EZH2调节SMAD3蛋白甲基化激活TGFβ通路影响乳腺癌侵袭转移的机制研究

Metastasis is the main factor affecting tumor treatment. TGFβ signaling pathway is involved in tumor metastasis, However, the molecular mechanism of regulating TGFβ signaling pathway has not been completely clarified. Recently, the study of non-histone methylation modification has gradually become a hotspot. Previously, we found that EZH2 is involved in metastasis mediated by the TGFβ signaling pathway. Further, we demonstrated that EZH2 could bind to SMAD3 and modulate the methylation level of SMAD3. Based on above data, to confirm whether EZH2 promotes the activation of TGFβ signaling pathway through regulating the methylation level of SMAD3 and triggers tumor metastasis. We explore the molecular mechanism of regulating SMAD3 methylation by EZH2 to affect the activation of TGFβ signaling pathway via Immunoprecipitation, protein mass spectrometry and gene point mutation technology and validate the role of the EZH2/SMAD3 signaling axis in tumor metastasis in vitro and vivo through gene knockdown or high expression technology. Further, we assess the relationship between tumor metastasis, prognosis and the EZH2/SMAD3 signaling axis by clinic specimens analysis and investigate the possibility of treating breast tumor through blocking the EZH2/SMAD3 signaling pathway. Overall, our research will enrich the molecular mechanism of activating the TGFβ signaling pathway and explain the role of the non-histone protein methylation in tumor metastasis. Meanwhile, our research will provide a novel strategy for treating breast cancer metastasis.

侵袭转移是影响肿瘤预后的主要因素，TGFβ信号通路激活在其中扮演着重要角色，但其异常激活的具体调控机制尚不清楚。近年非组蛋白甲基化修饰研究逐渐成为热点。前期我们初步研究发现组蛋白甲基转移酶EZH2参与了TGFβ介导的乳腺癌侵袭转移，并且EZH2可与SMAD3结合影响其甲基化水平。为了明确EZH2是否通过调节SMAD3蛋白甲基化激活TGFβ通路促进肿瘤侵袭转移。我们拟通过免疫共沉淀、质谱分析、点突变等技术明确EZH2与SMAD3结合位点及甲基化的分子机制；通过基因敲减/过表达手段证实EZH2/SMAD3介导肿瘤侵袭转移的作用；通过临床样本分析EZH2/SMAD3信号轴与肿瘤侵袭转移和预后复发的关系，探索靶向干预EZH2/SMAD3信号轴临床治疗的可行性。上述研究将丰富TGFβ信号通路激活的机制和阐明非组蛋白甲基化在肿瘤侵袭转移中的作用，为乳腺癌治疗提供新的切入点和干预策略。

侵袭转移是影响肿瘤预后的主要因素，TGFβ信号通路激活在其中扮演着重要角色，但其异常激活的具体调控机制尚不清楚。近年非组蛋白甲基化修饰研究逐渐成为热点。本研究发现SMAD3蛋白甲基化是经典的TGFβ/SMADs信号通路激活的关键，SMAD3蛋白甲基化的缺失明显抑制乳腺癌肿瘤细胞的侵袭转移的能力，并且发现EZH2催化SMAD3蛋白K53位及K333位甲基化。此外，我们发现SMAD3蛋白甲基化的水平是预测乳腺癌患者局部或远处转移的有效指标，并且靶向SMAD3蛋白甲基化可以明显抑制乳腺癌细胞的侵袭转移的能力，有望成为乳腺癌患者的新型治疗方法。