MiR-27a-3p is translocated to the nucleus by acting on the IPO8 gene and binds to the HIF-1α promoter region, attracting Argonaute 2 and RNA polymerase II to activate HIF1α transcription, which increases the activation of downstream pathways, facilitating the development, invasion, and lung metastasis of breast cancer cells. This evidence concerns the gene HIF1A and breast cancer.