After cocultured with Hpa-V cells, the expression of circCNIH4 in MDA-MB-231/Hpa-V and SkBr3/Hpa-V was down-regulated to 0.73 and 0.49 compared to MDA-MB-231 and SkBr3 breast cancer cell line respectively (Fig. 7A, B). This evidence concerns the gene HPSE and breast cancer.