Development of novel anti-CDH1/E-cadherin monoclonal antibodies for versatile applications

Cadherin (CDH)-mediated extracellular homophilic binding is crucial for maintaining tissue homeostasis. The epithelial cell-cell adhesion molecule cadherin 1 (CDH1/E-cadherin) forms the adherens junctions in epithelial cells, and the loss of CDH1 facilitates the migration and invasion of carcinoma cells. Although several anti-CDH1 monoclonal antibodies (mAbs) are available for western blotting and immunohistochemistry (IHC), a highly sensitive anti-CDH1 mAb suitable for flow cytometry has not been developed. We developed anti-CDH1 mAbs through a flow cytometry-based high-throughput screening. Two anti-CDH1 mAb clones, Ca₁Mab-3 (IgG₁, κ) and Ca₁Mab-5 (IgG₁, κ), reacted with human CDH1-overexpressed Chinese hamster ovary-K1 (CHO/CDH1) cells in flow cytometry. Furthermore, Ca₁Mab-3 and Ca₁Mab-5 recognized endogenous CDH1-expressing human luminal-type breast cancer cells, such as MCF-7, but not triple-negative breast cancer cells, like MDA-MB-231. The dissociation constant values of Ca₁Mab-3 and Ca₁Mab-5 for CHO/CDH1 were determined as 5.9 × 10^-10 M and 1.8 × 10^-9 M, respectively. Ca₁Mab-3 and Ca₁Mab-5 can detect endogenous CDH1 in western blotting and IHC using a cell block. Furthermore, Ca₁Mab-5 is available for IHC in formalin-fixed paraffin-embedded tumor tissues. These results indicate that Ca₁Mab-3 and Ca₁Mab-5 are versatile for basic research and are expected to contribute to clinical applications, such as tumor diagnosis and therapy.