FIGURE 1.

Evidence for EV-mediated extracellular release of the oncogenic EGFRvIII by human GBM cells in vivo and in vitro. A, analysis of GBM tissue samples for EGFRvIII mRNA. Hypoxanthine phosphoribosyltransferase 1 (HGPRT1) was used as a loading control, as described previously (31). Lower lane, EGFRvIII protein signal was detected by Western blotting in EV preparations from plasma of patients with EGFRvIII-expressing tumors where the EGFRvIII band is apparent, despite the fact that the quality of the archival plasma samples was relatively poor and negatively impacted protein integrity in exosomal isolates and the image quality. B, detection of EGFRvIII in plasma of SCID mice harboring human GBM intracranial xenografts positive (EGFRvIII+) or negative (EGFRvIII−) for EGFRvIII expression. C, detection of EGFR and P-EGFR in cell lysates and EV preparations of conditioned medium from control U373 indolent glioma cells and their aggressive variant (U373vIII) transfected with EGFRvIII expression vector (31).