title: Effects of azetidine-2-carboxylic acid on treatments of hepatoma cells with single or fractionated X-ray irradiations and on thermal radiosensitization in normal and thermotolerant cells.
abstract: The amino acid analog azetidine-2-carboxylic acid (azetidine) is a potent sensitizer to both hyperthermia and ionizing radiation. Incubation of H35 hepatoma cells with 2.5 mM azetidine before or after treatments with X-rays causes a time- and sequence-dependent enhancement of cell killing. Exposure of cells to 1-1.5 mM azetidine for 96 h in combination with repeated doses of 3 Gy X-rays at 24 h intervals causes an enhanced reduction of the surviving cell population due to both radiosensitization and an additional growth inhibition. Azetidine does not prevent the induction of thermotolerance after a heat shock. This thermotolerance proportionally reduces thermal radiosensitization but does not seem to affect azetidine radiosensitization. It is suggested that thermal radiosensitization and azetidine radiosensitization operate by different mechanisms.
authors.affiliation: Department of Radiation Oncology, Academic Hospital Vrije Universiteit, Amsterdam, The Netherlands. j.vanrijn.radiobiol@med.vu.nl
authors.forename: J
authors.initials: J
authors.lastname: van Rijn
authors.forename: J
authors.initials: J
authors.lastname: van den Berg
authors.forename: C A
authors.initials: CA
authors.lastname: van der Mast
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001383:Azetidinecarboxylic Acid / Q000008:administration & dosage / Q000627:therapeutic use*; D016923:Cell Death; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D019583:Dose Fractionation, Radiation; D004305:Dose-Response Relationship, Drug; D018869:Heat-Shock Response / Q000187:drug effects; D006979:Hyperthermia, Induced; D008114:Liver Neoplasms, Experimental / Q000188:drug therapy* / Q000532:radiotherapy; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D011879:Radiotherapy Dosage; D051381:Rats; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D011838:Radiation-Sensitizing Agents; D001383:Azetidinecarboxylic Acid