PIR and breast cancer: Upregulation of piR-021285, piRNA-823, piRNA-932, piR-016658, piR-651, piR-4987, piR-20365, piR-20485, and piR-20582 were associated with EMT, invasiveness, metastasis, lymph node metastasis, while downregulation of piR-36712, piR-016975, piR-FTH1 in BC tissue were related to EMT, chemosensitivity, and chemoresistance [31].