PGR and breast cancer: Collagen type I alpha 1 chain (COL1A1), encoding type I collagen, associated with oestrogen/progesterone receptor (ER/PR) status, is proposed as a regulator that facilitates breast cancer metastasis.14 In this regard, we hypothesized that hsa_circRNA_002178 might regulate the behaviours of breast cancer cells through interacting with in miR‐328‐3p and COL1A1.