Binding pocket-based design,synthesis and biological evaluation of novel selective BRD4-BD1 inhibitors

Bromodomain-containing protein 4 (BRD4), consisting of two tandem bromodomains (BD1 and BD2), is key epigenetic regulator in fibrosis and cancer, which has been reported that BD1 and BD2 have distinct roles in post-translational modification. But there are few selective inhibitors toward those two domains. Herein, this study designed and synthesized a series of novel selective BRD4-BD1 inhibitors, using computer-aided drug design (CADD) approach focused on exploring the difference of the binding pockets of BD1 and BD2, and finding the His437 a crucial way to achieve BRD4-BD1 selectivity. Our results revealed that the compound 3u is a potent selective BRD4-BD1 inhibitor with IC₅₀ values of 0.56?μM for BD1 but >100?μM for BD2. The compound exhibited a broad spectrum of anti-proliferative activity against several human cancer and fibroblastic cell lines, which might be related to its capability of reducing the expression of c-Myc and collagen I. Furthermore, it could induce apoptosis in A375 cells. To the contrary, the selective BD2 inhibitor, RVX-208, did not indicate any of these activities. Our findings highlight that the function of BRD4-BD1 might be predominant in fibrosis and cancer. And it is rational to further develop novel selective BRD4-BD1 inhibitors.     

BRD7 suppresses the growth of Nasopharyngeal Carcinoma cells (HNE1) through negatively regulating β-catenin and ERK pathways

BRD7 is a novel gene which involved NPC in our lab. Our previous studies showed that BRD7 was expressed at high level in normal nasopharyngeal epithelial tissues, but at low level in nasopharyngeal carcinoma biopsies and cell lines. In these papers, we found that ectopic expression of BRD7 can decrease cell proliferation and capability to form colonies in soft agar. FCM (Flow cytometry) assay indicated that the cell cycle progression from G1 to S phase was inhibited and the expression of cyclinD1 was significantly decreased after being transfected with BRD7 in HNE1 cells (NPC cells). To further investigate the molecular mechanism of BRD7 suppression of NPC cells growth, the cDNA microarray was performed to detect difference in gene expression profile induced by BRD7. The results indicated that 21 genes expression were changed after being transfected with BRD7 and the differentially expressed gene including α-catenin, cyclinD1, E2F3 was confirmed by western-blot. Next, we found that even though no obvious changes of the total expression of β-catenin were observed, the accumulation of β-catenin in nucleus was blocked. In addition, it was found that the expression of β-catenin was up-regulated in the complex composed of β-catenin and α-catenin in HNE1 cells induction of BRD7. So, we concluded that over-expression of BRD7 increased the expression of α-catenin which “hold” β-catenin in the complex and inhibited its accumulating in nucleus. At last, we demonstrated the c-jun, p-MEK, and p-ERK1/2 expression were down-regulated, and the Ap-1 promoter activity was inactive after being transfected with BRD7. We also found that over-expression of BRD7 can inactivate the c-jun and p-ERK1/2 after being treated with EGF in HNE1 cells. These results indicated that BRD7 played a negative role in ERK1/2 pathway. Taken together, our present results provide new insights for BRD7 function to inhibit NPC cells growth through negative regulating β-catenin and ERK1/2 pathways.     

Design,synthesis and biological evaluation of novel 6-phenyl-1,3a,4,10b-tetrahydro-2H-benzo[c]thiazolo[4,5-e]azepin-2-one derivatives as potential BRD4 inhibitors

Bromodomain-containing protein 4 (BRD4) is a key epigenetic regulator in cancer, and inhibitors targeting BRD4 exhibit great anticancer activity. By replacing the methyltriazole ring of the BRD4 inhibitor I-BET-762 with an N-methylthiazolidone heterocyclic ring, fifteen novel BRD4 inhibitors were designed and synthesized. Compound 13f had a hydrophobic acetylcyclopentanyl side chain, showing the most potent BRD4 inhibitory activity in the BRD4-BD1 inhibition assay (IC₅₀ value of 110 nM), it also significantly suppressed the proliferation of MV-4-11 cells with high BRD4 level (IC₅₀ value of 0.42 μM). Furthermore, the potent apoptosis-promoting and G0/G1 cycle-arresting activity of compound 13f were indicated by flow cytometry. As the downstream-protein of BRD4, c-Myc was in significantly low expression by compound 13f treatment in a dose-dependent manner. All the findings supported that this novel compound 13f provided a perspective for developing effective BRD4 inhibitors.     

过表达E2F6基因抑制BRD7基因启动子活性

BRD7基因是采用cDNA代表性差异分析法克隆的一个新Bromodomain基因(GenBank 登录号AF152604)。它在鼻咽癌细胞和组织中表达明显下调,过表达BRD7基因可抑制鼻咽癌细胞的生长和细胞周期的进程。前期工作已克隆了BRD7基因启动子区,并将其启动子定位于450bp（-404→+46bp）的区域。为了进一步揭示BRD7基因在鼻咽癌细胞和组织中表达下调的分子机制,生物信息学分析表明BRD7启动子区有E2F6转录因子结合位点,电泳迁移率实验结果表明转录因子E2F6特异性地结合于BRD7启动子区。荧光素酶检测和绿色荧光蛋白表达检测都证实过表达E2F6基因能抑制BRD7基因启动子活性     

鼻咽癌相关基因 BRD7 对鼻咽癌细胞CNE1的影响

为了研究BRD7基因对鼻咽癌细胞CNE1的影响,通过脂质体转染方法,将BRD7基因导入NPC细胞株CNE1细胞中.通过细胞生长曲线发现该基因能够抑制CNE1细胞的生长.为了探讨可能的作用机制,进而采用蛋白质组技术研究该基因对鼻咽癌蛋白质表达谱的影响,从而研究该基因在CNE1中的地位和作用.通过对过表达BRD7基因后鼻咽癌细胞系CNE1的蛋白质表达谱改变的研究,鉴定出19个差异表达蛋白,这些蛋白质包括:BCCIP (BRCA2 and CDKN1A(p21(Waf1/Cipl)),FHL2(four and a half LIM domains 2),Chloride channel regulatory protein;Hin-1(high-in-normal-1),WISP-1(connective tissue growth factor related protein),SREC-4(scavenger receptor expressed by endothelial cells-2),folate receptor.这些差异蛋白涉及到基因表达调控、细胞黏附等众多的事件.从另一个侧面研究了BRD7基因与鼻咽癌的关系,扩展了BRD7基因的研究范围,并进一步充实了该基因做为鼻咽癌候选抑瘤基因的证据.     

候选抑瘤基因 BRD7 及家族蛋白的功能研究进展

溴区结构（bromodomain）是近年来发现的广泛分布于多种生物中的一种高度保守的结构域,溴区结构蛋白通过参与信号依赖性的基因转录调控而广泛参与细胞内重要的生命活动．BRD7基因是1999年克隆的一个新的bromodomain基因,GenBank登录号为AF152604或AF152605．eMotif分析表明,BRD7蛋白包含多个磷酸化位点和一个保守bromodomain功能域,Blast显示BRD7蛋白与人的Celtix-1及鼠的bromodomain蛋白BP75具有高度的同源性．利用转基因技术已证实,在鼻咽癌细胞系HNEl中过表达BRD7基因可以抑制其细胞生长和细胞周期G1-S的进程,并部分逆转鼻咽痛细胞HNE1的恶性表型．为了全面地揭示BRD7基因的细胞内生物学功能,深入了解BRD7基因的细胞内整体信息流向,中南大学肿瘤研究所细胞遗传室已从上、中、下游三个不同层面对BRD7基因的功能研究展开了初步的探索．     

候选抑瘤基因 BRD7 及家族蛋白的功能研究进展

溴区结构(bromodomain)是近年来发现的广泛分布于多种生物中的一种高度保守的结构域,溴区结构蛋白通过参与信号依赖性的基因转录调控而广泛参与细胞内重要的生命活动.BRD7基因是1999年克隆的一个新的bromodomain基因,GenBank登录号为AF152604或AF152605.eMotif分析表明,BRD7蛋白包含多个磷酸化位点和一个保守bromodomain功能域,Blast显示BRD7蛋白与人的Celtix-1及鼠的bromodomain蛋白BP75具有高度的同源性.利用转基因技术已证实,在鼻咽癌细胞系HNE1中过表达BRD7基因可以抑制其细胞生长和细胞周期G1-S的进程,并部分逆转鼻咽癌细胞HNE1的恶性表型.为了全面地揭示BRD7基因的细胞内生物学功能,深入了解BRD7基因的细胞内整体信息流向,中南大学肿瘤研究所细胞遗传室已从上、中、下游三个不同层面对BRD7基因的功能研究展开了初步的探索.     

HLA-A2-restricted peripheral blood cytolytic T lymphocyte response to HPV type 16 proteins E6 and E7 from patients with neoplastic cervical lesions

 The DNA from human papillomavirus (HPV) can be detected in 90% of cervical carcinomas. To address whether patients infected with HPV can mount efficient T cell responses to this pathogen we examined the cytotoxic T lymphocyte (CTL) response of peripheral blood mononuclear cells (PBMC) from patients with abnormal genital epithelial cells. PBMC from 11 HLA-A2⁺ patients were stimulated with CaSki, a cervical carcinoma cell line that is HPV 16⁺ and HLA-A2⁺. The CTL were screened for reactivity to the cervical carcinoma cell line C33A (HPV^–, HLA-A2⁺) transfected with the HPV 16 E6 or E7 genes or the plasmid without insert. The CTL of 1 patient showed particularly strong CaSki and HPV E6 or E7 protein-specific cytotoxicity in a HLA-A2-restricted fashion. In contrast, these CTL lysed neither a vector-only transfectant, the natural killer cell (NK) target, K562 nor the lymphokine-activated killer cell (LAK) target, Daudi. HLA-A2 restriction was demonstrated by the lack of recognition of a HLA-A2^– CaSki cell line developed in our laboratory. The CTL line was cloned and 99 clones were harvested and screened; 51 clones lysed CaSki, of which 17 did not lyse the A2^– CaSki. Of these HLA-A2^– restricted clones, 8 did not lyse C33A transfectants, 6 lysed all C33A transfectants, 3 lysed C33A-E7 only and none lysed C33A-E6 only. These data imply that, within the bulk CTL line, HLA-A2-restricted recognition of antigens was restricted to CaSki antigens, antigens common to cervical carcinoma (CaSki plus C33A), or HPV-16-E7-derived antigen on the clonal level. The E7-restricted clones were negative for recognition of known HLA-A2-binding peptides from E7. Received: 16 November 1995 / Accepted: 15 January 1996     

Inhibition of bromodomain-containing protein 9 for the prevention of epigenetically-defined drug resistance

Bromodomain-containing protein 9 (BRD9), an epigenetic “reader” of acetylated lysines on post-translationally modified histone proteins, is upregulated in multiple cancer cell lines. To assess the functional role of BRD9 in cancer cell lines, we identified a small-molecule inhibitor of the BRD9 bromodomain. Starting from a pyrrolopyridone lead, we used structure-based drug design to identify a potent and highly selective in vitro tool compound 11, (GNE-375). While this compound showed minimal effects in cell viability or gene expression assays, it showed remarkable potency in preventing the emergence of a drug tolerant population in EGFR mutant PC9 cells treated with EGFR inhibitors. Such tolerance has been linked to an altered epigenetic state, and 11 decreased BRD9 binding to chromatin, and this was associated with decreased expression of ALDH1A1, a gene previously shown to be important in drug tolerance. BRD9 inhibitors may therefore show utility in preventing epigenetically-defined drug resistance.     

鼻咽癌侯选抑瘤基因BRD7原核表达载体的构建及其表达

BRD7基因是一个鼻咽癌侯选抑瘤基因,为了构建BRD7基因的原核表达载体并使其在大肠杆菌得到表达,设计了带有SalⅠ,NotⅠ酶切位点的引物,以已构建好的质粒pGEM-T Easy/BRD7为模板,用PCR扩增出BRD7基因的完整阅读框架,并用SalⅠ,NotⅠ酶切PCR产物和原核表达载体PGEX-4T-2,然后用T4 DNA连接酶将其连接,得到重组表达质粒PGEX-4T-2/BRD7,经双酶切鉴定和测序验证,表达载体构建正确.重组表达质粒转化感受态大肠杆菌Jm105后用IPTG诱导,成功表达了一分子质量约为90 ku的融合蛋白;37℃诱导4 h后,SDS-聚丙烯酰胺凝胶(PAGE)电泳后,经扫描分析该融合蛋白产量占菌体蛋白总量28.48%, 蛋白质印迹(Western-blot)证实了该融合蛋白的表达获得成功.这为BRD7基因的蛋白纯化及抗体制备,进一步开展其功能研究奠定了基础.     

新基因BRD7对鼻咽癌蛋白质表达谱影响的初步研究

BRD7基因是与鼻咽癌相关的候选抑瘤基因.为了进一步研究该基因的作用机制,将pcDNA3.1(+)/BRD7的表达质粒经脂质体导入HNE1细胞,RNA斑点杂交筛选出阳性克隆,通过双向电泳分离过表达BRD7的HNE1细胞内蛋白质,筛选出差异表达的蛋白质点,并进行质谱分析鉴定.鉴定出10种表达上调的蛋白质点,包括精氨(基)琥珀酸裂解酶,TSA(thio-specific antioxdant), Proteaseome activator28 beta subunit(PA28),金属蛋白酶抑制因子-2前体等,这些蛋白质涉及细胞生长,细胞代谢等很多相关事件.这些结果说明BRD7基因可能通过多种途径影响鼻咽癌的发生发展.