Circ_ZFR affects FABP7 expression to regulate breast cancer progression by acting as a sponge for miR‐223‐3p.

Background: Breast cancer (BC) is a common malignancy in women. Circular RNAs (circRNAs) have been reported to play a key role in the development of BC; however, the effect of circular RNA zinc finger RNA binding protein (circ_ZFR) in BC is unknown. Methods: Abundances of circ_ZFR, fatty acid binding protein 7 (FABP7), and microRNA‐223‐3p (miR‐223‐3p) were measured by quantitative real‐time polymerase chain reaction (qRT‐PCR). The circular structure of circ_ZFR was validated by RNase R treatment. Cell proliferation, migration, invasion, and apoptosis were assessed by colony formation, cell counting kit‐8, Transwell, flow cytometry assays, respectively. All protein levels were determined by Western blot. Dual‐luciferase reporter assay was used to confirm the relationship between miR‐223‐3p and circ_ZFR or FABP7. A xenograft model was established to understand the effect of circ_ZFR on BC cell growth in vivo. Results: The expression levels of circ_ZFR and FABP7 were higher in BC tissues and cell lines, whereas miR‐223‐3p expression was lower. Knockdown of circ_ZFR or FABP7 in BC cells reduced proliferation, migration, invasion, and epithelial mesenchymal transition (EMT), and induced apoptosis in vitro, whereas the opposite effects were observed in circ_ZFR‐overexpressed cells. Furthermore, circ_ZFR might act as a sponge for miR‐223‐3p to regulate FABP7 expression, thereby promoting the progression of BC cells in vitro and in vivo. Conclusion: Circ_ZFR might act as a miRNA sponge for miR‐223‐3p to regulate FABP7, thereby promoting proliferation, migration, invasion, and EMT of BC cells, and inhibiting cell apoptosis. [ABSTRACT FROM AUTHOR]