Decreased eIF3e Expression Can Mediate Epithelial-to-Mesenchymal Transition through Activation of the TGF beta Signaling Pathway

作者：Desnoyers Guillaume; Frost Laura D; Courteau Lynn; Wall Michael L; Lewis Stephen M^*

来源：Molecular Cancer Research, 2015, 13(10): 1421-1430.

DOI：10.1158/1541-7786.MCR-14-0645

The eIF3e protein is a component of the multisubunit eIF3 complex, which is essential for cap-dependent translation initiation. Decreased eIF3e expression is often observed in breast and lung cancer and has been shown to induce epithelial-to-mesenchymal transition (EMT) in breast epithelial cells by an unknown mechanism. Here, we study the effect of decreased eIF3e expression in lung epithelial cells by creating stable clones of lung epithelial cells (A549) that express an eIF3e-targeting shRNA. Our data indicate that decreased eIF3e expression in lung epithelial cells leads to EMT, as it does in breast epithelial cells. Importantly, we show that decreased eIF3e expression in both lung and breast epithelial cells leads to the overproduction of the TGF beta cytokine and that inhibition of TGF beta signaling can reverse eIF3e-regulated EMT in lung epithelial cells. In addition, we discovered that several mRNAs that encode important EMT regulators are translated by a cap-independent mechanism when eIF3e levels are reduced. These findings indicate that EMT mediated by a decrease in eIF3e expression may be a general phenomenon in epithelial cells and that it requires activation and maintenance of the TGFb signaling pathway.

• 出版日期2015-10