Profiling of Exosomal miRNAs Targeting ESR1

The analysis of exosomal miRNAs was performed by HiSeq2500 (Illumina, San Diego, CA, USA) and at least 5 million reads per sample were obtained. Library preparation and sequencing was done by ZAO Genoanalytica as follows: miRNA was extracted from exosomes by PureLink RNA Micro Kit (12183-016 (Thermo Fisher Scientific, Waltham, MA, USA)) according to the manual. Library preparation was carried out with the NEBNext Small RNA Library Prep Set for Illumina (E7330S (New England Biolabs, Hitchin, UK)). The associations between miRNAs and ESR1 were searched by using the integrative database of human miRNA target predictions mirDIP [103 (link)], which aggregates the data from all known miRNA databases. The likelihood level was specified as medium. All studied miRNAs were found as potentially targeting ESR1. Some of them (miR-181a-2-3p and hsa-miR-874-3p) were found to be within 1% of top miRNAs annotated with ESR1 (very high confidence class). Moreover, these 6 miRNAs were selected concerning the literature indicated in Table 1. All hyperexpressed miRNAs are provided in Table S1 in the supporting file.