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Tang B, Zaro JL, Shen Y, Chen Q, Yu Y, Sun P, Wang Y, Shen WC, Tu J, Sun C. Acid-sensitive hybrid polymeric micelles containing a reversibly activatable cell-penetrating peptide for tumor-specific cytoplasm targeting. J Control Release 2018; 279:147-156. [DOI: 10.1016/j.jconrel.2018.04.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/20/2018] [Accepted: 04/09/2018] [Indexed: 12/29/2022]
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Zhou L, Wang HY, Tong S, Okamoto CT, Shen WC, Zaro JL. Single chain Fc-dimer-human growth hormone fusion protein for improved drug delivery. Biomaterials 2017; 117:24-31. [DOI: 10.1016/j.biomaterials.2016.11.051] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 01/09/2023]
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Shao J, Zaro JL, Shen WC. Proinsulin-Transferrin Fusion Protein Exhibits a Prolonged and Selective Effect on the Control of Hepatic Glucose Production in an Experimental Model of Type 1 Diabetes. Mol Pharm 2016; 13:2641-6. [PMID: 27280852 DOI: 10.1021/acs.molpharmaceut.6b00168] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An ideal basal insulin (INS) replacement therapy requires the distribution or action of exogenous INS to more closely mimic physiological INS in terms of its preferential hepatic action. In this paper, we introduce a novel strategy to exert liver-specific INS action by hepatic activation of INS's precursor, proinsulin (ProINS). We demonstrated the conversion of human ProINS-transferrin (Tf) fusion protein, ProINS-Tf, into an active and immuno-reactive form of INS-Tf in the liver via the slow Tf receptor mediated recycling pathway. ProINS-Tf displayed prolonged basal blood glucose lowering effects for up to 40 h in streptozotocin-induced type 1 diabetic mice following a single subcutaneous injection. The effect of ProINS-Tf on blood glucose levels was observed predominantly under fasting conditions, with little effect under free-feeding conditions. In addition, both the pyruvate tolerance assay in normal mice and the Akt-phosphorylation assay in H-4-II-E hepatoma cells indicated that the hepatic-activated ProINS-Tf possessed a much longer effect on the control of hepatic glucose production than INS. These results indicated that ProINS-Tf may serve as an effective and safe hepatoselective INS analog to reduce the frequency of INS injections as well as avert severe hypoglycemia episodes and other side effects frequently encountered with long-acting INS therapeutics due to their peripheral action.
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Affiliation(s)
- Juntang Shao
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , 1985 Zonal Avenue, Los Angeles, California 90033, United States
| | - Jennica L Zaro
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , 1985 Zonal Avenue, Los Angeles, California 90033, United States
| | - Wei-Chiang Shen
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , 1985 Zonal Avenue, Los Angeles, California 90033, United States
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Shao J, Zaro JL, Shen WC. Tissue barriers and novel approaches to achieve hepatoselectivity of subcutaneously-injected insulin therapeutics. Tissue Barriers 2016; 4:e1156804. [PMID: 27358753 DOI: 10.1080/21688370.2016.1156804] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 02/09/2016] [Accepted: 02/11/2016] [Indexed: 10/22/2022] Open
Abstract
Current subcutaneously (s.c.)-injected insulin (INS) products result in a hyperinsulin exposure to peripheral tissues (skeletal muscle and adipose) while INS hardly accesses to liver after injection. This unphysiological distribution raises risks of hypoglycemia episode and causes weight gain after long term treatment. An ideal INS replacement therapy requires the distribution or action of exogenous INS to more closely mimic physiological INS in terms of its preferential hepatic action. However, there are 2 factors that limit the ability of s.c. injected INS to restore the liver: peripheral gradient in INS deficient diabetes patients: (1) the transport of INS in capillary endothelium and peripheral tissues from the injection site; and (2) peripheral INS receptor (IR) mediated INS degradation. In this review, the tissue barriers against efficient liver targeting of s.c. injected INS are discussed and current advances in developing hepatoselective insulin therapeutics are introduced.
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Affiliation(s)
- Juntang Shao
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , Los Angeles, CA, USA
| | - Jennica L Zaro
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , Los Angeles, CA, USA
| | - Wei-Chiang Shen
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California , Los Angeles, CA, USA
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Yeh TH, Chen YR, Chen SY, Shen WC, Ann DK, Zaro JL, Shen LJ. Selective Intracellular Delivery of Recombinant Arginine Deiminase (ADI) Using pH-Sensitive Cell Penetrating Peptides To Overcome ADI Resistance in Hypoxic Breast Cancer Cells. Mol Pharm 2015; 13:262-71. [PMID: 26642391 DOI: 10.1021/acs.molpharmaceut.5b00706] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Arginine depletion strategies, such as pegylated recombinant arginine deiminase (ADI-PEG20), offer a promising anticancer treatment. Many tumor cells have suppressed expression of a key enzyme, argininosuccinate synthetase 1 (ASS1), which converts citrulline to arginine. These tumor cells become arginine auxotrophic, as they can no longer synthesize endogenous arginine intracellularly from citrulline, and are therefore sensitive to arginine depletion therapy. However, since ADI-PEG20 only depletes extracellular arginine due to low internalization, ASS1-expressing cells are not susceptible to treatment since they can synthesize arginine intracellularly. Recent studies have found that several factors influence ASS1 expression. In this study, we evaluated the effect of hypoxia, frequently encountered in many solid tumors, on ASS1 expression and its relationship to ADI-resistance in human MDA-MB-231 breast cancer cells. It was found that MDA-MB-231 cells developed ADI resistance in hypoxic conditions with increased ASS1 expression. To restore ADI sensitivity as well as achieve tumor-selective delivery under hypoxia, we constructed a pH-sensitive cell penetrating peptide (CPP)-based delivery system to carry ADI inside cells to deplete both intra- and extracellular arginine. The delivery system was designed to activate the CPP-mediated internalization only at the mildly acidic pH (6.5-7) associated with the microenvironment of hypoxic tumors, thus achieving better selectivity toward tumor cells. The pH sensitivity of the CPP HBHAc was controlled by recombinant fusion to a histidine-glutamine (HE) oligopeptide, generating HBHAc-HE-ADI. The tumor distribution of HBHAc-HE-ADI was comparable to ADI-PEG20 in a mouse xenograft model of human breast cancer cells in vivo. In addition, HBHAc-HE-ADI showed increased in vitro cellular uptake in cells incubated in a mildly acidic pH (hypoxic conditions) compared to normal pH (normoxic conditions), which correlated with pH-sensitive in vitro cytotoxicity in hypoxic MDA-MB-231 and human prostate cancer PC3 cells. Together, we conclude that the HBHAc-HE-based peptide delivery offers a useful means to overcome hypoxia-induced resistance to ADI in breast cancer cells, and to target the mildly acidic tumor microenvironment.
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Affiliation(s)
- Tzyy-Harn Yeh
- School of Pharmacy, College of Medicine, National Taiwan University , Taipei, Taiwan.,Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , Los Angeles, California 90033, United States
| | - Yun-Ru Chen
- Department of Metabolic Research, Beckman Research Institute, City of Hope , Duarte, California 91010, United States
| | - Szu-Ying Chen
- Department of Metabolic Research, Beckman Research Institute, City of Hope , Duarte, California 91010, United States.,Department of Medical Laboratory Science and Biotechnology, National Cheng Kung University , Tainan, Taiwan
| | - Wei-Chiang Shen
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , Los Angeles, California 90033, United States
| | - David K Ann
- Department of Metabolic Research, Beckman Research Institute, City of Hope , Duarte, California 91010, United States
| | - Jennica L Zaro
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California , Los Angeles, California 90033, United States
| | - Li-Jiuan Shen
- School of Pharmacy, College of Medicine, National Taiwan University , Taipei, Taiwan.,Graduate Institute of Clinical Pharmacy, College of Medicine, National Taiwan University , Taipei, Taiwan.,Department of Pharmacy, National Taiwan University Hospital , Taipei, Taiwan
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Zaro JL, Shen WC. Cationic and amphipathic cell-penetrating peptides (CPPs): Their structures and in vivo studies in drug delivery. Front Chem Sci Eng 2015. [DOI: 10.1007/s11705-015-1538-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Abstract
The combination of lipid drug delivery systems with prodrugs offers several advantages including improved pharmacokinetics, increased absorption, and facilitated targeting. Lipidization and use of lipid carriers can increase the pharmacological half-life of the drug, thus improving pharmacokinetics and allowing less frequent dosing. Lipids also offer advantages such as increased absorption through the intestines for oral drug absorption and to the CNS for brain delivery. Furthermore, the use of lipid delivery systems can enhance drug targeting. Endogenous proteins bind lipids in the blood and carry them to the liver to enable targeting of this organ. Drugs with significant side effects in the stomach can be specifically delivered to enterocytes by exploiting lipases for prodrug activation. Finally, lipids can be used to target the lymphatic system, thus bypassing the liver and avoiding first-pass metabolism. Lymphatic targeting is also important for antiviral drugs in the protection of B and T lymphocytes. In this review, both lipid-drug conjugates and lipid-based carriers will be discussed. An overview, including the chemistry and assembly of the systems, as well as examples from the clinic and in development, will be provided.
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Affiliation(s)
- Jennica L Zaro
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Ave., PSC 406BA, Los Angeles, California, 90033, USA,
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Abstract
Proinsulin-transferrin (ProINS-Tf) fusion protein was evaluated for its in vivo pharmacokinetics, efficacy, and mechanism. Our previous studies have shown that ProINS-Tf was converted to active insulin-transferrin (INS-Tf) via the transferrin (Tf)-receptor-mediated pathway in hepatoma cells. We hypothesized that this fusion protein can be administered as a prodrug and be converted to a biologically active protein with specificity for the liver versus other insulin (INS)-sensitive tissues (muscle and adipose). Administration as an inactive prodrug with liver-specific action compared with other INS-sensitive tissues conceivably reduces negative side effects seen with other INS analogs. In this report, the data show that ProINS-Tf exhibited a slow, but sustained, in vivo hypoglycemic efficacy and long plasma half-life. The fusion protein showed activity in the liver, as evidenced by decreased expression of two key hepatic glucose production (HGP) enzymes, PEPCK and glucose-6-phosphatase, and increased glycogen levels under feeding conditions. Furthermore, the INS receptor (IR) phosphorylation (activation) in liver and muscle tissues was compared with postinjection of INS or ProINS-Tf. While INS activated IR in both the liver and muscle, ProINS-Tf only showed activation in the liver. Thus, ProINS-Tf fusion protein can potentially be administered as a prodrug with sustained Tf-mediated activation and selectivity in inhibiting HGP.
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Sun C, Shen WC, Tu J, Zaro JL. Interaction between cell-penetrating peptides and acid-sensitive anionic oligopeptides as a model for the design of targeted drug carriers. Mol Pharm 2014; 11:1583-90. [PMID: 24697211 PMCID: PMC4012841 DOI: 10.1021/mp400747k] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Overcoming the nonspecific cellular uptake of cell-penetrating peptides (CPPs) is a major hurdle in their clinical application. Using pH as the activation switch, histidine-glutamic acid (HE) dipeptide repeats were fused to CPPs to trigger the membrane-penetrating activity at mildly acidic pH environments (i.e., pH 6.5 or below) while masking the internalization at neutral pH (i.e., pH 7.0 or above). In this study, a series of recombinant GST-fusion proteins containing an HE oligopeptide sequence (i.e., (HE)n with n = 8, 10, or 12) and a cationic CPP (i.e., YG(RG)6, YGR6G6, or Tat) were engineered for a pH-sensitive study comparing their cellular uptake and surface binding in cultured HeLa cells. Circular dichroism (CD) spectroscopy was performed to correlate differences between CPPs in secondary structure with the pH sensitivity. YGR6G6 with clustered arginine residues exhibited greater pH sensitivity in cellular uptake than YG(RG)6 with separated arginine residues. Increasing the stretch of HE repeats decreased cellular uptake and surface binding for both YG(RG)6 and YGR6G6. The ratio of cellular internalization at pH 7.5 vs 6.0 was not changed by the presence of serum. CD spectral data revealed that both (HE)10-Tat and (HE)10-YGR6G6 exhibited an unordered secondary structure, whereas (HE)10-YG(RG)6 adopted an antiparallel β-sheet conformation. This β-sheet conformation presumably stabilized the association of (HE)10 with YG(RG)6, leading to weakened pH sensitivity of (HE)10-YG(RG)6. On the other hand, the random-coiled structures, that is, (HE)10-YGR6G6 and (HE)10-Tat, both showed higher pH sensitivity as determined in cell experiments. The data presented in this study provide a basis for the future design of pH-sensitive HE-CPP carrier for targeted drug delivery.
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Affiliation(s)
- Chunmeng Sun
- State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University , 24 Tong Jia Xiang, Nanjing 210009, China
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Hackett MJ, Zaro JL, Shen WC, Guley PC, Cho MJ. Fatty acids as therapeutic auxiliaries for oral and parenteral formulations. Adv Drug Deliv Rev 2013; 65:1331-9. [PMID: 22921839 DOI: 10.1016/j.addr.2012.07.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 06/25/2012] [Accepted: 07/20/2012] [Indexed: 01/08/2023]
Abstract
Many drugs have decreased therapeutic activity due to issues with absorption, distribution, metabolism and excretion. The co-formulation or covalent attachment of drugs with fatty acids has demonstrated some capacity to overcome these issues by improving intestinal permeability, slowing clearance and binding serum proteins for selective tissue uptake and metabolism. For orally administered drugs, albeit at low level of availability, the presence of fatty acids and triglycerides in the intestinal lumen may promote intestinal uptake of small hydrophilic molecules. Small lipophilic drugs or acylated hydrophilic drugs also show increased lymphatic uptake and enhanced passive diffusional uptake. Fatty acid conjugation of small and large proteins or peptides has exhibited protracted plasma half-lives, site-specific delivery and sustained release upon parenteral administration. These improvements are most likely due to associations with lipid-binding serum proteins, namely albumin, LDL and HDL. These molecular interactions, although not fully characterized, could provide the ability of using the endogenous carrier systems for improving therapeutic outcomes.
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Affiliation(s)
- Michael J Hackett
- University of North Carolina, Chapel Hill, School of Pharmacy, Division of Molecular Pharmaceutics, USA
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Abstract
As an indispensable component of recombinant fusion proteins, linkers have shown increasing importance in the construction of stable, bioactive fusion proteins. This review covers the current knowledge of fusion protein linkers and summarizes examples for their design and application. The general properties of linkers derived from naturally-occurring multi-domain proteins can be considered as the foundation in linker design. Empirical linkers designed by researchers are generally classified into 3 categories according to their structures: flexible linkers, rigid linkers, and in vivo cleavable linkers. Besides the basic role in linking the functional domains together (as in flexible and rigid linkers) or releasing the free functional domain in vivo (as in in vivo cleavable linkers), linkers may offer many other advantages for the production of fusion proteins, such as improving biological activity, increasing expression yield, and achieving desirable pharmacokinetic profiles.
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Affiliation(s)
- Xiaoying Chen
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA 90089, USA
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Zhang D, Lee HF, Pettit SC, Zaro JL, Huang N, Shen WC. Characterization of transferrin receptor-mediated endocytosis and cellular iron delivery of recombinant human serum transferrin from rice (Oryza sativa L.). BMC Biotechnol 2012. [PMID: 23194296 PMCID: PMC3521190 DOI: 10.1186/1472-6750-12-92] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Transferrin (TF) plays a critical physiological role in cellular iron delivery via the transferrin receptor (TFR)-mediated endocytosis pathway in nearly all eukaryotic organisms. Human serum TF (hTF) is extensively used as an iron-delivery vehicle in various mammalian cell cultures for production of therapeutic proteins, and is also being explored for use as a drug carrier to treat a number of diseases by employing its unique TFR-mediated endocytosis pathway. With the increasing concerns over the risk of transmission of infectious pathogenic agents of human plasma-derived TF, recombinant hTF is preferred to use for these applications. Here, we carry out comparative studies of the TFR binding, TFR-mediated endocytosis and cellular iron delivery of recombinant hTF from rice (rhTF), and evaluate its suitability for biopharmaceutical applications. Result Through a TFR competition binding affinity assay with HeLa human cervic carcinoma cells (CCL-2) and Caco-2 human colon carcinoma cells (HTB-37), we show that rhTF competes similarly as hTF to bind TFR, and both the TFR binding capacity and dissociation constant of rhTF are comparable to that of hTF. The endocytosis assay confirms that rhTF behaves similarly as hTF in the slow accumulation in enterocyte-like Caco-2 cells and the rapid recycling pathway in HeLa cells. The pulse-chase assay of rhTF in Caco-2 and HeLa cells further illustrates that rice-derived rhTF possesses the similar endocytosis and intracellular processing compared to hTF. The cell culture assays show that rhTF is functionally similar to hTF in the delivery of iron to two diverse mammalian cell lines, HL-60 human promyelocytic leukemia cells (CCL-240) and murine hybridoma cells derived from a Sp2/0-Ag14 myeloma fusion partner (HB-72), for supporting their proliferation, differentiation, and physiological function of antibody production. Conclusion The functional similarity between rice derived rhTF and native hTF in their cellular iron delivery, TFR binding, and TFR-mediated endocytosis and intracellular processing support that rice-derived rhTF can be used as a safe and animal-free alternative to serum hTF for bioprocessing and biopharmaceutical applications.
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Affiliation(s)
- Deshui Zhang
- Ventria Bioscience, Fort Collins, CO 80524, USA.
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Kenien R, Shen WC, Zaro JL. Vesicle-to-cytosol transport of disulfide-linked cargo mediated by an amphipathic cell-penetrating peptide. J Drug Target 2012; 20:793-800. [DOI: 10.3109/1061186x.2012.719899] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
INTRODUCTION The development of biotechnology has enabled the creation of various recombinant fusion proteins as a new class of biotherapeutics. The uniqueness of fusion proteins lies in their ability to fuse two or more protein domains, providing vast opportunities to generate novel combinations of functions. Pharmacokinetic (PK) studies, which are critical components in preclinical and clinical drug development, have not been fully explored for fusion proteins. The lack of general PK models and study guidelines has become a bottleneck for translation of fusion proteins from basic research to the clinic. AREAS COVERED This article reviews the current status of PK studies for fusion proteins, covering the processes that affect PK. According to their PK properties, a classification of fusion proteins is suggested along with examples from the clinic or under development. Current limitations and future perspectives for PK of fusion proteins are also discussed. EXPERT OPINION A PK model for bifunctional fusion proteins is presented to highlight the importance of mechanistic studies for a thorough understanding of the PK properties of fusion proteins. The model suggests investigating the receptor binding and subsequent intracellular disposition of individual domains, which can have dramatic impact on the PK of fusion proteins.
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Affiliation(s)
- Xiaoying Chen
- University of Southern California School of Pharmacy, Department of Pharmacology and Pharmaceutical Sciences, CA 90089-9121, USA
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Zaro JL, Fei L, Shen WC. Recombinant peptide constructs for targeted cell penetrating peptide-mediated delivery. J Control Release 2012; 158:357-61. [DOI: 10.1016/j.jconrel.2012.01.039] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 01/24/2012] [Accepted: 01/27/2012] [Indexed: 01/03/2023]
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Abstract
Cell penetrating peptides (CPPs) are short strands of arginine- and/or lysine-rich peptides (<30 amino acids) that use their cationic nature for efficient intracellular accumulation. CPPs have been used for small interfering RNA (siRNA) delivery by direct complexation with the siRNA anionic phosphate backbone. During this process, however, part of the CPP cationic charges are neutralized, and the resultant loss of free positive charges may substantially compromise CPP's internalization capabilities and eventually reduce siRNA delivery efficiency. The purpose of this study was to design a novel type of polyplex for siRNA delivery to overcome the CPP neutralization issue. This novel polyplex consists of three components: siRNA, 21mer oligolysine (K21) chemically modified to incorporate CPP conjugation sites (K21-PDP), and CPP delivery moiety. The siRNA was first neutralized by cationic charges of K21-PDP to form a polyplex. Then a cationic (hexaarginine, R6) or an amphipathic (model amphipathic peptide, MAP) CPP was conjugated to the polyplex. Agarose gel shift assays indicated that the siRNA could be released from the polyplex after K21-PDP degradation or polyplex dilution. Furthermore, the total intracellular internalization of these two CPP-polyplexes was studied. Compared with R6-polyplex, MAP-polyplex exhibited 170- and 600-fold greater uptake of fluorescently labeled siRNA at 1 and 6 h post-transfection, respectively. MAP-polyplex also exhibited comparable GFP silencing effects as Lipofectamine 2000 complex in Huh7.5 cells stably transfected to express GFP-light chain 3 protein, whereas R6-polyplex did not demonstrate significant silencing activity. Further studies indicated that the K21-PDP-siRNA polyplex formation and conjugation of MAP to the polyplex were essential for siRNA polyplex uptake and gene silencing. MAP-polyplex was also shown to be unaffected by the presence of 10% FBS during transfection. In addition, MAP-polyplex uptake was dependent on vesicle formation and fusion due to 70 and 54% loss of uptake at 4 and 16 °C, respectively, compared to incubation at 37 °C. Therefore, the amphipathic CPP is a more suitable carrier moiety for delivery of siRNA polyplex.
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Affiliation(s)
- Robert H Mo
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles, California 90033, USA
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Wang Y, Chen YS, Zaro JL, Shen WC. Receptor-mediated activation of a proinsulin-transferrin fusion protein in hepatoma cells. J Control Release 2011; 155:386-92. [PMID: 21756950 DOI: 10.1016/j.jconrel.2011.06.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 06/02/2011] [Accepted: 06/18/2011] [Indexed: 11/19/2022]
Abstract
A proinsulin-transferrin (ProINS-Tf) recombinant fusion protein was designed and characterized for the sustained release of an active form of insulin (INS) by hepatoma cells. During incubation with H4IIE hepatoma cells, a gradual decline of ProINS-Tf concentration, with a concomitant generation of the immuno-reactive insulin-transferrin (irINS-Tf), was detected in the culture medium by using INS- or proinsulin (ProINS)-specific radioimmunoassay (RIA) system. Further studies indicated that the conversion of ProINS-Tf to irINS-Tf was a transferrin receptor (TfR) mediated process that was pH-sensitive, and temperature- and microtubule-dependent. These results suggest that the conversion occurred during the slow recycling route of transferrin (Tf)-TfR pathway, possibly processed by proteases in the slow recycling compartments juxtaposed to the trans-Golgi network (TGN). ProINS-Tf exhibited little activity in the short-term promotion of glucose uptake in adipocytes, indicating that it was in an inactive form similar to ProINS. Stimulation of Akt phosphorylation by ProINS-Tf was detected only after prolonged incubation with H4IIE cells. On the other hand, ProINS-Tf pre-incubated with H4IIE cells for 24h acquired an immediate activity of stimulating Akt phosphorylation. Furthermore, ProINS-Tf elicited a strong activity in the inhibition of glucose production following 24h incubation with H4IIE cells. Based on these findings, we conclude that the Tf-TfR endocytosis and recycling pathway enables the conversion and release of ProINS-Tf in an active form of irINS-Tf. Results from this study suggest that the Tf-TfR pathway can be exploited for the design of prohormone-Tf fusion proteins as protein prodrugs for their sustained and targeted activation.
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Affiliation(s)
- Yan Wang
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, United States
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Abstract
In contrast to the wide applications of recombinant bifunctional fusion proteins in clinical usage, the systematic study for the pharmacokinetics (PK) of bifunctional fusion proteins is left blank. In this report, recombinant fusion proteins consisting of transferrin (Tf) and growth hormone (GH) or granulocyte colony-stimulating factor (G-CSF) have been constructed as a model for studying the PK of bifunctional fusion proteins. The results showed that the insertion of different linkers between the two protein domains altered the binding affinities of the fusion proteins to both domain receptors, and that the fusion proteins' plasma half-lives were greatly affected. A strong correlation between GH receptor binding affinity and plasma half-life of GH-Tf fusion proteins was observed. In addition, we demonstrated that the intracellular processing after receptor binding plays an important role in determining the half-life of fusion proteins. While the binding of the GH domain to the GH receptor will lead to endocytosis and lysosomal degradation in target cells, binding of the Tf domain to the Tf receptor may recycle the fusion protein and prolong its plasma half-life. To further confirm the effects of receptor binding on plasma half-life, G-CSF-Tf bifunctional fusion proteins with the same three linkers as GH-Tf were evaluated. While the 3 fusion proteins showed a similar G-CSF receptor binding affinity, the G-CSF-Tf fusion protein with the higher Tf receptor binding affinity exhibited longer plasma half-life. The linker insertion further demonstrated the involvement of Tf in recycling and prolonging plasma half-life. Based on our results, a model was developed to summarize the factors in determining the PK of bifunctional fusion proteins. Our findings are useful for predicting the plasma half-lives, as well as for improving the pharmacokinetic profiles of therapeutic bifunctional fusion proteins by applying linker technology.
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Affiliation(s)
- Xiaoying Chen
- Department of Pharmacology and Pharmaceutical Sciences, University of Southern California School of Pharmacy, Los Angeles, California 90089-9121, USA
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Fei L, Ren L, Zaro JL, Shen WC. The influence of net charge and charge distribution on cellular uptake and cytosolic localization of arginine-rich peptides. J Drug Target 2010; 19:675-80. [DOI: 10.3109/1061186x.2010.531729] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Zaro JL, Vekich JE, Tran T, Shen WC. Nuclear localization of cell-penetrating peptides is dependent on endocytosis rather than cytosolic delivery in CHO cells. Mol Pharm 2009; 6:337-44. [PMID: 19718791 DOI: 10.1021/mp800239p] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The nuclear localization of various cell penetrating peptides (CPPs), including Tat [47-57], YG(R)9, YG(K)9, and model amphipathic peptide (MAP), was examined and correlated with the endocytosis and cytosolic transfer efficiency in CHO cells. The results showed that the internalization of the amphipathic peptide, MAP, was much higher than that of the other cationic CPPs tested. During subcellular fractionation analysis, MAP was only found in the vesicular fraction and was not detectable in the cytosol, similar to the intracellular localization of YG(K)9 as previously determined. This localization pattern differs greatly from the cationic CPPs oligoarginine and Tat, which were previously found primarily in the cytosol. Both quantitative and qualitative analysis of MAP showed high nuclear localization, with staining in perinuclear vesicles. On the other hand, YG(R)9 was found to be excluded from the nucleus. Lysosomotropic amines altered the nuclear localization of the CPPs tested, and the change was correlated with the release of degradation products from the treated cells. These results suggest that highly endocytosed CPPs such as MAP may be more suitable for nuclear drug delivery applications than peptides such as Tat and YG(R)9 that are efficiently delivered to the cytosol.
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Affiliation(s)
- Jennica L Zaro
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, PSC 404B, Los Angeles, California 90033-1039, USA
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Patel LN, Zaro JL, Shen WC. Cell Penetrating Peptides: Intracellular Pathways and Pharmaceutical Perspectives. Pharm Res 2007; 24:1977-92. [PMID: 17443399 DOI: 10.1007/s11095-007-9303-7] [Citation(s) in RCA: 299] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 03/20/2007] [Indexed: 12/19/2022]
Abstract
Cell penetrating peptides, generally categorized as amphipathic or cationic depending on their sequence, are increasingly drawing attention as a non-invasive delivery technology for macromolecules. Delivery of a diverse set of cargo in terms of size and nature ranging from small molecules to particulate cargo has been attempted using different types of cell penetrating peptides (CPPs) in vitro and in vivo. However, the internalization mechanism of CPPs is an unresolved issue to date, with dramatic changes in view regarding the involvement of endocytosis as a pathway of internalization. A key reason for the lack of consensus on the mechanism can be attributed to the methodology in deciphering the internalization mechanism. In this review, we highlight some of the methodology concerns, focus more on the internalization pathway and also provide a novel perspective about the intracellular processing of CPPs, which is a crucial aspect to consider when selecting a cell penetrating peptide as a drug delivery system. In addition, recent applications of cell penetrating peptides for the delivery of small molecules, peptides, proteins, oligonucleotides, nanoparticles and liposomes have been reviewed.
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Affiliation(s)
- Leena N Patel
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089, USA
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Abstract
The mechanism in which small cationic oligopeptides are able to reach the cytosol of cells is controversial. Macropinocytosis has been recently suggested as a major mechanism for internalization of these peptides. In this report, the involvement of macropinocytosis on cytosolic localization of oligoarginine was quantitatively investigated in HeLa cells. Using a method which allows for the separate measurement of cytosolic versus vesicular oligopeptide, the results show that neither macropinosome nor filopodia formation correlates with cytosolic delivery of oligoarginine. Additionally, unlike macropinocytosis, the cytosolic delivery of oligoarginine was not inhibited by incubation at 16 degrees C, or by treatment with amiloride. Oligoarginine treatment does not contribute to leakage from endocytic vesicles, indicating the lack of endosomolytic properties. Finally, the amount of oligoarginine found in the cytosol was not substantially increased after coincubation with EGF, a known stimulator of macropinocytosis. Taken together, these data indicate that membrane transduction of oligoarginine occurs separately from macropinocytosis in HeLa cells.
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Affiliation(s)
- Jennica L Zaro
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90033-1039, USA
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Zaro JL, Shen WC. Cytosolic delivery of a p16-peptide oligoarginine conjugate for inhibiting proliferation of MCF7 cells. J Control Release 2005; 108:409-17. [PMID: 16202470 DOI: 10.1016/j.jconrel.2005.08.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Revised: 08/20/2005] [Accepted: 08/30/2005] [Indexed: 11/16/2022]
Abstract
One of the major limitations in protein and peptide therapeutics is the requirement of delivery to the cytosol or nucleus of cells. It has recently been shown that a small peptide derived from the p16 protein is able to inhibit cell cycle progression when delivered to the cytosol after conjugation to cell penetrating peptides, however the correlation between delivery efficiency and biological activity has not been made. Additionally, whether or not the biological activity attained was due to membrane transduction has not been established. In this paper, the total internalization, and internalization via endocytosis and transduction of 125I-p16, 125I-p16-C(R)9, and 125I-p16-C(K)9 were determined in MCF7 cultured cell monolayers. The results showed that while p16 and p16-oligopeptide conjugates have similar total internalization, 125I-p16-C(R)9 is predominantly internalized via membrane transduction, while p16 and p16-oligolysine are primarily endocytosed. Therefore, the amount of 125I-p16-C(R)9 delivered to the cytosol is significantly higher than both 125I-p16-C(K)9 and 125I-p16. These results show that biological activity is correlated with membrane transduction efficiency, and not total internalization. Additionally, the biological activity and delivery to the cytosol were not sensitive to endocytic inhibitors, verifying that the biological effect is due to membrane transduction, and not endocytosis.
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Affiliation(s)
- Jennica L Zaro
- University of Southern California, School of Pharmacy, Department of Pharmaceutical Sciences, 1985 Zonal Avenue, PSC 404B, Los Angeles, CA 90033-1039, USA
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Zaro JL, Shen WC. Evidence that membrane transduction of oligoarginine does not require vesicle formation. Exp Cell Res 2005; 307:164-73. [PMID: 15922736 DOI: 10.1016/j.yexcr.2005.02.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Revised: 02/17/2005] [Accepted: 02/21/2005] [Indexed: 01/04/2023]
Abstract
The involvement of vesicular formation processes in the membrane transduction and nuclear transport of oligoarginine is currently a subject of controversy. In this report, a novel quantitative method which allows for the selective measurement of membrane transduction excluding concurrent endocytosis was used to determine the effects of temperature, endosomal acidification, endosomolysis, and several known inhibitors of endocytic pathways on the internalization of oligoarginine. The results show that, unlike endocytosis, transduction of oligoarginine was not affected by incubation at 16 degrees C as compared to the 37 degrees C control, and was only partially inhibited at 4 degrees C incubation. Additionally, membrane transduction was not inhibited to the same extent as endocytosis following treatment with ammonium chloride, hypertonic medium, amiloride, or filipin. The endosomolytic activity of oligoarginine was investigated by examining the leakage of FITC-dextran into the cytosolic compartment, which was not higher in the presence of oligoarginine. Furthermore, ammonium chloride showed no effect on the nuclear transport of oligoarginine. The data presented in this report indicate that membrane transduction is likely to occur at the plasma membrane without the formation of membrane vesicles, and the nuclear localization involves membrane transduction, rather than endocytosis of oligoarginine.
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Affiliation(s)
- Jennica L Zaro
- University of Southern California, School of Pharmacy, Department of Pharmaceutical Sciences, 1985 Zonal Avenue, PSC 404B, Los Angeles, CA 90033-1039, USA
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Abstract
A novel method was developed to quantitatively determine the membrane transduction efficiency of cationic oligopeptides, allowing for selective measurement of transduction, excluding concurrent adsorptive endocytosis. It was found that Tat-(47-57) (YGRKKRRQRRR), YG(l-R)(9), and guanidinated-YG(l-K)(9) were preferentially transduced to the cytosolic compartment, while YG(l-K)(9) was primarily endocytosed. Studies of various oligoarginine peptides (4-15 residues) demonstrated that internalization through transduction remained constant, while the amount internalized via endocytosis increased with arginine length, indicating that oligopeptide transduction requires the guanidine structure of arginine, while endocytosis depends only on the number of positive charges. The addition of unlabeled-YG(l-R)(9) dose-dependently inhibited transduction of 125I-labeled-YG(l-R)(9), while endocytosis remained constant. Unlabeled-YG(d-R)(9) and Tat-(47-57) were able to inhibit transduction similarly, while YG(l-K)(9) had no effect. These studies demonstrate specific surface binding sites required for transduction of oligoarginine, but not for endocytosis. Data generated from this study are essential to elucidate the transduction mechanism and to develop an efficient carrier system for cytoplasmic drug delivery.
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Affiliation(s)
- Jennica L Zaro
- Department of Pharmaceutical Sciences, University of Southern California, School of Pharmacy, Los Angeles, CA 90033-9121, USA
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