TGF-β signaling promotes metastasis by altering the expression of a variety of
downstream genes, including many protein-coding mRNAs, miRNAs, and in the current study, a
long non-coding RNA lncRNA-ATB. TGF-β signaling induces lncRNA-ATB, which
reinforces the pro-metastatic TGF-β response via two distinct mechanisms.
LncRNA-ATB competitively binds to miR-200s and sequesters them away from their mRNA
targets ZEB1 and ZEB2, which encode two key EMT
promoting transcription factors that repress the expression of E-cadherin and the miR-200s
themselves, thus promoting EMT. LncRNA-ATB also binds to and stabilizes
IL-11 mRNA, thereby increasing autocrine IL-11-STAT3 signaling to
enhance the survival and metastatic colonization of disseminated tumor cells in the lung
and liver. While ZEB1/2 and IL-11 are known to be activated by Smad-dependent pathways
downstream of TGF-β receptor activation, lncRNA-ATB is activated by a
Smad-independent non-canonical pathway that remains to be identified.