Characterisation of cisplatin-induced transcriptomics responses in primary mouse hepatocytes, HepG2 cells and mouse embryonic stem cells shows conservation of regulating transcription factor networks.

The toxic mechanisms of cisplatin have been frequently studied in many species and in vitro cell models. The Netherlands Toxicogenomics Centre focuses on developing in vitro alternatives using genomics technologies for animal-based assays on, e.g. genotoxic hazards. Models such as human hepatocellular carcinoma cell line (HepG2) cells, mouse primary hepatocytes (PMH) and mouse embryonic stem cells (mESC) are used. Our aim was to identify possibly robust conserved mechanisms between these models using cisplatin as model genotoxic agent. Transcriptomic data newly generated from HepG2 cells and PMH exposed to 7 µM cisplatin for 12, 24 and 48h and 24 and 48h, respectively, were compared with published data from mESC exposed to 5 µM cisplatin for 2-24h. Due to differences in response time between models and marginal changes after shorter exposure periods, we focused on 24 and 48h. At gene level, 44 conserved differentially expressed genes (DEG), involved in processes such as apoptosis, cell cycle, DNA damage response and DNA repair, were found. Functional analysis shows that limited numbers of pathways are conserved. Transcription factor (TF) network analysis indicates 12 common TF networks responding among all models and time points. Four TF, HNF4-α, SP1, c-MYC and p53, capable of regulating ±50% of all DEG, seem of equal importance in all models and exposure periods. Here we showed that transcriptomic responses across several in vitro cell models following exposure to cisplatin are mainly determined by a conserved complex network of 4 TFs. These conserved responses are hypothesised to provide most relevant information for human toxicity prediction and may form the basis for new in vitro alternatives of risk assessment.