A specific Upregulated lncRNA in Colorectal Cancer Promotes Cancer Progression by Modulating miR-185-5p/CCND2 Axis

Abstract BackgroundAdenomatous polyposis coli (APC) gene mutations were found in most colorectal cancer patients and functioned as an important inducer of tumorigenesis. Long non-coding RNA (lncRNA) plays a crucial role in the pathogenesis of various diseases, including colorectal cancer (CRC). Here we investigated the role of SURC which is specific upregulated in CRC progression. MethodsBased on the previous microarray results, weighted correlation network analysis (WGCNA) and lncRNA-mRNA co-expression network analysis were used to identify a lncRNA (SURC) and found it was specific up-regulated in CRC patients by qPCR and FISH staining. Chromatin immunoprecipitation (ChIP) assay was used to demonstrate the regulatory effect and mechanism of APC mutation on SURC expression. The effects of SURC on proliferation and cell cycle were determined by in vitro and in vivo experiments. Chromatin Isolation by RNA Purification (CHIRP) and luciferase reporter assay were carried out to illustrate the interaction between SURC, miR-185-5p and CCND2.ResultsWe found that SURC was specific up-regulated in CRC, but not in other solid tumor, when compared with normal adjacent tissues. High expression of SURC correlates with poorer disease-free survival and overall survival of CRC patients. Mutated APC protein resulted in stabilization of β-catenin in CRC, which promotes the transcription of SURC via binding to its promoter. Knockdown of SURC impaired CRC cell proliferation, colony formation and CRC tumor growth. Mechanistically, after transcription, SURC was transferred to cytoplasm and inhibits miR-185-5p expression via binding to miR-185-5p and inhibiting the synthesis of miR-185-5p from pri-miR-185-5p, which results in CCND2 expression.ConclusionCollectively, these results indicated that SURC promoted CRC tumor growth via interacting with miR-185-5p and regulating the activity of miR-185-5p/CCND2 axis which would be a novel diagnosis and prognosis prediction target for CRC.