Expression Of Ras And ERK1/2 Protein In Human Glioma And Its Clinical Significance

Background and objectionDespite advances in the ability to diagnose and treat many cancers, successfultreatment of primary brain tumors remains extremely challenging.As the most prevalentprimary brain tumors of adults. Malignant gliomas are highly invasive and very difficultto treat, despite of surgery,γ-irradiation and chemotherapy. Current treatments forglioblastoma multiforme result in a poor median survival of less than 12months.Thislimited survival for glioblastoma patients indicates a need for innovative therapiestargeting glioblastomas. Novel therapies are likely to arise from the targeting ofmultiple molecular pathways altered during glioma formation and progression.Two signal transduction cascades known to contribute to the formation ofglioblastomas are the Ras-Raf-MEK-ERK/mitogen-activated protein kinase(MAPK)and phosphatidylinositol3- kinase (PI3K)-AKT-target of rapamycin (TOR)pathways.TheRas–Raf–MEK–ERK/MAPK pathway mediates cellular responses togrowth signals,differentiation and programmed cell death.Ras and ERK are two keyproteins in this pathway. The Ras family members are small GTPases that stimulateproliferation, invasion,and secretion of angiogenic factors through activation ofdownstream effectors including Raf family members .Despite the lack of activatingmutations of Ras family members in central nervous system tumors.gliomas through theactivation of upstream growth factor receptors including epidermal growth factorreceptor (EGFR) and platelet-derived growth factor receptor(PDGFR).Thecontributions of Ras in glioma formation have been dissected in several studies ofgenetically defined human and murine glioma models in which oncogenic Ras can drive gliomagenesis.The importance of increased Ras-activity in GBMs is further supportedby studies demonstrating reduced growth of GBM cell lines when treated withdominant-negative Ras mutants or Ras pathway inhibitor drugs.ERK1 ?ERK2 are twoisoforms of extracellular signal-regulated kinase (ERK)that belong to the family ofmitogen-activated protein kinases.In the ERK signaling pathway, ERK1/2 is activatedby MEK1/2, which is activated by Raf. Raf is activated by the Ras GTPase, whoseactivation is induced by RTKs such as the epidermal growth factor receptor. Thisenzymes are activated through a sequential phosphor- ylation cascade that amplifies andtransduces signals from the cell membrane to the nucleus.mediate different events,suchas proliferatio- n,differentiation and apoptosis.Nowdays,The expression Ras,ERK1/2and p-ERK1/2 in human glioma and its biological function and mechanism has beenlittle reported,This study was focused on the expression of the Ras,ERK1/2 andp-ERK1/2 in different grades of glioma specimens and normal human brain tissues byemiquantitative reverse transcriptase-polymeRase chain reaction (RT-PCR) andimmunohistochemistry.To investigate the expression of ERK/MAPK signal pathway innormal brain tissues and glioma tissues and analyze their clinical significance.MethodThe 48 specimens of glioma were selected from October,2006 to 2008 from thedepartment of neurosurgery in the First Hospital of Nanjing Medical University,and allpathologically validated.including 15 with WHO I-II,21with WHO III,12 with WHO IVand 8 specimens of normal brain tissue.All specimens of glioma have no treatment suchas radiotherapy and chemotherapy. The experimental method is as follows.1 Detected the expression of the Ras mRNA level by Reverse TranscriptionPolymeRase Chain Reaction(RT-PCR)Total RNA was extracted using Trizol in different grades of glioma tissues,measureRNA of pure and Total RNA by RT,enlarge cDNA by RT- PCR,Analysis the expression of the Ras mRNA level .2 Detecteetected the expression of Ras,ERK1/2 and p-ERK1/2 in immunohistochemistrymethodWe dedected the expression of Ras,ERK1/2 and p-ERK1/2 in different grades ofglioma and normal brain tissues in immunohistochemistry method.and utilized theimage analysis software (HPLAS-1000)to count and analysis the specimens. Statisticanalysis was completed with statistic software SPSS13.0,analysis of variance,Chi-Square Tests was used. p<0.05 , was as the level for statistical significance .Results1 The erpression of Ras protein and the relationship between the differentpathological grade of glioma and normal brain tissuesRas was expressed in glioma, and the expression of Ras couple with advancingpathological grades. The expression of Ras protein in higher grade astrocytomas (gradeⅢandⅣ)was significantly higher than that in lower grade astrocytomas (gradeⅠandⅡ).2 The expression of the Ras mRNA in different grades of glioma and normalbrain tissuesThe expression of the Ras protein was weak in normal human brain tissues,butstrong expression in higher grade glioma tissues (gradeⅢ~Ⅳ)were higher than thatin lower grade glioma tissues (gradeⅠ~Ⅱ).3 The erpression of ERK1/2 and p-ERK1/2 protein and the relationship betweenthe different pathological grade of glioma and normal brain tissuesERK1/2 and p-ERK1/2 protein was expressed in glioma, Compared with normalbrain tissue,ERK1/2 and p-ERK1/2 protein expression were significantly different.4 The erpression of ERK1/2 and p-ERK1/2 protein and the relationship betweenthe different pathological grade of glioma The expression of ERK1/2 and p-ERK1/2 couple with advancing pathologicalgrades.The expression of ERK1/2 and p-ERK1/2 in higher grade astrocytomas(gradeⅢandⅣ)was significantly higher than that in lower grade astrocytomas(gradeⅠandⅡ).ConclusionConclusionsThe experimental results confirmed that Ras,ERK1/2 and p-ERK1/2 expression wassignificantly higher than normal brain tissue,and in increased with glioma grade.Rasand ERK1/2 as the two important proteins in ERK/MAPK signaling pathway,wereinvolved proliferation and development procession in glioma.This results provide atheoretical basis to explain the molecular biology diagnosis of glioma,prognosisassessment.and to further explore the molecular therapy targerted to ERK pathway.