OCT4 Suppresses Metastasis in Breast Cancer Cells Through Activation of STAT3 Signaling

Background: Metastatic breast cancer is the major cause of death in breast cancer patients. Activation of epithelial-mesenchymal transition (EMT) induces migration and invasion of breast cancer cells (BCCs). OCT4 (POU5F1) is a key transcription factor for reprograming and plays an important role in self-renewal. Recent studies recovered OCT4 may correlate with cancer progression. However, it is no sufficient proofs to verify how OCT4 plays in metastasis of breast cancer. In this present study, we show the role of OCT4 in the migration and invasion of BCCs in vitro and metastasis in vivo.Methods: PCR, Western Blot and Immunofluorescence staining were performed to determine to OCT4 expression in BCCs. Wound-healing assay and invasion assay were utilized to analyze the mobility of BCCs. Tumor metastasis was assessed with nude mice by subcutaneously injection. IHC assay was used to evaluate phosphorylated signal transducer and activator of transcription 3 (p-STAT3) expression in breast cancer tissues and normal breast tissues. To study whether OCT4 regulate EMT through STAT3 signal, we used shRNA to knockdown STAT3 gene expression in BCCs.Results: OCT4 changed cell morphology of BCCs, decreased cell adhesion, and inhibited migration, invasion and metastatic ability of BCCs. In the meantime, overexpression of OCT4 activated STAT3 signaling and changed EMT-related protein expressions in BCCs. However, knockdown of STAT3 in BCCs with overexpression of OCT4 could facilitate EMT.Conclusion: Our data demonstrate that OCT4 suppresses EMT in BCCs through activation of STAT3 signaling, which is a key mechanism in impeding BCCs migration and invasion. Collectively, these data suggest that elevating OCT4 expression may be an effective method for reducing the metastatic potential of BCCs, which could also contribute to developing new methods for diagnosis and new molecular target therapies in breast cancer metastasis.