| Background: Ovarian cancer is a common gynecological malignant tumor which has top mortality rates. Surgery and chemotherapy are very effective in reducing tumor burden, however, relapses occur frequently and there is a lack of credible second-line options. Therefore, new treatment with antibody has been brought up according to ovarian cancer pathological features, a variety of antibodies have get in clinical research. Preliminary results of these treatment show efficacy in some patients, however, there are antibody resistance appear which induce poor efficacy and Tumor recurrence. Therefore, investigate the molecular mechanism of antibody resistance, looking for effective intervention strategy has great significance.Previously, we established a trastuzumab-resistant ovarian cancer cell line, named as SKOV3-T, which was developed through continuously culturing SKOV3 cells in the presence of trastuzumab, Microarray chip analysis showSKOV3-T cells have lower HER2 and higher IGF-1R expression, suggesting that tumor escape is relate to lower HER2, and IGF-1R over-expression is relate to antibody resistance. Base on previous study, we will further determine IGF-1R biological function in antibody resistance and try to reverse resistance by using IGF-1R antibody, explore the adaptive mechanism change of resistance cell.Methods: First we compare SKOV3 with SKOV3-T by using Western Blot, FACS, cell proliferation, clone formation and tumorigenesis. Then transfer IGF-1R plasmid into SKOV3 to up-regulate IGF-1R, transfer IGF-1R-siRNA lentivirus into SKOV3-T to down-regulate IGF-1R, respectively compared with parental cells to validate IGF-1R potential role in the HER2 antibody resistance by using cell growth/proliferation, clone formation and tumorigenesis.. Then, we developed a novel anti-IGF-1R monoclonal antibody, named as LMAb1, and explore the antibody reverse resistance effect by using cell growth/proliferation, migration, clone formation and in vivo carcinogenicity; and preliminary investigate the mechanisms of tumor stem cell change during antibody resistance occurrence.Results: The resistance cells are stronger than sensitive cells in proliferation, migration, clone formation and tumorigenesis; IGF-1R over-expression can make sensitive cells stronger in proliferation, clone formation, cycle and tumorigenesis, vice versa, suggesting that IGF-1R play an important role in resistance cells, and relate to cell proliferation, tumorigenesis; furthermore, LMAb1 show anti-tumor efficacy in proliferation, clone formation, migration and tumorigenesis, can improve mice survival time,cell singling show LMAb1 can inhibit IGF-1R activation, blocking the MAPK, AKT downstream signaling pathways, partly reverse antibody resistance.Meanwhile, FACS show that the proportion of stem-like cells in resistance cells was increased significantly,the stem-like cells are more stronger in cell proliferation, migration, clone formation and tumorigenesis, suggesting that there are some cells turn into stem cell during resistance occurrence.Conclusion: IGF-1R has an important role in ovarian cancer HER2 antibody resistance, IGF-1R over-expression result in cell proliferation, migration, clone formation and tumorigenesis more stronger; LMAb1 can specificity block IGF-1R signals and show inhibition effect in proliferation, cycle, clone formation and tumorigenesis, indicate LMAb1 can partly reverse the resistance; the appearance of resistance in ovarian cancer is associated with increase in stem-like cells which cause SKOV3-T have much stronger feature of tumorigenicity, resistance, proliferation. |
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