title: Release of prostaglandin E(1) from N-(2-hydroxypropyl)methacrylamide copolymer conjugates by bone cells.
abstract: Bone-targeting N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-PGE(1) conjugates, containing cathepsin K sensitive spacers, were incubated with induced osteoclasts and osteoblasts, their precursors, and control non-skeletal cells. The release of PGE(1) was monitored by an HPLC assay. In both murine and human cell lines, osteoclasts appeared to be the most active cells in the cleavage (PGE(1) release). Incubation with osteoblasts also resulted in fast PGE(1) release, whereas precursor and control cells released PGE(1) with a substantially slower rate than bone cells (apparently through ester bond cleavage). Experiments in the presence of inhibitors revealed that other enzymes, in addition to cathepsin K, were participating in the cleavage of the conjugate. Confocal fluorescence studies exposed internalization of the conjugate by endocytosis with ultimate localization in the lysosomal/endosomal compartment.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Huaizhong
authors.initials: H
authors.lastname: Pan
authors.forename: Jihua
authors.initials: J
authors.lastname: Liu
authors.forename: Yuanyi
authors.initials: Y
authors.lastname: Dong
authors.forename: Monika
authors.initials: M
authors.lastname: Sima
authors.forename: Pavla
authors.initials: P
authors.lastname: Kopecková
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Brandi
authors.forename: Jindrich
authors.initials: J
authors.lastname: Kopecek
mesh_terms: D000527:Alprostadil / Q000737:chemistry / Q000493:pharmacokinetics*; D000818:Animals; D056649:Cathepsin G; D002403:Cathepsins / Q000378:metabolism*; D002460:Cell Line; D011992:Endosomes / Q000201:enzymology*; D006801:Humans; D008247:Lysosomes / Q000201:enzymology*; D051379:Mice; D010010:Osteoclasts / Q000201:enzymology*; D011109:Polymethacrylic Acids / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics*; D012697:Serine Endopeptidases / Q000378:metabolism*
chemical_list: D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; C534096:Ctsg protein, mouse; D000527:Alprostadil