title: Effect of polyethylene glycol linker chain length of folate-linked microemulsions loading aclacinomycin A on targeting ability and antitumor effect in vitro and in vivo.
abstract: OBJECTIVE
  To establish a novel formulation tumor-targeted drug carrier of lipophilic antitumor antibiotics, aclacinomycin A (ACM), folate-linked microemulsions were prepared and investigated both in vitro and in vivo.
  
  
  METHODS
  Three kinds of folate-linked microemulsions with different polyethylene glycol (PEG) chain lengths loading ACM were formulated with 0.24 mol% folate-PEG(2000)-distearoylphosphatidylethanolamine (DSPE), folate-PEG(5000)-DSPE, and folate-lipid (without PEG linker) in microemulsions. In vitro studies were done in a human nasopharyngeal cell line, KB, which overexpresses the folate receptor (FR), and a human hepatoblastoma cell line, [FR(-)] HepG2. In vivo experiments were done in a KB xenograft by systemic administration of folate-linked microemulsions loading ACM.
  
  
  RESULTS
  The association of folate-linked microemulsions to KB cells could be blocked by 2 mmol/L free folic acid. Selective FR-mediated cytotoxicity of folate-linked microemulsions loading ACM was obtained in KB but not in HepG2 cells. The association of the folate-PEG(5000)-linked microemulsion and folate-PEG(2000)-linked microemulsion with the cells was 200- and 4-fold higher, whereas their cytotoxicity was 90- and 3.5-fold higher than those of nonfolate microemulsion, respectively. The folate-PEG(5000)-linked microemulsions showed 2.6-fold higher accumulation in solid tumors 24 hours after i.v. injection and greater tumor growth inhibition than free ACM.
  
  
  CONCLUSIONS
  These findings suggest that a folate-linked microemulsion is feasible for tumor-targeted ACM delivery. This study shows that folate modification with a sufficiently long PEG chain on emulsions is an effective way of targeting emulsion to tumor cells.
authors.affiliation: Institute of Medicinal Chemistry, Hoshi University, Ebara 2-4-41, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Shiokawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hattori
authors.forename: Kumi
authors.initials: K
authors.lastname: Kawano
authors.forename: Yukino
authors.initials: Y
authors.lastname: Ohguchi
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kawakami
authors.forename: Kazunori
authors.initials: K
authors.lastname: Toma
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Maitani
mesh_terms: D015250:Aclarubicin / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D000903:Antibiotics, Antineoplastic / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D002277:Carcinoma / Q000473:pathology*; D002626:Chemistry, Pharmaceutical; D004655:Emulsions; D005492:Folic Acid / Q000737:chemistry*; D018197:Hepatoblastoma / Q000473:pathology*; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008113:Liver Neoplasms / Q000473:pathology*; D049329:Nanostructures; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D010714:Phosphatidylethanolamines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*; D014407:Tumor Cells, Cultured
chemical_list: D000903:Antibiotics, Antineoplastic; D004655:Emulsions; D008055:Lipids; D010714:Phosphatidylethanolamines; C038089:1,2-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; D015250:Aclarubicin; D005492:Folic Acid