Growth factor pre-treatment differentially regulates phosphoinositide turnover downstream of lysophospholipid receptor and metabotropic glutamate receptors in cultured rat cerebrocortical astrocytes

Reactive gliosis is an aspect of neural plasticity and growth factor (GF) stimulation of astrocytes in vitro is widely regarded as a model system to study astrocyte plasticity. Astrocytes express receptors for several ligands including lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P), agonists for the G-protein-coupled lysophospholipid receptors (lpRs). Activation of lpRs by LPA or S1P leads to multiple pharmacological effects including the influx of calcium, phosphoinositide (PI) hydrolysis, phosphorylation of extracellular receptor regulated kinase (ERK), release of arachidonic acid, and induces mitogenesis. Treatment of astrocytes in vitro with a growth factor cocktail (containing epidermal growth factor [EGF], basic fibroblast growth factor [bFGF] and insulin) led to a marked attenuation of lpR-induced PI hydrolysis. In contrast, under identical conditions, GF treatment led to marked potentiation of PI hydrolysis downstream of activation of another abundantly expressed G-protein coupled receptor, mGluR5. Quantitative gene expression analysis of GF-treated or control astrocytes by TaqMan RT-PCR indicated that GF treatment did not change gene expression of lpa1 and s1p1, but increased gene expression of s1p5 which is expressed at very low levels in basal conditions. These results suggest that GF differentially affected PLC activation downstream of mGluR5 versus lpR activation and that the changes in mRNA levels of lpRs do not account for marked attenuation of agonist-induced phosphoinositide turnover.     

Lysophosphatidic acid induces human natural killer cell chemotaxis and intracellular calcium mobilization

We have investigated the effects of the bioactive lipid lysophosphatidic acid (LPA) on several functions of activated human natural killer (NK) cells. Flow cytometric and immunoblot analyses show that these cells express LPA(1, )LPA(2) and LPA(3). LPA but not its precursor phosphatidic acid (PA) induces the chemotaxis of NK cells, an activity that is inhibited by prior treatment of the cells with pertussis toxin (PTX). In addition, LPA induces the mobilization of intracellular calcium, an effect that is markedly inhibited by PTX, but is not inhibited by the addition of EGTA. PA also induces calcium flux in NK cells, but with much lower efficacy than LPA. Cross-desensitization experiments demonstrate that LPA and PA utilize different receptors. Moreover, LPA or PA but not sphingosine 1-phosphate, enhances IFN-gamma secretion by activated NK cells. Our results may shed some light on the findings that activated NK cells are found at the sites of tumor growth.     

急性脑血栓患者血浆溶血磷脂酸的研究

目的探讨急性脑血栓患者血浆溶血磷脂酸(LPA)的变化及与血糖、血脂、病变部位的关系。方法采用有机溶剂抽提及分光光度计定量分析法。结果急性脑血栓形成组LPA值高于正常对照组,分别为(4.0±1.7)、(1.0±0.6)μmol/L(P<0.005);合并血糖或血脂增高的急性脑血栓患者高于无血糖及血脂增高者,分别为(4.7±2.0)、(4.6±2.0)、(3.3±0.7)μmol/L(P<0.01)。结论LPA作为血小板活化程度的指示物,可指示脑血栓形成的启动,可对急性脑血栓作出预报,并证实早期血栓形成;LPA值的高低与血糖血脂有密切关系;皮层支血栓LPA值高于深穿支血栓,LPA值升高程度与脑血栓严重程度相关,可用来预测脑血栓患者的预后。     

Lysophosphatidic acid transactivates both c-Met and epidermal growth factor receptor, and induces cyclooxygenase-2 expression in human colon cancer LoVo cells

AIM: To examine whether lysophosphatidic acid (LPA) induces phosphorylation of c-Met and epidermal growth factor receptor (EGFR), both of which have been proposed as prognostic markers of colorectal cancer, and whether LPA induces cyclooxygenase-2 (COX-2) expression in human colon cancer cells. METHODS: Using a human colon cancer cell line, LoVo cells, we performed immunoprecipitation analysis, followed by Western blot analysis. We also examined whether LPA induced COX-2 expression, by Western blot analysis. RESULTS: Immunoprecipitation analysis revealed that 10 umol/L LPA induced tyrosine phosphorylation of c-Met and EGFR in LoVo cells within a few minutes. We found that c-Met tyrosine phosphorylation induced by LPA was not attenuated by pertussis toxin or a matrix metalloproteinase inhibitor, in marked contrast to the results for EGFR. In addition, 0.2-40 umol/L LPA induced COX-2 expression in a dose-dependent manner. CONCLUSION: Our results suggest that LPA acts upstream of various receptor tyrosine kinases (RTKs) and COX-2, and thus may act as a potent stimulator of colorectal cancer.     

臭氧抑制溶血磷脂酸引起的神经病理性疼痛和背根神经髓鞘相关糖蛋白及TNF-α上调

目的:探讨单次椎间孔注射臭氧在溶血磷脂酸(lysophosphatidic acid,LPA)脱髓鞘神经病理性疼痛模型中对背根神经髓鞘相关糖蛋白(myeline-associated glycoprotein,MAG)及肿瘤坏死因子α(tumor necrosis factorα,TNF-α)表达的影响。方法:健康成年雄性小鼠鞘内注射1 nmol LPA进行神经病理性疼痛造模,造模后24 h将小鼠随机分为:人造脑脊液[LPA+aCSF(artificial cerebralspinal fluid)]组和臭氧(LPA+O3)组。同节段椎间孔分别单次注射aCSF或臭氧。在注射LPA前(t0)、注射臭氧或aCSF前(t1)、注射臭氧或aCSF后24 h(t2)、3天(t3)、7天(t4)、14天(t5)时进行疼痛行为学检测(每组8只,共48只),并用蛋白质免疫印迹法在不同时间点(t0-t4)检测背根神经髓鞘蛋白MAG及TNF-α的表达变化(每组3只,共30只)。结果:①与人造脑脊液组对比,臭氧注射后24 h机械缩足反射阈值和热缩足反射潜伏期显著上升,维持到第7天;②与人工脑脊液组对比,臭氧注射后24 h TNF-α表达显著下降,3天时最低,并维持到第7天;③与人工脑脊液组对比,臭氧组注射后24 h和3天MAG的蛋白定量表达稳定,无进一步降解,仅在第7天时稍下降。结论:在溶血磷脂酸脱髓鞘神经病理性疼痛中单次椎间孔注射臭氧通过抑制炎症因子释放以及维持MAG稳定性可以明显缓解神经病理性疼痛。     

Inhibitory effects of lysophosphatidic acid receptor-5 on cellular functions of sarcoma cells

Abstract

Lysophosphatidic acid (LPA) is a bioactive lipid that interacts with G protein-coupled LPA receptors (LPA receptor-1 (LPA₁) to LPA₆). Here, we investigated the effects of LPA signaling via LPA₅ on cellular functions of sarcoma cells by generating Lpar5 overexpressing and Lpar5 knockdown cells from rat osteosarcoma and malignant fibrous histiocytoma cells, respectively. The cell motility activity of Lpar5 overexpressing cells was significantly lower, while Lpar5 knockdown cells showed high cell motility, compared with respective controls. Gelatin zymography showed that LPA₅ suppressed the activation of matrix metalloproteinase-2. LPA₅ also inhibited the cell motility activity of endothelial cells, correlating with the expression levels of vascular endothelial growth factor genes. These results suggest that LPA signaling via LPA₅ negatively regulates the cellular functions of rat sarcoma cells.     

Emerging Roles for Lysophospholipid Mediators in Pregnancy

Recent progress in lipid research has unveiled new biologic roles for lysophospholipids as mediators of intercellular signaling. Lysophosphatidic acid (LPA) and sphingosine 1‐phosphate (S1P) are representative lysophospholipids. Accumulating evidence suggests that, acting as intercellular mediators, these and other lysophospholipids may play important roles in physiological and pathological situations. This review discusses the possible involvement of LPA and S1P in reproductive processes, with a focus on the regulatory mechanisms of pregnancy maintenance. As LPA promotes prostaglandin synthesis, mediators in the LPA pathway may also play a significant role in implantation and parturition. S1P signaling is thought to be essential in vascular formation within the uteroplacental unit and in fetomaternal immunologic interactions. Derangements in either one of these lysophospholipid signaling pathways could result in pregnancy complications that may include implantation failure, preeclampsia, and preterm labor.     

乙肝相关性肝癌临床病理学特征与高敏C反应蛋白和溶血磷脂酸表达的相关性

目的探讨乙肝相关性肝癌临床病理学特征与溶血磷脂酸(LPA)和高敏C反应蛋白(hs-CRP)表达的相关性。方法选取2019年1月至2020年1月间河南省驻马店市中心医院收治的198例乙肝相关性肝癌患者作为乙肝组,198例酒精相关性肝癌患者作为酒精组。两组患者都进行血清hs-CRP和LPA表达检测,调查患者的病理学特征并进行相关性分析。结果乙肝组患者血清hs-CRP和LPA含量均高于酒精组,差异均有统计学意义(均P <0.05)。两组患者血清ALP、AFP、ALT、AST和GGT含量比较,差异均无统计学意义(P> 0.05)。乙肝组不同临床分期和组织学分化患者的血清hs-CRP和LPA含量比较,差异均有统计学意义(均P <0.05)。乙肝组患者的临床分期和组织学分化与血清hs-CRP和LPA表达均存在相关性,差异均有统计学意义(均P <0.05)。患者的临床分期和组织学分化均为影响hs-CRP和LPA表达的重要因素,差异均有统计学意义(均P <0.05)。结论相对于酒精相关性肝癌,乙肝相关性肝癌的血清hs-CRP和LPA呈现高表达,与患者的临床病理学特征存在相...     

溶血磷脂酸诱导PC12细胞凋亡的机制研究

目的 探究溶血磷脂酸诱导PC12细胞凋亡的机制并提出干预措施。方法 实验1:不同浓度LPA(0 μM 、10 μM、20 μM、40 μM)处理PC12细胞24 h; 实验2:LPA(40 μM)分别处理PC12细胞不同时间(0 h、6 h、12 h、24 h); 实验3:正常组(0 μM LPA)、LPA组(40 μM LPA)和干预组(5 μM SP600125预处理2 h+40 μM LPA)培养24 h; CCK-8检测细胞活力; TUNEL染色检测细胞凋亡比例; WesternBlot检测Bcl2、caspase 3、磷酸化JNK水平。结果 LPA以时间依赖和浓度依赖的方式使PC12细胞的细胞活力和Bcl2水平降低,而使PC12细胞的凋亡指数和caspase 3水平增高; SP600125(5 μM)预处理不仅明显阻断LPA诱导的PC12细胞活力下降、细胞凋亡,并且极大地抑制了LPA诱导的JNK通路的激活、Bcl2水平的下调和caspase 3水平的上调。结论 JNK特异性抑制剂SP600125预处理能够明显阻断LPA诱导的PC12细胞损伤。     

溶血磷脂酸在卵巢癌诊断中的价值分析

目的明确溶血磷脂酸（LPA）在卵巢癌诊断中的作用。方法通过对2006～2008年人院的450例卵巢肿瘤患者进行手术前测定CA125和LPA,其中的恶性肿瘤患者于术后4周复测CA125和LPA以进行对比研究。结果相比较于CAl25,LPA在卵巢癌的诊断和随访中具有更高的诊断价值,二者的统计结果具有显著性差异（P〈0．05）。结论LPA在卵巢癌的诊断和随访中具有重要的价值。