Relationship Between Expression Of Rac1 In Hunman Gliomas And Its Biological Behavior

Background:Glioblastoma multiforme (GBM) is an extremely invasive, well-vascularized tumor believed to be of astroglial origin. It is the most prevalent and lethal of all primary malignant brain tumors, with a median survival rate of months.Despite the standard treatment of surgical resection of all primary malignant brain tumors followed by radiation and/or chemotherapy,the survival rate has increased only slightly over the past three decades.But how does glioma cell cause a series of pathophysiological changes in central nervous system? What is the molecular mechanism? These are weak links of current reaseach in glioma. In addition.It is thought that the malignant astrocytomas undergone mutisteps proceesing, which resulted in the deregulation of cell growth. These steps include:(a) the loss of function of the tumor suppressor p53; (b) the loss of function of cell cycle inhibitors, such as p16 and p19; (c) the amplification and mutation of genes encoding growth factor receptors; (d) activation of genes and proteins encoding growth-regulatory proteins, such as protein kinase C; Each of these proteins has been shown to play roles in tumor progression, cell proliferation, resistance to radiation treatment or chemotherapeutic agents, and cell migration.However, little is known about the signaling proteins that regulate survival of glioma cells.It may be related to the mechanisms of anti-apotosis.The full name of Racl is Ras-related C3 of botulinum toxin substrate 1(ras-related C3 botulinum toxinsubstratel),Rac1 gene is 29kb,contains 7 exons, located on human chromosome 7p22.Racl gene transcripts are 1.2kb and 2.5kb, both have high expressing in the tissue-specific tissues.In the transcription process, through alternative splicing,2.5kb of the Rac1 gene transcripts can be added a known exon 3b (57 nucleotides).Containing the exon 3b Rac1 gene product is known as Raclb,This is a continuing activity of a mutant.Recent studies have found that, Rac1 is a downstream molecule Ras,it was involved in Ras malignant transformation.The Rac1 of dominant negative body can inhibit the malignant transformation of Ras mutant. Rac1 itself and a variety of downstream molecules such as GEF, TRE (cis-acting element) 17 are all of a cancer gene,.Its activation can lead to malignant transformation of fibroblasts,The study also found that, Rac1 in human breast cancer is elevated,and in tumors with widespread mutations in different Ras, Rac1 has no point mutation;maybe Rac1 also play an important role in the development of liver cancer.Rac1 is closely related to secretion and apoptosis in tumor cells. Rac1 can induce exocytosis by extension,the formation of new membrane sheet and the pseudopod membrane folds.The relation with synaptic vesicles, suggesting that Rac1 controls the release of neurotransmitters. It is not clear that how Rac1 affects cells. One possibility is that Rac1 activation of phospholipase C directly causes phosphatidylinosito1-3,4, 5-triphosphate (PIP3) production,the intracellular calcium concentration,promote cell secretion.The activated Racl can inhibit apoptotic response of tumor cells by intracellular interaction of oxidase and superoxide production; The anti-apoptotic effect of Rac1 may also be associated with the NF-κB activation,NF-κB can inhibit Ras activation of the malignant transformation of cells in apoptosis.Dominant negative Racl mutant significantly enhanced physical TNF2a induced apoptosis in non-small cell lung cancer. Research also shows that,Rac1 can promote apoptosis.Apoptosis,in the role of Rac1 and its downstream effector,not only to cell foam,formation of apoptotic bodies,but also similar stimulating neighboring cells to maintain tissue integrity.The role of Racl to target proteins can induce apoptosis by activated protein (MAP) kinase pathway. Rac1 can raise the transcription of FasL to increased the expression of FasL; Also increased mitochondrial membrane potential and increased production of reactive oxygen species,These are related to cell apoptosis induced by Racl.Racl on apoptosis in addition to its effects,more by the effects of upstream signals involved in the process of apoptosis.At the same time studies show that in gastrointestinal cancer,Rac1 transcriptional activity was significantly higher than the corresponding adjacent tissues and benign lesions,The changement of Rac1 maybe is related to gastrointestinal cancer.Rac1 mainly express in the intestinal epithelium and skin. Studies have shown that progress at different stages of colorectal cancer,Rac1 expression was significantly increased,suggesting Rac1 participation in normal and malignant intestinal epithelial growth.Racl is closely related to tumor invasion and metastasis. Rac1 regulates the adhesion of cell,and the interstitial degradation of cell Found that Rac1 can regulate the activity of matrix metalloproteinases and Rac1 can activate matrix metalloproteinases collagenaseⅣ),and increased expression of collagenase,Wuming Fu et al studies have shown that,Racl play an important role in human ovarian cancer invasion and metastasis.Rac1 is also involved in tumor angiogenesis,Dominant negative Rac1 can inhibit vascular endothelial growth factor (VEGF) secretion in different degrees to inhibit tumor angiogenesis. Dominant negative Rac1 addition to enhanced expression of p53, but in the case of hypoxia inducible factor can inhibit the 21α(HIF21α) protein expression,thereby inhibiting the transcription of VEGF,VEGF mRNA expression levels decrease from the dual approach to inhibit VEGF generated. Racl also mediated hemolytic creamy acid-induced production of COX 22,and 22 and cyclooxygenase tumor angiogenesis of colorectal cancer are closely related. These are tips that Rac1 is the impact of tumor angiogenesis important molecules. There is no research about Racl with human glioma domestic and foreign。By using immunofluorescence,RT-PCR,Western blot etc,we test expression of Racl in glioma three glioma cell lines,respectively,from mRNA,protein and morphological detection. And to explore the expression of the relationship with glioma grade. To provide reference for glioma immunotherapy.Objective:We detect the expression of Racl in glioma three glioma cell lines respectively,from mRNA,protein and morphological detection. And to explore the expression of the relationship with glioma grade.Methods:1,Forty-five casesof human glioma specimens with detail clinical information and were obtained in Department of neurosurgery,Zhujiang Hospital,Southern Medical University from september 2009 to september 2010,All patients were initial cases, no line of preoperative radiotherapy and chemotherapy. The fresh specimenswere put into vials, immediately put into liquid nitrogen preservation. According to WHO classification of nervous system tumors (2000) for classification,Ⅱgrade 15 cases,Ⅲgrade 15 cases,Ⅳgrade in 15 cases (Ⅰgrade glioima was too less to collect).All pathological diagnosis were confirmed by two experienced by the two pathologists doctors.10 normal control brain tissue samples from brain injury or cerebral hemorrhage patients underwent decompression surgery.2,Detect Racl protein by immunofluorescence technology between gliomas and normal brain tissue.3,Detect the levels of Racl mRNA by RT-PCR between gliomas and normal brain tissue.4,Detect the levels of Racl protein by RT-PCR between gliomas and normal brain tissue. Results:1,fluorescence intensity of Racl significantly reduced in the normal control group,and significantly increase in the high grade.it is statistically significant between the two groups (F=1002.001,P=0.000)2,The result of Racl mRNA detected by RealTime PCR is showed by differential expression of multiple samples (2-ΔΔCt). Three levels of tumor group were 95% the number of space does not contain 1,indicating that the control group were significantly different. The three tumor group data for statistical analysis, we found a significant difference between groups (F=34.018,P=0.000). And it is statistically significant between two groups,expression of Racl mRNA increases when levels of group risies. expression of mRNA of Racl is highest in the high grade of tumors.3,The results of Racl protein in tumor cells is higher than the control group.and significantly increase in the high grade.it is statistically significant Between the two groups (F=1047.572,P=0.000)Conclusion:1,The expression of Racl in gliomas is higher than that in normal brain tissues.2,The expression of Racl in gliomas of gradeⅢ-Ⅳis much higher than that of gradeⅠ-Ⅱ,which demonstrate that Racl is relevant to the malignant level of glioma.3,The new method targeting the Racl may be a helpful way to diagnose the human gliomas,and Racl call be the criterion of the malignant level of gliomas. Accordingly can be helpful to the diagnosis and prognosis judgement of gliomas in clinic.