title: Evaluation of phenolphthalein, diazepam and quinacrine dihydrochloride in the in vitro mammalian cell micronucleus test in Chinese hamster ovary (CHO) and TK6 cells.
abstract: The in vitro micronucleus assay has been extensively used as an in vitro screening tool to identify test articles that might have aneugenic or clastogenic potential. Currently, the Organization for Economic Co-operation and Development (OECD) is working towards a final version of the guideline for the conduct of the in vitro mammalian cell micronucleus Test (MNvit). A few questions regarding appropriate cytotoxicity measurements and cytotoxicity limits to use remain to be answered. In order to resolve the remaining questions, we compared the induction of micronuclei at the top dose (50-60% cytotoxicity) determined by either Relative Cell Counts (RCC), Relative Increase in Cell Counts (RICC), Relative Population Doublings (RPD), or Cytokinesis-Blocked Proliferating Index (CBPI) using weak and strong inducers of micronuclei in both the presence and absence of cytochalasin B (CYB) in Chinese hamster ovary (CHO) and human lymphoblastoid TK6 cells. In order to assess extensive dose-response relationships, we selected expected weak (diazepam, phenolphthalein, quinacrine dihydrochloride dihydrate) and strong (cytosine arabinoside, mitomycin C, vinblastine sulphate) inducers of micronuclei with a variety of different mechanisms of action for testing. The results clearly demonstrated that all six compounds produced positive responses using either cytotoxicity measurement. The outcome from these studies further supports the cytotoxicity measurements and cytotoxicity limits proposed in the draft OECD guideline.
authors.affiliation: Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340, USA. maik.schuler@pfizer.com
authors.forename: Maik
authors.initials: M
authors.lastname: Schuler
authors.forename: Ramadevi
authors.initials: R
authors.lastname: Gudi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Cheung
authors.forename: Shyam
authors.initials: S
authors.lastname: Kumar
authors.forename: Donna
authors.initials: D
authors.lastname: Dickinson
authors.forename: Maria
authors.initials: M
authors.lastname: Engel
authors.forename: Anna
authors.initials: A
authors.lastname: Szkudlinska
authors.forename: Megan
authors.initials: M
authors.lastname: Colman
authors.forename: Nkechi
authors.initials: N
authors.lastname: Maduka
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Sherman
authors.forename: Catherine
authors.initials: C
authors.lastname: Thiffeault
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D003571:Cytochalasin B / Q000494:pharmacology; D003603:Cytotoxins / Q000633:toxicity*; D003975:Diazepam / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D015162:Micronucleus Tests / Q000379:methods*; D009153:Mutagens / Q000633:toxicity*; D020113:Phenolphthalein / Q000633:toxicity*; D011796:Quinacrine / Q000633:toxicity*
chemical_list: D003603:Cytotoxins; D009153:Mutagens; D003571:Cytochalasin B; D020113:Phenolphthalein; D011796:Quinacrine; D003975:Diazepam