正常和腺样囊性癌涎腺中赖氨酸18位点乙酰化组蛋白H3表达的研究

目的探讨赖氨酸18位点（lysine 18 site,lys18）乙酰化组蛋白H3（acetyl-histone H3）在涎腺腺样囊性癌（adenoid cystic carcinoma,ACC）和正常涎腺中表达的意义。方法免疫组织化学Envision二步法检测60例ACC和49例正常涎腺中lys18乙酰化组蛋白H3的表达,分析其与ACC发生部位、组织学分级、临床分期、神经侵犯等肿瘤临床病理特征的关系。结果正常涎腺中导管细胞、腺泡细胞以及ACC肿瘤细胞中均有lys18乙酰化组蛋白H3阳性表达,表达位于细胞核。但lys18乙酰化组蛋白H3在ACC中的表达显著低于正常涎腺（χ2=46.745,P=0.000 1）,且其表达与ACC的临床病理特征没有相关性（P〉0.05）。结论组蛋白H3 lys18低乙酰化可能与ACC的肿瘤发生有关。     

The epigenetic effect of nicotine on dopamine D1 receptor expression in rat prefrontal cortex

Nicotine is a highly addictive drug and exerts its effect partially through causing dopamine release, thereby increasing intrasynaptic dopamine levels in the brain reward systems. Dopaine D1 receptor (DRD1) mRNAs and receptors are localized in reward‐related brain regions, which receive cholinergic input. The aim of this study is to evaluate whether nicotine administration affects the expression of DRD1s, and if so, whether epigenetic mechanisms, such as histone acetylation, are involved. Twenty Male Sprague Dawley rats received nicotine (0.4 mg/kg/day, s.c.) or saline injections for 15 days. After nicotine/saline treatment, rats were perfused with saline; prefrontal cortex (PFC), corpus striatum (STR), and ventral tegmental area (VTA) were dissected. Homogenates were divided into two parts for total RNA isolation and histone H4 acetylation studies. DRD1 mRNA expression was significantly higher in the PFC of the nicotine‐treated group compared with controls; similar trends were observed in the VTA and STR. To study epigenetic regulation, the 2kb upstream region of the DRD1 gene promoter was investigated for histone H4 acetylation in PFC samples. After chromatin immunoprecipitation with anti‐acetyl histone H4 antibody, we found an increase in histone acetylation by two different primer pairs which amplified the ?1365 to ?1202 (P < 0.005) and ?170 to +12 (P < 0.05) upstream regions of the DRD1 promoter. Our results suggest that intermittent subcutaneous nicotine administration increases the expression of DRD1 mRNA in the PFC of rats, and this increase may be due to changes in histone H4 acetylation of the 2kb promoter of the DRD1 gene. Synapse 67:545–552, 2013. © 2013 Wiley Periodicals, Inc.     

Radiosynthesis and preliminary evaluation of an 18F-labeled tubastatin A analog for PET imaging of histone deacetylase 6

Histone deacetylase 6 (HDAC6) is a unique member of the HDAC family because of its characteristics, namely, its cytoplasmic localization and ubiquitin binding. HDAC6 has been implicated in cancer metastasis and neurodegeneration. In the present study, we performed radiosynthesis and biological evaluation of a fluorine-18–labeled ligand [¹⁸F] 3 , which is an analog of the HDAC6-selective inhibitor tubastatin A, for positron emission tomography (PET) imaging. [¹⁸F] 3 was synthesized by a two-step reaction composed of ¹⁸F-fluorination and formation of a hydroxamic acid group. IC₅₀ values of 3 against HDAC1 and HDAC6 activities were 996 nM and 33.1 nM, respectively. A biodistribution study in mice demonstrated low brain uptake of [¹⁸F] 3 . Furthermore, bone radioactivity was stable at around 2% ID/g after injection, suggesting high tolerance to defluorination. Regarding metabolic stability, 70% of the compound was observed as the unchanged form at 30 minutes post injection in mouse plasma. A small animal PET study in mice showed that pretreatment with cyclosporine A had no effect on initial brain uptake of [¹⁸F] 3 , suggesting low brain uptake of [¹⁸F] 3 was not caused by the P-glycoprotein–mediated efflux. While PET imaging using [¹⁸F] 3 has a limitation with respect to neurodegenerative diseases, further studies evaluating its utility for certain cancers are worth evaluating.     

Pharmacoepigenetics: an element of personalized therapy?

Introduction: Epigenetics is a rapidly growing field describing heritable alterations in gene expression that do not involve DNA sequence variations. Advances in epigenetics and epigenomics have influenced pharmacology, leading to the development of a new specialty, pharmacoepigenetics, the study of the epigenetic basis for the individual variation in drug response.

Areas covered: We present an overview of the major epigenetic mechanisms and their effects on the expression of drug metabolizing enzymes and drug transporters, as well as the epigenetic status of drug protein targets affecting therapy response. Recent advances in the development of pharmacoepigenetic biomarkers and epidrugs are also discussed.

Expert opinion: There is growing evidence that pharmacoepigenetics has the potential to become an important element of personalized medicine. Epigenetic modifications influence drug response, but they can also be modulated by drugs. Moreover, they can be monitored not only in the affected tissue, but also in body fluids. Nevertheless, there are very few examples of epigenetic biomarkers implemented in the clinical setting. Explanation of the interplay between genomic and epigenomic changes will contribute to the personalized medicine approach. Ultimately, both genetic biomarkers and epigenetic mechanisms should be taken into consideration in predicting drug response in the course of successful personalized therapy.     

丙戊酸联合伏立诺他增强阿糖胞苷对人Dami白血病细胞株杀伤作用的机制研究

目的探讨丙戊酸(VPA)联合伏立诺他(SAHA)增强阿糖胞苷(Ara-c)对人Dami白血病细胞株的杀伤作用,并探讨其分子学机制。方法设空白对照组、Ara-c组、VPA组、SAHA组、VPA+Ara-c组、SAHA+Ara-c组,VPA+SAHA+Ara-c组,分别作用于对数生长期的Dami白血病细胞,MTT比色法检测药物对细胞的生长抑制作用;用PI法通过流式细胞仪检测细胞周期;RT-PCR方法检测转录因子GATA-1、胞苷脱氨酶(CDA)及脱氧胞苷激酶(DCK)mRNA水平的变化。结果 VPA和SAHA共同联合Ara-c用药组细胞生长抑制率明显高于VPA联合Ara-c组及SAHA联合Ara-c组,各组间相比,具有显著性差异。Dami细胞经过VPA和SAHA处理后均出现细胞周期阻滞现象,主要阻滞在G1期,与对照组相比差异有显著性(P0.05);VPA和SAHA联合用药组G1期细胞所占比例高于SAHA组(P0.05),与VPA组差异无显著性(P0.05)。VPA组、SAHA组、VPA和SAHA联合用药组GATA-1和CDA mRNA表达水平均低于对照组(P0.05),各组间差异无显著性(P0.05);VPA组DCK mRNA表达水平高对照组(P0.05)、SAHA组与对照组比较差异无显著性(P0.05)、VPA和SAHA联合用药组DCK mRNA表达水平高于VPA组和SAHA组(P0.05)。结论 VPA联合SAHA可增强阿糖胞苷对Dami白血病细胞的杀伤作用,可能是通过增加DCK的表达,从而增加阿糖胞苷体内活性代谢产物所致。