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Contact. On a cellular level, biological processes begin with binding. Before a substance, whether a manmade pharmaceutical or the body's own antibodies, can enter a cell, it must find a firm footing adhering to the cell surface. This is accomplished by ligands, protein molecules tethered to the outside of a cell that are specifically designed to fit into surface receptors on the target cells. Ligand-receptor pairs are as specific to one another as a lock and key. Joyce Wong, Clare Boothe Luce Assistant Professor of Biomedical Engineering, has been investigating the factors that govern ligand-receptor binding with the aim of creating new systems for more effective, targeted drug delivery. Wong and colleagues at the University of California, Santa Barbara, the University of California, Davis, Alza Corporation, and Strasbourg's Centre National de la Recherche Scientifique have been working on a series of experiments. The researchers employed liposomes, artificially created microscopic sacs designed to carry potent drugs to targeted cells, polymer tethers, and a well-documented ligand-receptor pair, biotin-streptavidin. They revealed that not only the interplay between the ligand and receptor is significant in the overall range, rate, and ultimate strength of the bond formation, but also the length and dynamics of the tether chain. Wong now plans to test these results in real cells, specifically the Anti-HER2 cells that are implicated in breast cancer. She is also investigating how other factors, such as the flow rate of blood carrying the therapeutic agents, impact binding. This work is also crucial to the development of other therapeutic modalities, such as the creation of bioengineered tissue. The July 20 issue of the journal Science covered the work of the researchers.


Tea time. Drinking green tea may offer some protection against the development of breast cancer, according to recent research by Professors Gail Sonenshein and Adrianne Rogers at the Boston University School of Medicine. Epidemiological studies have indicated that green tea may reduce the risk of some cancers, and there is evidence that breast cancer is less common in countries such as China and Japan, where green tea is widely consumed. Sonenshein and Rogers conducted in vivo studies on female rats and in vitro studies on human breast cancer cells. Female rats were divided into two groups and treated with a breast cancer-inducing substance. One group was given only water to drink, the other only green tea. Tumors in the tea-drinking rats developed later than in the water-drinking rats and were significantly smaller and less malignant. The researchers attribute the tumor-suppressing effect to a group of compounds known as green tea polyphenols (GTPs). The scientists also treated cultured human breast cancer cells with GTPs. They found that the GTPs inhibited cell growth, and at high levels killed the cancer cells. They further demonstrated that the presence of GTPs increased the amount of a cyclin-dependent kinase inhibitor (p27Kip1) produced by the cells; p27Kip1 had previously been shown to be associated with smaller, well-differentiated, more slowly proliferating breast tumors. Their research was reported in the July 2001 issue of the Journal of Cellular Biochemistry.

"Research Briefs" is written by Joan Schwartz in the Office of the Provost. To read more about BU research, visit http://www.bu.edu/research.

       

15 May 2003
Boston University
Office of University Relations