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

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.

• Authors: Bo Lin, Mingyue Zhu, Wenting Wang, Wei Li, Xu Dong, Yi Chen, Yan Lu, Junli Guo, Mengsen Li
• Journal: International journal of cancer (Int J Cancer) Vol. 141 Issue 7 Pg. 1413-1421 (10 01 2017) ISSN: 1097-0215 [Electronic] United States
• PMID: 28653316 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2017 UICC.

Chemical References

• alpha-Fetoproteins
• Caspase 3
• Caspase 8

Topics

• Apoptosis
• Binding Sites
• Carcinoma, Hepatocellular (metabolism)
• Caspase 3 (chemistry, metabolism)
• Caspase 8 (chemistry, 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, metabolism, physiology)