Aberrant expression of long noncoding RNAs in colorectal cancer with liver metastasis

Long noncoding RNA (lncRNA) plays a crucial role in the regulation of various cellular processes and human diseases. However, little is known about the role of lncRNAs in colorectal liver metastasis (CLM). In the present study, we aimed to determine whether lncRNAs are differentially expressed in CLM tissue and to further assess their clinical value. lncRNA arrays were employed to screen for differentially expressed lncRNAs in colorectal cancer (CRC) tissues with synchronous, metachronous, or nonliver metastasis. Based on bioinformatics data, a quantitative reverse-transcription polymerase chain reaction (qRT-PCR) assay was performed to identify target lncRNAs in an expanded set of CRC samples with various subtypes of liver metastasis. The relationships between the target lncRNAs and the clinical characteristics and patient prognosis were further analyzed. After determining the expression profile of lncRNAs (n = 1332) in CLM tissue, 40 differentially expressed lncRNAs that were potentially related to CLM were selected for further examination in an expanded set of clinical samples, and three novel target lncRNAs, termed lncRNA-CLMAT1-3, were verified. High lncRNA-CLMAT3 expression strongly correlated with liver metastasis (P = 0.03) and lymph node metastasis (P = 0.009). Moreover, patients displaying high lncRNA-CLMAT3 expression exhibited a shorter median overall survival duration than those displaying low lncRNA-CLMAT3 expression (30.7 vs. 35.2 months, P = 0.007). Multivariate analysis demonstrated that the lncRNA-CLMAT3 expression level is an independent prognostic factor (hazard ratio 2.05, P = 0.02) after adjusting for other known prognostic factors. lncRNA-CLMAT3 over-expression was significantly associated with CLM and was an independent predictor of poor survival for patients with CRC.