<i>IGF2BP1</i> Promotes the Liver Cancer Stem Cell Phenotype by Regulating MGAT5 mRNA Stability by m6A RNA Methylation

Abstract

The aim of this study was to elucidate the mechanism of action of the insulin-like growth factor 2 mRNA-binding protein 1 (<i>IGF2BP1</i>) on the phenotype of the liver cancer stem cells (LCSCs). To gain insight into the mechanism of action of the <i>IGF2BP1</i> on LCSCs, the <i>IGF2BP1</i> shRNA sequences were transfected into hepatocellular carcinoma (HCC) cells. The LCSC phenotypes were measured by stemness gene expressions, spheroid formations, percentages of the CD133⁺ cells, colony formations, and tumorigenesis in vivo. Next, we screened for possible molecular mechanisms from the Cancer Genome Atlas (TCGA) database, and a methylated RNA immunoprecipitation-quantitative polymerase chain reaction (MeRIP-qPCR) was used to adjust the binding of <i>IGF2BP1</i> to the target gene, alpha-1,6-mannosylglycoprotein 6-beta-N-acetylglucosaminyltransferase (<i>MGAT5</i>). The MeRIP-qPCR was used to detect the binding of <i>IGF2BP1</i> and <i>MGAT5</i> through N⁶ methyladenosine (m6A) modification. Furthermore, we adjusted the attenuation of the mRNA of the <i>MGAT5</i> using quantitative real-time PCR (qRT-PCR). The <i>IGF2BP1</i> was upregulated in the LCSCs. Furthermore, the <i>IGF2BP1</i> promoted self-renewal and chemoresistance in human LCSCs and tumorigenesis in mice and it enhanced the expression of stemness genes in the LCSCs compared with the HCC cells. Further exploration indicated that the <i>IGF2BP1</i> binds directly to the <i>MGAT5</i> and inhibits its mRNA attenuation, suggesting that the <i>IGF2BP1</i> impacts <i>MGAT5</i> mRNA stability through m6A modification. Thus, it can be concluded that the <i>IGF2BP1</i> facilitated the LCSC phenotypes by promoting the <i>MGAT5</i> mRNA stability through the upregulation of m6A modification of the <i>MGAT5</i> mRNA.