Abstract: ObjectiveTo study the effect of anti-human decoy receptor 3（DcR3）neutralization monoclonal antibody on growth and apoptosis of breast carcinoma cell，and to explore the expression and clinical significance of DcR3 in the sera of breast carcinoma patients. MethodsHuman breast carcinoma cell line MCF-7 was treated with anti-DcR3 monoclonal antibody in vitro. Cell viability and Caspase 3/7 activity were evaluated by CellTiter-Blue Cell Viability Assay and Apo-ONE Homogeneous Caspase-3/7 Assay, respectively. Morphology and the apoptotic rate were assessed by Hoechst 33342 and propidium iodide double fluorescent chromatin staining. Expression of DcR3 in the sera of breast carcinoma patients was performed with ELISA. ResultsDcR3 monoclonal antibody inhibited the growth and induced the apoptosis of breast carcinoma MCF-7 cells（P<0.05）.The expression of DcR3 in the sera of breast carcinoma patients was significantly higher than that in healthy controls（P<0.01）.The expression of sera DcR3 was correlated to tumor size and clinical TNM stages（P<0.05）. ConclusionDcR3 has the effect on inhibiting cell viability in breast carcinoma cells，which may be related to the apoptosis. DcR3 is associated with the tumorigenesis and progress of breast carcinoma, and detection of sera DcR3 expression could contribute to the diagnosis and prognosis of breast carcinoma patients.