Molecular basis for the interplay of apoptosis and proliferation mediated by Bcl-xL:Bim interactions in pancreatic cancer cells.

Abstract

A major mechanism through which cancer cells avoid apoptosis is by promoting the association of anti-apoptotic members of the pro-survival Bcl-2 protein family (like Bcl-2 and Bcl-xL) with BH(3) domain-only proteins (like Bim and Bid). Apoptosis and cell proliferation have been shown to be linked for many cancers but the molecular basis for this link is far from understood. We have identified the Bcl-xL:Bim protein-protein interface as a direct regulator of proliferation and apoptosis in pancreatic cancer cells. We were able to predict and subsequently verify experimentally the effect of various Bcl-xL single-point mutants (at the position A142) on binding to Bim by structural analysis and computational modeling of the inter-residue interactions at the Bcl-xL:Bim protein-protein interface. The mutants A142N, A142Q, and A142Y decreased binding of Bim to Bcl-xL and A142S increased this binding. The Bcl-xL mutants, with decreased affinity for Bim, caused an increase in apoptosis and a corresponding decrease in cell proliferation. However, we could prevent these effects by introducing a small interfering RNA (siRNA) targeted at Bim. These results show a novel role played by the Bcl-xL:Bim interaction in regulating proliferation of pancreatic cancer cells at the expense of apoptosis. This study presents a physiologically relevant model of the Bcl-xL:Bim interface that can be used for rational therapeutic design for the inhibition of proliferation and cancer cell resistance to apoptosis.

• Authors: Ravinder Abrol, Mouad Edderkaoui, William A Goddard 3rd, Stephen J Pandol
• Journal: Biochemical and biophysical research communications (Biochem Biophys Res Commun) Vol. 422 Issue 4 Pg. 596-601 (Jun 15 2012) ISSN: 1090-2104 [Electronic] United States
• PMID: 22609401 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2012 Elsevier Inc. All rights reserved.

Chemical References

• Apoptosis Regulatory Proteins
• BCL2L11 protein, human
• Bcl-2-Like Protein 11
• Membrane Proteins
• Proto-Oncogene Proteins
• bcl-X Protein

Topics

• Amino Acid Substitution
• Apoptosis
• Apoptosis Regulatory Proteins (chemistry, genetics, metabolism)
• Bcl-2-Like Protein 11
• Cell Proliferation
• Humans
• Membrane Proteins (chemistry, genetics, metabolism)
• Mutation
• Pancreatic Neoplasms (metabolism, pathology)
• Protein Conformation
• Proto-Oncogene Proteins (chemistry, genetics, metabolism)
• bcl-X Protein (chemistry, metabolism)