Lysophosphatidic Acid Levels Research Articles

Characterization of lysophosphatidic acid subspecies produced by autotaxin using a modified HPLC ESI-MS/MS method

Lysophosphatidic acid (LPA) is a bioactive lipid with a plethora of biological functions including roles in cell survival, proliferation, and migration. Although high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC ESI-MS/MS) technology has been used to measure the levels of LPA in human blood, serum and plasma, current methods cannot readily detect the minute levels of LPA from cell culture. In this study, a modified HPLC ESI-MS/MS method with enhanced sensitivity was developed, which allows accurate measurements of LPA levels with a limit of quantitation at approximately 10 femtomoles. The method was validated by quantitation of LPA levels in the media of previously characterized cell lines ectopically expressing autotaxin. Specifically, autotaxin overexpression induced an increase in the 16:0, 18:2, 18:1, 18:0, and 20:4 subspecies of LPA, but not the 22:6 LPA subspecies. Lastly, this HPLC ESI-MS/MS method was cross-validated via biological assays previously utilized to assay LPA levels. Hence, this HPLC ESI-MS/MS method will allow researchers to measure in vitro LPA levels and also distinguish between specific LPA subspecies for the delineation of individual biological mechanisms.

No Involvement of Lysophosphatidic Acid Receptor-3 in Cell Migration of Mouse Lung Tumor Cells Stimulated by 12-O-Tetradecanoylphorbol-13-acetate

The tumor promoting agent 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulates cell migration of several tumor cells. Recently, we reported that loss of lysophosphatidic acid (LPA) receptor-3 (LPA3) enhanced cell migration of murine lung tumor LL/2 cells. In the present study, we investigated whether LPA3 is involved in cell migration of mouse lung tumor cells stimulated by TPA. Exogenous LPA3 gene (Lpar3)-expressing (LL/2-a3) cells and LL/2-AB cells as a vector control generated from LL/2 cells were used. In a cell migration assay, TPA treatment significantly stimulated cell migration of LL/2-AB and LL/2-a3 cells, while the cell migration abilities of LL/2-a3 were markedly lower than those of LL/2-AB cells. Using quantitative real-time reverse transcription (RT)-polymerase chain reaction (PCR) analysis, no effect of TPA treatment on the expression levels of LPA1, LPA2 and LPA3 genes was detected in either type of cells. These results suggest that the LPA3 may not be involved in the enhanced migration ability by TPA in mouse lung tumor cells.

Atorvastatin decreased plasma lysophosphatidic acid level in patients with ischemic stroke

Atorvastatin decreased plasma lysophosphatidic acid level in patients with ischemic stroke

Lysophosphatidic acid (LPA)—a perspective marker in ovarian cancer

To compare plasma lysophosphatidic acid (LPA) levels in ovarian cancer patients in women with benign ovarian tumors and in women with no ovarian pathology. We correlated clinico-pathological parameters with plasma LPA levels. Capillary electrophoresis with indirect ultraviolet detection was used to analyze the plasma LPA levels of 159 patients (81 patients with ovarian cancer, 27 women without ovarian or uterine pathologies, and 51 patients with benign ovarian tumors) during a 5-year period. Patients with ovarian cancer had a significantly higher plasma LPA level (n=81; median (med), 11.53 μmol/l; range, 1.78-43.21 μmol/l) compared with controls with no ovarian pathology (n=27; med, 1.86 μmol/l; range, 0.94-9.73 μmol/l), and patients with benign ovarian tumor (n=51; med, 6.17 μmol/l; range, 1.12-25.23 μmol/l; P<0.001). We found that plasma LPA levels were associated with the International Federation of Gynecology and Obstetrics stage. The histological subtype and grade of ovarian cancer did not influence the plasma LPA levels in this study. The plasma LPA level can be a useful marker for ovarian cancer, particularly in the early stages of the disease.

Ethanol-Induced Alterations in Fatty Acid-Related Lipids in Serum and Tissues in Mice

Chronic alcohol consumption is a major factor for several human diseases, and alcoholism is associated with a host of societal problems. One of the major alcohol-induced metabolic changes is the increased NADH levels, which reduces glucose synthesis and increases fatty acid (FA) synthesis. Probably more important is the induction of FA synthesizing enzymes under the control of sterol regulatory element binding proteins (SREBP), plus increased malonyl-CoA, which blocks FA entry to the mitochondria for oxidation. The changes in FA-related lipids, particularly lysophospholipids and ceramides (Cers), in different tissues in ethanol-fed mice have not been reported. We systematically determined the levels of FA-related lipids, including FAs, phosphatidylcholines, phosphatidylethanolamines, lysophosphatidic acid, lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylinositol, sphingomyelins, and ceramides (Cers), in the serum and different tissues by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). The study was performed in C57BL/6J mice fed with Lieber-DeCarli diet, in which ethanol was added to account for 27.5% of total calories. The serum and tissues were collected from these mice at the time of killing, and the results were compared to pair-fed controls. The important observation was that ethanol-induced tissue-specific changes, which were related to different FA chains. Several 22:6 FA, 18:0 FA, 18:0 to 18:3 FA-containing lipids were significantly increased in the serum, liver, and skeletal muscle, respectively. In the kidney, all 22:6 FA-containing lipids detected were increased. In addition, alterations in other lipids in tissues, except adipose tissue, were also observed. We found tissue-specific alterations in the levels of FA-related lipids after ethanol administration. The implications of these findings pertinent to human physiology/pathology warrant further investigation. More studies are needed to explore the mechanisms on the different effects of ethanol on certain lipids in different tissues.

Apolipoprotein A-I (apoA-I) and apoA-I mimetic peptides inhibit tumor development in a mouse model of ovarian cancer

We examined whether reduced levels of Apolipoprotein A-I (apoA-I) in ovarian cancer patients are causal in ovarian cancer in a mouse model. Mice expressing a human apoA-I transgene had (i) increased survival (P < 0.0001) and (ii) decreased tumor development (P < 0.01), when compared with littermates, following injection of mouse ovarian epithelial papillary serous adenocarcinoma cells (ID-8 cells). ApoA-I mimetic peptides reduced viability and proliferation of ID8 cells and cis-platinum-resistant human ovarian cancer cells, and decreased ID-8 cell-mediated tumor burden in C57BL/6J mice when administered subcutaneously or orally. Serum levels of lysophosphatidic acid, a well-characterized modulator of tumor cell proliferation, were significantly reduced (>50% compared with control mice, P < 0.05) in mice that received apoA-I mimetic peptides (administered either subcutaneously or orally), suggesting that binding and removal of lysophosphatidic acid is a potential mechanism for the inhibition of tumor development by apoA-I mimetic peptides, which may serve as a previously unexplored class of anticancer agents.

Effects of lysophosphatidic acid and its receptors LPA__AMB__frac13; on radiation pneumonitis

Radiation pneumonitis (RP) is a serious complication of radiation therapy for thoracic tumors. Lysophosphatidic acid (LPA) and its receptors LPA⅓ were reported to participate in the processes of inflammation. We tested the hypothesis that LPA and its receptors LPA⅓, take part in the pathogenesis of RP. In our study, irradiation increased LPA levels in the lung and expression of LPA⅓. To further determine the role of LPA⅓, we performed pharmacological knockout of LPA⅓ by a specific antagonist, VPC-12249. On day 60 post-irradiation, RP was significantly alleviated in a dose-dependent manner in mice treated with VPC-12249, as shown by H&E staining, malondialdehyde (MDA, an indicator of oxidative damage) assay in lung, and concentrations of proinflammatory and profibrotic cytokines in plasma, including IL-1β, TNF-α, and TGF-β1. Additionally, VPC-12249 administration decreased the phosphorylation of IκB-α (the initial event that activates the NF-κB signal way), and expression of TGF-β1, CTGF, and α-SMA mRNA. Our findings suggest that LPA and LPA⅓ may play a pivotal role in RP, and LPA-LPA⅓ may serve as novel therapeutic targets for the treatment of RP.

Lysophosphatidic Acid Level and the Incidence of Silent Brain Infarction in Patients with Nonvalvular Atrial Fibrillation

Lysophosphatidic acid (LPA), which is proposed to play an important role in normal physiological situations such as wound healing, vascular tone, vascular integrity and reproduction, may be involved in the etiology of some diseases such as atherosclerosis, cancer, obesity or myocardial infarction. Abnormal findings, including silent brain infarction (SBI), are frequently observed by magnetic resonance imaging (MRI) in patients with nonvalvular atrial fibrillation (NVAF). However, whether there is a relationship between LPA level and the prevalence of SBI has not been extensively studied. In the present study, the association between them was investigated. 235 patients with NVAF, 116 cases of SBI without NVAF and 120 cases of healthy volunteers (control group), who did not receive any antithrombotic therapy, were enrolled in this study. Plasma LPA levels in the NVAF with SBI group were significantly higher than that in the control group (p < 0.01), NVAF without SBI group (p < 0.01) and SBI without NVAF group (p < 0.01). The LPA levels are lower in the control group than in the NVAF without SBI and SBI without NVAF groups (p < 0.01), however, the latter two groups did not significantly differ from each other for LPA levels (p > 0.05) There were significant differences in the positive rate of platelet activation between each of the groups (p < 0.01). The positive rate of platelet activation was significantly higher in the NVAF with SBI group. We suggest that LPA might be a novel marker for estimation of the status of platelet activation and the risk factor for SBI onset in NVAF patients. We expected that plasma LPA levels could predict the occurrence of SBI in NVAF patients.

The absence of LPA receptor 2 reduces the tumorigenesis by ApcMin mutation in the intestine.

Lysophosphatidic acid (LPA) is a lipid mediator that mediates several effects that promote cancer progress. The LPA receptor type 2 (LPA(2)) expression is often elevated in several types of cancers, including colorectal cancer (CRC). In this study, we investigated the role of LPA(2) in the development of intestinal adenomas by comparing Apc(Min/+) mice with Apc(Min/+)/Lpar2(-/-) mice. There were 50% fewer intestinal adenomas in Apc(Min/+)/Lpar2(-/-) mice than Apc(Min/+) mice. Smaller-size adenomas (<1 mm) were found at higher frequencies in Apc(Min/+)/Lpar2(-/-) mice compared with Apc(Min/+) mice at the two age groups examined. The expression level of LPA(2) correlated with increased size of intestinal adenomas. Reduced tumor multiplicity and size in Apc(Min/+)/Lpar2(-/-) mice correlated with decreased proliferation of intestinal epithelial cells. Apc(Min/+)/Lpar2(-/-) mice showed an increased level of apoptosis, suggesting that LPA(2)-mediated signaling stimulates intestinal tumor development and progress by regulating both cell proliferation and survival. In addition, the expression levels of Krüpple-like factor 5 (KLF5), β-catenin, cyclin D1, c-Myc, and hypoxia-inducible factor-1α (HIF-1α) were significantly altered in Apc(Min/+)/Lpar2(-/-) mice compared with Apc(Min/+) mice. In vitro studies using HCT116 cells showed that LPA induced cyclin D1, c-Myc, and HIF-1α expression, which was attenuated by knockdown of LPA(2). In summary, intestinal tumor initiated by Apc mutations is altered by LPA(2)-mediated signaling, which regulates tumor growth and survival by altering multiple targets.

Group VIA phospholipase A2 in both host and tumor cells is involved in ovarian cancer development.

Host-tumor cell interactions are recognized to be critical in tumor development. We have shown that group VIA phospholipase A(2) [calcium-independent phospholipase A(2)β (iPLA(2)β)] is important in regulating extracellular lysophosphatidic acid (LPA) levels around human epithelial ovarian cancer (EOC) cells. To explore the role of iPLA(2)β in host-tumor cell interactions, we have used immunocompetent iPLA(2)β knockout (iPLA(2)β(-/-)) mice and the mouse EOC cell line ID8. Tumorigenesis and ascites formation were reduced in iPLA(2)β(-/-) mice compared with wild-type (WT) mice by more >50% and were reduced further when ID8 cell iPLA(2)β levels were lowered (by>95%) with shRNA. LPA and lysophosphatidylcholine (LPC) levels in the tumor microenvironment were reduced to ∼80% of WT levels in iPLA(2)β(-/-) mice. LPA, but not LPC, stimulated ID8 cell migration and invasion with cells in which iPLA(2)β expression had been down-regulated in vitro. LPA, but not LPC, also enhanced in vivo ascites formation (by ∼5-fold) and tumorigenesis in iPLA(2)β(-/-) mice. This is the first demonstration of a role for host cell iPLA(2)β in cancer, and these findings suggest that iPLA(2)β is a potential target for developing novel antineoplastic therapeutic strategies.

Lysophosphatidic Acid in Patients With Ovarian Cancer

Purpose: We seek to compare lysophosphatidic acid (LPA) plasma levels (all subtypes) in patients with ovarian cancer and patients without this disease. Patients and Methods: Capillary electrophoresis with indirect ultraviolet detection was used to analyze the plasma LPA levels (with all subtypes) of 133 patients (60 patients with ovarian cancer, 43 patients without ovarian pathology, and 30 patients with benign ovarian tumors) during a 3-year period. The Kolmogorov-Smirnov test and Mann-Whitney U test were used for statistical analysis. Results: Patients with ovarian cancer had a significantly higher plasma LPA level (all subtypes; n = 60; median, 6.99 μmol/L; range, 4.53-43.21 μmol/L) compared with controls with no ovarian pathology (n = 43, median, 2.92 μmol/L; range, 0.94-22.93 μmol/L) and patients with benign ovarian tumor (n = 30; median, 7.73 μmol/L; range, 1.12-28.84 μmol/L; P < .001). We found that plasma LPA levels were associated with the International Federation of Gynecology and Obstetrics stage and ovarian cancer histologic type. Patients with endometrial ovarian cancer had significantly higher plasma LPA levels in comparison with other histologic types of epithelial ovarian carcinoma. Conclusion: The plasma LPA level can be a useful marker for ovarian cancer, particularly in the early stages of the disease.

Abstract 5034: Both host and tumor cells group VIA phospholipase A2 are involved in ovarian cancer development, and lysophosphatidic acid restores the lost activities

Abstract Host-tumor cell interactions are recognized to be critical in tumor development. We have shown that group VIA phospholipase A2 (calcium-independent phospholipase A2beta, iPLA2β) is important in regulating extracellular lysophosphatidic acid (LPA) levels around human epithelial ovarian cancer (EOC) cells. To explore the role of iPLA2β in host-tumor cell interactions, we have used immunocompetent iPLA2β knockout (KO) mice and the mouse EOC cell line ID8. Tumorigenesis and ascites formation were reduced in iPLA2β-KO mice compared to wild type (WT) mice and were reduced further when ID8 cell iPLA2β levels were lowered with shRNA. LPA and lysophosphatidylcholine (LPC) levels in the tumor microenvironment were reduced in KO mice. LPA, but not LPC, restored ID8 cell migration, invasion, and colony formation with cells in which iPLA2β expression had been suppressed in vitro. LPA, but not LPC, also enhanced in vivo ascites formation and tumorigenesis in iPLA2β-KO mice. Autotaxin (ATX) activity in the tumor microenvironment correlated with tumor loading and was reduced in KO mice and enhanced by LPA in vivo. This is the first demonstration of a role for host cell iPLA2β in cancer, and these findings suggest that iPLA2β is a potential target for developing novel antineoplastic therapeutic strategies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5034.

Abstract 2368: Autotaxin/Enpp2 controls of bone metastasis formation through osteoclast function

Abstract Autotaxin (ATX, NPP-2) is a secreted protein with both an oncogenic action on mouse breast tissue and metastatic properties on breast cancer cells. Due to its lysophospholipase D activity, ATX generates lysophosphatidic acid (LPA) from lysophosphatidylcholine and controls LPA levels in the blood. We have recently showed that platelet-derived LPA promotes the progression of osteolytic bone metastases of breast cancer cells. However, how LPA is produced at the metastatic site and the role of ATX by cancer cells in this metastasis process are still unknown. Here, we found that in vitro, forced expression of ATX in human breast cancer MDA-B02 cells (MDA-B02/ATX) increased invasiness, proliferation and enhanced their pro-osteoclastic function. In vivo, intravenous injection of MDA-B02/ATX cells to inmmunodeficiency BALB/C nude mice enhanced osteolytic bone metastasis formation, as judged by increased bone loss and tumor burden, and higher active osteoclast number at the bone metastatic site. Mouse 4T1 breast cancer cells induced the formation of osteolytic bone metastases after intracardiac injection in immunocompetent BALB/C mice. We found that 4T1 cells expressed active ATX. In vitro, silencing ATX[O1] expression inhibited invasion but not proliferation of 4T1-siATX cells. In vivo, silencing ATX expression inhibited the extent of osteolytic bone lesions and decreased the number of active osteoclasts at bone the metastatic site. Altogether, these results demonstrated that expression of ATX by cancer cells controls bone metastasis formation and that targeting ATX in patients might contribute to the development of additional therapies against bone metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2368.

Deletion of Lysophosphatidic acid Receptors 1 and 2 Protects Against Lipopolysaccharide‐Induced Acute Lung Injury in Mice

Lysophosphatidic acid (LPA), a bioactive phospholipid, exhibits both pro‐ and anti‐inflammatory responses in the airway. LPA activates intracellular signaling pathways by ligating to G‐protein‐coupled LPA receptors (LPA‐Rs). Here, we have evaluated the role of LPA and LPA‐Rs in a LPS‐induced murine model of acute lung injury (ALI). Wild type and genetically engineered LPA1 and LPA2 knockout (LPA1−/− and LPA2−/−) mice were intratracheally challenged with LPS, and after 24 h, bronchoalveolar lavage (BAL) fluids and lung tissues were collected. LPS challenge increased LPA1–3 protein expression in the lung and LPA levels in BAL fluids, as measured by LC‐MS/MS. LPA1−/− and LPA2−/− mice reduced lung inflammation after LPS challenge as determined by IL‐6 levels, and infiltration of neutrophils in BAL fluids. Further, intratracheal administration of Ki16425, an antagonist of LPA1&amp;3, prior to LPS challenge attenuated LPS‐induced IL‐6 release and interstitial infiltration of neutrophils without altering total protein concentration in BAL fluids. Taken together, these results show that inhibition of LPA receptors protects against LPS‐induced lung inflammation, but not pulmonary microvascular injury. These studies identify LPA‐Rs as novel pro‐inflammatory components in LPS‐induced ALI. This work was supported by NIH grant HL 091916 to Y.Z.

Boronic acid-based inhibitor of autotaxin reveals rapid turnover of LPA in the circulation

Autotaxin (ATX) is a secreted nucleotide pyrophosphatase/phosphodiesterase that functions as a lysophospholipase D to produce the lipid mediator lysophosphatidic acid (LPA), a mitogen, chemoattractant, and survival factor for many cell types. The ATX-LPA signaling axis has been implicated in angiogenesis, chronic inflammation, fibrotic diseases and tumor progression, making this system an attractive target for therapy. However, potent and selective nonlipid inhibitors of ATX are currently not available. By screening a chemical library, we have identified thiazolidinediones that selectively inhibit ATX-mediated LPA production both in vitro and in vivo. Inhibitor potency was approximately 100-fold increased (IC(50) approximately 30 nM) after the incorporation of a boronic acid moiety, designed to target the active-site threonine (T210) in ATX. Intravenous injection of this inhibitor into mice resulted in a surprisingly rapid decrease in plasma LPA levels, indicating that turnover of LPA in the circulation is much more dynamic than previously appreciated. Thus, boronic acid-based small molecules hold promise as candidate drugs to target ATX.

Quantification of lysophosphatidic acids in rat brain tissue by liquid chromatography–electrospray tandem mass spectrometry

Lysophosphatidic acid (LPA) is a lipid mediator with multiple biological functions. A highly selective and sensitive liquid chromatography–tandem mass spectrometry (LC/MS/MS) method was developed for the determination of LPAs (16:0 LPA, 18:0 LPA, 18:1 LPA, 20:4 LPA) in rat brain cryosections. After partitioning the LPAs from other lipophilic material present in the tissue with a liquid–liquid extraction, a reversed-phase column and ion pair technique was used for separating analytes with a gradient elution. An internal standard (17:0 LPA) was included in the analysis. Detection and quantification of the LPAs were carried out with a triple quadrupole mass spectrometer using negative electrospray ionization (ESI) and multiple reaction monitoring (MRM). The artificial formation of LPAs from lysophosphatidylcholines during the sample preparation procedure and instrumentation was carefully studied during the method development. The method was validated; acceptable selectivity, accuracy, precision, recovery, and stability were obtained for concentrations within the calibration curve range of 0.02–1.0 μM for LPAs. The quantification limit of the assay was 54 fmol injected into column for each LPAs. The method was applied to comparative studies of LPA levels in rat brain cryosections after the various chemical pre-treatments of the sections.

Cancer Cell Expression of Autotaxin Controls Bone Metastasis Formation in Mouse through Lysophosphatidic Acid-Dependent Activation of Osteoclasts

BackgroundBone metastases are highly frequent complications of breast cancers. Current bone metastasis treatments using powerful anti-resorbtive agents are only palliative indicating that factors independent of bone resorption control bone metastasis progression. Autotaxin (ATX/NPP2) is a secreted protein with both oncogenic and pro-metastatic properties. Through its lysosphospholipase D (lysoPLD) activity, ATX controls the level of lysophosphatidic acid (LPA) in the blood. Platelet-derived LPA promotes the progression of osteolytic bone metastases of breast cancer cells. We asked whether ATX was involved in the bone metastasis process. We characterized the role of ATX in osteolytic bone metastasis formation by using genetically modified breast cancer cells exploited on different osteolytic bone metastasis mouse models.Methodology/Principal FindingsIntravenous injection of human breast cancer MDA-B02 cells with forced expression of ATX (MDA-B02/ATX) to inmmunodeficiency BALB/C nude mice enhanced osteolytic bone metastasis formation, as judged by increased bone loss, tumor burden, and a higher number of active osteoclasts at the metastatic site. Mouse breast cancer 4T1 cells induced the formation of osteolytic bone metastases after intracardiac injection in immunocompetent BALB/C mice. These cells expressed active ATX and silencing ATX expression inhibited the extent of osteolytic bone lesions and decreased the number of active osteoclasts at the bone metastatic site. In vitro, osteoclast differentiation was enhanced in presence of MDA-B02/ATX cell conditioned media or recombinant autotaxin that was blocked by the autotaxin inhibitor vpc8a202. In vitro, addition of LPA to active charcoal-treated serum restored the capacity of the serum to support RANK-L/MCSF-induced osteoclastogenesis.Conclusion/SignificanceExpression of autotaxin by cancer cells controls osteolytic bone metastasis formation. This work demonstrates a new role for LPA as a factor that stimulates directly cancer growth and metastasis, and osteoclast differentiation. Therefore, targeting the autotaxin/LPA track emerges as a potential new therapeutic approach to improve the outcome of patients with bone metastases.

Comparison of total plasma lysophosphatidic acid and serum CA-125 as a tumor marker in the diagnosis and follow-up of patients with epithelial ovarian cancer

To evaluate the role of lysophosphatidic acid (LPA) as a tumor marker in diagnosis and follow-up of patients with epithelial ovarian cancer. Eighty-seven epithelial ovarian cancer patients, 74 benign ovarian tumor patients, and 50 healthy women were enrolled in the study. Twenty-nine of 87 epithelial ovarian cancer patients were followed up for 6 cycles of paclitaxel-carboplatin chemotherapy. CA-125 and total plasma LPA levels were measured preoperatively and before each chemotherapy cycle. Preoperative total plasma LPA and serum CA-125 levels were significantly higher in patients with epithelial ovarian cancer compared to patients with benign ovarian tumors and healthy women. Cut-off value for LPA was determined as 1.3 µmol/L and sensitivity, specificity, positive predictive value and negative predictive value were 95%, 92%, 95% and 92%, respectively. Mean total plasma LPA level of 29 patients who received chemotherapy was 7.21±6.63 µmol/L preoperatively and 6.84±6.34 µmol/L, 6.34±5.92 µmol/L, 6.14±5.79 µmol/L, 5.86±5.68 µmol/L, 5.23±5.11 µmol/L and 5.21±5.32 µmol/L in measurements held just before the 1st, 2nd, 3rd, 4th, 5th and 6th chemotherapy cycles, respectively (ANOVA, p=0.832). Total plasma LPA levels decreased slightly with chemotherapy administration and there was a weak negative correlation (Spearman, r(s)=-0.151, p=0.034), compared to a significant negative correlation in CA-125 (Spearman, r(s)=-0.596, p<0.001). LPA is a better biomarker for diagnosis of epithelial ovarian cancer compared to CA-125. However, measurement of total plasma LPA levels during chemotherapy administration have no superiority to the serum CA-125 levels.

Early diagnosis value in of serum lysophosphatidic acid and CA-125 detection ovarian cancer

Objective To explore the clinical value of early diagnosis of ovarian cancer by serum lysophosphatidic acid(LPA) and CA-125.Methods 50 patients with ovarian cancer from October 2005 to February 2008 were selected as ovarian cancer group,at the same period selected 44 patients with ovarian benign tumor(ovarian benign disease group),and 50 healthy women as the healthy control group.All patients were diagnosed and confirmed by preoperative blood and pathology.The serum LPA and CA-125 of two groups were detected.Results The serum LPA level and the positive rate in the ovarian cancer group was higher than that of the ovaries benign group or the control group(P＜0.05).The CA-125 level in the ovarian cancer group was similar to that of the ovaries benign group(P＞0.05),while the CA-125 level in the ovarian cancer group or the ovaries benign group was higher than that of the control group(P＜0.05).The specificity of the LPA was better than that of the CA-125 detection.In the early diagnosis of ovarian cancer,the sensitivity of the combination(85.7%) was better than either of them(P＜0.01);the plasma LPA level and positive rate of CA-125 of the phase Ⅱ～Ⅳ ovarian cancer patients were higher than that of phase Ⅰ (P＜0.01);the CA-125 positive rate of the serious cystadenocarcinoma was higher than that of the cystadenocarcinoma(P＜0.01).Conclusion LPA is a sensitive biomarker for the early diagnosis of ovarian cancer,especially combined with CA-125.It should be widely used in clinic. Key words: Ovarian neoplasms; Lysophosholipids; CA-125 antigen

VEGFR-2 silencing by small interference RNA (siRNA) suppresses LPA-induced epithelial ovarian cancer (EOC) invasion

Background The VEGF–VEGF receptor (VEGFR) signaling axis has emerged as a promising target for cancer therapy, attributing to its vital role in tumor angiogenesis and growth. We have previously reported the regulation of epithelial ovarian cancer (EOC) invasion and migration by VEGF and the implication of VEGF-VEGFR-2 axis in lysophosphatidic acid (LPA)-induced EOC invasion. However, the expression profile of VEGF and VEGFRs in EOC, their association with tumor aggressiveness, and their regulation by LPA remain unclear. Objectives and methods In this study, we examined the expression of VEGFR-1, VEGFR-2, neuropilin-1 (NRP-1), NRP-2, VEGF 121, and VEGF 165 in established EOC cell lines and assessed their correlation with cell invasiveness. Moreover, using an ovarian cancer tissue qPCR array, we analyzed VEGFR-2 expression across a panel of 48 tissues with different disease stages and histological grades. We also tested the effect of LPA on VEGF and VEGFR-2 expression and examined whether blocking VEGFR-2 by RNA interference (RNAi) affects LPA-induced EOC invasion. Results We show that VEGF and VEGFR-2 expression correlates with cell invasiveness and VEGFR-2 expression in ovarian cancer tissues correlate with tumor grade. In addition, LPA, at 20 μM, significantly induced the expression of VEGF 121, VEGF 165, and VEGFR-2 in SKOV3 and DOV13 cells ( P < 0.05). VEGFR-2 small interference RNA (siRNA) transfection remarkably decreased LPA's invasion-promoting effect ( P < 0.001) in SKOV3 cells without significantly decreasing SKOV3 cells' basal invasiveness. In DOV13 cells, VEGFR-2 silencing significantly decreases both the basal level cell invasion and LPA's invasion promoting effect ( P < 0.001). Conclusion These results suggest that decreasing VEGFR-2 expression by RNAi may prove to be an effective method to reduce the metastatic potential of EOC cells exposed to elevated levels of LPA.