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Exploitation of Cell Transformation Assays for better in vitro carcinogenicity testing

Image of a transformed focus
©EU, 2017
Sep 18 2017

JRC scientists – in close collaboration with the Universities of Milan and Florence in Italy – investigated the relationship between increasing concentrations of two carcinogens, namely nickel chloride and benzopyrene, and specific features of cell transformation assays (CTAs).

This work paves the way for improved exploitation of CTAs for carcinogenicity testing.

CTAs have long been proposed for the identification of chemical carcinogenicity potential. This in vitro assay measures transformation, which is an event in the multi-step process of tumour induction, through the alteration of the morphology of transformed cells, called foci.

It was stated by experts that results from CTAs should be further exploited to improve the assessment of carcinogenicity in vitro. Despite the wide fields of application and several 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 foci are evaluated through morphological features using a microscope.

Therefore, the team of researchers from the JRC and two Italian Universities (Milan and Florence) undertook the first attempt to quantitatively evaluate the role played by different concentrations of carcinogens on the morphology of transformed cells. This study was based on the automated digital processing of foci image, rather than through visual scoring, as it was previously developed by the same team. The further potential of CTAs using BALB/c 3T3 cells was addressed by analysing the effect of increasing concentrations of two known carcinogens, benzopyrene and NiCl2, on foci morphology.

The main result of this statistical evaluation allowed to quantify morphological changes that can be visually appreciated but not precisely determined if visual scoring is used. Therefore, it has the potential of providing new quantitative parameters in CTAs, and of exploiting all the information encoded in foci.

Read more in: Callegaro G et al.: "Relationship between increasing concentrations of two carcinogens and statistical image descriptors of foci morphology in the cell transformation assay" J. Appl. Toxicol. 37 (2017) 709-720, doi: 10.1002/jat.3419