Isoginkgetin, a potential CDK6 inhibitor, suppresses SLC2A1/GLUT1 enhancer activity to induce AMPK-ULK1-mediated cytotoxic autophagy in hepatocellular carcinoma

Autophagy. 2023 Apr;19(4):1221-1238. doi: 10.1080/15548627.2022.2119353. Epub 2022 Sep 13.

Abstract

Isoginkgetin (ISO), a natural biflavonoid, exhibited cytotoxic activity against several types of cancer cells. However, its effects on hepatocellular carcinoma (HCC) cells and mechanism remain unclear. Here, we revealed that ISO effectively inhibited HCC cell proliferation and migration in vitro. LC3-II expression and autophagosomes were increased under ISO treatment. In addition, ISO-induced cell death was attenuated by treatment with chloroquine or knockdown of autophagy-related genes (ATG5 or ULK1). ISO significantly suppressed SLC2A1/GLUT1 (solute carrier family 2 member 1) expression and glucose uptake, leading to activation of the AMPK-ULK1 axis in HepG2 cells. Overexpression of SLC2A1/GLUT1 abrogated ISO-induced autophagy. Combining molecular docking with thermal shift analysis, we confirmed that ISO directly bound to the N terminus of CDK6 (cyclin-dependent kinase 6) and promoted its degradation. Overexpression of CDK6 abrogated ISO-induced inhibition of SLC2A1/GLUT1 transcription and induction of autophagy. Furthermore, ISO treatment significantly decreased the H3K27ac, H4K8ac and H3K4me1 levels on the SLC2A1/GLUT1 enhancer in HepG2 cells. Finally, ISO suppressed the hepatocarcinogenesis in the HepG2 xenograft mice and the diethylnitrosamine+carbon tetrachloride (DEN+CCl4)-induced primary HCC mice and we confirmed SLC2A1/GLUT1 and CDK6 as promising oncogenes in HCC by analysis of TCGA data and human HCC tissues. Our results provide a new molecular mechanism by which ISO treatment or CDK6 deletion promotes autophagy; that is, ISO targeting the N terminus of CDK6 for degradation inhibits the expression of SLC2A1/GLUT1 by decreasing the enhancer activity of SLC2A1/GLUT1, resulting in decreased glucose levels and inducing the AMPK-ULK1 pathway.

Keywords: Autophagy; CDK6; SLC2A1/GLUT1; hepatocellular carcinoma; isoginkgetin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Animals
  • Antineoplastic Agents* / pharmacology
  • Autophagy / physiology
  • Autophagy-Related Protein-1 Homolog / metabolism
  • Biflavonoids* / pharmacology
  • Biflavonoids* / therapeutic use
  • Carcinoma, Hepatocellular* / drug therapy
  • Carcinoma, Hepatocellular* / genetics
  • Carcinoma, Hepatocellular* / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Cyclin-Dependent Kinase 6 / metabolism
  • Cyclin-Dependent Kinase 6 / pharmacology
  • Cyclin-Dependent Kinase 6 / therapeutic use
  • Glucose Transporter Type 1 / genetics
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Liver Neoplasms* / drug therapy
  • Liver Neoplasms* / genetics
  • Liver Neoplasms* / metabolism
  • Mice
  • Molecular Docking Simulation

Substances

  • isoginkgetin
  • Biflavonoids
  • AMP-Activated Protein Kinases
  • Cyclin-Dependent Kinase 6
  • Glucose Transporter Type 1
  • Antineoplastic Agents
  • ULK1 protein, human
  • Autophagy-Related Protein-1 Homolog
  • Intracellular Signaling Peptides and Proteins
  • SLC2A1 protein, human
  • CDK6 protein, human

Grants and funding

This work was supported by National Natural Science Foundation of China (81503221, 81903760, and 81903914), Natural Science Foundation of Guangdong Province (2017A030313659, 2021A1515110841, and 2021A1515220185), Shenzhen Fundamental Research and Discipline Layout Project (JCYJ20170413093108233, JCYJ20190806151816859, andJCYJ20210324113003007), and Sanming Project of Medicine in Shenzhen (SZZYSM202106004); Natural Science Foundation of Guangdong Province for Distinguished Young Scholars [2017A030313659, 2021A1515220185]