Identification and function of a monoclonal antibody against pancreatic cancer stem cell / 肿瘤研究与临床

ABSTRACT

Objective To identify-and study a monoclonal antibody (McAb) against pancreatic cancer stem cell in vitro,as well as to provide candidate antibody-drug for cancer stem cell-targeted therapy of pancreatic cancer.Methods Cell culture in serum-free medium and PKH26 staining were used to determine the existence of cancer stem cell in PANC-1 cell line.Flow cytometry was used to detect the expression of CD24 and CD44 in PANC-1 cells and sphere cells,Immunofluorescence was used to detect the expression of CD24 and antigen recognized by 15D2.The effects of 15D2 on self-renewal,proliferation and chemosensitivity to gemcitabine of PANC-1 parent or sphere cells were identified by serum-free suspension culture and CCK-8 assay,Immunohistochemistry was applied to detect the level of antigen recognized by 15D2 in cancer and adjacent tissues.Results PANC-1 cells could survive,proliferate and form sphere cells in serum-free medium.The sphere-forming rate was (2.5±0.5) ％.The percentage of CD44+ CD24+ cells population in sphere cells increased by 11.4 folds compared to PANC-1 cells,in which single nearly 97 ％ CD24+ cells was CD44+ CD24+ cells.Therefore,CD24+ was selected for cancer stem cell marker in PANC-1 in this study.The two-color immunofluorescence assay showed that 15D2 could recognize cells which was also stained by CD24.In vitro functional experiments demonstrated that 15D2 significantly suppressed the sphere formation of PANC-1 cells,with the inhibitory rate being 30.4 ％.Meanwhile,the combination of 15D2 and gemcitabine can significantly attenuate the growth of PANC-1 sphere cells.The IC50 was 0.10 μmol/L in 15D2+gemeitabine group,and 0.39 μmol/L in mlgM+gemcitabine group,Immunohistochemical results showed that the antigen recognized by 15D2 was greatly expressed in about 76.9 ％ (11/13) human pancreatic cancer tissues and hardly detected in adjacent normal tissues (10.0 ％,1/10).Conclusion McAb 15D2 can inhibit self-renewal and drug-resistance of pancreatic cancer stem cell in PANC-1 cell line,and it might become a candidate drug for target pancreatic cancer stem cell treatment.