It is obvious that (A) tumor-suppressing miRNAs are downregulated by lncRNAs in breast cancer progression, (B) PTEN downregulation occurs, (C) the way is paved for inducing factors involved in breast cancer malignancy such as PI3K/Akt, (D) breast cancer cells promote their proliferation and invasion, and (E) finally, they can obtain resistance to chemotherapy [36,256]. This evidence concerns the gene PTEN and breast cancer.