光发分子影像技术监测CXCR4信号对三阴性乳腺癌顺铂化疗敏感性影响的分子机制

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer for which there is no effective treatment. Previously, we and others demonstrated that CXCR4 surface expression is an independent prognostic factor for disease relapse and survival in breast cancer. In this study, we will investigate the effects of CXCR4 gene silencing on cisplatin chemosensitivity in human triple-negative breast cancer cell lines. In vivo and in vitro analyses to demonstrate whether CXCR4 knockdown cells can enhance the sensitivity to cisplatin, with a decrease in the metastasis properties of TNBC cells, causing reversion of EMT and increasing apoptosis, and that suppressing CXCR4 signaling may render TNBC cells responsiveness to cisplatin treatment. In contrast, whether overexpression of CXCR4 stimulate TNBC cell growth and enhance resistance to cisplatin compared with that of control cells. To further understand the molecular events involved in the anti-tumor efficacy resulting from CXCR4 knockdown, we next examine the cell cycle and the expression of metastasis and apoptosis related genes expression, such as MMP9, p53, Bcl-2, Bax, and caspase-3 using immunohistochemistry and western blot. .Because the emergence of drug resistance is closely related to the abnormal enhancement of DNA-damage repair and PARP-1 is important molecules of DNA repair, we hypothesize that the CXCR4 up-regulating PARP1 might be involved in the CDDP resistance. In order to study the mechanisms of silencing of CXCR4 sensitizes triple-negative breast cancer cells to cisplatin, the research will investigate relationship of CXCR4 and PARP-1 expression. We hope to disclose whether CXCR4 gene silencing causes PARP-1 activity inhibition and induce cisplatin chemosensitivity in human TNBC. .Since bioluminescence imaging (BLI) is an emerging approach that is based on detection of light emission from cells or tissues, in this study, we are going to generate a construct fluorescent indicator serving as a reporter of CXCR4 to monitor CDDP’s anti-TNBC efficancy with non-invasive longitudinal measurement. Our findings may provide better understanding of the mechanism of Silencing of CXCR4 sensitizes triple-negative breast cancer cells to cisplatin, hence a better therapeutic treatment, such as CXCR4 targeted therapy, can be developed for the disease. Our real-time in-vivo bioluminescence imaging system for CXCR4 can be further developed into a tool to test for efficacy of therapeutic drug to TNBC.

CXCR4与配体CXCL2结合后，激活信号通路调节下游靶基因表达，促进肿瘤转移。我们前期研究显示CXCR4与三阴性乳腺癌（TNBC）内脏转移、顺铂（CDDP）的敏感性有关。CDDP的抗癌机制主要是DNA损伤，而聚腺苷二磷酸核糖聚合酶（Poly(ADP-ribose)polymerase,PARP-1）的作用是修复损伤DNA,当PARP-1高表达时，很快对受损DNA进行修复而导致肿瘤耐药。故本项目推测CXCR4对CDDP抗癌作用的影响与其促进PARP-1相关；通过构建可以反映CXCR4和CDDP药物敏感性的关联生物发光影像报告系统，在细胞乃至活体小动物水平实时、动态地监测CXCR4对CDDP抗癌作用，旨在建立CDDP抗TNBC作用的生物发光分子影像平台，也为拓展CXCR4靶向药物抗 TNBC疗效评价提供筛选平台。

CXCR4与配体CXCL2结合后，激活信号通路调节下游靶基因表达，促进肿瘤转移。我们前期研究显示CXCR4与三阴性乳腺癌（TNBC）内脏转移、顺铂（CDDP）的敏感性有关。CDDP的抗癌机制主要是DNA损伤，而聚腺苷二磷酸核糖聚合酶（Poly(ADP-ribose)polymerase,PARP-1）的作用是修复损伤DNA,当PARP-1高表达时，很快对受损DNA进行修复而导致肿瘤耐药。故本项目推测CXCR4对CDDP抗癌作用的影响与其促进PARP-1相关；通过构建可以反映CXCR4和CDDP药物敏感性的关联生物发光影像报告系统，在细胞乃至活体小动物水平实时、动态地监测CXCR4对CDDP抗癌作用，旨在建立CDDP抗TNBC作用的生物发光分子影像平台，也为拓展CXCR4靶向药物抗 TNBC疗效评价提供筛选平台。本研究发现较系统地说明了敲减或者过表达Notch3基因对CXCR4的影响。结合临床资料分析，我们发现Notch3可能是一个抑癌基因，在小样本的临床研究中发现，Notch3高表达可能是三阴性乳腺癌预后良好的指标。更进一步的体外及体内研究中发现PARP-1 抑制剂PJ34对MDA-MB231细胞具有增殖抑制作用，且呈时间及浓度依赖性;并能诱导 MDA-MB231细胞凋亡，而CXCR4抑制剂AMD3100及敲减CXCR4能使PJ34抑制细胞增殖及诱导凋亡的作用增强，敲减CXCR4后，PARP-1抑制剂能够明显抑制三阴性乳腺癌的上皮-间质转化。在临床数据研究中发现示高表达CXCR4和PARP-1的乳腺癌病人的复发生存率较低。

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