The Long Noncoding RNA, LINC01555, Promotes Invasion and Metastasis of Colorectal Cancer by Activating the Neuropeptide, Neuromedin U

BACKGROUND This study aimed to investigate the role of the long noncoding RNA (lncRNA), LINC01555, on the migration and invasion of colorectal cancer (CRC) cells, its expression in CRC tissue, and its interaction with the neuropeptide, neuromedin U (NmU). MATERIAL AND METHODS LINC01555 expression in SW620 and HCT116 CRC cells, and NCM460 normal colorectal cells, and 48 resection specimens containing CRC and adjacent normal tissue, was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Cox regression analysis was used to assess the relationship between LINC01555 expression and patient survival. The effects of LINC01555 expression on CRC cell proliferation, migration, and invasion were assessed using the cell counting kit-8 (CCK-8) assay, the colony formation assay, and the transwell assay. Functional studies determined the interaction between LINC01555 and NmU in the development of CRC. RESULTS The Cancer Genome Atlas (TCGA) dataset showed that LINC01555 was highly expressed in CRC tissue when compared with adjacent normal colorectal tissue. LINC01555 expression was positively correlated with tumor stage, but negatively correlated with disease-free survival (DFS) and overall survival (OS) and was an independent risk factor for CRC. The receiver operating characteristic (ROC) curve analysis showed the diagnostic specificity of LINC01555 in CRC. Knockdown of LINC01555 inhibited cell proliferation, migration, and invasion of CRC cells. Functional studies showed that knockdown of NmU reduced cell migration and invasion of CRC cells that overexpressed LINC01555. CONCLUSIONS Increased expression of LINC01555 was found in CRC tissues and promoted the invasion of CRC cells by upregulating the expression of NmU.