SMYD3 plays a pivotal role in mediating the epithelial-mesenchymal transition process in breast cancer.

In previous reports, we highlighted the significant involvement of SMYD3, a histone methyltransferase (HMT), in various aspects of cancer progression, including cell adhesion, migration, and invasion. In this study, we delved deeper into understanding the relationship between SMYD3 and epithelial-mesenchymal transition (EMT) both in cell lines and clinical samples. Our investigation uncovered a notable correlation between heightened SMYD3 expression and the presence of EMT markers in human breast cancer tissues. We found that the induction of SMYD3 expression is facilitated by transforming growth factor beta 1 (TGF-β1), which achieves this by suppressing miR-124, an inhibitor that targets SMYD3, through alterations in DNA methylation. Conversely, our experiments demonstrated that reducing SMYD3 levels through RNA interference impeded TGF-β1-induced EMT in breast cancer cells. Furthermore, our results revealed that SMYD3 alone has the capability to modulate the expression of markers associated with EMT. An intriguing aspect of our study is the revelation that SMYD3 influences the activation of vimentin by binding to its response elements within the core promoter region. Notably, this effect is independent of SMYD3's histone methyltransferase activity. These findings collectively underscore the pivotal role of SMYD3 in driving EMT, both in cell lines and primary cancer tissues, particularly emphasizing its significance in TGF-β1-induced EMT in breast cancer.