[摘要]：Several lines of evidence suggest that aberrant Notch signaling contributes to the development of several types of cancer. Activation of Notch receptor is executed through intramembrane proteolysis by gamma-secretase, which is a multimeric membrane-embedded protease comprised of presenilin, nicastrin (NCT), anterior pharynx defective 1 and PEN-2. In this study, we report the neutralization of the gamma-secretase activity by a novel monoclonal antibody A5226A against the extracellular domain of NCT, generated by using a recombinant budded baculovirus as an immunogen. This antibody recognized fully glycosylated mature NCT in the active gamma-secretase complex on the cell surface, and inhibited the gamma-secretase activity by competing with the substrate binding in vitro. Moreover, A5226A abolished the gamma-secretase activity-dependent growth of cancer cells in a xenograft model. Our data provide compelling evidence that NCT is a molecular target for the mechanism-based inhibition of gamma-secretase, and that targeting NCT might be a novel therapeutic strategy against cancer caused by aberrant gamma-secretase activity and Notch signaling. Oncogene (2012) 31, 787-798; doi:10.1038/onc.2011.265; published online 4 July 2011
