Circulating microRNAs and liquid biopsy: murine xenograft models for technical validation of clinical protocols

In oncology, liquid biopsy is applied to detect with high efficiency clinically relevant analytes, such as tumor cells, cell-free nucleic acids, and exosomes in peripheral blood and other body fluids of cancer patients. Liquid biopsy is considered one of the most advanced non-invasive diagnostic systems useful, in the next future, for enabling personalized treatments in precision medicine. Medical actions include, but are not limited to, early diagnosis, staging, prognosis, anticipation (lead time) and prediction of therapy responses, as well as follow up. Experimental system for validation of the proposed liquid biopsy approaches is highly needed. In this review article we will discuss the establishment of xenotransplanted mouse model systems for the validation of liquid biopsy protocols aimed to identify changes in the miRNA plasma content. Human colon cancer HT-29 and LoVo cells have been xenotransplanted and miR-221-3p and miR-222-3p have been comparatively analyzed in cultured HT-29 and LoVo cells, xenotransplants and plasma samples.