Release of prostaglandin E(1) from N-(2-hydroxypropyl)methacrylamide copolymer conjugates by bone cells.
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.
Pan
Huaizhong
H
Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, Salt Lake City, Utah 84112, USA.
Liu
Jihua
J
Dong
Yuanyi
Y
Sima
Monika
M
Kopecková
Pavla
P
Brandi
Maria Luisa
ML
Kopecek
Jindrich
J
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*
D011109:Polymethacrylic Acids; C030613:polymethacrylic acid; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; C534096:Ctsg protein, mouse; D000527:Alprostadil