• 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.

• Biomolecules & Therapeutics
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• v.32 no.3
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• pp.319-328
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• 2024

Lysophosphatidic acid receptor 1 (LPA₁) plays a critical role in brain injury following a transient brain ischemic stroke. However, its role in permanent brain ischemic stroke remains unknown. To address this, we investigated whether LPA₁ could contribute to brain injury of mice challenged by permanent middle cerebral artery occlusion (pMCAO). A selective LPA₁ antagonist (AM152) was used as a pharmacological tool for this investigation. When AM152 was given to pMCAO-challenged mice one hour after occlusion, pMCAO-induced brain damage such as brain infarction, functional neurological deficits, apoptosis, and blood-brain barrier disruption was significantly attenuated. Histological analyses demonstrated that AM152 administration attenuated microglial activation and proliferation in injured brain after pMCAO challenge. AM152 administration also attenuated abnormal neuroinflammatory responses by decreasing expression levels of pro-inflammatory cytokines while increasing expression levels of anti-inflammatory cytokines in the injured brain. As underlying effector pathways, NF-κB, MAPKs (ERK1/2, p38, and JNKs), and PI3K/Akt were found to be involved in LPA₁-dependent pathogenesis. Collectively, these results demonstrate that LPA₁ can contribute to brain injury by permanent ischemic stroke, along with relevant pathogenic events in an injured brain.

• Journal of Embryo Transfer
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• v.32 no.4
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• pp.275-285
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• 2017

Lysophosphatidic acid (LPA) is an important signaling molecule. Here, the effect and mechanism of LPA on the preimplantation development of porcine embryos during in vitro culture (IVC) was examined. Porcine embryos were cultured in porcine zygote medium (PZM-3) supplemented with $30{\mu}M$ LPA during different days. There was a significantly higher cleavage rate in Day 1-7 and significantly higher total cell number of blastocysts in Day 1-3 and Day 4-7. It was also found that messenger RNA (mRNA) expression level of PCNA, BCL2 and BAX in blastocysts obtained from D1-7 group were significantly higher and BCL2/BAX mRNA ratio in D1-3 group was significantly lower than control group but Day 4-7 and Day 1-7 groups were comparable with control group. Treatment with $20{\mu}M$ PLC inhibitor significantly decreased the embryo cleavage rate and blastocyst formation rate. Moreover, LPA as an activator of PLCs, enhanced the $30{\mu}M$ LPA + $20{\mu}M$ U73122 group embryo cleavage rate which similar with control group. In conclusion, the results suggest that treatment with LPA during IVC improves the porcine early embryo cleavage by activation of PLC signaling pathway and regulate the mRNA expression that contribute to total cell number of blastocysts during blastocyst formation.

• Archives of Pharmacal Research
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• v.26 no.12
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• pp.1055-1060
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• 2003

Lysophosphatidic acid (LPA) is a well-known mitogen in various cell types. However, we found that LPA inhibits melanocyte proliferation. Thus, we further investigated the possible signaling pathways involved in melanocyte growth inhibition. We first examined the regulation of the three major subfamilies of mitogen-activated protein (MAP) kinases and of the Akt pathway by LPA. The activations of extracellular signal-regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK) were observed in concert with the inhibition of melanocyte proliferation by LPA, whereas p38 MAP kinase and Akt were not influenced by LPA. However, the specific inhibition of the ERK or JNK pathways by PD98059 or D-JNKI1, respectively, did not restore the antiproliferative effect. We next examined changes in the expression of cell cycle related proteins. LPA decreased cyclin $D_1 and cyclin D_2$ levels but increased $p21^{WAF1/CIP1}$ (p21) and $p27^{KIP1}$ (p27) levels, which are known inhibitors of cyclin-dependent kinase. Flow cytometric analysis showed the inhibition of DNA synthesis by a reduction in the S phase and an increase in the $G_0/G_1$ phase of the cell cycle. Our results suggest that LPA induces cell cycle arrest by regulating the expressions of cell cycle related proteins.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.147-152
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• 2009

Lysophosphatidic acid (LPA), a simple phospholipid-derived mediator implicated in diverse biological actions, acts through the specific G-protein coupled receptors, LPA receptor (LPAR) $1{\sim}5$. Our previous study showed that LPAR3 is expressed in the uterine endometrium in a cell type- and stage-specific manner and LPA via LPAR3 increases PTGS2 expression in the uterine endometrium during the period of implantation. Although LPAR3 is considered to be predominant LPA receptor in the uterine endometrium, other LPA receptors might playa role to mediate LPA functions in the uterine endometrium during pregnancy. Among LPARs, we investigated expression of LPAR1 during the estrous cycle and pregnancy in this study. Uterine endometrial tissue samples were collected from day (D) 12 and D15 of the estrous cycle and from D12, D15, D30, D60, D90 and D114 of pregnancy. Northern blot analysis determined that LPAR1 mRNA was constitutively expressed in the uterine endometrial tissues during the estrous cycle and pregnancy of all stages. Analysis by immunoblotting revealed that LPAR1 proteins were present in the porcine uterine endometrium during the estrous cycle and pregnancy. Immunohistochemical experiments demonstrated that LP AR1 protein was localized to endometrial epithelium and stromal cell, specifically to nuclei of these cell types. Results in this study show that LPAR1 is constitutively expressed in the uterine endometrium during the estrous cycle and pregnancy. These results suggest that LPA via LPAR1 may playa role in the uterine endometrial function throughout pregnancy in pigs.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.27-31
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• 2017

Reliable follow-up of bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA) is essential in clinical practice. When there is a difference in the BMD values from DXA systems in the same patient, cross calibration equation is required for the reliable follow-up. Unfortunately, no equation is existed in BMD measure between GE Lunar Prodigy Advance (US, GE Healthcare; LPA) and Osteosys Dexxum T (Korea, Osteosys; ODT) DXA systems. In this study, we evaluate the agreement of BMD values between LPA and ODT and suggest the cross calibration equation using European spine phantom (ESP) with two systems. We performed BMD measurements using ten scans with ESP in each DXA systems. We compared BMD values and calculated cross calibration equation by linear regression analysis. The comparison between the LPA and ODT bone densitometers used the ESP. Compared to the ESP BMD values, ODT underestimated 14.36% and LPA overestimated 12.96%. The average of total BMD measurement values acquired with ODT were 21.44% lower than those from LPA. Cross-calibration equation for LPA and ODT was derived from ESP. We calculated simple cross calibration equation for LPA and ODT DXA systems. Cross-calibration equation is necessary for the reliable follow-up of BMD values in two different systems.

• 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.

• Journal of Ginseng Research
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• v.40 no.4
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• pp.325-333
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• 2016

Background: Ginseng extracts are known to have angiogenic effects. However, to date, only limited information is available on the molecular mechanism underlying the angiogenic effects and the main components of ginseng that exert these effects. Human umbilical-vein endothelial cells (HUVECs) are used as an in vitro model for screening therapeutic agents that promote angiogenesis and wound healing. We recently isolated gintonin, a novel ginseng-derived lysophosphatidic acid (LPA) receptor ligand, from ginseng. LPA plays a key role in angiogenesis and wound healing. Methods: In the present study, we investigated the in vitro effects of gintonin on proliferation, migration, and tube formation of HUVECs, which express endogenous LPA1/3 receptors. Results: Gintonin stimulated proliferation and migration of HUVECs. The LPA1/3 receptor antagonist, Ki16425, short interfering RNA against LPA1 or LPA3 receptor, and the Rho kinase inhibitor, Y-27632, significantly decreased the gintonin-induced proliferation, migration, and tube formation of HUVECs, which indicates the involvement of LPA receptors and Rho kinase activation. Further, gintonin increased the release of vascular endothelial growth factors from HUVECs. The cyclooxygenase-2 inhibitor NS-398, nuclear factor kappa B inhibitor BAY11-7085, and c-Jun N-terminal kinase inhibitor SP600125 blocked the gintonin-induced migration, which shows the involvement of cyclooxygenase-2, nuclear factor kappa B, and c-Jun N-terminal kinase signaling. Conclusion: The gintonin-mediated proliferation, migration, and vascular-endothelial-growth-factor release in HUVECs via LPA-receptor activation may be one of in vitro mechanisms underlying ginsenginduced angiogenic and wound-healing effects.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.215-220
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• 1999

In fabricated linear power amplifier(LPA), the third-order inter-modulation distortion(IMD) for main amplifier alone is 10.61dBc, and the IMD for LPA with predistorter and feedforward loop combined is 32.50dBc. Therefore, the IMD characteristic results an improvement of approximately 22dB. The main amplifier efficiency with single tone input is close to 30%, and the efficiency of the overall LPA with predistorter is 27.4% and predicted feedforward loop efficiency without predistorter is about 20%. Therefore, LPA with predistorter and feedforward loop combined is improved by 7.4%.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.349-352
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• 2000

In this paper, predistorter for PCS has been designed and fabricated. In predistorter system IMD signal generator was very important element. In this LPA IMD signal generator was fabricated using main signal cancellation and error signal cancellation of feedforward method and two amplifier that had same IMD characteristics. This LPA showed IMD characteristics of 52㏈c operation in 48㏈m(60W) and made 12㏈ IMD characteristic improvement when it was excited by two tone. In this LPA, to make more IMD characteristic improvement the IMD characteristic resemblance between main amplifier and predistortion amplifier is very important.