Neuromyelitis Optica Spectrum Disorder Complicated by Posterior Reversible Encephalopathy Syndrome as an Initial Manifestation.

A 25-year-old woman was admitted to our hospital due to tonic convulsion with severe headache after having experienced symptoms of nausea and vomiting for a month. Brain magnetic resonance imaging showed extensive symmetrical lesions in the cortical and subcortical areas of parieto-occipital lobes and basal ganglia, consistent with typical characteristics of posterior reversible encephalopathy syndrome (PRES). Furthermore, some residual lesions in the left side of dorsal medulla oblongata and central area of the cervical spinal cord along with the presence of serum anti-aquaporin-4 antibody yielded the diagnosis of neuromyelitis optica spectrum disorder (NMOSD). We herein discuss the mechanism by which PRES may occur together with NMOSD.

L1CAM Is a Marker for Enriching Corticospinal Motor Neurons in the Developing Brain.

The cerebral cortical tissue of murine embryo and pluripotent stem cell-derived neurons can survive in the adult brain and extend axons to the spinal cord. These features suggest that cell transplantation can be a strategy to reconstruct the corticospinal tract (CST). It is unknown, however, which cell population makes for safe and effective donor cells. To address this issue, we grafted the cerebral cortex of E14.5 mouse to the brain of adult mice and found that the cells in the graft extending axons along the CST expressed CTIP2. By using CTIP2:GFP knock-in mouse embryonic stem cells (mESCs), we identified L1CAM as a cell surface marker to enrich CTIP2+ cells. We sorted L1CAM+ cells from E14.5 mouse brain and confirmed that they extended a larger number of axons along the CST compared to L1CAM- cells. Our results suggest that sorting L1CAM+ cells from the embryonic cerebral cortex enriches subcortical projection neurons to reconstruct the CST.

Promotion of cell-invasive activity through the induction of LPA receptor-1 in pancreatic cancer cells.

Lysophosphatidic acid (LPA) is a simple biological lipid and mediates several biological functions with LPA receptors (LPA1 to LPA6). In the present study, to assess whether LPA receptors promote cell-invasive activity of pancreatic cancer cells, highly invasion PANC-R9 cells were established from PANC-1 cells, using Matrigel-coated Cell Culture Insert. The cell-invasive activity of PANC-R9 cells was shown to be approximately 15 times higher than that of PANC-1 cells. LPAR1 expression level was markedly elevated in PANC-R9 cells in comparison with PANC-1 cells, while LPAR3 expression level was reduced. The cell-invasive activity of PANC-R9 cells was enhanced by LPA, but LPA had no impact on PANC-1 cell invasion. Before initiation of the cell invasion assay, PANC-R9 cells were pretreated with dioctanoylglycerol pyrophosphate (DGPP), an antagonist of LPA1/LPA3. The invasive activity of PANC-R9 cells was markedly suppressed by DGPP. Autotaxin (ATX) is a key enzyme that catalyzes the conversion of lysophosphatidylcholine (LPC) to LPA. ATX expression level was elevated in PANC-R9 cells compared with PANC-1 cells. In the presence of LPC, the cell motile activity of PANC-R9 cells was markedly stimulated. In contrast, LPC did not affect the cell motile activity of PANC-1 cells. PANC-R9 cell motility was inhibited by an ATX inhibitor, PF-8380. These results suggest that LPA signaling via LPA1 is a potent molecular target for the regulation of tumor progression in PANC-1 cells.

Lysophosphatidic acid receptor-2 (LPA2) and LPA5 regulate cellular functions during tumor progression in fibrosarcoma HT1080 cells.

Lysophosphatidic acid (LPA) receptors (LPA1 to LPA6) regulate a variety of malignant properties in cancer cells. In the present study, we investigated the roles of LPA receptors in the promotion of cellular functions during tumor progression in fibrosarcoma cells. To obtain long-term anticancer drug treated cells, human fibrosarcoma HT1080 cells were treated with methotrexate (MTX) and cisplatin (CDDP) for 6 months. LPAR2 and LPAR5 expressions were significantly higher in MTX-treated (HT-MTX) cells than in HT1080 cells. The cell motile and invasive activities of HT-MTX cells were significantly elevated compared with HT1080 cells. Although LPAR5 expression was increased in MTX and CDDP treated (HT-M-C) cells, no change of LPAR2 expression was observed. The cell motile and invasive activities of HT-M-C cells were lower than those of HT1080 cells. Moreover, to evaluate whether LPA receptors promote cell invasive activity, highly invasion (HT1080-M6) cells were established from HT1080 cells. The cell invasive activity of HT1080-M6 cells was approximately 4.5 times higher than HT1080 cell invasion. LPAR2 expression was markedly elevated in HT1080-M6 cells compared with HT1080 cells. The high cell invasion activity of HT1080-M6 cells was significantly suppressed by an antagonist of LPA2, H2L5186303. These results suggest that LPA2 acts as a key regulator of malignant properties in HT1080 cells.

Induction of GPR40 positively regulates cell motile and growth activities in breast cancer MCF-7 cells.

Free fatty acid (FFA) receptors belong to a member of G-protein-coupled receptors. GPCR 120 (GPR120) and GPR40 are identified as FFA receptors and activated via the binding of long- and medium-chain FFAs. The aim of this study was to assess the effects of GPR120 and GPR40 on cell motility and growth in breast cancer cells treated with tamoxifen (TAM). MCF-7 cells were continuously treated with TAM for approximately 6 months. The expression level of GPR40 gene was markedly higher in the long-term TAM treated (MCF-TAM) cells than in MCF-7 cells. In cell motility assay, MCF-TAM cells indicated the high cell motile activity, compared with MCF-7 cells. The cell motile activity of MCF-TAM cells was suppressed by a selective GPR40 antagonist, GW1100. To evaluate the effects of GPR40 on cell growth activity under estrogen-free conditions, cells were maintained in serum-free DMEM without phenol red for 2 days. In estrogen-free conditioned medium, the cell growth rate of MCF-TAM cells was significantly higher than that of MCF-7 cells. In addition, treatment of GW1100 reduced the cell growth rate of MCF-TAM cells. These results suggest that the cell motile and growth activities may be positively regulated through the induction of GPR40 by the long-term TAM treatment in MCF-7 cells.

Involvement of LPA signaling via LPA receptor-2 in the promotion of malignant properties in osteosarcoma cells.

Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors mediates various biological effects in cancer cells. This study aimed to investigate the roles of LPA receptors in the regulation of cellular functions during tumor progression in osteosarcoma cells. Long-term cisplatin (CDDP)-treated MG63-C and MG63-R7-C cells were generated from osteosarcoma MG-63 and highly-migratory MG63-R7 cells, respectively. LPAR2 and LPAR3 expression levels were significantly higher in MG63-C cells than in MG-63 cells, while LPAR1 expression was reduced. MG63-C cells were highly motile, compared with MG-63 cells. MG63-C cell motility was suppressed by LPA2 knockdown and enhanced by the LPA1/LPA3 antagonist, dioctanoylglycerol pyrophosphate. LPAR2 and LPAR3 expression levels were significantly elevated in MG63-R7-C cells in comparison with MG63-R7 cells. MG63-R7-C cells were found to be highly invasive, correlating with metalloproteinase-2 activation. MG63-R7-C cells formed large colonies, whereas colony formation was absent from MG63-R7 cells. Notably, MG63-R7-C cell activities were inhibited by LPA2 knockdown. These results suggest that LPA signaling via LPA2 plays an important role in the acquisition of malignant properties during tumor progression in MG-63 cells.

Involvement of FFA1 and FFA4 in the regulation of cellular functions during tumor progression in colon cancer cells.

Free fatty acid receptor 1 (FFA1) and FFA4 mediate a variety of biological responses through binding of medium- and long-chain free fatty acids. The aim of this study was to investigate an involvement of FFA1 and FFA4 in the regulation of cellular functions during tumor progression in colon cancer cells. The long-term fluorouracil (5-FU) and cisplatin (CDDP) treated cells were generated from DLD1 cells (DLD-5FU and DLD-CDDP cells, respectively). FFAR1 expressions were lower in DLD-5FU and DLD-CDDP cells than in DLD1 cells. In contrast, DLD-5FU and DLD-CDDP cells showed the high FFAR4 expressions, compared with DLD1 cells. The cell motile activities of DLD-5FU and DLD-CDDP cells were reduced by GW9508 which is an agonist of FFA1 and FFA4. Moreover, GW1100, an antagonist of FFA1, inhibited the cell motile activities of DLD-5FU and DLD-CDDP cells. To evaluate whether FFA1 and FFA4 regulate the enhancement of cell motility, invasion and colony formation, highly migratory (hmDLD1) cells were established from DLD1 cells. FFAR1 expression was significantly higher in hmDLD1 cells than in DLD1 cells, but no change of FFAR4 expression was observed. The elevated cell motile and invasive activities and colony formation of hmDLD1 cells were suppressed by FFA1 inhibition. These results suggest that FFA1 and FFA4 are involved in the regulation of cellular functions during tumor progression in colon cancer DLD1 cells.

Involvement of LPA receptor-5 in the enhancement of cell motile activity by phorbol ester and anticancer drug treatments in melanoma A375 cells.

Lysophosphatidic acid (LPA) signaling through six subtypes of LPA receptors (LPA1 to LPA6) regulates a variety of biological responses in cancer cells. The aim of our study was to evaluate an involvement of LPA receptors in the activation of cell motility by phorbol ester and anticancer drug treatments in melanoma A375 cells. Cells were treated with 12-O-tetradecanoylphorbol- 13-acetate (TPA) and phorbol-12,13-dibutyrate (PDBu) for 3 days. The cell motile activity of TPA treated cells was significantly higher than that of PDBu treated cells, correlating with LPAR5 expression levels. LPA5 knockdown suppressed the high cell motile activity induced by TPA. To assess whether the cell motile activity of A375 cells is stimulated through LPA5 induced by anticancer drugs, the long-term cisplatin (CDDP) and dacarbazine (DTIC) treated cells were generated from A375 cells (A375-CDDP and A375-DTIC cells, respectively). The expression levels of LPA receptor genes were changed in A375-CDDP and A375-DTIC cells. In particular, CDDP and DTIC treatment markedly elevated LPAR5 expressions. The cell motile activities of A375-CDDP and A375-DTIC cells were significantly higher than that of untreated cells. These results suggest that the cell motile activity is regulated through the induction of LPA5 by phorbol ester and anticancer drug treatments in A375 cells.

Effects of LPA1 and LPA6 on the regulation of colony formation activity in colon cancer cells treated with anticancer drugs.

Lysophosphatidic acid (LPA) is a simple physiological lipid and exhibits a variety of cellular responses via the activation of G protein-coupled transmembrane LPA receptors (LPA receptor-1 (LPA1) to LPA6). The aim of our study was to investigate effects of LPA receptors on soft agar colony formation in colon cancer cells treated with anticancer drugs. DLD1 cells were treated with fluorouracil (5-FU) or cisplatin (CDDP) for at least six months (DLD-5FU and DLD-CDDP cells, respectively). LPAR1 gene expression was markedly elevated in DLD-5FU cells. In contrast, DLD-CDDP cells showed the high expression of LPAR6 gene. In colony formation assay, DLD-5FU cells formed markedly large-sized colonies, while no colony formation was observed in DLD1 and DLD-CDDP cells. The large-sized colonies formed in DLD-5FU cells were suppressed by LPA1 knockdown. In contrast, LPA6 knockdown increased the size of colonies. In addition, DLD-5FU cells were further treated with CDDP for three months (DLD-C-F cells). DLD-CDDP cells were also treated with 5-FU (DLD-F-C cells). DLD-C-F cells formed large-sized colonies, but not DLD-F-C cells, correlating with LPAR1 and LPAR6 gene expression levels. These results suggest that LPA1 and LPA6 may regulate the colony formation activity in DLD1 cells treated with anticancer drugs.

Lysophosphatidic acid signaling via LPA1 and LPA3 regulates cellular functions during tumor progression in pancreatic cancer cells.

Lysophosphatidic acid (LPA) signaling via G protein-coupled LPA receptors exhibits a variety of biological effects, such as cell proliferation, motility and differentiation. The aim of this study was to evaluate the roles of LPA1 and LPA3 in cellular functions during tumor progression in pancreatic cancer cells. LPA1 and LPA3 knockdown cells were generated from PANC-1 cells. The cell motile and invasive activities of PANC-1 cells were inhibited by LPA1 and LPA3 knockdown. In gelatin zymography, LPA1 and LPA3 knockdown cells indicated the low activation of matrix metalloproteinase-2 (MMP-2) in the presence of LPA. Next, to assess whether LPA1 and LPA3 regulate cellular functions induced by anticancer drug, PANC-1 cells were treated with cisplatin (CDDP) for approximately 6 months. The cell motile and invasive activities of long-term CDDP treated cells were markedly higher than those of PANC-1 cells, correlating with the expression levels of LPAR1 and LPAR3 genes. In soft agar assay, the long-term CDDP treated cells formed markedly large sized colonies. In addition, the cell motile and invasive activities enhanced by CDDP were significantly suppressed by LPA1 and LPA3 knockdown as well as colony formation. These results suggest that LPA signaling via LPA1 and LPA3 play an important role in the regulation of cellular functions during tumor progression in PANC-1 cells.

Different effects of G-protein-coupled receptor 120 (GPR120) and GPR40 on cell motile activity of highly migratory osteosarcoma cells.

G-protein-coupled receptor 120 (GPR120) and GPR40 are members of free fatty acid (FFA) receptors and mediate a variety of biological responses through binding of medium- and long-chain FFAs. Recently, it has been reported that GPR120 and GPR40 regulated cellular functions of cancer cells. In the present study, to assess whether GPR120 and GPR40 are involved in the enhancement of cell motile activity of osteosarcoma cells, we established highly migratory (MG63-R7) cells from osteosarcoma MG-63 cells. The expression level of GPR120 gene was significantly higher in MG63-R7 cells than in MG-63 cells, while no change of GPR40 expression was observed. In cell motility assay, the cell motile activity of MG63-R7 cells was approximately 200 times higher than that of MG-63 cells. The cell motile activity of MG63-R7 cells was stimulated by GW9508, which is an agonist of GPR120 and GPR40. Moreover, a GPR40 antagonist GW1100 elevated the cell motile activity of MG63-R7 cells in the presence of GW9508. To confirm the effects of GPR120 and GPR40 on the cell motile activity of MG63-R7 cells, GPR120 knockdown cells were generated from MG63-R7 cells. The cell motile activity of MG63-R7 cells was markedly suppressed by GPR120 knockdown. These results indicated that GPR120 enhanced and GPR40 inhibited the cell motile activity of highly migratory osteosarcoma cells.

Enhanced cellular functions through induction of LPA2 by cisplatin in fibrosarcoma HT1080 cells.

Lysophosphatidic acid (LPA) is a simple biophysical lipid which interacts with at least six subtypes of G protein-coupled LPA receptors (LPA1-LPA6). In cancer cells, LPA signaling via LPA receptors is involved in the regulation of malignant properties, such as cell growth, motility, and invasion. The aim of this study was to assess whether LPA receptors regulate cellular functions of fibrosarcoma cells treated with anticancer drug. HT1080 cells were maintained by the stepwise treatment of cisplatin (CDDP) at a range of 0.01 to 1.0 µM for approximately 6 months. The cell motile and invasive activities of long-term CDDP-treated (HT-CDDP) cells were significantly stimulated by LPA treatment, while HT-CDDP cells in the static state showed the low cell motile and invasive activities in comparison with HT1080 cells. Since the expression level of LPAR2 gene was markedly elevated in HT-CDDP cells, LPA2 knockdown cells were generated from HT-CDDP cells. The cell motile and invasive activities of HT-CDDP cells were reduced by LPA2 knockdown. In colony assay, large-sized colonies formed by long-term CDDP treatment were suppressed by LPA2 knockdown. In addition, LPA2 knockdown cells reduced LPA production by autotaxin (ATX), correlating with ATX expression level. These results suggest that LPA signaling via LPA2 may play an important role in the regulation of cellular functions in HT1080 cells treated with CDDP.

Lysophosphatidic acid (LPA) signaling via LPA4 and LPA6 negatively regulates cell motile activities of colon cancer cells.

Lysophosphatidic acid (LPA) is an extracellular biological lipid and interacts with six subtypes of G protein-coupled LPA receptors (LPA1 to LPA6). LPA receptors exhibit a variety of cellular functions, depending on types of cancer cells. In this study, to assess the roles of LPA4 and LPA6 in cell growth and motile activities of colon cancer cells, LPA4 and LPA6 knockdown cells were established from DLD1 and HCT116 cells. LPA treatment increased the cell growth activities of LPA4 and LPA6 knockdown cells, compared with control cells. The cell motile activities of LPA4 and LPA6 knockdown cells were significantly higher than those of control cells. To evaluate the effects of LPA4 and LPA6 on cell motile activity induced by anticancer drug, long-term fluorouracil (5-FU) treated (DLD-5FU) cells were generated. The expression levels of LPAR1, LPAR4 and LPAR6 genes were significantly increased in DLD-5FU cells. DLD-5FU cells showed the high cell motile activity, compared with DLD1 cells. The increased cell motile activity was markedly stimulated by LPA4 and LPA6 knockdown. In contrast, the cell motile activity enhanced by 5-FU treatment was suppressed by LPA1 knockdown. These results suggest that LPA signaling via LPA4 and LPA6 negatively regulates the cell motile activities of DLD1 and HCT116 cells as well as long-term 5-FU treated cells.

Different effects of GPR120 and GPR40 on cellular functions stimulated by 12-O-tetradecanoylphorbol-13-acetate in melanoma cells.

G-protein-coupled receptor 120 (GPR120) and GPR40 exhibit a variety of biological responses by the binding of free fatty acids. 12-O-Tetradecanoylphorbol-13-acetate (TPA) is a tumor promoting agent of skin carcinogenesis. It is known that TPA treatment stimulates cell motile activity of cancer cells, including melanoma cells. In the present study, we investigated whether GRP120 and GPR40 are involved in regulation of cell motile activity induced by TPA in two melanoma cell lines. A375 and G361 cells were treated with TPA at a concentration of 10 nM for 24 h. The cell motile activity of A375 cells was significantly increased by TPA, correlating with GPR40 expression. In contrast, TPA suppressed the cell motile activity of G361 cells, while GPR120 and GPR40 expressions were increased. The cell motile activity of A375 cells treated with TPA was markedly increased by GPR120 knockdown. In addition, to assess roles of GPR120 and GPR40 in cellular functions of A375 cells by the long-term TPA treatment, cells were treated with TPA (1 nM) for at least 3 months. The long-term TPA treatment induced the high cell motile activity and elevated GPR120 and GPR40 expressions. The high cell motile activity of A375 cells stimulated by the long-term TPA treatment was enhanced by GPR120 knockdown. These results suggest that GPR120 negatively and GPR40 positively regulate cell motile activities induce by TPA in melanoma cells.

Diverse effects of G-protein-coupled free fatty acid receptors on the regulation of cellular functions in lung cancer cells.

Free fatty acids (FFAs) are dietary nutrients which mediate a variety of biological effects through binding to G-protein-coupled FFA receptors (FFARs). G-protein-coupled receptor 120 (GPR120) and GPR40 are identified as FFARs for long- and medium-chain fatty acids. Here we investigated whether GPR120 and GPR40 are involved in the acquisition of malignant properties in lung cancer cells. Three lung cancer RLCNR, LL/2 and A549 cells used in this study expressed GPR120 and GPR40 genes. The cell motile activities of all cells were significantly suppressed by a GPR40 antagonist GW1100. In addition, GPR40 knockdown inhibited the cell motile activity of A549 cells. In gelatin zymography, matrix metalloproteinase-2 (MMP-2) activity in GPR40 knockdown was significantly lower than that in control cells. Next, to evaluate effects of GPR120 and GPR40 on cellular functions induced by anti-cancer drug, the long-term cisplatin (CDDP) treated (A549-CDDP) cells were generated. The expression levels of GPR120 and GPR40 were significantly decreased in A549-CDDP cells. While A549-CDDP cells showed the high cell motile activity, GW1100 suppressed the cell motile activity of A549-CDDP cells. These results demonstrate that GPR120 negatively and GPR40 positively regulate cellular functions during tumor progression in lung cancer cells.

Different induction of LPA receptors by chemical liver carcinogens regulates cellular functions of liver epithelial WB-F344 cells.

Lysophosphatidic acid (LPA) signaling via LPA receptors (LPA1 to LPA6 ) mediates a variety of cellular functions, including cell motility. In the present study, we investigated the effects of LPA receptors on cell motile activity during multi-stage hepatocarcinogenesis in rat liver epithelial WB-F344 cells treated with chemical liver carcinogens. Cells were treated with a initiator (N-nitrosodiethylamine (DEN)) and three promoters (phenobarbital (PB), okadaic acid (OA) and clofibrate) every 24 h for 2 days. Cell motile activity was elevated by DEN, correlating with Lpar3 expression. PB, OA, and clofibrate elevated Lpar1 expression and inhibited cell motile activity. To evaluate the effects of long-term treatment on cell motility, cells were treated with DEN and/or PB for at least 6 months. Lpar3 expression and cell motile activity were significantly elevated by the long-term DEN treatment with or without further PB treatment. In contrast, long-term PB treatment with or without further DEN elevated Lpar1 expression and inhibited cell motility. When the synthesis of extracellular LPA was blocked by a potent ATX inhibitor S32826 before cell motility assay, the cell motility induced by DEN and PB was markedly suppressed. These results suggest that activation of the different LPA receptors may regulate the biological functions of cells treated with chemical carcinogens. © 2015 Wiley Periodicals, Inc.

Negative effects of G-protein-coupled free fatty acid receptor GPR40 on cell migration and invasion in fibrosarcoma HT1080 cells.

G-protein-coupled receptor 40 (GPR40) and GPR120 mediate a variety of biological functions by the binding of long and medium chain free fatty acids. In the present study, we investigated a role of GPR40 in the pathogenesis of fibrosarcoma HT1080 cells. The GPR40 gene expression was detected in HT1080 cells, but not the GPR120 gene. The cell motile and invasive activities were markedly enhanced by GPR40 knockdown, compared with control cells. To evaluate whether GPR40 is involved in the cellular functions of HT1080 cells during anticancer drug treatment, HT1080 cells were maintained in condition medium containing cisplatin (CDDP) (0.01-1.0 µM) for 6 mo. The expression levels of the GPR40 gene was elevated by the long-term CDDP treatment in HT1080 cells, while the GPR120 gene expression remained unchanged. The cell motile and invasive activities of HT1080 cells treated with CDDP were significantly lower than those of untreated cells. In gelatin zymography, the activities of matrix metalloproteinase-2 (MMP-2) and MMP-9 of HT1080 cells were enhanced by the long-term CDDP treatment. In addition, GW9508 which is an agonist of GPR40 and GPR120 suppressed the cell motile and invasive activities of HT1080 cells treated with CDDP as well as the MMP activation. These results suggest that GPR40 negatively regulates the tumor progression of fibrosarcoma cells. © 2015 Wiley Periodicals, Inc.

Different roles of GPR120 and GPR40 in the acquisition of malignant properties in pancreatic cancer cells.

Free fatty acids (FFAs) act as extracellular signaling molecules through binding to G-protein-coupled FFA receptors (FFARs). GPR120 and GPR40 are identified as FFARs for medium- and long-chain fatty acids. In the present study, we investigated roles of GPR120 and GPR40 in cellular functions of pancreatic cancer PANC-1 cells, using GPR120 and GPR40 knockdown cells (PANC-sh120 and PANC-sh40 cells respectively). In cell motility assay, PANC-sh120 cells showed the low cell motility, compared with control cells. In contrast, the cell motility of PANC-sh40 cells was significantly higher than that of control cells. Activity levels of matrix metalloproteinases (MMPs) were measured by gelatin zymography. While PANC-sh120 cells indicated the reduced MMP-2 activity, MMP-2 activity in PANC-sh40 cells was significantly higher than that in control cells. On the other hand, no activation of MMP-9 was detected in all cells. In colony assay, the large sized colonies were markedly formed in PANC-sh40 cells. No colony formation was observed in PANC-sh120 cells as well as control cells. These results suggest that distinct effects of GPR120 and GPR40 are involved in the acquisition of malignant property in pancreatic cancer cells.

LPA signaling through LPA receptors regulates cellular functions of endothelial cells treated with anticancer drugs.

Lysophosphatidic acid (LPA) signaling via LPA receptors provides a variety of cellular functions, including angiogenesis. In this study, to assess an involvement of LPA receptors in cell motile activities of endothelial cells during chemotherapy, F-2 cells were treated with cisplatin (CDDP) and doxorubicin (DOX) at a concentration of 0.01 µM every 24 h for at least 1 month. The treatment of CDDP and DOX inhibited the expression levels of the LPA receptor-1 (Lpar1), Lpar2, and Lpar3 genes in F-2 cells. The cell motile activities of CDDP and DOX treated cells were relatively lower than those of untreated cells. Next, we investigated whether cancer cells could stimulate the cell motile activities of F-2 cells treated with CDDP and DOX. For cell motility assay, CDDP- and DOX-treated cells were co-cultured with pancreatic cancer PANC-1 cells. The cell motile activities of CDDP- and DOX-treated cells were significantly enhanced by the existence of PANC-1 cells, correlating with the LPA receptor expressions. In addition, the elevated cell motile activities were suppressed by the pretreatment of an autotaxin inhibitor S32826. These results suggest that LPA signaling via LPA receptors may regulate the cell motile activities of F-2 cells treated with anticancer drugs.

Diverse effects of LPA4, LPA5 and LPA6 on the activation of tumor progression in pancreatic cancer cells.

Lysophosphatidic acid (LPA) is an extracellular biological lipid which interacts with G protein-coupled LPA receptors (LPA1 to LPA6). LPA signaling via LPA receptors mediates several cellular responses. In the present study, to assess the roles of LPA4, LPA5 and LPA6 in cellular functions of pancreatic cancer cells, we generated LPA receptor knockdown cells from PANC-1 cells (PANC-sh4, PANC-sh5 and PANC-sh6 cells, respectively). In cell motility assay, PANC-sh4 and PANC-sh5 cells enhanced the cell motile activities, compared with control cells. In contrast, the cell motile activity of PANC-sh6 cells was suppressed. The invasive activities of PANC-sh4 and PANC-sh5 cells were markedly stimulated, while PANC-sh6 cells showed the low invasive activity. In colony assay, PANC-sh4 and PANC-sh5 cells formed the large sized colonies, but not PANC-sh6 cells. When endothelial cells were incubated with supernatants from PANC-sh4 and PANC-sh5 cells, the cell motility and tube formation of endothelial cells were significantly induced, but not PANC-sh6 cells. These results suggest that the diverse roles of LPA4, LPA5 and LPA6 are involved in the activation of tumor progression in pancreatic cancer cells.