Development of a Novel Anti−CD44 Monoclonal Antibody for Multiple Applications against Esophageal Squamous Cell Carcinomas

CD44 is a cell surface glycoprotein, which is expressed on normal cells, and overexpressed on cancer cells. CD44 is involved in cell adhesion, migration, proliferation, survival, stemness, and chemo−resistance. Therefore, CD44 is thought to be a promising target for cancer diagnosis and therapy. In this study, we established anti−CD44 monoclonal antibodies (mAbs) by immunizing mice with a CD44 variant (CD44v3−10) ectodomain and screening using enzyme−linked immunosorbent assay. We then characterized them using flow cytometry, Western blotting, and immunohistochemistry. One of the established clones (C(44)Mab−46; IgG(1), kappa) reacted with CD44 standard isoform (CD44s)−overexpressed Chinese hamster ovary−K1 cells (CHO/CD44s) or esophageal squamous cell carcinoma (ESCC) cell lines (KYSE70 and KYSE770). The apparent K(D) of C(44)Mab−46 for CHO/CD44s, KYSE70, and KYSE770 was 1.1 × 10(−8) M, 4.9 × 10(−8) M, and 4.1 × 10(−8) M, respectively. C(44)Mab−46 detected CD44s of CHO/CD44s and KYSE70, and CD44 variants of KYSE770 in Western blot analysis. Furthermore, C(44)Mab−46 strongly stained the formalin−fixed paraffin−embedded ESCC tissues in immunohistochemistry. Collectively, C(44)Mab−46 is very useful for detecting CD44 in various applications.