EGFRvIII/STAT3 targets in glioblastoma pathogenesis

Next generation sequencing platforms were used to identify STAT3 targets in the background of EGFRvIII expresssion Overall design: mRNA of 3 EGFRvIII positive brain tumor stem cell lines (BTSC #68, 73, and 90) were compared to an EGFRvIII negative line (#41) to identify EGFRvIII-regulated targets in human BTSC. EGFRvIII-dependent targets in mouse astrocytes were identified by mRNA-seq analyses of EGFRvIII- or MSCV-expressing astrocytes. STAT3-differentially regulated genes in EGFRvIII expressing mouse astrocytes were obtained by subjecting EGFRvIII,STAT3f/f and EGFRvIII, STAT3-/- astrocytes to mRNA-Seq analyses. Sites of STAT3 occupancy in EGFRvIII expressing astrocytes were identified by ChIP-Seq using a STAT3 antibody or IgG control. We identified OSMR as a direct target of STAT3 in both EGFRvIII-expressing human BTSC and mouse astrocytes. Therefore to identify OSMR-regulated genes, we used a lentiviral mediated RNAi system to knockdown OSMR in EGFRvIII-expressing astrocytes. OSMR-dependent differentially expressed genes were obtained by comparison of OSMR knockdown (KD1 and KD2) astrocytes to control groups (ShRNA control and Vector control)