| Objective Ovarian cancer tops all the malignant tumors of female reproductive system in mortality rate. Although some progress has been made in its diagnosis and treatment in recent years, long-term survival rate, especially of patients of advanced stages was not markedly improved. Therefore, it is very important to find a new treatment besides chemotherapy, surgery and radiotherapy. To date, Molecular Targeted Therapy, which targets the characteristic changes of tumor cells, has increasingly attracted attention. Signaling pathway regulated by ErbB family is one of the most important pathways that regulate tumors. ErbB family provides an ideal target for the anti-tumor therapy with its over-expression in tumor tissues, including ovarian cancer. However, views are different about its over-expression in primary malignant tumors in epithelial tissues: some reported it as the marker of potential invasion and metastasis of tumors, while others reported it as the inhibitor of tumor proliferation. It is still a controversial issue whether ErbB4 may serve as a tumor promoter or inhibitor.The present study takes ovarian cancer cell line OVCAR-3 as the research subject and studies the impact of ErbB4 on the biological behaviors, such as cell proliferation and invasion, by blocking the signaling pathway of ErbB4 with anti-ErbB4 monoclonal antibody (Ab-3). The study explores the relationship between ErbB4 and the tumorigenesis and development of ovarian cancer, which may serve as a theoretical basis for further study as well as molecular targeting therapy.Methods Culture human ovarian cancer cells OVCAR-3 in vitro. Detect the expression of ErbB4 in OVCAR-3 cells by immunohistochemisty (IHC). Evaluate with MTT assay the effect of anti-ErbB4 monoclonal antibody (Ab-3) of different concentrations (0.625, 1.25, 2.5, 5, 10μg / ml) on the growth of OVCAR-3 cells. Measure the cell cycle and apoptosis by flow cytometry (FCM) after the 24-hour, 48-hour and 72-hour treatment of anti-ErbB4 monoclonal antibody(Ab-3)(2.0μg/ml). Detect the invasion of OVCAR-3 cells with transwell chamber after the cells are incubated with anti-ErbB4 monoclonal antibody(Ab-3)(2.0μg/ml) for 24 hours.Results Immunohistochemitry (IHC) indicates that ErbB4 shows positive expression in OVCAR-3 cells, mainly in cellular membrane. Anti-ErbB4 monoclonal antibody (Ab-3) of different concentrations (0.625～10μg/ml)can inhibit the proliferation of OVCAR-3 cells in dose-dependent and time-dependent manner. Its 50% inhibition concentration (IC50) is 4.48μg/ml after 72 hours'treatment. Flow cytometry (FCM) shows that after the 24-hour, 48-hour and 72-hour treatment of anti-ErbB4 monoclonal antibody (Ab-3) (2.0μg/ml), the OVCAR-3 cell cycle is arrested in S phase and the apoptosis of cells is increased by 0.19%, 6.06% and 11.60% respectively. After the OVCAR-3 cells are incubated with anti-ErbB4 monoclonal antibody(Ab-3)(2.0μg/ml) for 24 hours, the number of cells whose membrane is invaded (78.0±6.1) is lower than the control group (132.0±17.2) (P<0.01).Conclusion (1) ErbB4 expresses positively in human OVCAR-3 cell line. (2) Anti-ErbB4 monoclonal antibody (Ab-3) can inhibit the proliferation and invasion of OVCAR-3 which expresses endogenous ErbB4, and induce the apoptosis of the cells. The possible mechanisms are as follows: firstly, anti-ErbB4 monoclonal antibody (Ab-3) could prevent ErbB4 from binding to ligand NRG and could interact with the extracellular domain of human ErbB4 to inhibit autophosphorylation. Secondly, anti-ErbB4 monoclonal antibody (Ab-3) may also prevent ErbB4 from binding to other family members of ErbB (ErbB1; ErbB2; ErbB3) so as to inhibit its dimerization and, hence its downstream intracellular signaling. (3) The study indirectly indicates that ErbB4 may play a significant role in human ovarian cancer and may serve as a molecular target for anticancer therapy.
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