Design and biological activity of epidermal growth factor receptor-targeted peptide doxorubicin conjugate

The nonspecific toxicity of anticancer drug doxorubicin (DOX) toward both tumor and normal cells can result in serious side effects, thereby limiting its clinical applications. In this wok, epidermal growth factor receptor (EGFR) antagonist peptide GE11 was introduced into DOX structure via a disulfide bond which can be cleaved by reduced glutathione (GSH). We have investigated the intracellular delivery and in vitro cytotoxicity of GE11-DOX conjugate and free DOX in high (SMMC-7721) and low (MCF-7) EGFR expressing cancer cell models. GE11-DOX accumulated at higher levels in SMMC-7721 cells than in MCF-7 cells, while the cellular uptake of free DOX was almost the same in both cells. Furthermore, pretreating with anti-EGFR monoclonal antibody reduced intracellular accumulation of GE11-DOX in SMMC-7721, indicating the involvement of EGFR pathway in the transport of conjugate. Our results suggest that GE11-DOX conjugate has the potential to be a therapeutic agent for treating EGFR overexpressing tumor.