lncRNA-WAL promotes triple-negative breast cancer aggression by inducing β-catenin nuclear translocation.

Because of its insensitivity to existing radiotherapy, namely chemotherapy and targeted treatments, triple-negative breast cancer (TNBC) remains a great challenge to overcome. Increasing evidence has indicated abnormal Wnt/β-catenin pathway activation in TNBC but not luminal or HER2+ breast cancer, and lncRNAs play a key role in a variety of cancers. Through lncRNA microarray profiling between activated and inactivated wnt/β-catenin pathway of TNBC tissues, lnc-WAL (wnt/β-catenin associated lncRNA; WAL) was selected as the top upregulated lncRNA in wnt/β-catenin pathway activation compared with the inactivation group. RIP-seq was used to compare the β-catenin and IgG groups, where lnc-WAL could interact with β-catenin. Clinically, increased lnc-WAL in TNBC tumor tissue was associated with shorter survival. lnc-WAL promoted EMT, the proliferation, migration and invasion of breast cancer stem cells (BCSCs), and TNBC cells. Mechanistically, lnc-WAL inhibited β-catenin protein degradation via Axin-mediated phosphorylation at serine 45. Subsequently, β-catenin accumulated in the nucleus and activated the target genes. Importantly, wnt/β-catenin pathway activation stimulated the transcription of lnc-WAL. These results pointed to a master regulatory role of lnc-WAL/Axin/β-catenin in the malignant progression of TNBC. Our findings provide important clinical translational evidence that lnc-WAL may be a potential therapeutic target against TNBC. Implications: The positive feedback between lnc-WAL and the Wnt/β-catenin pathway promotes TNBC progression, and lnc-WAL could be a potential prognostic marker for TNBC patients.