Lysophosphatidic Acid Receptor Genes Research Articles

TXA2 mediates LPA1-stimulated uterine contraction in late pregnant mouse

Lysophosphatidic acid (LPA) is known to increase uterine contraction in the estrus cycle and early pregnancy, however, the effect of LPA in late pregnant uterus and its mechanisms are not clear. In the present study, we show the LPA receptor subtypes expressed and the mechanism of LPA-induced contractions in late pregnant mouse uterus. We determined the relative mRNA expression of LPA receptor genes by quantitative PCR and elicited log concentration-response curves to oleoyl-L-α-LPA by performing tension experiments in the presence and absence of nonselective and selective receptor antagonists and inhibitors of the TXA2 pathway. LPA1 was the most highly expressed receptor subtype in the late pregnant mouse uterus and LPA1/2/3 agonist (Oleoyl-L-α LPA) elicited increased contractions in this tissue that had lesser efficacy compared to oxytocin. LPA1/3 antagonist, Ki-16425, and a potent LPA1 antagonist (AM-095) significantly inhibited the LPA-induced contractions. Further, the nonselective COX inhibitor, indomethacin, and potent thromboxane A2 synthase inhibitor, furegrelate significantly impaired LPA-induced contractions. Moreover, selective thromboxane receptor (TP) antagonist, SQ-29548, and Rho kinase inhibitor, Y-27632 almost eliminated LPA-induced uterine contractions. LPA1 stimulation elicits contractions in the late pregnant mouse uterus using the contractile prostanoid, TXA2 and may be targeted to induce labor in uterine dysfunctions/ dystocia.

Platelet-derived lysophosphatidic acid mediated LPAR1 activation as a therapeutic target for osteosarcoma metastasis

Osteosarcoma is the most common primary malignant bone cancer, with high rates of pulmonary metastasis. Osteosarcoma patients with pulmonary metastasis have worse prognosis than those with localized disease, leading to dramatically reduced survival rates. Therefore, understanding the biological characteristics of metastatic osteosarcoma and the molecular mechanisms of invasion and metastasis of osteosarcoma cells will lead to the development of innovative therapeutic intervention for advanced osteosarcoma. Here, we identified that osteosarcoma cells commonly exhibit high platelet activation-inducing characteristics, and molecules released from activated platelets promote the invasiveness of osteosarcoma cells. Given that heat-denatured platelet releasate maintained the ability to promote osteosarcoma invasion, we focused on heat-tolerant molecules, such as lipid mediators in the platelet releasate. Osteosarcoma-induced platelet activation leads to abundant lysophosphatidic acid (LPA) release. Exposure to LPA or platelet releasate induced morphological changes and increased invasiveness of osteosarcoma cells. By analyzing publicly available transcriptome datasets and our in-house osteosarcoma patient-derived xenograft tumors, we found that LPA receptor 1 (LPAR1) is notably upregulated in osteosarcoma. LPAR1 gene KO in osteosarcoma cells abolished the platelet-mediated osteosarcoma invasion in vitro and the formation of early pulmonary metastatic foci in experimental pulmonary metastasis models. Of note, the pharmacological inhibition of LPAR1 by the orally available LPAR1 antagonist, ONO-7300243, prevented pulmonary metastasis of osteosarcoma in the mouse models. These results indicate that the LPA–LPAR1 axis is essential for the osteosarcoma invasion and metastasis, and targeting LPAR1 would be a promising therapeutic intervention for advanced osteosarcoma.

The Japanese lamprey (Lethenteron camtschaticum) expresses functional lysophosphatidic acid receptors

Lysophosphatidic acid (LPA) signaling plays diverse roles in the development of various vertebrates such as mammals and fish. The lamprey is a fish that retains ancestral features of vertebrates, but information regarding lamprey LPA receptor genes is limited. Here, using information from the lamprey genome database, we cloned two LPA receptor genes, Lpar1 and Lpar5, from the Japanese lamprey (Lethenteron camtschaticum). Lamprey Lpar1 had a high amino acid identity to mouse and medaka fish Lpar1, whereas Lpar5 amino acid sequences were more diverse between species. Our functional analyses using a heterologous expression system demonstrated that Lpar1 and Lpar5 responded to LPA treatment with G12/13-associated cellular responses, which are indicative of cytoskeletal actions. The existence of functional LPA receptors in the Japanese lamprey suggests that LPA receptor-dependent signals contribute to lamprey growth and development.

Altered cleavage plane orientation with increased genomic aneuploidy produced by receptor-mediated lysophosphatidic acid (LPA) signaling in mouse cerebral cortical neural progenitor cells

The brain is composed of cells having distinct genomic DNA sequences that arise post-zygotically, known as somatic genomic mosaicism (SGM). One form of SGM is aneuploidy—the gain and/or loss of chromosomes—which is associated with mitotic spindle defects. The mitotic spindle orientation determines cleavage plane positioning and, therefore, neural progenitor cell (NPC) fate during cerebral cortical development. Here we report receptor-mediated signaling by lysophosphatidic acid (LPA) as a novel extracellular signal that influences cleavage plane orientation and produces alterations in SGM by inducing aneuploidy during murine cortical neurogenesis. LPA is a bioactive lipid whose actions are mediated by six G protein-coupled receptors, LPA1–LPA6. RNAscope and qPCR assessment of all six LPA receptor genes, and exogenous LPA exposure in LPA receptor (Lpar)-null mice, revealed involvement of Lpar1 and Lpar2 in the orientation of the mitotic spindle. Lpar1 signaling increased non-vertical cleavage in vivo by disrupting cell–cell adhesion, leading to breakdown of the ependymal cell layer. In addition, genomic alterations were significantly increased after LPA exposure, through production of chromosomal aneuploidy in NPCs. These results identify LPA as a receptor-mediated signal that alters both NPC fate and genomes during cortical neurogenesis, thus representing an extracellular signaling mechanism that can produce stable genomic changes in NPCs and their progeny. Normal LPA signaling in early life could therefore influence both the developing and adult brain, whereas its pathological disruption could contribute to a range of neurological and psychiatric diseases, via long-lasting somatic genomic alterations.

Modulation of lysophosphatidic acid (LPA) receptor activity: the key to successful neural regeneration?

Modulation of lysophosphatidic acid (LPA) receptor activity: the key to successful neural regeneration?

HeLa E-Box Binding Protein, HEB, Inhibits Promoter Activity of the Lysophosphatidic Acid Receptor Gene Lpar1 in Neocortical Neuroblast Cells.

Lysophosphatidic acid (LPA) is an endogenous lysophospholipid with signaling properties outside of the cell and it signals through specific G protein-coupled receptors, known as LPA1–6. For one of its receptors, LPA1 (gene name Lpar1), details on the cis-acting elements for transcriptional control have not been defined. Using 5′RACE analysis, we report the identification of an alternative transcription start site of mouse Lpar1 and characterize approximately 3,500 bp of non-coding flanking sequence 5′ of mouse Lpar1 gene for promoter activity. Transient transfection of cells derived from mouse neocortical neuroblasts with constructs from the 5′ regions of mouse Lpar1 gene revealed the region between −248 to +225 serving as the basal promoter for Lpar1. This region also lacks a TATA box. For the region between −761 to −248, a negative regulatory element affected the basal expression of Lpar1. This region has three E-box sequences and mutagenesis of these E-boxes, followed by transient expression, demonstrated that two of the E-boxes act as negative modulators of Lpar1. One of these E-box sequences bound the HeLa E-box binding protein (HEB), and modulation of HEB levels in the transfected cells regulated the transcription of the reporter gene. Based on our data, we propose that HEB may be required for a proper regulation of Lpar1 expression in the embryonic neocortical neuroblast cells and to affect its function in both normal brain development and disease settings.

Cell type-selective pathways and clinical associations of lysophosphatidic acid biosynthesis and signaling in the ovarian cancer microenvironment.

The peritoneal fluid of ovarian carcinoma patients promotes cancer cell invasion and metastatic spread with lysophosphatidic acid (LPA) as a potentially crucial mediator. However, the origin of LPA in ascites and the clinical relevance of individual LPA species have not been addressed. Here, we show that the levels of multiple acyl‐LPA species are strongly elevated in ascites versus plasma and are associated with short relapse‐free survival. Data derived from transcriptome and secretome analyses of primary ascite‐derived cells indicate that (a) the major route of LPA synthesis is the consecutive action of a secretory phospholipase A2 (PLA2) and autotaxin, (b) that the components of this pathway are coordinately upregulated in ascites, and (c) that CD163+CD206+ tumor‐associated macrophages play an essential role as main producers of PLA2G7 and autotaxin. The latter conclusion is consistent with mass spectrometry‐based metabolomic analyses of conditioned medium from ascites cells, which showed that tumor‐associated macrophages, but not tumor cells, are able to produce 20:4 acyl‐LPA in lipid‐free medium. Furthermore, our transcriptomic data revealed that LPA receptor (LPAR) genes are expressed in a clearly cell type‐selective manner: While tumor cells express predominantly LPAR1‐3, macrophages and T cells also express LPAR5 and LPAR6 at high levels, pointing to cell type‐selective LPA signaling pathways. RNA profiling identified cytokines linked to cell motility and migration as the most conspicuous class of LPA‐induced genes in macrophages, suggesting that LPA exerts protumorigenic properties at least in part via the tumor secretome.

Influence of splicing mutation within the lysophosphatidic acid receptor 1 gene (LPAR1) on semen quality in Holstein-Friesian bulls

Effect of single nucleotide polymorphism (SNP) in splicing site of the LPAR1 (lysophosphatidic acid receptor 1) gene on selected quality traits was investigated in frozen-thawed semen of Holstein-Friesian bulls. Splicing mutation A/G in the LPAR1 gene (rs43581860) was identified in 120 Holstein-Friesian bulls using PCR-RFLP technique (Hph I). Heterozygotes AG were the most frequent (37.5%) compared with AA (30.8%) and GG (31.7%) homozygotes. Observed differences in total motility (TM), sperm membrane integrity (SYBR-14/PI) and ATP content were significant between homozygotes AA or GG and heterozygotes AG. For all three traits disadvantageous effect of heterozygotes AG was detected. This means that LPAR1 splicing mutation has significant effect on semen quality and should be considered as a new marker of semen quality in Holstein-Friesian bulls.

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.

LPA1 receptor-mediated thromboxane A2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction.

Lysophosphatidic acid (LPA) has been recognized recently as an endothelium-dependent vasodilator, but several lines of evidence indicate that it may also stimulate vascular smooth muscle cells (VSMCs), thereby contributing to vasoregulation and remodeling. In the present study, mRNA expression of all 6 LPA receptor genes was detected in murine aortic VSMCs, with the highest levels of LPA1, LPA2, LPA4, and LPA6 In endothelium-denuded thoracic aorta (TA) and abdominal aorta (AA) segments, 1-oleoyl-LPA and the LPA1-3 agonist VPC31143 induced dose-dependent vasoconstriction. VPC31143-induced AA contraction was sensitive to pertussis toxin (PTX), the LPA1&3 antagonist Ki16425, and genetic deletion of LPA1 but not that of LPA2 or inhibition of LPA3, by diacylglycerol pyrophosphate. Surprisingly, vasoconstriction was also diminished in vessels lacking cyclooxygenase-1 [COX1 knockout (KO)] or the thromboxane prostanoid (TP) receptor (TP KO). VPC31143 increased thromboxane A2 (TXA2) release from TA of wild-type, TP-KO, and LPA2-KO mice but not from LPA1-KO or COX1-KO mice, and PTX blocked this effect. Our findings indicate that LPA causes vasoconstriction in VSMCs, mediated by LPA1-, Gi-, and COX1-dependent autocrine/paracrine TXA2 release and consequent TP activation. We propose that this new-found interaction between the LPA/LPA1 and TXA2/TP pathways plays significant roles in vasoregulation, hemostasis, thrombosis, and vascular remodeling.-Dancs, P. T., Ruisanchez, E., Balogh, A., Panta, C. R., Miklós, Z., Nüsing, R. M., Aoki, J., Chun, J., Offermanns, S., Tigyi, G., Benyó, Z. LPA1 receptor-mediated thromboxane A2 release is responsible for lysophosphatidic acid-induced vascular smooth muscle contraction.

Functional lysophosphatidic acid receptors expressed in Oryzias latipes

Lysophosphatidic acid (LPA) signaling is known to play biological and pathophysiological roles in many types of animals. Medaka (Oryzias latipes) is an experimental fish that can be easily maintained, propagated, and analyzed, and whose genome has been completely sequenced. However, there is limited information available regarding medaka LPA receptors. Here, using information from the medaka genome database, we examine the genomic structures, expression, and functions of six LPA receptor genes, Lpar1–Lpar6. Our analyses reveal that the genomic structures of Lpar1 and Lpar4 are different from those deduced from the database. Functional analyses using a heterologous expression system demonstrate that all medaka LPA receptors except for LPA5b respond to LPA treatment with cytoskeletal changes. These findings provide useful information on the structure and function of medaka LPA receptor genes, and identify medaka as a useful experimental model for exploration of the biological significance of LPA signaling.

Lysophosphatidic acid receptors in cancer pathobiology.

Lysophosphatidic acid (LPA) receptors (LPA₁ to LPA₆) are G protein-coupled transmembrane and mediate a variety of biological responses through the binding of LPA, such as cell proliferation, migration, morphogenesis and differentiation. Previously, high secretion levels of LPA were found in blood and ascites from patients with aggressive ovarian cancer. So far, numerical studies have demonstrated that LPA signaling via LPA receptors contributes to the acquisition of malignant potency by several cancer cells. Moreover, genetic and epigenetic alterations of LPA receptor genes have been detected in cancer cells. Therefore, it is suggested that LPA signaling may be a target molecule for the establishment of chemoprevention agents in clinical cancer approaches. Here, we review the current knowledge for the biological roles of LPA signaling via LPA receptors in the pathogenesis of cancer cells.

Ethionine regulates cell motile activity through LPA receptor-3 in liver epithelial WB-F344 cells

Lysophosphatidic acid (LPA) receptors (LPA1 to LPA6) indicate a variety of cellular responses, such as cell proliferation, migration, differentiation, and morphogenesis. However, the role of each LPA receptor is not functionally equivalent. Ethionine, an ethyl analog of methionine, is well known to be one of the potent liver carcinogens in rats. In this study, to assess whether ethionine may regulate cell motile activity through LPA receptors, rat liver epithelial (WB-F344) cells were treated with ethionine for 48 h. In cell motility assay with a cell culture insert, the treatment of ethionine at 1.0 and 10 μM enhanced significantly high cell motile activity, compared with untreated cells. The expression levels of LPA receptor genes in cells treated with ethionine were measured by quantitative real time RT-PCR analysis. The expression of the Lpar3 gene in ethionine-treated cells was significantly higher than that in untreated cells. Furthermore, to confirm an involvement of LPA3 on cell motility increased by ethionine, the Lpar3 knockdown cells were also used. The cell motile activity by ethionine was completely suppressed in the Lpar3 knockdown cells. These results suggest that LPA signaling through LPA3 may be involved in cell motile activity stimulated by ethionine in WB-F344 cells.

Lysophosphatidic acid (LPA) signalling in cell migration and cancer invasion: A focussed review and analysis of LPA receptor gene expression on the basis of more than 1700 cancer microarrays

Lysophosphatidic acid (LPA) is a ubiquitously present signalling molecule involved in diverse cellular processes such as cell migration, proliferation and differentiation. LPA acts as an autocrine and/or paracrine signalling molecule via different G-protein-coupled LPA receptors (LPARs) that trigger a broad range of intracellular signalling cascades, especially the RHOA pathway. Mounting evidence suggests a crucial role of the LPA/LPAR-axis in cancer cell metastasis and promising studies are underway to investigate the therapeutic potential of LPAR-antagonists. This review summarises current knowledge on how LPA promotes cytoskeletal remodelling to enhance the migratory and invasive properties of cells, which may ultimately contribute to cancer metastasis. Furthermore, we provide comprehensive transcriptome analyses of published microarrays of more than 350 normal tissues and more than 1700 malignant tissues to define the expression signatures of LPARs and the LPA-generating enzymes autotaxin (ATX) and lipase member 1 (LIPI). These analyses demonstrate that ATX is highly expressed in a variety of carcinomas and sarcomas, whereas LIPI is almost exclusively overexpressed in highly aggressive Ewing's sarcomas, which underscores the potential contribution of LPA in metastatic disease. In addition, these analyses show that different cancer entities display distinct expression signatures of LPARs that distinguish them from one another. Finally, we discuss current approaches to specifically target the LPA/LPAR circuits in experimental cancer therapy.

Hydrogen peroxide stimulates cell motile activity through LPA receptor-3 in liver epithelial WB-F344 cells

Hydrogen peroxide which is one of reactive oxygen species (ROS) mediates a variety of biological responses, including cell proliferation and migration. In the present study, we investigated whether lysophosphatidic acid (LPA) signaling is involved in cell motile activity stimulated by hydrogen peroxide. The rat liver epithelial WB-F344 cells were treated with hydrogen peroxide at 0.1 or 1μM for 48h. In cell motility assays, hydrogen peroxide treated cells showed significantly high cell motile activity, compared with untreated cells. To measure the expression levels of LPA receptor genes, quantitative real time RT-PCR analysis was performed. The expressions of LPA receptor-3 (Lpar3) in hydrogen peroxide treated cells were significantly higher than those in control cells, but not Lpar1 and Lpar2 genes. Next, to assess the effect of LPA3 on cell motile activity, the Lpar3 knockdown cells from WB-F344 cells were also treated with hydrogen peroxide. The cell motile activity of the knockdown cells was not stimulated by hydrogen peroxide. Moreover, in liver cancer cells, hydrogen peroxide significantly activated cell motility of Lpar3-expressing cells, but not Lpar3-unexpressing cells. These results suggest that LPA signaling via LPA3 may be mainly involved in cell motile activity of WB-F344 cells stimulated by hydrogen peroxide.

Lysophosphatidic acid receptor‐3 increases tumorigenicity and aggressiveness of rat hepatoma RH7777 cells

Lysophosphatidic acid (LPA), which interacts with G protein-coupled transmembrane LPA receptors exhibits several biological effects, such as cell proliferation, migration, and differentiation. Recently, it has been reported that alteration of LPA receptor genes occurs in several cancer cells. In this study, to assess the biological role of LPA receptor-3 (LPA3 ) in the pathogenesis of tumor cells, we generated the Lpar3-expressing cells (RHa3B12 and RHa3G8) from rat hepatoma RH7777 cells, and examined their abilities of cell migration and tumorigenicity, compared with the Lpar3-unexpressing cells. In cell motility and invasion assays, RHa3B12 and RHa3G8 cells showed significantly higher intrinsic activity without LPA treatment than control RH7777AB cells. LPA treatment further increased cell motility and invasion of these cells. The cell motility of RHa3B12 and RHa3G8 cells stimulated by LPA treatment was significantly suppressed by pretreatment with inhibitors of Gi or Gq proteins. In a soft agar assay, the large sized colonies were formed in RHa3B12 and RHa3G8 cells, but not in RH7777AB cells. The cell survival of RHa3G8 cells treated with cisplatin (CDDP) or doxorubicin (DOX) was higher than that of RH7777AB cells, correlating with the elevated expression levels of multidrug-resistance related genes, Mdr1a, Mdr1b, and Gstp1. These results suggest that LPA3 may be involved in progression and aggressiveness of rat hepatoma RH7777 cells.

Induction of lysophosphatidic acid receptor-3 by 12-O-tetradecanoylphorbol-13-acetate stimulates cell migration of rat liver cells

12-O-tetradecanoylphorbol-13-acetate (TPA) which is one of tumor promoting agents stimulates cell migration ability of several tumor cells. In the present study, we investigated whether lysophosphatidic acid (LPA) receptors are involved in cell migration of rat liver cells stimulated by TPA. The rat liver epithelial WB-F344 and hepatoma RH7777 cells were treated by TPA for 48 h. The expression levels of LPA receptor genes in those cells were measured by real-time reverse transcription (RT)–polymerase chain reaction (PCR) analysis. The expressions of the LPA receptor-3 ( Lpar3) gene were significantly elevated in WB-F344 and RH7777 cells treated by TPA, but not Lpar1 and Lpar2 genes. In cell migration assay, TPA treatment showed markedly high cell migration in both cells. The pretreatment with inhibitors of Gi protein suppressed those migration abilities. We next generated the Lpar3 knockdown cells from WB-F344 cells and investigated the effect on cell migration. Interestingly, the cell migration of the knockdown cells was not stimulated by TPA. These results suggest that TPA-stimulated cell migration of rat liver cells may be mainly dependent on the LPA 3-mediated effect.

Distinct DNA methylation patterns of lysophosphatidic acid receptor genes during rat hepatocarcinogenesis induced by a choline-deficient l-amino acid-defined diet

Altered expressions of lysophosphatidic acid (LPA) receptor genes have been reported in tumor cells of human and rats. Recently, we detected the frequent mutations of LPA receptor-1 (LPA1) gene in rat hepatocellular carcinomas (HCCs) induced by a choline-deficient L-amino acid-defined (CDAA) diet. In this study, the DNA methylation patterns of LPA receptor genes and their expression levels during rat hepatocarcinogenesis induced by the CDAA diet were investigated. Six-week-old F344 male rats were continuously fed with the CDAA diet, and animals were then killed at 7 days and 2, 12, 20, and 75 weeks, respectively. Genomic DNAs were extracted from livers and HCCs for the assessment of methylation status by bisulfite sequencing, comparing to normal livers. The livers of rats fed the CDAA diet were unmethylated in LPA1 and LPA2 genes as well as normal livers. In LPA3 gene, although normal livers were unmethylated, the livers at 7 days and 2 and 12 weeks weakly or moderately methylated and those at 20 weeks markedly methylated. Moreover, 4 HCCs were completely methylated in LPA3 gene. Expression levels of LPA receptor genes in the livers of rats fed the CDAA diet and HCCs were correlating with DNA methylation status. These results indicate that DNA methylation status of the LPA3 gene was disturbed in the livers of rats fed the CDAA diet and established HCCs, suggesting that alterations of the LPA receptor genes might be involved during rat hepatocarcinogenesis induced by the CDAA diet.

Genetic and Epigenetic Alterations of Lysophosphatidic Acid Receptor Genes in Rodent Tumors by Experimental Models

Lysophosphatidic acid (LPA) is a bioactive mediator and induces several biological effects, including cell proliferation, migration, morphogenesis and differentiation. LPA interacts with at least six G protein-coupled receptors (GPCRs), including LPA receptor-1 (LPA1), LPA2, LPA3, LPA4, LPA5 and LPA6. These receptors show different biological functions through the binding of LPA, depending on the type of cells. In human malignancies, a high level of LPA production was found in plasma and ascites in ovarian cancer cases. Moreover, aberrant expression levels of LPA receptor genes were detected in some cancer cells. Therefore, it is suggested that LPA receptors may be involved in the pathogenesis of tumor cells as well as LPA per se. Recently, we have reported that alterations of LPA receptor genes also occur in rodent tumors. In this review, we summarize the recent evidence in the investigations of LPA receptor alterations in rodent tumors by experimental models.

Mutations of Lysophosphatidic Acid Receptor Genes in Human Osteosarcoma Cells

Objective: Lysophosphatidic acid (LPA), which is a bioactive phospholipid, interacts with specific G protein-coupled transmembrane receptors. Recently, alterations in LPA receptor genes have been reported in some tumor cells. In this study, to assess an involvement of LPA receptor genes in the development of human cancer cells, we looked for the presence of mutations in LPA receptor 1–6 (LPA1–6) genes in MG63 osteosarcoma, HT1080 fibrosarcoma, A549 lung adenocarcinoma, MCF-7 breast carcinoma, and G-361 melanoma cells. Methods: Genomic DNAs were extracted from each cell and polymerase chain reaction-single-strand conformation polymorphism analysis was performed to identify the mutations. Results: MG63 showed mutations in LPA1 and LPA3 genes, while no mutations in the LPA receptor genes were found in HT1080, A549, MCF-7 and G-361 cells. Sequence analysis revealed a CGC to CGT (Arg to Arg) transition at codon 314 in LPA1, and a GCG to GTG (Ala to Val) transition at codon 247 in LPA3. Conclusion: These results indicated that the mutations in LPA1 and LPA3 genes occur in MG63 cells, suggesting that the alterations in LPA receptor genes may play some role in the pathogenesis in human osteosarcoma cells.