Exosomes are tiny vesicles that shuttle genetic information between cells, and throughout the circulating blood. Although originally believed to function in disposal of cell waste, exosomes, despite their miniscule size, are now known to boast a number of key functions in both the normal and disease setting. Despite their small size, exosomes hold the potential to reduce the mortality associated with breast cancer through early detection of the disease based on serum-derived exosomes. The proposed work will focus on exosome-encapsulated microRNAs (ExomiRs). Once secreted by the cell, ExomiRs enter the bloodstream and could serve as a blood-based marker of the presence of cancer. We have established that secreted ExomiRs are detectable in sera from patients with breast cancer, and have identified specific microRNAs that are elevated in the circulation of animal models of breast cancer. We will translate these “pre-clinical” findings to the clinical setting, by isolating exosomes from breast cancer patient serum and comparing the microRNA content to those in healthy people, to determine whether they may serve as a useful biomarker of disease. We have access to a Biobank of >1200 serum samples from breast cancer patients, which were attained with ethical approval and patient consent. Thus we can rapidly assess whether ExomiRs are relevant in the patient setting, and whether they are linked to disease status, subtype, or patient outcome. Analysis of ExomiRs in the circulation of breast cancer patients may provide new, non-invasive markers of disease progression or response to therapy, resulting in improved patient outcome.
