Long non-coding RNAs (lncRNAs) are frequently dysregulated in a variety of human 
cancers. However, their biological roles in these cancers remain incompletely 
understood. In this study, we analyze the gene expression profiles of colon 
cancer tissues and identify a previously unannotated lncRNA, FLJ39051, that we 
term GSEC (G-quadruplex-forming sequence containing lncRNA), as a lncRNA that is 
upregulated in colorectal cancer. We further demonstrate that knockdown of GSEC 
results in the reduction of colon cancer cell motility. We also show that GSEC 
binds to the DEAH box polypeptide 36 (DHX36) RNA helicase via its 
G-quadruplex-forming sequence and inhibits DHX36 G-quadruplex unwinding 
activity. Moreover, knockdown of DHX36 restores the reduced migratory activity 
of colon cancer cells caused by GSEC knockdown. These results suggest that GSEC 
plays an important role in colon cancer cell migration by inhibiting the 
function of DHX36 via its G-quadruplex structure.