Mechanistic Interrogation of Cell Transformation in Vitro: The Transformics Assay as an Exemplar of Oncotransformation

The rodent-based life-time cancer bioassay is still the basic experimental paradigm to assess the carcinogenic potential of chemicals, with relatively little progress regarding the acceptance of in vitro tests. The Transformics Assay is an in vitro test which combines the BALB/c 3T3 Cell Transformation Assay (CTA) with microarray transcriptomics. It has been shown to improve upon the mechanistic understanding of the CTA, helping to identify mechanisms of action leading to chemical-induced transformation thanks to RNA extractions in specific time points along the process of in vitro transformation. In this study the lowest transforming concentration of the carcinogenic benzo(a)pyrene (B(a)P) has been tested in order to find molecular signatures of initial events relevant for oncotransformation. Some biological interpretations are presented related to the Enrichment Analysis provided by Metacore. Results show that after 72 hrs of exposure, the immune and inflammatory responses are the main processes involved in cell response. Furthermore, pathways and processes related to cell cycle regulation, cytoskeletal adhesion and remodeling processes, cell differentiation and transformation were observed. All these data are interpreted as a consequence of the initial aryl hydrocarbon receptor (AhR) activation leading to a cascade of cellular events and microenvironment modification.