Transcriptomics effects of ingestion of food additive titanium dioxide (E171) in the colon of a chemically induced colorectal cancer model

Titanium dioxide, a white colorant, is the mineral the most produced worldwide. It is used in food under the name of E171. Previous studies showed that in a chemically induced colorectal cancer mouse model, E171 increase significantly the number of tumours. The aim of this study was to understand the molecular mechanisms behind these effects of E171 exposure. BALB/c mice were exposed by gavage to 5 mg/kg bw/day of E171 for 2, 7, 14 and 21 days. Whole genome mRNA microarray analyses on the distal colon were performed. The results show that E171 induced a downregulation of genes involved in the innate and adaptive immune system, suggesting impairment of this system. In addition, over time, signalling genes involved in colorectal cancer and other types of cancers were modulated. In relation to cancer development, effects potentially associated with oxidative stress were observed through modulation of genes related to antioxidant production. E171 affected genes involved in biotransformation of xenobiotics which can form reactive intermediates resulting in toxicological effects. These transcriptomics data reflect the early biological responses induced by E171 which precede tumour formation in an AOM/DSS mouse model. Total of 31 colon of mice samples, every sample was in duplicate. Two different type of exposure: exposed to AOM and DSS (CRC), exposed to AOM/DSS and 5mg/kg bw/day of E171 (CRCE). Four time points: 2, 7, 14 and 21 days. At each time point 4 mice are euthanised (2 males, 2 females)'