Analysis of change in circulating microRNAs in mice during breast tumor development

The aim of this study was to analyse alterations in circulating microRNA expression during breast tumour progression in a murine model, and to apply significantly altered miRNAs to patient samples to identify novel circulating microRNA markers or tumour progression. Athymic nude mice (n=10) received an injection of 2 x 105 MDA-MB-231 cells. Tumour volume was monitored weekly and blood sampling performed at weeks 1 and 6 following tumour induction. A microRNA array was performed comparing circulating 384 microRNAs in animals with early (week 1, n=5) versus late (week 6, n=5) disease. Five animals were included in the study (n=2 samples from each, total n=10 microArrays performed), with whole blood sampled one week following tumor induction and again at 6 weeks in the presence of established disease. The change in microRNA profile was then compared at week 1 and week 6, which the "early" sample providing the baseline measurements for each animal.