Circ_HIPK3, derived from the exon 2 splicing of the homeodomain interacting protein kinase 3 (HIPK3), sponges miR-193a and eliminates the inhibition of high mobility group protein box 1 (HMGB1) through the phosphatidylinositol 3-kinase (PI3K)/AKT serine/threonine kinase (AKT) signaling pathway involved in regulating the migration and invasion of BC cells [50]. Here, PIK3CA is linked to breast cancer.