Fusion protein of adenovirus E4orf4 and human epidermal growth factor inhibits tumor cell growth.

Adenovirus early region 4 open reading frame 4 (E4orf4) protein is a novel cell death factor that selectively induces apoptosis in cancer cells. This study evaluated tumor inhibitory effects of a protein made by fusion E4orf4 and human epidermal growth factor (EGF). EGF was used to ensure the selective targeting of EGF receptor (EGFR)-overexpressing tumor cells. Results showed that EGF-E4orf4 stimulated EGFR phosphorylation in a time- and dose-dependent manner. Confocal microscopy analysis showed both EGF-E4orf4 and EGF could be internalized via EGFR but they had different intercellular trafficking pathways. In vitro study showed that EGF-E4orf4 significantly inhibited the proliferation of BGC823 and in vivo study showed EGF-E4orf4 suppressed tumor growth in a dose-dependent fashion with an inhibition rate of 79% for MDA-MB-231 and 49% for BGC 823 (p < 0.05). No toxic effects were observed in the nude mice with a dose as high as 10 mg/kg of EGF-E4orf4. These results indicated that EGF-E4orf4 could be a potential drug for cancer therapy. 2009 UICC.