Fig. 4.

Detection of human prostate cancer by serum levels of tumor-associated miRNA miR-141. (A) Serum levels of miR-141 discriminate patients with advanced prostate cancer from healthy controls. Serum levels of the prostate cancer-expressed miRNA miR-141 were measured in 25 healthy control men and 25 patients with metastatic prostate cancer (clinical data on subjects is provided in Table S3). Ct values were converted to absolute number of copies/μl serum by using a dilution series of known input quantities of synthetic target miRNA run simultaneously (on the same plate) as the experimental samples (dilution curves are provided in Fig. S2). Values shown have been normalized by using measurements of C. elegans synthetic miRNA controls spiked into plasma after denaturation for RNA isolation (details of normalization method are provided in SI Text). The dashed line indicates a 100% specificity threshold. (B) Receiver Operating Characteristic (ROC) plot. The data shown in A were used to draw the ROC plot shown. (C) Serum levels of nontumor-associated miRNAs are not substantially different between patients with prostate cancer and controls. Serum levels of miR-16, miR-24, and miR-19b were measured as negative controls as they are not expected to be cancer-associated in the serum. Absolute quantification of miRNAs and data normalization were carried out as described for A.