title: Tumor-targeted delivery of 8-hydroxyquinoline.
abstract: RIF-1 mouse tumors express high levels of beta-glucuronidase activity relative to most normal tissues. The high activity can be exploited for targeting specific drugs preferentially to tumor tissues. In this study we examined the kinetics of 8-hydroxyquinoline (8-OHQ) accumulation in tumor and in several normal tissues resulting from the in vivo deconjugation of 8-hydroxyquinolyl-glucuronide (8-OHQ-GlcA). Tumors were acidified with D-glucose and NaHCO3 prior to the administration of 8-OHQ-GlcA; subsequently the deconjugated aglycone, 8-OHQ, accumulated preferentially in tumors and reached peak levels between 30 and 60 min after the 8-OHQ-GlcA injection. Mild hyperthermia of 30 min at 43 degrees C to the tumors further increased their peak 8-OHQ levels by a factor of 2-3. Some normal tissues, mostly kidney, liver, and colon, also accumulated 8-OHQ, but the aglycone appeared early in the normal tissues (near 30 min post-injection) and was significantly reduced by 60 min when 8-OHQ remained high in the tumor. Administration of 8-OHQ-GlcA alone, without prior tumor acidification, failed to produce measurable accumulations of 8-OHQ in tumors and in normal tissues. Tissue clearance of 8-OHQ is mediated primarily by the enzymatic reconjugation of 8-OHQ via UDP-glucuronosyltransferase (UDPGT). UDPGT activity was high in liver, kidney, and bowel, but low in the RIF tumor, spleen, muscle, and brain. Hyperthermia had only a modest effects on UDPGT activity: a heat dose of 30 min at 45 degrees C reduced activity less than 60%. Thus, preferential accumulation and prolonged retention of 8-OHQ in RIF tumors may be caused by a combination of factors: a) high tumor beta-glucuronidase activity, b) selective tumor acidification during hyperglycemia, c) low tumor UDPGT activity, and d) other factors, such as tumor blood flow.
authors.affiliation: Dept. of Medicine, University of Arkansas for Medical Sciences, Little Rock 72205-5484.
authors.forename: T P
authors.initials: TP
authors.lastname: Monson
authors.forename: K J
authors.initials: KJ
authors.lastname: Henle
authors.forename: W A
authors.initials: WA
authors.lastname: Nagle
authors.forename: A
authors.initials: A
authors.lastname: Mansouri
mesh_terms: D000818:Animals; D005966:Glucuronidase / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006912:Hydroxyquinolines; D051379:Mice; D008809:Mice, Inbred C3H; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000201:enzymology / Q000378:metabolism*; D015125:Oxyquinoline / Q000493:pharmacokinetics*; D011804:Quinolines / Q000008:administration & dosage / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D006912:Hydroxyquinolines; D011804:Quinolines; C056147:8-hydroxyquinoline glucuronide; D015125:Oxyquinoline; D005966:Glucuronidase