Effects of panitumumab on the proteome of treated EGFRvIII glioblastoma cells and on their extracellular vesicles

Abstract

Glioblastoma (GB) is an aggressive brain tumor for which reliable biomarkers of therapeutic response are still needed. Extracellular vesicles (EVs) can carry molecular components derived from their parent cells, thereby providing information on changes associated with the tumor and treatments. Among potential biomarkers, epidermal growth factor receptor variant III (EGFRvIII), is found in more than 40% of GB patients and is associated with aggressive tumor behavior and therapeutic resistance. EGFRvIII has also been detected on the surface of EVs, suggesting its potential value for monitoring tumor-associated molecular changes. This study investigated the effects of panitumumab, an anti-EGFR monoclonal antibody, on the proteomic profiles of EVs derived from EGFRvIII cells. U87 and U87-EGFRvIII cells and their derived EVs were characterized before and after treatment. EGFRvIII expression in cells and EVs was assessed by Western blotting and flow cytometry. Proteomic analyses were performed on cell lysates and EVs before and after treatment. Our results demonstrate that panitumumab significantly reduced surface EGFRvIII on EVs derived from U87-EGFRvIII cells, whereas no significant decrease was observed in cell lysates. This suggests that treatment may affect EGFRvIII trafficking or its incorporation into EVs. The proteomic analysis highlighted much more changes in EVs than in their parental cells after treatment, particularly in proteins associated with extracellular matrix organization and collagen. Together, these results demonstrate that panitumumab treatment is associated with changes in protein profile from EVs derived from EGFRvIII cells suggesting that the panitumumab treatment might have an impact on cells that could be reflected on EVs released by glioblastoma cells. In conclusion, our results suggest that EVs derived from EGFRvIII cells could serve as a useful circulating biomarker for assessing treatment efficacy and for preventing treatment escape.