Browsing by Author "Sang, Jianli"

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    MAGEA1 inhibits the expression of BORIS via increased promoter methylation
    (Company of Biologiists, 2019-01) Zhao, Jizhong; Wang, Yueqing; Liang, Qianjin; Xu, Yan; Sang, Jianli; Obstetrics and Gynecology, School of Medicine
    Melanoma-associated antigen A1 (MAGEA1) and BORIS (also known as CTCFL) are members of the cancer testis antigen (CTA) family. Their functions and expression-regulation mechanisms are not fully understood. In this study, we reveal new functions and regulatory mechanisms of MAGEA1 and BORIS in breast cancer cells, which we investigated in parental and genetically manipulated breast cancer cells via gene overexpression or siRNA-mediated downregulation. We identified the interaction between MAGEA1 and CTCF, which is required for the binding of MAGEA1 to the BORIS promoter and is critical for the recruitment of DNMT3a. A protein complex containing MAGEA1, CTCF and DNMT3a was formed before or after conjunction with the BORIS promoter. The binding of this complex to the BORIS promoter accounts for the hypermethylation and repression of BORIS expression, which results in cell death in the breast cancer cell lines tested. Multiple approaches were employed, including co-immunoprecipitation, glutathione S-transferase pull-down assay, co-localization and cell death analyses using annexin V-FITC/propidium iodide double-staining and caspase 3 activation assays, chromatin immunoprecipitation and bisulfite sequencing PCR assays for methylation. Our results have implications for the development of strategies in CTA-based immune therapeutics.
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    Ovarian cancer G protein coupled receptor 1 suppresses cell migration of MCF7 breast cancer cells via a Gα12/13-Rho-Rac1 pathway
    (Ubiquity Press, 2013-05-10) Li, Jing; Guo, Bin; Wang, Jing; Cheng, Xiaoyan; Xu, Yan; Sang, Jianli; Obstetrics and Gynecology, School of Medicine
    Background: Ovarian cancer G protein coupled receptor 1 (OGR1) mediates inhibitory effects on cell migration in human prostate and ovarian cancer cells. However, the mechanisms and signaling pathways that mediate these inhibitory effects are essentially unknown. Methods: MCF7 cell line was chosen as a model system to study the mechanisms by which OGR1 regulates cell migration, since it expresses very low levels of endogenous OGR1. Cell migratory activities were assessed using both wound healing and transwell migration assays. The signaling pathways involved were studied using pharmacological inhibitors and genetic forms of the relevant genes, as well as small G protein pull-down activity assays. The expression levels of various signaling molecules were analyzed by Western blot and quantitative PCR analysis. Results: Over-expression of OGR1 in MCF7 cells substantially enhanced activation of Rho and inhibition of Rac1, resulting in inhibition of cell migration. In addition, expression of the Gα12/13 specific regulator of G protein signaling (RGS) domain of p115RhoGEF, but not treatment with pertussis toxin (PTX, a Gαi specific inhibitor), could abrogate OGR1-dependent Rho activation, Rac1 inactivation, and inhibition of migration in MCF7 cells. The bioactive lipids tested had no effect on OGR1 function in cell migration. Conclusion: Our data suggest, for the first time, that OGR1 inhibits cell migration through a Gα12/13 -Rho-Rac1 signaling pathway in MCF7 cells. This pathway was not significantly affected by bioactive lipids and all the assays were conducted at constant pH, suggesting a constitutive activity of OGR1. This is the first clear delineation of an OGR1-mediated cell signaling pathway involved in migration.