MEF2D导致索拉菲尼对肝癌耐药的机制研究

Sorafenib is the first choice for liver cancer treatment, but the drug resistance limits its clinical efficacy. In spite of some advances, the underlying mechanism is still far from complete elucidation. Based on our previous finding that the effect of myocyte enhancer factor, MEF2D, promotes the resistance of hepatocellular carcinoma (HCC) to sorafenib and the bioinformatic data. We hypothesized that MEF2D enhances RAS/ERK pathway activity through negative regulation of SPRY4 , leading to the resistance of hepatocellular carcinoma to sorafenib. We intend to silence and increase the expression of MEF2D in resistant and parent HCC cells, respectively, in order to confirm that MEF2D induce the resistance of HCC to sorafenib in vitro and in vivo. Subsequently, we explore the underlying mechanism of sorafenib resistance: on molecular level, we confirm that MEF2D negatively regulates SPRY4 transcription by the binding of its promoter; in cellular models, we study if MEF2D increase RAS/ERK pathway activation and sorafenib resistance by its effect on SPRY4 expression; in animal models, we investigate if MEF2D affect the efficacy of sorafenib through SPRY4/RAS/ERK axis. Finally, we establish the association between MEF2D and the prognosis of sorafenib therapy via analyzing HCC specimens. This project will contribute to our comprehensive and in-depth understanding of the mechanisms of HCC’s sorafenib resistance, and provide molecular markers for predicting sorafenib's efficacy.

索拉菲尼是肝癌靶向治疗的首选药物，但耐药性的产生限制其临床疗效。虽然目前对索拉菲尼的耐药研究有一定进展，然而其机制尚未完全阐明。我们在索拉菲尼耐药的肝癌细胞株中发现肌细胞增强因子MEF2D表达上调，且MEF2D高表达的病人具有较差的索拉菲尼预后。结合前期基因芯片结果的生物信息学分析，我们推测MEF2D通过负调控SPRY4增强RAS/ERK通路活性从而导致肝癌对索拉菲尼耐药。我们拟分别在耐药株和敏感株中下调和上调MEF2D的表达，在细胞模型和动物模型中确定MEF2D对索拉菲尼耐药的促进作用。接着，在分子、细胞和动物模型层面上阐明MEF2D促进索拉菲尼耐药的分子机制，确定MEF2D通过SPRY4/RAS/ERK通路影响肝癌的索拉菲尼疗效。最后，拟通过临床样本分析建立MEF2D和索拉菲尼治疗肝癌预后的联系。本项目将有助于对索拉菲尼耐药机制的更全面和深入的了解，为预测索拉菲尼疗效提供分子标记物。

摘要.索拉菲尼是肝癌靶向治疗的首选药物，但耐药性的产生限制其临床疗效。虽然目前对索拉菲尼的耐药研究有一定进展，然而其机制尚未完全阐明。我们在索拉菲尼耐药的肝癌细胞株中发现肌细胞增强因子MEF2D表达上调，且MEF2D高表达的病人具有较差的索拉菲尼预后。我们分别在耐药株和敏感株中下调和上调MEF2D的表达，在细胞模型和动物模型中确定了MEF2D对索拉菲尼耐药的促进作用。接着，在分子、细胞和动物模型层面上阐明了MEF2D促进索拉菲尼耐药的分子机制。结合RNA测序结果的生物信息学分析，我们的结果提示MEF2D通过负调控SPRY4增强RAS/ERK通路活性从而导致肝癌对索拉菲尼耐药。更有意思的是，我们发现MEF2D调控SPRY4的分子机制是，通过HDAC4共结合在SPRY4的启动子，从而在转录水平抑制SPRY4的表达。最后，我们发现使用HDAC4抑制剂联合索拉非尼治疗策略，可以有效增加索拉非尼耐药细胞的敏感性。本项目提出了新的增加索拉非尼敏感性的联合治疗策略，同时找到了新的索拉非尼耐药分子标志物，为临床肝癌的索拉菲尼治疗方案提供理论依据。