MYC-Activated LncRNA MNX1-AS1 Promotes the Progression of Colorectal Cancer by Stabilizing YB1

Long noncoding RNAs (lncRNA) are involved in tumorigenesis and drug resistance. However, the roles and underlying mechanisms of lncRNAs in colorectal cancer are still unknown. In this work, through transcriptomic profiling analysis of 21 paired tumor and normal samples, we identified a novel colorectal cancer-related lncRNA, . - expression was significantly upregulated in colorectal cancer and associated with poor prognosis. and gain- and loss-of-function experiments showed that - promotes the proliferation of colorectal cancer cells. - bound to and activated Y-box-binding protein 1 (YB1), a multifunctional RNA/DNA-binding protein, and prevented its ubiquitination and degradation. A marked overlap between genes that are differentially expressed in - knockdown cells and transcriptional targets of YB1 was observed. YB1 knockdown mimicked the loss of viability phenotype observed upon depletion of - . In addition, MYC bound the promoter of the - locus and activated its transcription. experiments showed that ASO inhibited - , which suppressed the proliferation of colorectal cancer cells in both cell-based and patient-derived xenograft models. Collectively, these findings suggest that the MYC- -YB1 axis might serve as a potential biomarker and therapeutic target in colorectal cancer. SIGNIFICANCE: This study highlights the discovery of a novel colorectal cancer biomarker and therapeutic target, - , a long noncoding RNA that drives proliferation via a MYC/ /YB1 signaling pathway. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/10/2636/F1.large.jpg.