Genomic scale microarray analysis identifies Bcl-Inhibitors as potential drug coatings for endovascular stents

Zhaoqing Yang, Ph.D. 1, Dmitry Gagarin, M.D. 1, Ali Ramezani, Ph.D. 2, Robert G. Hawley, Ph.D. 2, and Timothy A. McCaffrey, Ph.D. 1

From The George Washington University Medical Center

1 Department of Biochemistry and Molecular Biology, & The Catherine Birch McCormick Genomics Center

2 Department of Anatomy and Cell Biology

Abstract

The inappropriate survival of cells in the neointima contributes to atherosclerotic plaque progression, while apoptosis in the fibrous cap of lesions contributes to myocardial infarction and stroke. Prior genomic-scale transcript profiling of human carotid artery plaque cells with known sensitivity or resistance to fas-induced apoptosis identified candidate genes involved in lesion cell apoptosis. Retroviral overexpression indicated that several candidate factors were not causative, but that Bcl-XL conferred complete resistance to apoptosis induced by fas ligation. Resistant cells failed to efficiently activate caspase 8, an effect which was also observed in Bcl-XL transfected cells. Small-molecule Bcl-2/XL inhibitors and siRNA knockdown of Bcl-XL markedly sensitized resistant cells to apoptosis, and partially restored caspase 8 activation. Caspase 3, 6, and 9 inhibitors reduced caspase 8 activation and blocked apoptosis. Complete knockdown of caspase 9 did not reduce apoptosis, while knockdown of Bid suppressed apoptosis, suggesting that mitochondrial pathways independent of caspase 9, such as Smac/Diablo or AIF, provide a necessary mitochondrial input to efficient caspase activation. Bcl-XL appears to modulate lesion cell apoptosis by suppressing mitochondrial amplification of caspase activation loops. The results may have direct implications for controlling plaque instability/progression, and identifies a new class of small-molecules to inhibit restenosis.

[Talk Slides]

Timothy A. McCaffrey, Ph.D.
The George Washington University
Biochemistry and Molecular Biology

Biography:

Timothy A. McCaffrey, Ph.D. received his B.A. from St. Mary's University, and his Masters and Doctorate from Purdue University. He received Post-Doctoral training at Cornell University Medical College in New York City, where he was promoted to an Assistant and then Associate Professor in the Department of Medicine. He founded the Genomics Core Facility at Weill/Cornell Medical School.

In 2001, he relocated his laboratory to The George Washington University Medical Center where he founded the Genomics Core Facility. In 2004, he was named Director of the Catherine Birch McCormick Genomics Center at GWU and Vice-Chairman for Research and Administration in the Department of Biochemistry and Molecular Biology. The MGC is working to stimulate genomics research at GW by funding pilot research grants, graduate and medical student fellowships, and lecture series.

Dr. McCaffrey's research has been most highly focused on the molecular biology and genetic regulation features and defects in cells that are involved in the development of atherosclerotic lesions. He is working to exploit our understanding of these mechanisms for the development of new drug targets to treat cardiovascular disease, as well as for creating new diagnostic tests for predicting people who are at risk of developing heart disease.

Building on this work, he is going to speak on the role of genomics and our expanding ability to use genetic information to ‘personalize’ our understanding of disease risk and our ability to target therapeutic interventions to individual patients.