GSE212004
RNAseq of 4T1 cells expressing exogenous LINC01133
The PI3K pathway represents the most hyperactivated oncogenic pathway in triple-negative breast cancer (TNBC), a highly aggressive tumor subtype encompassing ~15% of breast cancers with no targeted therapeutics. Despite critical contributions of its signaling arms to disease pathogenesis, PI3K pathway inhibitors have not achieved expected clinical responses in TNBC owing largely to still-incomplete understanding of the compensatory cascades that operate downstream of PI3K. Here, we investigated the contributions of long non-coding RNAs (lncRNAs) to PI3K activities in clinical and experimental TNBC, and discovered a prominent role for LINC01133 as a PI3K-AKT signaling effector. We found that LINC01133 exerted pro-tumorigenic roles in TNBC, and that it governed a previously undescribed mTORC2-dependent pathway that activated AKT in a PI3K-independent manner. Mechanistically, we show that LINC01133 induced the expression of the mTORC2 component PROTOR1/PRR5 by competitively coupling away its negative mRNA regulator, the heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNPA2B1). PROTOR1/PRR5 in turn was sufficient and necessary for LINC01133-triggered functions, casting previously unappreciated roles for this Rictor-binding protein in cellular signaling and growth. Notably, LINC01133 antagonism undermined cellular growth and we show that the LINC01133-PROTOR1/PRR5 pathway tightly associated with TNBC poor patient survival. Altogether, our findings uncovered a lncRNA-driven signaling shunt that acts as a critical determinant of malignancy downstream of the PI3K pathway and as a potential RNA-based theranostic in clinical TNBC management. We performed comparative gene expression profiling analyses using RNA-seq of triplicates of control 4T1 cells (harboring empty plasmid control) and 4T1 cell trioplicates expressing exogenous LINC01133. Overall design: The samples in this data set include total RNAs derived from three 4T1 cell replicates harboring empty pLVX vector (WT or control) and three 4T1 cell replicates harboring pLVX-LINC01133 expression plasmid.