Epha2/ephrina1Expressions In Human Malignant Gliomas And Their Relationship With Angiogenesis

Glioma is the most common malignant tumor in brain,which has highincidence, strongly invasive power and recurrence fast after surgery. most ofthese tumors are malignant and usually exhibit a poor prognosis. patientsmedian survival period is less than12months,despite surgical treatmentcombined with radiotherapy and/or chemotherapy. The Eph receptor tyrosinekinases and ephrin ligands have been studied extensively for their roles indevelopmental processes. In recent years, Eph receptors and ephrins have beenfound to be integral players in cancer formation and progression. Among theseare EphA2and ephrinA1, which are involved in the development andmaintenance of many different types of solid tumors. The function of EphA2and ephrinA1in tumorigenesis and tumor progression is complex and seemsto be dependent on cell type and microenvironment. These variables affect theexpression of the EphA2and ephrinA1proteins, the pathways through whichthey induce signaling, and the functional consequences of that signaling on thebehavior of tumor cells and tumor-associated cells.Objective: To investigate the expressions and significance of receptor oftyrosine kinase EphA2and its ligand ephrinA1in human malignant gliomasand their correlation with tumor angiogenesis and prognosis.Methods: Expressions of EphA2,ephrinA1and CD105-stainedmicrovessel density (MVD) were detected by immunohistochemical assay in62surgically resected human glioma tissues and8normal brain tissues. Thecorrelation between EphA2and ephrinA1expression and microvessel countsin glioma tissues were assessed.1Judgment of immunohistochemistry result:By the methods of thepercentage of positive cells and color intensity,(1) percentage of postivecells is divided into the following four grades:0score:postive cell<10%;1 score:postive cell10%～25%;2scores:postive cell25%～50%;3scores:postive cell50%～75%；4scores:postive cell>75%.(2)dyeingintensity:0score: not stained;1score: light yellow;2scores:brown-yellow;3scores: brown or dark brown; The results can be gotten byadding (1)and(2):0～1score as negative,marked "-";2～3scores as weakpositive,marked "+";4～5scores above as positive,marked "++";6～7scores above as strong postive, marked "+++".2Method of counting MVD:Any endothelial cell or endothelial cell clusterwhich is stained brown by anti-CD105monoclonal antibody in the tumortissue is signed one positive blood vessel marker,with or without lumen,ifonly it is obvious different from other connective tissue components. Weobserve one slice of every specimen,avoid the tumor necrosis region orbleeding region, and select the most abundant area of micrangium underlow power field(×100),which is"hot spot". we count the average of bloodvessels under five high power fields(×400),and count in eyepiecemicrometer grid range of0.25mm2,the arithmetic mean is signed as MVDmeasured value of this slice.3Statistical methods:According to the different methods of data acquisitionand various requirements of statistical analysis, all of the measurementdata is shown with Mean±SD. we choose x2-test, t '-test,pearson orspearman correlate analysis,survival analysis choose kaplan-meier and coxregression. We use SPSS13.0statistics software to processing data.WhenP＜0.05,the data has statistics significance. When P＜0.01,the data hassignificant statistics significance.Results:1Immunohistochemical staining revealed that specific EphA2, ephrinA1and CD105staining was present as brown-yellow in glioma cellscytoplasm or membrane.2Expression of EphA2, CD105and ephrinA1was not correlated withsex,age and tumor location, was significantly correlated with pathologicgrade. EphA2and CD105expression was significantly higher in high-grade gliomas (WHOⅢ~Ⅳ) than in low-grade gliomas (WHOⅠ~Ⅱ)(P<0.01).But ephrinA1expression was significantly lower inhigh-grade gliomas (WHOⅢ~Ⅳ) than in low-grade gliomas (WHOⅠ~Ⅱ)(P<0.01).3EphA2expression in57of62cases was examined (57/62,91.93%). ButEphA2expression was not detected in all8normal brain samples and5cases of low-grade gliomas (Ⅰ~Ⅱ). There was statistical difference inEphA2expression between human gliomas and normal brain samples(P<0.01).4ephrinA1expression was examined in30of62cases (30/62,48.39%).ephrinA1was expressed at low levels in most malignant gliomas and theincreased ephrinA1expression is associated with normal brain andlower-grade histology(Ⅰ~Ⅱ).5The expression average of MVD labelled with anti-CD105monoclonalantibody in normal brain tissues group and tumor group respectively were2.75±1.28and34.26±12.61, the expression of MVD is higher in gliomatissues group than in normal brain tissues group, the data had significantstatistics significance(P<0.01).The expression of MVD in low-gradeglioma group and high-grade glioma group respectively were16.75±2.99and38.46±10.14, the expression of MVD is higher in high-grade gliomagroup than in low-grade glioma group, the difference had significantstatistics significance(P<0.01).6The expression average of MVD respectively were17.60±6.58and35.72±11.97in5cases negative expression of EphA2and57casespositive expression of EphA2in glioma tissues, the data has significantstatistics significance through the statistical test (P<0.01), and MVDrespectively were39.19±10.20and25.80±8.93in32cases negativeexpression of ephrinA1and30cases positive expression of ephrinA1inglioma tissues, the data has significant statistics significance through thestatistical test (P<0.01).7With increase of EphA2positive expressions, CD105-MVD expression number in tumor tissue became more, ephrinA1became less, MVD wassignificantly positive correlated with expression of EphA2(r=0.713,P<0.01),and significantly negative correlated with expression ofephrinA1(r=－0.772, P<0.01). EphA2was significantly negative correlatedwith expression of ephrinA1too (r=－0.912, P<0.01).8In gliomas samples, EphA2positive and ephrinA1negative was29cases,positive for both EphA2and ephrinA1was28cases, negative for bothEphA2and ephrinA1was3cases, EphA2negative and ephrinA1positivewas2cases. Kaplan-Meier survival analysis and Logrank test showEphA2and MVD overexpression patients had significantly shortersurvival than patients with EphA2and MVD negative expression or lowlevel expression,however, ephrinA1overexpression patients hadsignificantly higher survival than patients with negative expression. COXregression analysis show EphA2,MVD and ephrinA1all were gliomasPrognosis risk factors,which had independent significance to Prognosis.Relative risk of EphA2was highest(5.861),the second was CD105-MVD(2.625),the smallest was ephrinA1(0.328).gliomas patients positive forEphA2and negative for ephrinA1had significantly shorter survival thanpatients with tumors positive for both EphA2and ephrinA1, negative forboth EphA2and ephrinA1, or negative for EphA2and positive forephrinA1.Conclusion:1Specifically over-expressed of EphA2and its ligand ephrinA1specificallylow-expressed in malignant gliomas may be closely correlated withinvasion of gliomas and dysPrognosis.And cooperation involved in theangiogenesis and play an important role in the initiation and progression ingliomas.2EphA2,MVD and ephrinA1all were gliomas Prognosis risk factors,whichhad independent significance to Prognosis. Simultaneous detection theexpression of EphA2, MVD and ephrinA1may have the significantguidance for the assessment of prognosis and postoperative patients radiotherapy and chemotherapy,with emphasis on the opportunities fortherapeutic targeting.