LncRNA GAL promotes colorectal cancer liver metastasis through stabilizing GLUT1

Colorectal cancer liver metastasis (CRLM) is the leading cause of colorectal cancer-related deaths and remains a clinical challenge. Enhancement of glucose uptake is involved in CRLM; however, whether long noncoding RNAs (lncRNAs) participate in these molecular events remains largely unclear. Here, we report an lncRNA, GAL (glucose transporter 1 (GLUT1) associated lncRNA), that was upregulated in CRLM tissues compared with primary colorectal cancer (CRC) tissues or matched normal tissues and was associated with the overall survival rates of CRLM patients. Functionally, GAL served as an oncogene because it promoted CRC cell migration and invasion in vitro and enhanced the ability of CRC cells to metastasize from the intestine to the liver in vivo. Mechanistically, GAL interacted with the GLUT1 protein to increase GLUT1 SUMOylation, inhibiting the effect of the ubiquitin-proteasome system on the GLUT1 protein. GLUT1-knockout (-/+) repressed the GAL-mediated increase in CRC cell uptake of glucose, migrate, and invade in vitro, as well as metastasis from the intestine to the liver in vivo, and enforced expression of GLUT1 rescued GAL knockout-induced biological functions in CRC cells. Taken together, our findings demonstrated that GAL promotes CRLM by stabilizing GLUT1, suggesting that the GAL-GLUT1 complex may act as a potential therapeutic target for CRLM.