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ORIGINAL RESEARCH ARTICLE

Pentameric Procyanidins Isolated from Theobroma cacao Seeds Selectively Downregulate ErbB2 in Human Aortic Endothelial Cells

Thomas P. Kenny^*, Carl L. Keen, Paul Jones, Hsing-Jien Kung, Harold H. Schmitz and M. Eric Gershwin^*,1

^* Division of Rheumatology, Allergy, and Clinical Immunology, University of California at Davis, Davis, California 95616; Department of Nutrition, University of California at Davis, Davis, California 95616; Mars, Inc., McLean, Virginia 22101; and University of California at Davis Cancer Center, Sacramento, California 95817

To whom requests for reprints should be addressed at ¹ Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, TB 192, Davis, CA 95616. E-mail: megershwin{at}ucdavis.edu

Flavonoids isolated from cocoa have biological activities relevant to oxidant defenses, vascular health, tumor suppression, and immune function. The intake of certain dietary flavonoids, along with other dietary substances such as tocopherols, ascorbate, and carotenoids, is epidemiologically associated with a reduced risk of cardiovascular disease. Flavonoids have also been shown to modulate tumor pathology in vitro and in animal models. We took advantage of the conserved sequences found in tyrosine kinases to study the influence of cocoa fractions and controls on gene expression. We report that the pentameric procyanidin (molecular weight of 1442 daltons) fraction isolated from cocoa was a potent inhibitor of tyrosine kinase ErbB2 expression, a receptor important in angiogenesis regulation. Consistent with this primary observation, the cocoa flavonoid fraction also suppressed human aortic endothelial cell (HAEC) growth and decreased expression of two tyrosine kinases responsive to ErbB2 modulation, namely VEGFR-2/KDR and MapK 11/p38ß2. These inhibitory effects were observed when HAECs were treated with the flavonol fraction (molecular weight 280 daltons) isolated from cocoa, which comprise the structural subunits from which the procyanidin flavonoid subclass is biosynthetically constructed. Down-regulation of ErbB2 and inhibition of HAEC growth by cocoa procyanidins may have several downstream implications, including reduced vascular endothelial growth factor (VEGF) activity and angiogenic activity associated with tumor pathology. These results suggest specific dietary flavonoids are capable of selectively inhibiting ErbB2 and therefore may offer important insight into the design of therapeutic agents that target tumors overexpressing ErbB2.

Key Words: oxidative defense • ErbB2 • procyanidin • flavonoids • vascular endothelial growth factor

This article has been cited by other articles:

				T. P. Kenny, C. L. Keen, P. Jones, H.-J. Kung, H. H. Schmitz, and M. E. Gershwin Cocoa Procyanidins Inhibit Proliferation and Angiogenic Signals in Human Dermal Microvascular Endothelial Cells Following Stimulation by Low-Level H2O2 Experimental Biology and Medicine, September 1, 2004; 229(8): 765 - 771. [Abstract] [Full Text] [PDF]