Med19促进乳腺癌生长、转移的分子机制及其作为乳腺癌靶向治疗靶标的研究

In a previous study,the applicant demonstrated that Med19 gene was significantly up-regulated in human breast cancer tissues compared with adjacent nontumor specimens,which was significantly associated with high-grade malignant feature and worse prognoses.Furthermore,Med19 knockdown via RNAi markedly suppressed the growth of breast cancer cells in vitro and in vivo.In addition, invasion and metastasis of breast cancer cells were also inhibited by Med19 knockdown.However,the molecular mechanisms of promoting breast cancer growth and metastasis by Med19 and the mechanisms of Med19 overexpression in breast cancer are largely unknown.Our previous results suggested that down-regulation of Med19 expression in breast cancer cells significantly inhibited the activities of mitogen-activated protein kinase(MAPKs) pathway.miR-10 and miR-422a targeted Med19 gene.The objectives of this project are to investigate:(1)the effects of Med19 on the development of breast cancer through MAPKs pathway in cells,animal model and human tissues;(2)the regulation of Med19 expression by miR-101 and miR-422a,and the signal transduction pathways of miR-101/miR-422a-Med19-MAPKs in breast cancer;(3) the role of Med19 as a marker for molecular targeted therapy of breast cancer;(4)the clinical value of Med19 expression for prediction outcome.The results from this project have the potential to find new signaling molecules that lay the foundation for development of novel breast cancer treatment and prevention strategies in the future.

申请人前期研究表明，Med19在人乳腺癌组织中显著高表达，并与肿瘤低分化和患者预后不良密切相关；抑制Med19表达，可抑制乳腺癌细胞增殖、侵袭、迁移和裸鼠体内成瘤。但Med19促进乳腺癌发生发展的机制及其在乳腺癌中异常高表达的机制不清楚。本项目芯片结果显示，下调乳腺癌细胞中Med19表达，显著抑制MAPKs通路活性；Med19是miR-101和miR-422a的靶基因。本项目拟在细胞、动物和人体组织水平研究Med19通过MAPKs通路对乳腺癌发生发展的影响；分析miR-101和miR-422a对Med19表达的调控作用，验证乳腺癌中miR-101/miR-422a-Med19-MAPKs信号通路；在原位移植瘤探讨Med19作为靶向治疗靶标的意义；结合临床标本，评估Med19表达在指导治疗、预测预后中的价值。研究结果可发现新的信号分子，为干预有效的信号环节、发展乳腺癌防治的新策略奠定基础。

乳腺癌是一种复杂的遗传性疾病，传统的治疗不能有效地阻止疾病进展，因此迫切需要研究乳腺癌进展的分子机制。我们先前的研究发现Med19在人乳腺癌组织中高表达并促进乳腺癌生长，但是Med19在乳腺癌中的作用和机制尚不清楚。本研究发现，Med19在人乳腺癌组织中显著高表达，并与肿瘤体积大、恶性程度高和预后差相关。体外实验和在体研究显示，Med19促进乳腺癌细胞增殖、上皮-间质转化、侵袭和迁移。Med19与上皮生长因子受体（EGFR）相互作用并促进其表达。Med19激活EGFR/MEK/ERK信号通路发挥其致瘤作用。Med19表达受miR-101–3p和 miR-422a调控。在人乳腺癌组织中Med19的表达与EGFR的表达呈正相关，与miR-101–3p和 miR-422a的表达呈负相关。Med19“串话”miR-101-3p/miR-422a 和 EGFR/MEK/ERK信号通路。本研究发现了一个新的在乳腺癌进展中起重要作用的 miR-101-3p/miR-422a-Med19-EGFR/MEK/ERK 信号轴，揭示了Med19促进乳腺癌进展的机制，提示Med19可作为乳腺癌治疗的潜在靶点。.阿霉素（ADM）为基础的化疗是乳腺癌最有效的化疗策略之一，然而耐药的产生限制了治疗效果。本研究发现阿霉素耐药的人乳腺癌细胞（MCF-7/ADM）和组织较亲本非耐药细胞（MCF-7）和组织具有较高的Med19表达和自噬水平。在阿霉素或自噬活化剂处理后，慢病毒介导的Med19敲减显著抑制自噬标记物 LC3‐II/LC3‐I 、Atg3、Atg5表达和P62 降解，红色荧光蛋白LC3 点的形成减少，阿霉素、顺铂、紫杉醇的抗增殖活性增强。Med19通过HMGB1/NFκB / p65信号通路促进自噬，介导乳腺癌细胞对阿霉素等化疗药物耐药。敲减Med19可部分逆转耐药，为临床化疗增敏提供了新策略。