Structural basis for alpha fetoprotein-mediated inhibition of caspase-3 activity in hepatocellular carcinoma cells

Int J Cancer. 2017 Oct 1;141(7):1413-1421. doi: 10.1002/ijc.30850. Epub 2017 Jul 7.

Abstract

Alpha-fetoprotein (AFP) is an early serum growth factor in the foetal liver development and hepatic carcinogenesis; However, the precise biological role of cytoplasmic AFP remains elusive. Although we recently demonstrated that cytoplasmic AFP might interact with caspase-3 and inhibit the signal transduction of apoptosis in human hepatocellular carcinoma (HCC) cells, the details of this interaction are not clear. To reveal the molecular relationship between AFP and caspase-3, we performed molecular docking, co-immunoprecipitation (Co-IP), laser confocal microscopy, site-directed mutagenesis and functional experiments to analyse the key amino acid residues in the binding site of caspase-3. The results of Co-IP, laser confocal microscopy and functional analyses were consistent with the computational model. We also used the model to explain why AFP cannot bind to caspase-8. These results provide the molecular basis for the AFP-mediated inhibition of caspase-3 activity in HCC cells. Altogether, we found that AFP interacts with caspase-3 through precise amino acids, namely loop-4 residues Glu-248, Asp-253 and His-257. The results further demonstrated that AFP plays a critical role in the inhibition of the apoptotic signal transduction that mediated by caspase-3. Thus, AFP might represent a novel biotarget for the therapy of HCC patients.

Keywords: alpha-fetoprotein; caspase-3; hepatocellular carcinoma; molecular docking.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Binding Sites
  • Carcinoma, Hepatocellular / metabolism*
  • Caspase 3 / chemistry
  • Caspase 3 / metabolism*
  • Caspase 8 / chemistry
  • Caspase 8 / metabolism
  • Cell Line, Tumor
  • Cell Proliferation
  • Humans
  • Immunoprecipitation
  • Liver Neoplasms / metabolism*
  • Microscopy, Confocal / methods
  • Molecular Docking Simulation / methods
  • Mutagenesis, Site-Directed
  • Protein Structure, Quaternary
  • Signal Transduction
  • alpha-Fetoproteins / chemistry
  • alpha-Fetoproteins / metabolism
  • alpha-Fetoproteins / physiology*

Substances

  • alpha-Fetoproteins
  • Caspase 3
  • Caspase 8