(4) Conclusions: We summarize functional evidence for leading tumor-suppressive (e.g., miR-205, miR-23b, miR-455-3p) and oncogenic (e.g., miR-21, miR-182, miR-449b) candidates, discuss their intersection with the androgen-receptor, TGF-β, WNT/β-catenin, and PI3K-AKT signaling, and outline outstanding requirements for the clinical qualification of miRNA panels in prostate cancer. This evidence concerns the gene TGFB1 and prostate carcinoma.