To clarify the role of c Myc in Angptl4 transcription, an experiment using RNAi against c Myc was also performed. Angptl4 mRNA expression in the LN229 vIII cells was significantly decreased selleck chem Ivacaftor by the knockdown Inhibitors,Modulators,Libraries of c Myc using siRNA. Similar results were obtained using another siRNA for c Myc. In a ChIP assay, bind ing of c Myc to the promoter sequence on Angptl4 was detected and the binding was significantly enhanced in the LN229 vIII cells. These findings indicate that c Myc is activated through the MAPK pathway in the LN229 vIII cells to directly regulate Angptl4 transcription. Discussion Although EGFRvIII has been shown to promote tumor growth of gliomas through various signaling pathways, the key signal molecules involved in the alteration of the tumor microenvironment have not yet been fully eluci dated.

In this study, we Inhibitors,Modulators,Libraries investigated whether EGFRvIII contributes to tumor angiogenesis, and showed dramatic increases in the microvessel density and vascular perme ability Inhibitors,Modulators,Libraries in tumor xenografts of LN229 vIII as compared to LN229 WT in mice, consistent with the results of a previ ous study. Considering that hypervascularity is a dis tinctive pathological characteristic of malignant gliomas, the EGFRvIII expression status may have a great impact on the clinical picture. Although EGFR is known to promote angiogenesis by induction of proangiogenic factors, such as VEGF A and interleukin 8, no dra matic induction of angiogenesis by wtEGFR was observed in our experiments. This difference leads to the specula tion that constitutive activation of EGFR may trigger strik ing induction of various transcripts, including pro angiogenic factors.

In order to examine the molecular mechanisms underlying the induction of angiogenesis by EGFRvIII, the expressions of 60 angiogenic factors in LN229 cells were examined by real time PCR analysis. Al though VEGF A is a representative angiogenic Inhibitors,Modulators,Libraries factor and a possible therapeutic target for glioblastoma, VEGF A induction by EGFRvIII was observed only to a certain extent in vivo, and not at all in vitro. Among the 60 angiogenic fac tors, we first found that Angptl4 expression was signifi cantly induced by EGFRvIII overexpression, and that Angptl4 acts as a pro angiogenic factor in tumor xeno grafts. Recently, Bonavia, et al.

showed that the NF kB/IL 8 pathway Inhibitors,Modulators,Libraries plays important selleck roles in EGFRvIII induced angiogenesis and growth in gliomas, however, no sig nificant change of the IL 8 expression was observed in our in vitro experiment. It is likely that the differences between our results and those of the previous report are related to differences in the cell lines. The molecular mechanisms of Angptl4 induced angio genesis in malignant gliomas still remain largely unknown. Angptl4 is expressed in the liver, adipose tissue and pla centa, as also in ischemic tissues.