Abstract
Accumulating evidences have revealed that dysregulated microRNAs (miRNAs) involve in the tumorigenesis, progression and even lead to poor prognosis of various carcinomas, including breast cancer. MiRNA-106b-5p (miR-106b) and miRNA-93-5p (miR-93) levels were confirmed to be significantly upregulated in breast cancer clinical samples (n=36) and metastatic cell line (MDA-MB-231) compared with those in the paired adjacent tissues and normal breast epithelial cell line (MCF-10A). Moreover, further research stated that the capability of migration, invasion and proliferation changed along with the altered expression of miR-106b and miR-93 in breast cancer. PTEN, the tumor-suppressor gene, was discovered to be reduced in breast cancer tissues or MDA-MB-231 cells with high levels of miR-106b and miR-93, which were inversely expressed in PTEN overexpression tissues or cells. Based on the investigation, miR-106b and miR-93 induced the migration, invasion and proliferation and simultaneously enhanced the activity of phosphatidylinositol-3 kinase (PI3K)/Akt pathway of MCF-7 cells, which could be blocked by upregulation of PTEN. Furthermore, suppression of PTEN reversed the function induced by anti-miR-106b and anti-miR-93 in MDA-MB-231 cells, indicating that PTEN was directly targeted by these miRNAs and acted as the potential therapeutic target for breast cancer therapy. In short, reductive PTEN mediated by miR-106b and miR-93 promoted cell progression through PI3K/Akt pathway in breast cancer.