Cellular Delivery Agents Research Articles

Synergistic Interaction of CPP2 Coupled with Thiazole Derivates Combined with Clotrimazole and Antineoplastic Drugs in Prostate and Colon Cancer Cell Lines.

Cell-penetrating peptides (CPPs) are small peptide sequences used mainly as cellular delivery agents that are able to efficiently deliver cargo into cells. Some CPPs also demonstrate intrinsic anticancer properties. Previously, our group developed a new family of CPP2-thiazole conjugates that have been shown to effectively reduce the proliferation of different cancer cells. This work aimed to combine these CPP2-thiazole conjugates with paclitaxel (PTX) and 5-fluorouracil (5-FU) in PC-3 prostate and HT-29 colon cancer cells, respectively, to evaluate the cytotoxic effects of these combinations. We also combined these CPP2-thiazole conjugates with clotrimazole (CLZ), an antifungal agent that has been shown to decrease cancer cell proliferation. Cell viability was evaluated using MTT and SRB assays. Drug interaction was quantified using the Chou–Talalay method. We determined that CPP2 did not have significant activity in these cells and demonstrate that N-terminal modification of this peptide enhanced its anticancer activity in both cell lines. Our results also showed an uneven response between cell lines to the proposed combinations. PC-3 cells were more responsive to the combination of CPP2-thiazole conjugates with CLZ than PTX and were more sensitive to these combinations than HT-29 cells. In addition, the interaction of drugs resulted in more synergism in PC-3 cells. These results suggest that N-terminal modification of CPP2 results in the enhanced anticancer activity of the peptide and demonstrates the potential of CPPs as adjuvants in cancer therapy. These results also validate that CLZ has significant anticancer activity both alone and in combination and support the strategy of drug repurposing coupled to drug combination for prostate cancer therapy.

Effective Cellular Delivery of Antisense Peptide Nucleic Acid by Conjugation to Guanidinylated Diaminobutanoic Acid-Based Peptide Dendrons.

A series of amino- and guanidino-terminating 3- and 4-generation 2,4-diaminobutanoic acid (Dab) dendrons have been robustly synthesized on a solid phase and characterized as cellular delivery agents in antisense peptide nucleic acid (PNA) conjugates in the pLuc705 HeLa cell splice switching system. The dendron-PNA conjugates exhibited splice correction activity at one digit micromolar concentrations, and guanidino-terminating dendrons were significantly more effective than analogous amine terminating ones. Furthermore, introduction of lipophilic groups such as phenyl, alkyl, or fatty acids increased efficacy, but also increased cellular toxicity. Fluorescence microscopy analyses supported an endosomal uptake mechanism and furthermore predominantly showed colocalization with late endosomes and lysosomes. The robust solid phase synthesis should make such Dab-dendrons a useful platform for further in vitro as well as in vivo optimization.

Catalyst: On Organic Systems Chemistry and Origins Research

Yitzhak Tor is a professor of chemistry and biochemistry and the George W. and Carol A. Lattimer Professor at the University of California, San Diego. He earned his doctorate degree at the Weizmann Institute of Science (1990) and was a postdoctoral fellow at the California Institute of Technology (1990–1993). His research focuses on the chemistry and biology of nucleosides, nucleotides, and nucleic acids as well as the development of cellular delivery agents and fluorescent nucleoside analogs. He is the editor-in-chief of Perspectives in Medicinal Chemistry and Organic Chemistry Insights .

Corrigendum: Amphiphilic Bicyclic Peptides as Cellular Delivery Agents.

The authors wish to make it known that co-author Dr. Shaban Anwar Darwish was also affiliated with the Organometallic and Organometalloid Chemistry Department, National Research Centre (El Bohouth St., Dokki, Giza, Egypt). Dr. Darwish was a visiting researcher at the University of Rhode Island but was still affiliated with the National Research Centre in Egypt at that time.

Amphiphilic bicyclic peptides as cellular delivery agents.

Two bicyclic peptides composed of tryptophan and arginine residues were synthesized from monocyclic peptide building blocks and evaluated as cellular delivery agents. [W5G]-(triazole)-[KR5] and [W5E]-(β-Ala)-[KR5] containing triazole and β-alanine linkers improved the cellular delivery of fluorescein (F')-labeled phosphopeptide F'-GpYEEI (F'-PP) by 7.6- and 19.3-fold, respectively, in human ovarian adenocarcinoma cells. However, parent monocyclic peptide [R5 ] and monocyclic peptide [WR]4 only enhanced the cellular uptake of the phosphopeptide by only 1.3- and 3.7-fold, respectively. Confocal microscopy showed that the corresponding fluorescein-labeled bicyclic peptide F'-[KW4E]-(β-Ala)-[KR5] was localized in the cytosol and nucleus. Studying the cellular uptake of F'-[KW4E]-(β-Ala)-[KR5] in the presence of endocytosis inhibitors indicated that the clathrin- and caveolin-dependent endocytosis are the main pathways for cellular uptake. The bicyclic peptide was able to improve antiproliferative activity of doxorubicin by 20 %. These data suggest that this bicyclic peptide can be utilized as a new class of cell-penetrating peptides and cellular delivery tools.

Synthesis and Characterization of Dual-Functionalized Core-Shell Fluorescent Microspheres for Bioconjugation and Cellular Delivery

The efficient transport of micron-sized beads into cells, via a non-endocytosis mediated mechanism, has only recently been described. As such there is considerable scope for optimization and exploitation of this procedure to enable imaging and sensing applications to be realized. Herein, we report the design, synthesis and characterization of fluorescent microsphere-based cellular delivery agents that can also carry biological cargoes. These core-shell polymer microspheres possess two distinct chemical environments; the core is hydrophobic and can be labeled with fluorescent dye, to permit visual tracking of the microsphere during and after cellular delivery, whilst the outer shell renders the external surfaces of the microspheres hydrophilic, thus facilitating both bioconjugation and cellular compatibility. Cross-linked core particles were prepared in a dispersion polymerization reaction employing styrene, divinylbenzene and a thiol-functionalized co-monomer. These core particles were then shelled in a seeded emulsion polymerization reaction, employing styrene, divinylbenzene and methacrylic acid, to generate orthogonally functionalized core-shell microspheres which were internally labeled via the core thiol moieties through reaction with a thiol reactive dye (DY630-maleimide). Following internal labeling, bioconjugation of green fluorescent protein (GFP) to their carboxyl-functionalized surfaces was successfully accomplished using standard coupling protocols. The resultant dual-labeled microspheres were visualized by both of the fully resolvable fluorescence emissions of their cores (DY630) and shells (GFP). In vitro cellular uptake of these microspheres by HeLa cells was demonstrated conventionally by fluorescence-based flow cytometry, whilst MTT assays demonstrated that 92% of HeLa cells remained viable after uptake. Due to their size and surface functionalities, these far-red-labeled microspheres are ideal candidates for in vitro, cellular delivery of proteins.

Rapid modification of retroviruses using lipid conjugates

Methods are needed to manipulate natural nanoparticles. Viruses are particularlyinteresting because they can act as therapeutic cellular delivery agents. Here we examine anew method for rapidly modifying retroviruses that uses lipid conjugates composed of alipid anchor (1,2-distearoyl-sn-glycero-3-phosphoethanolamine), a polyethylene glycol chain,and biotin. The conjugates rapidly and stably modified retroviruses and enabled them tobind streptavidin. The implication of this work for modifying viruses for gene therapy andvaccination protocols is discussed.

Layered double hydroxide nanomaterials as potential cellular drug delivery agents

Abstract This paper briefly reviews the recent progress in using layered double hydroxide (LDH) nanomaterials as cellular delivery agents. The advantages of LDHs as cellular delivery agents are summarized, and the processes of interaction/de-intercalation of anionic drugs (genes) into/from LDH nanoparticles are discussed. Then the cellular delivery of LDH-drug (gene) nanohybrids and subsequent intracellular processes are presumably proposed. At the end, some challenges and remarks for efficient delivery of drugs (genes) via LDH nanoparticles are provided to the best of our knowledge.