• Biomolecules & Therapeutics
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• v.25 no.2
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• pp.194-201
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• 2017

Lysophosphatidylethanolamine (LPE), a lyso-type metabolite of phosphatidylethanolamine, has been reported to be an intercellular signaling molecule. LPE mobilizes intracellular $Ca^{2+}$ through G-protein-coupled receptor (GPCR) in some cells types. However, GPCRs for lysophosphatidic acid (LPA) were not implicated in the LPE-mediated activities in LPA GPCR overexpression systems or in SK-OV3 ovarian cancer cells. In the present study, in human SH-SY5Y neuroblastoma cells, experiments with $LPA_1$ antagonists showed LPE induced intracellular $Ca^{2+}$ increases in an $LPA_1$ GPCR-dependent manner. Furthermore, LPE increased intracellular $Ca^{2+}$ through pertussis-sensitive G proteins, edelfosine-sensitive-phospholipase C, 2-APB-sensitive $IP_3$ receptors, $Ca^{2+}$ release from intracellular $Ca^{2+}$ stores, and subsequent $Ca^{2+}$ influx across plasma membranes, and LPA acted on $LPA_1$ and $LPA_2$ receptors to induce $Ca^{2+}$ response in a 2-APB-sensitive and insensitive manner. These findings suggest novel involvements for LPE and LPA in calcium signaling in human SH-SY5Y neuroblastoma cells.

• Experimental and Molecular Medicine
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• v.51 no.2
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• pp.9.1-9.10
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• 2019

Mesangial cell proliferation has been identified as a major factor contributing to glomerulosclerosis, which is a typical symptom of diabetic nephropathy (DN). Lysophosphatidic acid (LPA) levels are increased in the glomerulus of the kidney in diabetic mice. LPA is a critical regulator that induces mesangial cell proliferation; however, its effect and molecular mechanisms remain unknown. The proportion of ${\alpha}-SMA^+/PCNA^+$ cells was increased in the kidney cortex of db/db mice compared with control mice. Treatment with LPA concomitantly increased the proliferation of mouse mesangial cells (SV40 MES13) and the expression of cyclin D1 and CDK4. On the other hand, the expression of $p27^{Kip1}$ was decreased. The expression of $Kr{\ddot{u}}ppel$-like factor 5 (KLF5) was upregulated in the kidney cortex of db/db mice and LPA-treated SV40 MES13 cells. RNAi-mediated silencing of KLF5 reversed these effects and inhibited the proliferation of LPA-treated cells. Mitogen-activated protein kinases (MAPKs) were activated, and the expression of early growth response 1 (Egr1) was subsequently increased in LPA-treated SV40 MES13 cells and the kidney cortex of db/db mice. Moreover, LPA significantly increased the activity of the Ras-related C3 botulinum toxin substrate (Rac1) GTPase in SV40 MES13 cells, and the dominant-negative form of Rac1 partially inhibited the phosphorylation of p38 and upregulation of Egr1 and KLF5 induced by LPA. LPA-induced hyperproliferation was attenuated by the inhibition of Rac1 activity. Based on these results, the Rac1/MAPK/KLF5 signaling pathway was one of the mechanisms by which LPA induced mesangial cell proliferation in DN models.

• Biomolecules & Therapeutics
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• v.28 no.6
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• pp.512-518
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• 2020

Stroke is a leading cause of long-term disability in ischemic survivors who are suffering from motor, cognitive, and memory impairment. Previously, we have reported suppressing LPA₅ activity with its specific antagonist can attenuate acute brain injuries after ischemic stroke. However, it is unclear whether suppressing LPA₅ activity can also attenuate chronic brain injuries after ischemic stroke. Here, we explored whether effects of LPA₅ antagonist, TCLPA5, could persist a longer time after brain ischemic stroke using a mouse model challenged with tMCAO. TCLPA5 was administered to mice every day for 3 days, starting from the time immediately after reperfusion. TCLPA5 administration improved neurological function up to 21 days after tMCAO challenge. It also reduced brain tissue loss and cell apoptosis in mice at 21 days after tMCAO challenge. Such long-term neuroprotection of TCLPA5 was associated with enhanced neurogenesis and angiogenesis in post-ischemic brain, along with upregulated expression levels of vascular endothelial growth factor. Collectively, results of the current study indicates that suppressing LPA₅ activity can provide long-term neuroprotection to mice with brain ischemic stroke.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.5
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• pp.503-511
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• 2018

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, NF-kB, ROCK and PKC pathways. In the case of PKC activation, it was observed that $PKC{\delta}$ and $PKC{\mu}$ 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 $PKC{\delta}$ 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.

• Biomedical Science Letters
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• v.15 no.4
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• pp.349-353
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• 2009

Lysophosphatidic Acid (LPA) is a bioactive lysophospholipid that is a potent signaling molecule able to provoke a variety of cellular responses in many cell types such as differentiation, inflammation and apoptosis. In this study, we have investigated the effect of LPA on Nitric oxide (NO)-induced apoptosis in rabbit articular chondrocytes. LPA dramatically reduced NO induced apoptosis of chondrocytes determined by phase contrast microscope and MTT assay. When chondrocytes alone treated with LPA, LPA induced phosphorylation of p70S6kinase, a serine/threonine kinase that acts downstream of phosphatidylinositol 3,4,5-trisphosphate (PIP3) and phosphoinositide-dependent kinase-1 (PDK-1) in the PI3 kinase pathway, dose-dependently detected by Western blot analysis. Phosphorylation of p70S6k with LPA was reduced expression of p53 in NO-induced apoptosis of chondrocytes. Also, inhibition of p70S6kinase with rapamycin was enhanced expression of p53 in chondrocytes. Our findings collectively suggest that LPA regulates NO induced apoptosis through p70S6kinase pathway in rabbit articular chondrocytes.

• Journal of dental hygiene science
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• v.17 no.5
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• pp.433-438
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• 2017

Relative to its incidence, oral cancer has serious negative social effects. The exact causes of oral cancer have not been clarified, but many studies have implicated smoking and drinking. However, the fundamental mechanism of oral cancer causation has yet to be elucidated. Lysophosphatidic acid (LPA) augments epithelial mesenchymal transition (EMT) and development of various cancer cells. However, a detailed mechanistic explanation for LPA-induced EMT and the effects of EMT-promoting conditions on oral squamous cell carcinoma development remain elusive. In the present study, a quantitative reverse transcription polymerase chain reaction was used to analyze TWIST1, Slug, E-cadherin, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) transcript expression. Immunoblotting was used to analyze TWIST1, Slug, E-cadherin, and GAPDH protein expression. siRNAs were used to silence TWIST1 and Slug transcript expression. A matrigel-coated in vitro invasion insert was used to analyze oral cancer cell invasion. The results of the present study show that the expression levels of TWIST1 and Slug, which are EMT factors, were increased by LPA treatment in YD-10B oral squamous cell carcinoma. Conversely, E-cadherin expression was significantly reduced. In addition, transfection of the cells with TWIST1 and Slug siRNA strongly inhibited LPA-induced oral cancer cell invasion. The present study shows that TWIST1 and Slug mediate LPA-induced oral cancer cell EMT and invasiveness. The present study confirmed the mechanism by which LPA promotes oral cancer cell development, with TWIST1 and Slug providing novel biomarkers and promising therapeutic targets for oral cancer cell development.

• Journal of Ginseng Research
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• v.45 no.5
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• pp.583-590
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• 2021

Background: Gintonin, isolated from ginseng, acts as a ginseng-derived lysophosphatidic acid (LPA) receptor ligand and elicits the [Ca²⁺]_i transient through six LPA receptor subtypes (LPARSs). However, the long-term effects of gintonin-enriched fraction (GEF) on the gene expression of six LPARSs remain unknown. We examined changes in the gene expression of six LPA receptors in the mouse whole brain, heart, lungs, liver, kidneys, spleen, small intestine, colon, and testis after long-term oral GEF administration. Methods: C57BL/6 mice were divided into two groups: control vehicle and GEF (100 mg/kg, p.o.). After 21-day saline or GEF treatment, total RNA was extracted from nine mouse organs. Quantitative-real-time PCR (qRT-PCR) and western blot were performed to quantify changes in the gene and protein expression of the six LPARSs, respectively. Results: qRT-PCR analysis before GEF treatment revealed that the LPA6 RS was predominant in all organs except the small intestine. The LPA2 RS was most abundant in the small intestine. Long-term GEF administration differentially regulated the six LPARSs. Upon GEF treatment, the LPA6 RS significantly increased in the liver, small intestine, colon, and testis but decreased in the whole brain, heart, lungs, and kidneys. Western blot analysis of the LPA6 RS confirmed the differential effects of GEF on LPA6 receptor protein levels in the whole brain, liver, small intestine, and testis. Conclusion: The LPA6 receptor was predominantly expressed in all nine organs examined; long-term oral GEF administration differentially regulated LPA3, LPA4, and LPA6 receptors in the whole brain, heart, lungs, liver, kidneys, small intestine, and testis.

• Journal of dental hygiene science
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• v.19 no.2
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• pp.141-146
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• 2019

Background: Oral cancer has a high incidence worldwide and has been closely associated with smoking, alcohol, and infection by the human papillomavirus. Metastasis is highly important for oral cancer survival. Lysophosphatidic acid (LPA) is a bioactive lipid mediator that promotes various cellular processes, including cell survival, proliferation, metastasis, and invasion. Signal transducer and activator of transcription (STATs) are transcription factors that mediate gene expression. Among the seven types of STATs in mammals, STAT3 is involved in invasion and metastasis of numerous tumors. However, little is known about the role of STAT3 in oral tumor invasion. In the present study, we hypothesized that STAT3 mediates LPA-induced oral cancer invasion. Methods: Immunoblotting was performed to analyze LPA-induced STAT3 activation. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed to assess the survival rates of YD-10B cells. STAT3 levels in LPA-treated oral tumor cells were evaluated by performing in vitro invasion assay. Results: To the best of our knowledge, this is the first study to demonstrate that LPA enhances STAT3 phosphorylation in oral cancer. In addition, treatment with WP1066, a selective inhibitor of STAT3, at a concentration that does not cause severe reduction in cell viability, significantly attenuated LPA-induced YD-10B cancer cell invasion. Conclusion: The results suggested that LPA induces oral tumor cells with greater invasive potential via STAT3 activation. Our findings provided important insights into the mechanisms underlying mouth neoplasms.

• Biomolecules & Therapeutics
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• v.15 no.3
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• pp.150-155
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• 2007

In the present study, we have tested the effect of dioleoyl phosphatidic acid (PA) on intracellular $Ca_{2+}$ concentration ($[Ca^{2+}]_{i}$) in two human colon cancer cell lines (HCT116 and HT29). PA and lysophosphatidic acid (LPA), a bioactive lysolipid, increased $[Ca^{2+}]_{i}$ in both HCT116 and HT29 cell lines. Increases of $[Ca^{2+}]_{i}$ by PA and LPA were more robust in HCT116 cells than in HT29 cells. A specific inhibitor of phospholipase C (U73122), however, was not inhibitory to the cell responses. Pertussis toxin, a specific inhibitor of $G_{i/o}$ type G proteins, however, had an inhibitory effect on the responses except for an LPA-induced one in HT29 cells. Ruthenium red, an inhibitor of the ryanodine receptor, was not inhibitory on the responses, however, 2-APB, a specific inhibitor of inositol 1,4,5-trisphosphate receptor, completely inhibited both lipid-induced $Ca^{2+}$ increases in both cell types. Furthermore, by using Ki16425 and VPC32183, two structurally dissimilar specific antagonists for $LPA_{1}/LPA_{3}$ receptors, an involvement of endogenous LPA receptors in the $Ca^{2+}$ responses was observed. Ki16425 completely inhibited the responses but the susceptibility to VPC32183 was different to PA and LPA in the two cell types. Expression levels of five LPA receptors in the HCT116 and HT29 cells were also assessed. Our data support the notion that PA could increase $[Ca^{2+}]_{i}$ in human colon cancer cells, probably via endogenous LPA receptors, G proteins and $IP_{3}$ receptors, thereby suggesting a role of PA as an intercellular lipid mediator.

• Journal of Chest Surgery
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• v.33 no.5
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• pp.422-427
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• 2000

Confusion of a patent ductus arteriosus (PDA) for the descending thoracic aorta is a fatal error occurring occasionally in infants or neonates. As a result, the left pulmonary artery (LPA) may be misconceived as the PDA, and ligated. This surgical mishap of other hospital leads to serious congestive heart failure and loss of left lung function due to the underdevelopment in the peripheral vascular and alveolar structures in neonates and premature infants. In this report, 3 cases of LPA ligation and subsequent treatment are presented.