title: Relationship between increasing concentrations of two carcinogens and statistical image descriptors of foci morphology in the cell transformation assay.
abstract: Cell Transformation Assays (CTAs) have long been proposed for the identification of chemical carcinogenicity potential. The endpoint of these in vitro assays is represented by the phenotypic alterations in cultured cells, which are characterized by the change from the non-transformed to the transformed phenotype. Despite the wide fields of application and the numerous advantages of CTAs, their use in regulatory toxicology has been limited in part due to concerns about the subjective nature of visual scoring, i.e. the step in which transformed colonies or foci are evaluated through morphological features. An objective evaluation of morphological features has been previously obtained through automated digital processing of foci images to extract the value of three statistical image descriptors. In this study a further potential of the CTA using BALB/c 3T3 cells is addressed by analysing the effect of increasing concentrations of two known carcinogens, benzo[a]pyrene and NiCl2, with different modes of action on foci morphology. The main result of our quantitative evaluation shows that the concentration of the considered carcinogens has an effect on foci morphology that is statistically significant for the mean of two among the three selected descriptors. Statistical significance also corresponds to visual relevance. The statistical analysis of variations in foci morphology due to concentration allowed to quantify morphological changes that can be visually appreciated but not precisely determined. Therefore, it has the potential of providing new quantitative parameters in CTAs, and of exploiting all the information encoded in foci. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Earth and Environmental Sciences, University of Milan Bicocca, Piazza della Scienza, 1, 20126, Milan, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Callegaro
authors.affiliation: European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM), Chemical Safety and Alternative Methods Unit; Directorate F, European Commission Joint Research Centre, TP 126, Via E. Fermi, 2749, I-21027, Ispra, (VA), Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Corvi
authors.affiliation: European Union Reference Laboratory for Alternatives to Animal Testing (EURL ECVAM), Chemical Safety and Alternative Methods Unit; Directorate F, European Commission Joint Research Centre, TP 126, Via E. Fermi, 2749, I-21027, Ispra, (VA), Italy.
authors.forename: Susan
authors.initials: S
authors.lastname: Salovaara
authors.affiliation: Department of Earth and Environmental Sciences, University of Milan Bicocca, Piazza della Scienza, 1, 20126, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Urani
authors.affiliation: Department of Statistics, Computer Science, Applications, University of Florence, Viale Morgagni 59, I-50100, Florence, Italy.
authors.forename: Federico M
authors.initials: FM
authors.lastname: Stefanini
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D001564:Benzo(a)pyrene / Q000633:toxicity; D015197:Carcinogenicity Tests / Q000379:methods / Q000706:statistics & numerical data; D002273:Carcinogens / Q000633:toxicity*; D002471:Cell Transformation, Neoplastic / Q000187:drug effects* / Q000473:pathology*; D003627:Data Interpretation, Statistical; D004305:Dose-Response Relationship, Drug; D007090:Image Interpretation, Computer-Assisted; D051379:Mice; D008853:Microscopy / Q000379:methods / Q000706:statistics & numerical data; D009532:Nickel / Q000633:toxicity
chemical_list: D002273:Carcinogens; D001564:Benzo(a)pyrene; C022838:nickel chloride; D009532:Nickel
keywords: BALB/c 3T3 cell line; Benzo[a]Pyrene; Cell Transformation Assay; Dose-response; Extended linear mixed-effects models; Foci; Nickel chloride; Statistical image descriptors