title: Acid-Sensitive Peptide-Conjugated Doxorubicin Mediates the Lysosomal Pathway of Apoptosis and Reverses Drug Resistance in Breast Cancer.
abstract: The extended use of doxorubicin (DOX) could be limited because of the emergence of drug resistance associated with its treatment. To reverse the drug resistance, two thiol-modified peptide sequences HAIYPRHGGC and THRPPMWSPVWPGGC were, respectively, conjugated to DOXO-EMCH, forming a maleimide bridge in this study (i.e., T10-DOX and T15-DOX). The structures and properties of peptide-DOX conjugates were characterized using (1)H NMR, (13)C NMR, mass spectrometry, and high-performance liquid chromatography. Their stability was also evaluated. By using MCF-7/ADR cells as an in vitro model system and nude mice bearing MCF-7/ADR xenografts as an in vivo model, the ability of these novel peptide-DOX conjugates to reverse drug resistance was accessed as compared with free DOX. As a result, the IC50 values for T10-DOX and T15-DOX significantly decreased (31.6 ± 1.6 μM and 27.2 ± 0.8 μM), whereas the percentage of apoptotic cell population increased (35.4% and 39.3%). The in vivo extent of inhibition was more evident in the mice groups treated with peptide-DOX conjugates (59.6 ± 8.99% and 46.4 ± 6.63%), which had DOX primarily accumulated in tumor. These conjugates also showed a longer half-life in plasma and cleared much more slowly from the body. Furthermore, T10-DOX may be more effective than T15-DOX with a higher efficacy and a lower side effect. Most importantly, evidence was provided to support the enhanced intracellular drug accumulation and the induction of lysosomal pathway of apoptosis underlying the drug resistance. As an endosomal/lysosomal marker, cathepsin D permealized the destabilized organelle membrane and was detected in the cytoplasm, leading to the activation of the effector caspase-3 in cell apoptosis. This report is among the first to demonstrate that peptide-DOX-like conjugates promote apoptosis through the initiation of the lysosomal pathway.
authors.affiliation: †Nanjing Medical University, Nanjing 211166, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Sheng
authors.affiliation: ‡Department of Pharmacy, Suzhou Municipal Hospital, Suzhou 215001, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Xu
authors.affiliation: †Nanjing Medical University, Nanjing 211166, China.
authors.forename: Yiwen
authors.initials: Y
authors.lastname: You
authors.affiliation: †Nanjing Medical University, Nanjing 211166, China.
authors.forename: Feifei
authors.initials: F
authors.lastname: Xu
authors.affiliation: †Nanjing Medical University, Nanjing 211166, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000494:pharmacology*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D006207:Half-Life; D006801:Humans; D008247:Lysosomes / Q000187:drug effects*; D061986:MCF-7 Cells; D051379:Mice; D008819:Mice, Nude; D010455:Peptides / Q000494:pharmacology*
chemical_list: D010455:Peptides; D004317:Doxorubicin; D053148:Caspase 3
keywords: acid sensitive; doxorubicin; drug resistance reversal; lysosomal pathway; peptide conjugates; transferrin receptor-mediated drug delivery