藤黄酸抗B细胞非霍奇金淋巴瘤新机制- - 调控SRC-3/组蛋白乙酰化转录复合物SUMO化修饰

As a new oncogene,SRC-3 has been verified could control the transcriptional activity of downstream gene targets through SRC-3 histone actylation transcription complexes(SRC-3/NR/HAT/HDAC1), meanwhile, it was also discovered SUMO (smallubiquitin-related modifier protein,SUMO)modification could affect the stability of SRC-3/NR/HAT/HDAC complexes. The anomalous SUMO junction of SRC-3/NR/HAT/HDAC complexes，especially, the anomalous SUMO junction of SRC-3 was closely associated with tumorigenesis. Gambogic acid is a natural product with high-efficiency and low-toxicity. In past years, our group has verified that gambogic acid could down-regulate the protein and mRNA levels of SRC-3. After serious consideration about our results and others, we suggested that gambogic acid could probably control the SUMO junction of SRC-3 through regulation of enzymes about SUMO conjugation. By this way, gambogic acid could alter the stability of SRC-3 histone actytion translation complexes. This study aim to determine the function of SUMO modification of SRC-3/NR/HAT/HDAC complexes in B-NHL(B-cell-Non-Hodgkin's Lymphoma, B-NHL) and how gambogic acid regulates the SUMO midification of SRC-3. Meanwhile the role of the regulation mechanism of gambogic acid in anti-lymphoma will be explored which will provide new breakthrough for the treatment of B-NHL.

类固醇受体共活化因子3（SRC-3）作为新受关注的癌因子，以SRC-3组蛋白乙酰化转录复合物（SRC-3/NR/p300/HDAC1）形式调控下游靶基因转录，同时发现类泛素蛋白（small ubiquitin-related modifier protein, SUMO）修饰可调控此转录复合物活性.SPOP异常引起SRC-3表达及SUMO化异常与恶性肿瘤发生密切相关。藤黄酸是一种高效低毒的抗肿瘤天然药物，前期实验中我们发现藤黄酸可下调SRC-3，推测藤黄酸可通过调控淋巴瘤中SPOP表达直接或间接调节SRC-3 的SUMO化，从而调节SRC-3组蛋白乙酰化转录复合物活性。本课题以B细胞-非霍奇金淋巴瘤为研究对象，深入探讨淋巴瘤中SPOP及SRC-3 SUMO化状态与转录复合物的活性的关系，并以此通路为靶点探讨藤黄酸的作用机理，为淋巴瘤的治疗寻找新的药物。

类固醇受体共活化因子3（SRC-3）作为新受关注的癌因子，调控下游靶基因转录，参与多种肿瘤的发生、发展。前期实验中我们发现藤黄酸具有抗多种血液系统肿瘤效应，下调SRC-3的表达。本项目以SRC-3的表达水平、表观遗传学调控和淋巴瘤为切入点与研究对象，利用免疫组织化学染色、免疫印迹、免疫共沉淀、流式细胞学、荧光共聚焦等多种实验方法证实SRC-3高表达与淋巴瘤发病相关性，以及藤黄酸通过靶向作用SRC-3、改变组蛋白乙酰化水平，从而调控下游基因转录，以达到抗肿瘤效应的机制，并进一步分析藤黄酸靶向作用SRC-3的途径。研究发现：1.与正常或炎性淋巴组织相比，淋巴瘤高表达SRC-3，提示SRC-3高表达与淋巴瘤发病相关，小样本中侵袭性淋巴瘤SRC-3表达水平更高，提示SRC-3水平可能与其恶性程度呈正相关；2.藤黄酸通过诱导细胞凋亡与周期阻滞发挥其抗淋巴瘤效应；3.藤黄酸通过直接下调SRC-3对下游癌基因以及细胞周期调控基因的转录水平进行调控，使肿瘤细胞出现凋亡和周期阻滞；4.藤黄酸通过改变SRC-3/HDAC结合水平，改变组蛋白乙酰化状态对下游基因转录进行间接调控，发挥其抗肿瘤效应；5.动物模型中证实藤黄酸的抗淋巴瘤效应；6.藤黄酸通过泛素化降解途径下调SRC-3表达，该过程中Cullin3表达与SRC-3的结合均增加，SPOP与SRC-3结合增加；7.SRC-3泛素化前期与SUMO-1结合增多，后出现SUMO2/3结合增加，提示SUMO-1结合后可能抑制SRC-3对下游基因的转录活化，而SUMO2/3的结合可能促进SRC-3的泛素化。淋巴瘤是经典的“多重打击”肿瘤，多种癌基因的过度表达促进其发生发展。我们的研究证实藤黄酸可以通过作用SRC-3下调多种癌基因的表达，发挥强大的抗淋巴瘤效应，具有重要的临床意义。