In vivo selection reveals long non-coding RNAs implicated in colon to liver metastasis

Colorectal cancer (CRC) is the third most common malignancy in both American men and women. Most of the deaths attributed to CRC are a result of metastatic spread to the liver. In this study, colon cancer cells that highly metastasized to liver in vivo were compared to less metastatic parental cells to investigate the role for long non-coding RNAs (lncRNAs) in CRC metastasis. The highly metastatic daughter cells (LS-3B) were found to be 63-fold more metastatic than the parental cell line (LS-PAR) in vivo. A lncRNA microarray comparing LS-PAR and LS-3B cells revealed that 104 lncRNAs had fold changes > 2.0 and an FDR < 0.05. Real time PCR mediated validation revealed many lncRNAs exhibited high fold changes such as a 60-fold increase in LOC101448202, a 20-fold increase in MRPL23-AS1 and 50-fold decreases in GNAS-AS1 and LOC101928131. In vivo metastasis differences could be recapitulated in vitro as LS-3B cells closed wounds faster than their parental LS-PAR cells. However, intestinal epithelial cancer cells with robust downregulation of MRPL23-AS1, C1QTNF1-AS1, GNAS-AS1, LINCR-0002 and LOC101448202 failed to display differences in comparison to controls in in vitro migration assays. Three of the five lncRNAs with microarray probes for currently available GEO-datasets were significantly altered in liver CRC-associated tumor biopsies as compared to the primary tumor of non-metastatic CRC. Further studies on the lncRNAs identified will better define their roles in metastasis and how they might be useful if targeted therapeutically.