title: Enhancing cellular uptake of activable cell-penetrating peptide-doxorubicin conjugate by enzymatic cleavage.
abstract: The use of activable cell-penetrating peptides (ACPPs) as molecular imaging probes is a promising new approach for the visualization of enzymes. The cell-penetrating function of a polycationic cell-penetrating peptide (CPP) is efficiently blocked by intramolecular electrostatic interactions with a polyanionic peptide. Proteolysis of a proteinase-sensitive substrate present between the CPP and polyanionic peptide affords dissociation of both domains and enables the activated CPP to enter cells. This ACPP strategy could also be used to modify antitumor agents for tumor-targeting therapy. Here, we aimed to develop a conjugate of ACPP with antitumor drug doxorubicin (DOX) sensitive to matrix metalloproteinase-2 and -9 (MMP-2/9) for tumor-targeting therapy purposes. The ACPP-DOX conjugate was successfully synthesized. Enzymatic cleavage of ACPP-DOX conjugate by matrix metalloproteinase (MMP)-2/9 indicated that the activation of ACPP-DOX occurred in an enzyme concentration-dependent manner. Flow cytometry and laser confocal microscope studies revealed that the cellular uptake of ACPP-DOX was enhanced after enzymatic-triggered activation and was higher in HT-1080 cells (overexpressed MMPs) than in MCF-7 cells (under-expressed MMPs). The antiproliferative assay showed that ACPP had little toxicity and that ACPP-DOX effectively inhibited HT-1080 cell proliferation. These experiments revealed that the ACPP-DOX conjugate could be triggered by MMP-2/9, which enabled the activated CPP-DOX to enter cells. ACPP-DOX conjugate may be a potential prodrug delivery system used to carry antitumor drugs for MMP-related tumor therapy.
authors.affiliation: Department of Pharmaceutics, School of Pharmaceutical Sciences, Peking University, Beijing, People's Republic of China.
authors.forename: Nian-Qiu
authors.initials: NQ
authors.lastname: Shi
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.forename: Bai
authors.initials: B
authors.lastname: Xiang
authors.forename: Xian-Rong
authors.initials: XR
authors.lastname: Qi
mesh_terms: D000135:Acid Phosphatase; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use; D001693:Biological Transport, Active; D001943:Breast Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage* / Q000378:metabolism / Q000627:therapeutic use; D016503:Drug Delivery Systems; D005260:Female; D005354:Fibrosarcoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D050997:Nanomedicine; D017027:Protein Tyrosine Phosphatases / Q000008:administration & dosage* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D004317:Doxorubicin; D000135:Acid Phosphatase; C428439:prostatic acid phosphatase; D017027:Protein Tyrosine Phosphatases; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9