Redox Regulation of NOX Isoforms on FAK/SRC Phosphorylation Driven Epithelial-to-Mesenchymal Transition in Malignant Cervical Epithelial Cells.

Epithelial-to-mesenchymal transition (EMT) promulgates epithelial cell associated disease-defining characteristics in tumorigenesis and organ fibrosis. Growth factors such as epidermal growth factor and fibroblast growth factor in addition to cytokines such as transforming growth factor-β1 (TGF-β1) is said to play a prominent role in remodeling related pathological events of cancer progression such as invasion, metastasis, apoptosis, EMT, etc. through redox related cellular secondary messengers, in particular the reactive oxygen species (ROS). However, the signaling cascade underlying the redox mechanism and thereby the progression of EMT remains largely unknown. In this study, upon TGF-β1 treatment, we observed an induction in NOX isoforms-NOX2 and NOX4-that have time (early and late) and cellular localization (nucleus and autophagosome co-localized) dependent effects in mediating EMT associated cell proliferation and migration through activation of the focal adhesion kinase (FAK)/SRC pathway in HeLa, human cervical cancer cells. Upon silencing NOX2/4 gene expression and using the SRC inhibitor (AZD0530), progression of TGF-β1 induced EMT related cellular remodeling, extra cellular matrix (ECM) production, cell migration and invasion, got significantly reverted. Together, these results indicate that NOX2 and NOX4 play important, albeit distinct, roles in the activation of cytokine mediated EMT and its associated processes via tyrosine phosphorylation of the FAK/SRC pathway.