Antitumor Effect of Peptide–Camptothecin Conjugate Targeting CD133 Protein

The peptide-drug conjugate (PDC) has emerged as one of the new approaches for cancer therapy, which has the advantages of improved drug target ability and reduced adverse effects compared with the traditional chemotherapy. CD133 is a surface antigen specific to cancer stem cells, which are thought to be responsible for the self-renewal, proliferation, metastasis, and chemoresistance of cancer cells. A PDC for CD133 was designed by us, and it consists of CD133 targeting peptide LS-7 (amino acid sequence LQNAPRS), a pH-sensitive linker (succinyl), and a cytotoxic payload, the cytotoxic molecule camptothecin (CPT) with potent toxicity in vivo and in vitro. An antitumor study exhibited that the conjugate LS-7-CPT has not only improved its cytotoxicity in tumor cells but also retained its anticancer effect in vivo. In addition, the acute toxicity in mice of LS-7-CPT has been improved and the maximum tolerated dose has been increased by at least 56.2-fold. Pull-down and in vivo fluorescent imaging results indicated that LS-7-CPT was enriched in mice tumors by targeting CD133 protein. As far as we know, this is the first report for a PDC molecule designed for CD133, which is important for the study of CPT drug development.