title: Doxorubicin loaded pH-sensitive polymeric micelles for reversal of resistant MCF-7 tumor.
abstract: In order to overcome multidrug resistance in solid tumors, doxorubicin (DOX) loaded pH-sensitive micelles of which surface was decorated with folate (PHSM/f) were evaluated both in vitro and in vivo experiments. PHSM/f were fabricated from a mixture of two block copolymers of poly(L-histidine) (M(n): 5K)-b-PEG (M(n): 2K)-folate (polyHis/PEG-folate) (75 wt.%) and poly(L-lactic acid) (M(n): 3K)-b-PEG (M(n): 2K)-folate (PLLA/PEG-folate) (25 wt.%). The PHSM/f showed more than 90% cytotoxicity of DOX resistant MCF-7 (MCF-7/DOX(R)) when cultured with PHSM/f at a concentration of 10 microg/ml DOX. The result was interpreted by a sequential event of active internalization of PHSM/f via folate-receptor mediated endocytosis and ionization of His residues which result in micelle destabilization and probably disturbance of endosomal membranes. This potential mechanism may endow the drug carriers to bypass Pgp efflux pump and sequestration of DOX in acidic intracellular compartments, yielding high cytotyoxicity. Experimental evaluation of tumor regression was carried out in a small animal model bearing s.c. MCF-7 or MCF-7/DOX(R) xenografts. The tumor (MCF-7/DOX) volumes of mice treated with PHSM/f were significantly less than control groups treated with free DOX or similar micelles but without folate (PHSM). In the MCF-7/DOX(R) xenograft model, the accumulated DOX level of PHSM/f in solid tumors was 20 times higher than free DOX group, and 3 times higher than PHSM group. The results demonstrate that PHSM/f is a viable means for treating drug resistant tumors.
authors.affiliation: Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, 421 Wakara Way, Suite 315, Salt Lake City, Utah 84108, USA.
authors.forename: Eun Seong
authors.initials: ES
authors.lastname: Lee
authors.forename: Kun
authors.initials: K
authors.lastname: Na
authors.forename: You Han
authors.initials: YH
authors.lastname: Bae
mesh_terms: D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage / Q000737:chemistry / Q000627:therapeutic use; D004339:Drug Compounding; D016503:Drug Delivery Systems; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004355:Drug Stability; D005260:Female; D005492:Folic Acid / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008823:Micelles; D009368:Neoplasm Transplantation; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*
chemical_list: D000903:Antibiotics, Antineoplastic; D008823:Micelles; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; C033223:polyhistidine; D019344:Lactic Acid; D006639:Histidine; D004317:Doxorubicin; D005492:Folic Acid