PDCD4 and breast cancer: 4-ABP has been suggested to have the ability to impair the estrogen-related pathways, and increase the BC risk.44 EDC could also stimulate breast tumorigenesis by hormonal dysregulation and affecting the endocrine system.45 Hair dye chemicals may also affect the expression of some miRNAs and consequently their target genes; for example, EDCs caused an increase in the expression of oncomiR, miR-21, in MCF-7 BC cell line, and a decrease in the expression of miR-21 target genes, PDCD4 and PTEN.46 Taken together, we suggest that EDCs could affect the expression of hsa_circ_0001445.