title: HPMA based macromolecular therapeutics: internalization, intracellular pathway and cell death depend on the character of covalent bond between the drug and the peptidic spacer and also on spacer composition.
abstract: Polymeric conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) have been tested as potential carrier for anticancer drug - doxorubicin (Dox). Two types of conjugates were synthesized: (a) conjugates containing Dox bound through an amidic bond to an oligopeptidic side-chain (usually GFLG) and (b) hydrolytically cleavable conjugates wherein Dox is bound to the polymeric carrier through a pH sensitive bond. The mechanism of action of both conjugates is different and reflects the diverse way and intensity of their intracellular accumulation. All conjugates containing doxorubicin bound via an amidic bond directly penetrate the plasma membrane and are detectable in all associated cellular membranes, i.e. membranes of the endocytic compartment, a nuclear membrane as well as membranes of Golgi and endoplasmic reticulum. We have never been able to detect released doxorubicin inside the nuclei of the treated cells. The cytotoxicity of these conjugates seems to be primarily caused by the damage of cellular membranes. Necrosis is the main mechanism of the cell death. Conjugates containing hydrolytically bound doxorubicin are internalized by endocytosis and fluid phase pinocytosis and doxorubicin is cleaved from the polymeric carrier at low pH in late endosomes and lysosomes. An apoptosis is the main mechanism of the cell death. The spacer influences the rate of the intracellular release of the drug rather than the rate of internalization.
authors.affiliation: Department of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, Prague 4 142 20, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Hovorka
authors.forename: Tomás
authors.initials: T
authors.lastname: Etrych
authors.forename: Vladimír
authors.initials: V
authors.lastname: Subr
authors.forename: Jirí
authors.initials: J
authors.lastname: Strohalm
authors.forename: Karel
authors.initials: K
authors.lastname: Ulbrich
authors.forename: Blanka
authors.initials: B
authors.lastname: Ríhová
mesh_terms: D016475:3T3 Cells; D000178:Acrylamides / Q000737:chemistry*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D003911:Dextrans / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D004705:Endocytosis / Q000502:physiology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006576:Heterocyclic Compounds, 4 or More Rings / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D000432:Methanol / Q000494:pharmacology; D051379:Mice; D008856:Microscopy, Fluorescence; D010873:Pinocytosis / Q000502:physiology
chemical_list: D000178:Acrylamides; D000903:Antibiotics, Antineoplastic; D003911:Dextrans; D006576:Heterocyclic Compounds, 4 or More Rings; C503870:vacuolin-1; D004317:Doxorubicin; C032976:N-(2-hydroxypropyl)methacrylamide; D000432:Methanol