Abstracts
2001 Digestive Disease Week

# 1773 In Vitro Activity of Genistein-17.1A Monoclonal Antibody Immunoconjugate Against Colon Cancer Cells.
George I. Salti, Michelle Gentile, Tapas K. Das Gupta, Chicago, IL

BACKGROUND: The monoclonal antibody 17.1A recognizes a cell adhesion molecule that is overexpressed on colon and other cancers of the gastrointestinal tract. The murine monoclonal IgG 17.1A has been used clinically to treat colon cancer. We have previously shown that genistein, a major component of soy, has anti-colon cancer effects in vitro (Eur J Cancer, 2000). The purpose of this study was to enhance the activity of 17.1A mAb against colon cancer cells by coupling it to genistein.

METHODS: Synthesis of Gen-17.1A immunoconjugate was achieved by a photochemical conjugation method using the heterobifunctional photoreactive cross-linking agent sulpha-SANPAH. Purity of the immunoconjugate was evaluated by SDS-PAGE. Binding of Gen-17.1A to HT-29 and SW-620 colon cancer cell lines was shown using flow cytometric analysis.

RESULTS: Treatment of these cell lines with the immunoconjugate resulted in a greater level cell growth inhibition than by the molar equivalent of 17.1A or genistein alone. Similarly, Gen-17.1A induced apoptosis in HT-29 and SW-620 cells as evidenced by the acridine orange/ethidium bromide staining method. Equimolar concentrations of 17.1A or genistein alone did not induce apoptosis in these cell lines.

CONCLUSION: Our findings suggest that the activity of 17.1A mAb against colon cancer cells is enhanced by coupling it to genistein.