以组蛋白去乙酰化酶为靶标的抗癌药物研发进展

基因表达的精确控制是细胞增殖分化和器官正常生长和发育的基础。基因转录和激活程序依赖于组蛋白乙酰化酶(histone acetylase，HAT)和组蛋白去乙酰化酶(histone deacetylase，HDAC)的协同作用。当HDAC过度表达并被转录因子募集，就会导致特定基因的不正常抑制，从而导致癌症及其他疾病。目前以HDAC作为抗癌靶点的研究方兴未艾，现综述HDAC类似蛋白(HDLP)的晶体结构和当前存在的HDAC抑制剂的作用机制、结构种类、研发状况和构效关系，以及新的HDAC抑制剂CS055的研发策略。     

冷冻保存时长对卵裂期胚胎组蛋白表观遗传修饰的影响

【目的】研究不同的冷冻保存时长对人类卵裂期胚胎的组蛋白表观遗传修饰的影响。【方法】采用经患者知情同意捐献用于科研的慢速冷冻的卵裂期胚胎,根据冷冻时长分为6、9和12年组,以新鲜胚胎为对照组,每组6枚捐献胚胎。采用细胞免疫荧光技术观察去乙酰化酶HDAC1、组蛋白（H3K9ac、H3K4me3、H3K9me3）的表达量在各组胚胎中的差异,并以单细胞RT-qPCR技术检测去乙酰化酶HDAC1、甲基化酶（SUV39H1、SET?DB1）、去甲基化酶KDM5A对应mRNA的表达量。【结果】4组胚胎的去乙酰化酶HDAC1、组蛋白（H3K9ac、H3K4me3和H3K9me3）的蛋白表达量无统计学意义的差异（P>0.05）。同时去乙酰化酶HDAC1、甲基化酶SUV39H1对应mRNA的表达量也无统计学意义的差异（P>0.05）。随着胚胎冷冻时长的增加,甲基化酶SETDB1对应mRNA的表达量有递增趋势,然而差异无统计学意义（P>0.05）。去甲基化酶KDM5A对应的mRNA的表达量也随冷冻时长的增加而增强,差异有统计学意义（P<0.05）。【结论】慢速冷冻保存时长对卵裂期胚胎的组蛋白（H3K9ac、H3K4me3和H3K9me3）的蛋白表达量无显著影响,甲基化酶（SUV39H1、SETDB1）对应的mRNA表达量没有明显影响;但随着冷冻保存时长增加,胚胎去甲基化酶KDM5A对应的mRNA表达量增加,有可能导致胚胎转录抑制程度增强。     

组蛋白修饰在酒精成瘾中的作用及机制

酒精是全世界最常用且已被公认的成瘾物质,随着我国经济的快速发展,与饮酒相关的健康问题和社会问题亦急剧增加。酒精成瘾是一种精神疾病,会对人体带来多方面的影响。本文从表观遗传学的角度介绍酒精成瘾对组蛋白修饰的作用及其机制,有助于读者了解酒精成瘾的发生机制以及与之相关的长期神经适应。     

Subnuclear partitioning of rRNA genes between the nucleolus and nucleoplasm reflects alternative epiallelic states

Eukaryotes can have thousands of 45S ribosomal RNA (rRNA) genes, many of which are silenced during development. Using fluorescence-activated sorting techniques, we show that active rRNA genes in Arabidopsis thaliana are present within sorted nucleoli, whereas silenced rRNA genes are excluded. DNA methyltransferase (met1), histone deacetylase (hda6), or chromatin assembly (caf1) mutants that disrupt silencing abrogate this nucleoplasmic–nucleolar partitioning. Bisulfite sequencing data indicate that active nucleolar rRNA genes are nearly completely demethylated at promoter CGs, whereas silenced genes are nearly fully methylated. Collectively, the data reveal that rRNA genes occupy distinct but changeable nuclear territories according to their epigenetic state.     

Antidepressant-Like Properties of Novel HDAC6-Selective Inhibitors with Improved Brain Bioavailability

HDAC inhibitors have been reported to produce antidepressant and pro-cognitive effects in animal models, however, poor brain bioavailability or lack of isoform selectivity of current probes has limited our understanding of their mode of action. We report the characterization of novel pyrimidine hydroxyl amide small molecule inhibitors of HDAC6, brain bioavailable upon systemic administration. We show that two compounds in this family, ACY-738 and ACY-775, inhibit HDAC6 with low nanomolar potency and a selectivity of 60- to 1500-fold over class I HDACs. In contrast to tubastatin A, a reference HDAC6 inhibitor with similar potency and peripheral activity, but more limited brain bioavailability, ACY-738 and ACY-775 induce dramatic increases in α-tubulin acetylation in brain and stimulate mouse exploratory behaviors in novel, but not familiar environments. Interestingly, despite a lack of detectable effect on histone acetylation, we show that ACY-738 and ACY-775 share the antidepressant-like properties of other HDAC inhibitors, such as SAHA and MS-275, in the tail suspension test and social defeat paradigm. These effects of ACY-738 and ACY-775 are directly attributable to the inhibition of HDAC6 expressed centrally, as they are fully abrogated in mice with a neural-specific loss of function of HDAC6. Furthermore, administered in combination, a behaviorally inactive dose of ACY-738 markedly potentiates the anti-immobility activity of a subactive dose of the selective serotonin reuptake inhibitor citalopram. Our results validate new isoform-selective probes for in vivo pharmacological studies of HDAC6 in the CNS and reinforce the viability of this HDAC isoform as a potential target for antidepressant development.     

Enrichment of Oct3/4‐positive cells from a human bronchial epithelial cell line

Most adult stem cells are in the G0 phase of the cell cycle, accounting for only a small percentage of the cells in the tissue. Thus, isolation of stem cells from tissues for further study represents a major challenge. The anti‐tumor drug 5‐fluorouracil (5‐FU) selectively kills proliferating cells, sparing cells in the G0 phase. Thus, the objective of this study was to determine whether 5‐FU can be used to enrich stem cells in a human bronchial epithelial (HBE) cell population in vitro. Side population (SP) cells were isolated from untreated HBE cells or HBE cells treated with 5‐FU, and the resulting cells were subjected to colony formation assays, culturing of cell spheres, and tumorigenicity assays. Expression of Oct3/4, Sox2, PCK, and β‐catenin were examined by Western blot analysis and immunofluorescence. Treatment with 5‐FU increased the percentage of SP cells from 0.3% to 1.5%, and the clonogenic ability of 5‐FU‐treated cells was more than twofold higher than that of HBE cells. Cells that survived after 5‐FU treatment exhibited a higher capacity for sphere formation. Furthermore, spheres formed from 5‐FU‐treated cells possessed the capacity to generate differentiated progenies. Cells treated with 5‐FU also exhibited tumorigenic potential, based on tumor formation assays in nude mice, and Oct3/4‐positive cell aggregates were identified in the resulting tumors. In this study, we have shown that 5‐FU treatment enriched the population of cells expressing the putative embryonic markers Oct3/4 and Sox2 and exhibiting nuclear accumulation of β‐catenin. Furthermore, 5‐FU‐treated cells expressed low levels of the epithelial differentiation marker PCK. Analysis of epigenetic modifications suggested that Oct3/4‐positive cells possessed characteristics of stem cells. These results demonstrate that treatment with 5‐FU can enrich the stem cell population present in a human bronchial epithelial cell line, and implicate combined treatment with 5‐FU and serum‐free medium as a new method for isolation of stem‐like cells from the HBE cell line.     

Brief overview of selected approaches in targeting pancreatic adenocarcinoma

Introduction: Pancreatic adenocarcinoma (PDAC) has the worst prognosis of any major malignancy, with 5-year survival painfully inadequate at under 5%. Investigators have struggled to target and exploit PDAC unique biology, failing to bring meaningful results from bench to bedside. Nonetheless, in recent years, several promising targets have emerged.

Areas covered: This review will discuss novel drug approaches in development for use in PDAC. The authors examine the continued efforts to target Kirsten rat sarcoma viral oncogene homolog (KRas), which have recently been successfully abated using novel small interfering RNA (siRNA) eluting devices. The authors also discuss other targets relevant to PDAC including those downstream of mutated KRas, such as MAPK kinase and phosphatidylinositol 3-kinase.

Expert opinion: Although studies into novel biomarkers and advanced imaging have highlighted the potential new avenues toward discovering localized tumors earlier, the current therapeutic options highlight the fact that PDAC is a highly metastatic and chemoresistant cancer that often must be fought with virulent, systemic therapies. Several newer approaches, including siRNA targeting of mutated KRas and enzymatic depletion of hyaluronan with PEGylated hyaluronidase are particularly exciting given their early stage results. Further research should help in elucidating their potential impact as therapeutic options.     

人新饱食分子蛋白1在妊娠期代谢异常中的研究进展

人新饱食分子蛋白1(Nesfatin-1)是一种分泌性肽,与抑食功能有关,但其作用机制尚未完全阐明。国内外学者研究发现,Nesfatin-1不仅影响抑食功能,还参与能量代谢。目前,Nesfatin-1在2型糖尿病、代谢综合征、妊娠期糖尿病及摄食行为中的研究较多,而在妊娠期代谢异常等方面涉及甚少。该文就Nesfatin-1在妊娠期代谢异常的研究进展作一综述。     

Phenethyl Isothiocyanate Protects against High Fat/Cholesterol Diet-Induced Obesity and Atherosclerosis in C57BL/6 Mice

This study concerns obesity-related atherosclerosis, hyperlipidemia, and chronic inflammation. We studied the anti-obesity and anti-atherosclerosis effects of phenethyl isothiocyanate (PEITC) and explored their underlying mechanisms. We established an animal model of high fat/cholesterol-induced obesity in C57BL/6 mice fed for 13 weeks. We divided the mice into five groups: control (CON), high fat/cholesterol (HFCD), HFCD with 3 mg/kg/day gallic acid (HFCD + G), and HFCD with PEITC (30 and 75 mg/kg/day; HFCD + P30 and P75). The body weight, total cholesterol, and triglyceride were significantly lower in the HFCD + P75 group than in the HFCD group. Hepatic lipid accumulation and atherosclerotic plaque formation in the aorta were significantly lower in both HFCD + PEITC groups than in the HFCD group, as revealed by hematoxylin and eosin (H&E) staining. To elucidate the mechanism, we identified the expression of genes related to inflammation, reverse cholesterol transport, and lipid accumulation pathway in the liver. The expression levels of peroxisome proliferator activated receptor gamma (PPARγ), liver-X-receptor α (LXR-α), and ATP binding cassette subfamily A member 1 (ABCA1) were increased, while those of scavenger receptor A (SR-A1), cluster of differentiation 36 (CD36), and nuclear factor-kappa B (NF-κB) were decreased in the HFCD + P75 group compared with those in the HFCD group. Moreover, PEITC modulated H3K9 and H3K27 acetylation, H3K4 dimethylation, and H3K27 di-/trimethylation in the HFCD + P75 group. We, therefore, suggest that supplementation with PEITC may be a potential candidate for the treatment and prevention of atherosclerosis and obesity.