Cooperative involvement of NFAT and SnoN mediates transforming growth factor-β (TGF-β) induced EMT in metastatic breast cancer (MDA-MB 231) cells
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Epithelial to mesenchymal transition (EMT) is a secondary phenomenon concomitantly associated with the tumor progression. The regulatory signals and mechanistic details of EMT are not fully elucidated. Here, we shared a TGF-β mediated mechanism of EMT in breast cancer (MDA-MB 231) cells. Initial exposure of TGF-β for 48 h, enhanced the rate of cell proliferation and associated with EMT of MDA-MB 231 cells. The EMT was characterized by observing the increased N-cadherin, fibronectin, Snail expression and associated with the morphological change with a reduced E-cadherin expression. NFAT, a transcription factor, alters tumor suppressive function of TGF-β towards tumor progression. Up regulation of NFAT, coupled with a foremost translocation of one oncogenic protein SnoN from cytoplasm to nucleus was noticed during this TGF-β mediated EMT. Silencing of NFAT also showed the inhibition of TGF-β mediated EMT characterized by down regulation of N-cadherin and associated with reduced expression of SnoN. In addition, it was also observed that NFAT sequestering the Smad3 prevents the proteasome mediated degradation of SnoN and this SnoN has a role on the regulation of MMP-2, MMP-9 activity. Increased Smad3-SnoN interaction and proteasome mediated degradation of SnoN were detected after silencing of NFAT with a reduced MMP-2, MMP-9 activity. All of these observations provide a fresh mechanism in which by a twofold involvement of NFAT and SnoN plays a crucial role in TGF-β mediated EMT by recruiting the effector molecules N-cadherin and MMP-2, MMP-9.
KeywordsTGF-β NFAT SnoN Breast cancer EMT
Authors want to thank Department of Biotechnology and Department of NanoScience, University of Calcutta, respectively for Fluorescence Microscopy and Bio imaging instrument facility. Authors also want to specially thank Subhadip Kundu, Soham Mitra and Tarun Keswani for their support during the experiments. This work was supported by grants from Department of Biotechnology (DBT/PR 9779/27/67/2007), Government of India and Indian Council of Medical Research (Immuno/18/11/21/2002-ECD-1) India and DST FIST and UGC-SAP.
Conflict of interest
The authors have no conflict of interest.
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