BRD4-IRF2-BAD信号通路调控肝癌细胞凋亡的分子机制研究

溴结构域蛋白4 (BRD4）是一种肿瘤相关的表观调控蛋白。申请人前期研究发现，化学性降解BRD4能够诱导BCL-2家族促凋亡成员BAD表达升高，使肝癌细胞发生凋亡。但是，BRD4如何调控BAD的表达尚未见报道。RNA-Seq检测发现，BRD4降解可在短时间内导致干扰素调节因子2 （IRF2）表达下调；应用特异性siRNA敲降BRD4和IRF2后，BAD表达明显上调，并激活了凋亡信号的传导。研究表明IRF2可与BRD4协同调控基因的表达，并且IRF2作为转录抑制子可参与调控多个BCL-2家族促凋亡成员的表达。据此，我们提出假设：BRD4-IRF2通过调控BAD的表达，介导了肝癌细胞的凋亡。在本研究中，我们拟从分子、细胞、动物和临床层面：（1）阐明BRD4-IRF2-BAD信号通路对肝癌细胞凋亡的调控作用；（2）探讨IRF2的表达水平对靶向BRD4治疗肝癌的影响，为改善肝癌的治疗探索新思路。

Bromodomain-containing protein 4 (BRD4) is a cancer-associated epigenetic protein. In our previous study, we found that degradation of BRD4 by a small molecule resulted in increased expression of BAD, a pro-apoptotic BCL-2 family member, and led to apoptosis of hepatocellular carcinoma (HCC) cells. However, how BRD4 regulates the expression of BAD remains to be investigated. The applicant's previous RNA-Seq found that degradation of BRD4 rapidly reduced the expression of Interferon regulatory factor 2 (IRF2). After silencing BRD4 and IRF2 with specific siRNA, the expression of BAD was up-regulated and activated the apoptosis signaling pathway. Considering BRD4 and IRF2 could act in concert in regulation of gene transcription, and as a transcriptional factor, IRF2 involves in the regulation of expression of multiple of BCL-2 family members. Therefore, we propose that BRD4 regulates the expression of BAD, and thereof apoptosis signaling in HCC cells indirectly through IRF2. In this study, we intend to conduct research at the molecular, cellular, animal and clinical levels: (1) the role of BRD4-IRF2-BAD axis in regulation of apoptosis signaling of hepatocellular carcinoma cells; (2) the role of IRF2 in regulation of the anti-HCC activity by targeting BRD4, and explores new ideas for improving the treatment of HCC.