title: Effect of modification of the physicochemical properties of ICAM-1-derived peptides on internalization and intracellular distribution in the human leukemic cell line HL-60.
abstract: The objective of this work is to test the hypothesis that increasing the hydrophilicity of DOX-peptide conjugates may modify their entry mechanisms into HL-60 cells from passive diffusion to receptor-mediated uptake. To test this hypothesis, the entry mechanisms and the intracellular disposition of DOX-cIBR7, DOX-PEGcIBR7, FITC-cIBR, and FITC-cIBR7 were evaluated in HL-60 cells. To increase the hydrophilicity of the peptide, the cIBR peptide (cyclo(1,12)Pen-PRGGSVLVTGC) was modified to cIBR7 peptide (cyclo(1,8)CPRGGSVC) by removing the hydrophobic residues at the C-terminus. DOX-cIBR7 conjugate, which has higher hydrophilicity than DOX-cIBR, was synthesized. Second, a hydrophilic linker (11-amino-3,6,9-trioxaundecanate linker) was incorporated between DOX and cIBR7 to generate DOX-PEGcIBR7 with higher hydrophilicity than DOX-cIBR7. As controls, FITC-cIBR and FITC-cIBR7 were used to check for any endocytic uptake process of the peptide. As previously found with DOX-cIBR, DOX-cIBR7, and DOX-PEGcIBR7, conjugates enter the cells via passive diffusion and not via the energy-dependent endocytic process. This result suggests that an increase in hydrophilicity does not influence the entry mechanism of the DOX-peptide conjugates. In contrast to the DOX-cIBR7 conjugate, the FITC-cIBR7 conjugate showed energy-dependent cellular entry into the cells and followed an endocytic pathway similar to that for dextran. Finally, the entry of DOX-cIBR7 and DOX-PEGcIBR into the cell cytosol was shown to be due to the properties of DOX and not to those of the peptide.
authors.affiliation: Department of Pharmaceutical Chemistry, The University of Kansas, Simons Research Laboratories, 2095 Constant Avenue, Lawrence, Kansas 66047, USA.
authors.forename: Sumit
authors.initials: S
authors.lastname: Majumdar
authors.forename: Bimo A
authors.initials: BA
authors.lastname: Tejo
authors.forename: Ahmed H
authors.initials: AH
authors.lastname: Badawi
authors.forename: David
authors.initials: D
authors.lastname: Moore
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Krise
authors.forename: Teruna J
authors.initials: TJ
authors.lastname: Siahaan
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000737:chemistry; D004317:Doxorubicin / Q000737:chemistry / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology*; D018922:HL-60 Cells / Q000378:metabolism; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000737:chemistry / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000737:chemistry / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D000903:Antibiotics, Antineoplastic; D010456:Peptides, Cyclic; C515000:cIBR peptide; D018799:Intercellular Adhesion Molecule-1; D004317:Doxorubicin