Effects of doxorubicin-encapsulating AG73 peptide-modified liposomes on tumor selectivity and cytotoxicity

Doxorubicin-encapsulating liposomal formulations, known as Doxil, have been used for the treatment of Kaposi's sarcoma and ovarian cancer. However, there is still a need for a drug delivery system for doxorubicin that limits the treatment's side effects, namely, mucositis and hand-and-foot syndrome. The AG73 peptide derived from the laminin α1 chain is a ligand for syndecans, and syndecan-2 is highly expressed in some cancer cells. In this study, to develop a safer and more selective liposomal formulation, we prepared doxorubicin-encapsulating AG73 peptide-modified liposomes (AG73-Dox). First, we assessed the selectivity of AG73-Dox for cancer cells, including syndecan-2 over-expressing cells, using flow cytometry and confocal microscopy. AG73-Dox showed selective cellular uptake on cancer cells and enhancement of the intracellular uptake. Next, we examined the cytotoxicity of AG73-Dox using a WST assay. AG73-Dox exhibited a higher cytotoxicity against cancer cells than other control liposomes. In addition, we showed that the antitumor efficacy of AG73-Dox in vivo was better than that of free Dox. When we examined the biodistribution of liposomes, AG73 peptide-modified liposomes (AG73-L) tended to bind to intratumoral vessels and extravasated in the tumor tissue. Thus, further optimization of AG73-L toward tumor targeting may lead to a development of a useful tool for cancer therapy.