line Pair ◽  
Type I ◽  
Cytosolic Phospholipase ◽  
4T1 Cells

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

scholarly journals Enhancement of Cortisol-Induced 11β-Hydroxysteroid dehydrogenase Type 1 Expression by Interleukin 1β in Cultured Human Chorionic Trophoblast Cells

Endocrinology ◽  
2006 ◽  
Vol 147 (5) ◽  
pp. 2490-2495 ◽  
Author(s):  
Wenjiao Li ◽  
Lu Gao ◽  
Yan Wang ◽  
Tao Duan ◽  
Leslie Myatt ◽  
...  
Keyword(s):  
Gene Expression ◽  
Phospholipase A2 ◽  
Mrna Expression ◽  
Reporter Gene ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Cytosolic Phospholipase A2 ◽  
Trophoblast Cells ◽  
Cytosolic Phospholipase

Chorion is the most abundant site of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) expression within intrauterine tissues. It is important to study the regulation of 11β-HSD1 expression in the chorion in terms of local cortisol production during pregnancy. Using real-time PCR and enzyme activity assay, we found that cortisol (1 μm) and IL-1β (10 ng/ml) for 24 h significantly increased 11β-HSD1 mRNA expression and reductase activity in cultured human chorionic trophoblasts. A further significant increase of 11β-HSD1 mRNA expression and reductase activity was observed with cotreatment of cortisol and IL-1β. To explore the mechanism of induction, 11β-HSD1 promoter was cloned into pGL3 plasmid expressing a luciferase reporter gene. By transfecting the constructed vector into WISH cells, an amnion-derived cell line, we found that cortisol (1 μm) or IL-1β (10 ng/ml) significantly increased reporter gene expression. Likewise, an additional increase in reporter gene expression was observed with cotreatment of cortisol and IL-β. To explore the physiological significance of 11β-HSD1 induction in the chorion, we studied the effect of cortisol on cytosolic phospholipase A2 and cyclooxygenase 2 expression. We found that treatment of chorionic trophoblast cells with cortisol (1 μm) induced both cytosolic phospholipase A2 and cyclooxygenase 2 mRNA expression. We conclude that cortisol up-regulates 11β-HSD1 expression through induction of promoter activity, and the effect was enhanced by IL-1β, suggesting that more biologically active glucocorticoids could be generated in the fetal membranes in the presence of infection, which may consequently feed forward in up-regulation of prostaglandin synthesis.

scholarly journals Cytosolic phospholipase A2 is coupled to muscarinic receptors in the human astrocytoma cell line 1321N1: characterization of the transducing mechanism

1997 ◽  
Vol 323 (1) ◽  
pp. 281-287 ◽  
Author(s):  
Yolanda BAYON ◽  
Marita HERNANDEZ ◽  
Andrés ALONSO ◽  
Lucía NUÑEZ ◽  
Javier GARCIA-SANCHO ◽  
...  
Keyword(s):  
Phospholipase A2 ◽  
Cell Line ◽  
G Proteins ◽  
Muscarinic Receptors ◽  
Cytosolic Phospholipase A2 ◽  
Alternative Mechanism ◽  
Cytosolic Phospholipase ◽  
Astrocytoma Cell Line ◽  
Astrocytoma Cell ◽  
Arachidonate Release

The cholinergic agonist carbachol induced the release of arachidonic acid in the 1321N1 astrocytoma cell line, and this was blocked by atropine, suggesting the involvement of muscarinic receptors. To assess the mechanisms of signalling involved in the response to carbachol, a set of compounds characterized by eliciting responses through different mechanisms was tested. A combination of 4β-phorbol 12β-myristate 13α-acetate and thapsigargin, an inhibitor of endomembrane Ca2+-ATPase that induces a prolonged elevation of cytosolic Ca2+ concentration, induced an optimal response, suggesting at first glance that both protein kinase C (PKC) and Ca2+ mobilization were involved in the response. This was consistent with the observation that carbachol elicited Ca2+ mobilization and PKC-dependent phosphorylation of cytosolic phospholipase A2 (cPLA2; phosphatide sn-2-acylhydrolase, EC 3.1.1.4) as measured by a decrease in electrophoretic mobility. Nevertheless, the release of arachidonate induced by carbachol was unaltered in media containing decreased concentrations of Ca2+ or in the presence of neomycin, a potent inhibitor of phospholipase C which blocks phosphoinositide turnover and Ca2+ mobilization. Guanosine 5´-[γ-thio]triphosphate added to the cell-free homogenate induced both [3H]arachidonate release and cPLA2 translocation to the cell membrane fraction in the absence of Ca2+, thus suggesting the existence of an alternative mechanism of cPLA2 translocation dependent on G-proteins and independent of Ca2+ mobilization. From the combination of experiments utilizing biochemical and immunological tools the involvement of cPLA2 was ascertained. In summary, these data indicate the existence in the astrocytoma cell line 1321N1 of a pathway involving the cPLA2 which couples the release of arachidonate to the occupancy of receptors for a neurotransmitter, requires PKC activity and G-proteins and might operate in the absence of Ca2+ mobilization.

scholarly journals Characterization of phospholipase A2 in monocytic cell lines. Functional and biochemical aspects of membrane association

1991 ◽  
Vol 276 (3) ◽  
pp. 631-636 ◽  
Author(s):  
W Rehfeldt ◽  
R Hass ◽  
M Goppelt-Struebe
Keyword(s):  
Substrate Specificity ◽  
Phospholipase A2 ◽  
Cell Lines ◽  
Cytosolic Phospholipase A2 ◽  
Biologically Active ◽  
Ph Optimum ◽  
Monocytic Cell ◽  
Cytosolic Phospholipase ◽  
Membrane Bound ◽  
Phospholipase A2 Activity

Phospholipase A2 activity was characterized in the human monocytic tumour-cell lines U937 and THP1. The enzyme showed an alkaline pH optimum and substrate specificity for arachidonoyl-phosphatidylcholine. The activation of phospholipase A2 required bivalent cations (Ca2+ greater than Mg2+ = Sr2+ greater than Ba2+). Investigation of the subcellular distribution of the enzyme revealed that the phospholipase A2 activity was shifted to the cytosol in the presence of EDTA, indicating that the association of the enzyme with the cellular membranes is Ca2+ (bivalent-cation)-dependent. Stimulation of THP1 cells for 2-4 h with the phorbol ester phorbol 12-myristate 13-acetate (PMA) activated cytosolic and membrane-bound phospholipase A2. At this time, no effect of PMA on phospholipase A2 activity was observed in the less mature U937 cells. However, when both cell lines were induced to differentiate along the monocytic pathway by a 2-3-day treatment with PMA, the cells released significant amounts of arachidonic acid and prostanoids. Compared with undifferentiated control cells, these PMA-differentiated cells showed a decrease in cytosolic phospholipase A2 activity and an increase in membrane-bound activity. Membrane-bound and cytosolic enzyme showed the same pH optimum, Ca(2+)-dependency and substrate specificity. These data indicate that membrane-bound and cytosolic phospholipase A2 activities represent one enzyme and that the membrane-bound form is the biologically active phospholipase A2.

scholarly journals Thrombin produces phosphorylation of cytosolic phospholipase A2 by a mitogen-activated protein kinase kinase-independent mechanism in the human astrocytoma cell line 1321N1

1997 ◽  
Vol 328 (1) ◽  
pp. 263-269 ◽  
Author(s):  
Marita HERNÁNDEZ ◽  
Yolanda BAYÓN ◽  
Mariano SÁNCHEZ CRESPO ◽  
María Luisa NIETO
Keyword(s):  
Phospholipase A2 ◽  
Map Kinase ◽  
Cell Line ◽  
Cytosolic Phospholipase A2 ◽  
Thrombin Receptor ◽  
Primary Sequence ◽  
Jun Kinase ◽  
Cytosolic Phospholipase ◽  
Astrocytoma Cell ◽  
Mitogen Activated Protein

The release of [3H]arachidonic acid was studied in the 1321N1 astrocytoma cell line upon stimulation with thrombin. The effect of thrombin was antagonized by hirudin only when both compounds were added simultaneously, which suggests activation of thrombin receptor. Evidence that the cytosolic phospholipase A2 (cPLA2) takes part in thrombin-induced arachidonate release was provided by the finding that thrombin induced retardation of the mobility of cPLA2 in SDS/polyacrylamide gels, which is a feature of the activation of cPLA2 by mitogen-activated protein (MAP) kinases. Thrombin induced activation of two members of the MAP kinase family whose consensus primary sequence appears in cPLA2, namely p42-MAP kinase and c-Jun kinase. However, the activation of c-Jun kinase preceded the phosphorylation of cPLA2 more clearly than the activation of p42-MAK kinase did. Both cPLA2 and c-Jun kinase activation were not affected by PD-98059, a specific inhibitor of MAP kinase kinases, which indeed completely blocked p42-MAP kinase shift. Heat shock, a well-known activator of c-Jun kinase, also phosphorylated cPLA2 but not p42-MAP kinase. These data indicate the existence in astrocytoma cells of a signalling pathway triggered by thrombin receptor stimulation that activates a kinase cascade acting on the Pro-Leu-Ser-Pro consensus primary sequence, activates cPLA2, and associates the release of arachidonate with nuclear signalling pathways.

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