Abstract: ObjectiveTo study the biological characteristics and function of the anti- hepatocellular carcinoma cancer stem cells (HCC-CSC) monoclonal antibody 15B7 in vivo and in vitro, and to investigate whether the targeting liver stem cells can inhibit recurrence, spontaneous lung metastasis and prolong the survival of tumor-bearing mice. MethodsMonoclonal antibody 15B7 which could recognize HCC-CSC was identified by two-color immunofluorescence, two-color flow cytometry and subcutaneous tumor formation assay. CD133+ phenotype cells were sorted from BEL7402 cell lines by the flow cytometry and cultured in serum free medium. The function of 15B7 was identified by CCK8 cell proliferation, invasion assay, migration assay and flow cytometry. The inhibition of implanted tumor growth and spontaneous lung metastasis of monoclonal antibody 15B7 were studied by tumor treatment experiments and the survival of mice was also observed. The antigen of 15B7 was identified by western blotting. ResultsThe results of two-color immunofluorescence and two-color flow cytometry showed that monoclonal antibody 15B7 could recognized cells which also were partly co-stained with ESA or CD133. 15B7+ or ESA+ cells or CD133+ cells sorted by flow cytometry could form mammospheres after serum-free suspension culture. 1×104 15B7+ cells were inoculated into the nude mice and developed visible tumors in 2 months. In vitro functional experiments showed that monoclonal antibody 15B7 could inhibit the proliferation, migration and invasion of CD133+ cells, and the inhibition rates was 13.8%, 15.7% and 30.9%, respectively. Furthermore, CD133+ cells incubated with monoclonal antibody 15B7 were induced G1 phase arrest. Animal experiment revealed that monoclonal antibody 15B7 significantly inhibited tumor growth by 60.5%. Conclusion15B7 not only inhibited tumor growth. The results indicated that targeting cancer stem cell antibody therapy had significant advantages and monoclonal antibody 15B7 might become a candidate drug for targeted HCC-CSC treatment.