膳食纤维、肿瘤干细胞和Wnt信号活性的连续谱:结肠直肠癌预防和治疗的可能性

Wnt信号转导参与了人类结肠直肠癌(colorectal cancer, CRC)的发生.尽管Wnt信号转导活性与细胞增殖间的关系已经明了,但也有研究表明,高水平的Wnt活性与细胞凋亡间存在关系.我们分析了10种人类CRC细胞系,结果发现组蛋白去乙酰酶抑制剂(inhibitors of histone deacetylass, HDACis),例如丁酸盐,可通过过度诱导Wnt信号转导而促使CRC细胞凋亡;因此,通过HDACis过度活化Wnt信号转导可作为结肠直肠癌新的预防和治疗措施.我们的研究结果可以解释膳食纤维及其产物丁酸盐对于CRC保护作用的研究结果和丁酸盐的抗肿瘤作用为何相互矛盾.我们认为,体外研究中观察到的Wnt活性水平和CRC细胞凋亡水平的变化表明体内存在CRC细胞亚型,它们对于丁酸盐的反应程度不同.Wnt活性与肠道干细胞的更新和CRC干细胞的转移潜能相关,本文在此基础上讨论HDACis介导的Wnt信号转导调节作为CRC干细胞治疗方法的可能性,认为对Wnt阳性的CRC干细胞进行靶向治疗可作为CRC的基因疗法.     

结肠癌患者Wnt信号通路的变化和作用

目的探讨结肠癌患者Wnt信号通路的变化情况及其作用意义。方法利用Human Ge-nome U133Plus2.0基因芯片对结肠正常黏膜组织和癌组织基因表达谱进行检测,分析Wnt信号通路基因表达变化情况。结果Wnt信号通路中FRP、Frizzled、CK2、p53、PP2A、CKIα、JNK、CaMKII、CaN、c-jun、cyc-D等关键基因均呈下调,调控着细胞周期、基因转录等。结论Wnt信号通路可能是调控结肠癌演变过程的重要信号通路之一。     

中波段紫外线对角质形成细胞凋亡的诱导和钙信号的影响

目的　观察中波段紫外线 (UVB)照射诱导人永生化角质形成细胞 (HaCaT细胞 )的凋亡和对细胞静息Ca2 + 及thapsigargin和adrenaline引起的Ca2 + 运动影响。方法　采用四甲基偶氮唑盐 (MTT)染色法分析受UVB照射后细胞存活率的变化 ,用流式细胞术、琼脂糖凝胶电泳和Hoechst332 5 8核染色法观察UVB对HaCaT细胞凋亡的影响 ,采用Fura 2 /AM荧光分光光度法测定胞浆游离Ca2 + 浓度的变化。结果　在 1 2 5～ 6 2 5J·m-2 的UVB照射剂量之间和照射后培养时间 2 4h内的条件下 ,UVB照射以剂量和时间依赖的方式抑制细胞的存活率 ;在照射后培养时间 1 8h内以剂量依赖的方式诱导细胞凋亡 ;2 5 0J·m-2 UVB照射后 ,细胞的静息钙迅速下降 ,在照射后第 6h静息钙降至最低 ,且thapsigargin(1 0μmol·L-1 )和adrenaline(1 0 μmol·L-1 )所引起的钙释放及由此产生的钙内流也随照射后培养时间的延长而逐渐减少。结论　UVB照射可诱导HaCaT细胞的凋亡及引起细胞钙稳态的失衡。     

德都红花-7味散对大鼠肝再生过程的双向调节作用机制研究

目的 探讨在肝再生过程中德都红花-7味散对酪氨酸激酶(JAK)/信号转导及转录激活因子(STAT)信号通路的影响.方法 按照随机数字表法将SD大鼠分为4组:假手术组、模型组、阳性对照组和实验组,每组20只.阳性对照组灌胃护肝片(0.28 g·kg-1),实验组灌胃德都红花七味散(0.6 g·kg-1).大鼠部分肝切除术...     

JNK信号传导通路在赭曲毒素A体外诱导人肾小管上皮细胞凋亡中的作用

目的探讨赭曲毒素A(OA)诱导人肾小管上皮细胞(HKC)凋亡的作用机制。方法体外培养HKC,随机分为空白对照组、溶剂(0.04%乙醇)对照组、OA 1μmol·L-1处理组及c-Jun氨基端激酶(JNK)阻断剂SP600125 0.5μmol·L-1预处理+OA组。细胞处理24h后,分别采用流式细胞仪检测细胞的凋亡率,免疫细胞化学染色和Western蛋白印迹法检测凋亡相关蛋白天冬氨酸半胱氨酸蛋白酶(caspase)3蛋白的表达以及JNK的磷酸化水平(p-JNK)。结果OA组细胞凋亡率明显高于溶剂对照组〔(4.24±0.17)%vs(1.06±0.14)%〕,SP600125预处理+OA组HKC凋亡率〔(2.44±0.38)%〕明显低于OA组。OA组caspase 3蛋白的表达和p-JNK水平明显升高,SP600125预处理+OA组caspase 3蛋白的表达和p-JNK水平较OA组明显降低。结论OA可能通过激活JNK,上调caspase 3蛋白的表达而诱导HKC凋亡。     

TGF-β1诱导的肝癌细胞SMMC-7721上皮间质转化对细胞Wnt/β-catenin表达的影响

目的探讨TGF-β1诱导的肝癌细胞SMMC-7721上皮间质转化对细胞信号通路蛋白Wnt/β-catenin表达的影响。方法采用5μg·mL-1 TGF-β1诱导SMMC-7721发生上皮间质转化,分别采用RT-PCR和Western blot法检测细胞中Wnt1、β-catenin、Vimentin mRNA和总蛋白的表达。结果 TGF-β1能显著诱导肝癌细胞SMMC-7721发生上皮间质转化,细胞中Wnt1、β-catenin、Vimentin mRNA和相应总蛋白的表达均显著增加(P<0.05)。结论 TGF-β1诱导肝癌细胞SMMC-7721上皮间质转化时可促进细胞Wnt/β-catenin的表达。     

Enhanced protection of Ins-1 β cells from apoptosis under hypoxia by delivery of DNA encoding secretion signal peptide-linked exendin-4

In this study, we developed an expression system of exendin-4, a glucagon-like peptide (GLP-1) analog, using a secretion signal peptide (SP) to facilitate exendin-4 secretion. For delivery of the exendin-4 expression system, high-molecular-weight polyethylenimine (25 kDa, PEI25k), low-molecular-weight polyethylenimine (2 kDa, PEI2k), and polyamidoamine (PAMAM) dendrimers were evaluated as gene carriers to Ins-1 β cells. As a result, PEI25k showed the highest transfection efficiency. For the construction of the exendin-4 expression vector, DNA coding the SP sequence was inserted upstream of the exendin-4 cDNA, resulting in the construction of pβ-SP-Ex-4. Transfection assay showed that the secretion level of exendin-4 increased in the pβ-SP-Ex-4 transfected cells, compared with the pβ-Ex-4 transfected cells. To identify the β-cell protection effect of pβ-SP-Ex-4 delivery, the Ins-1 β cells were transfected with pβ-SP-Ex-4 or pβ-Ex-4 and incubated under normoxia or hypoxia. An MTT assay showed that the pβ-SP-Ex-4 transfected cells had higher β-cell viability than the pβ-Ex-4 transfected cells under hypoxia. In addition, the pβ-SP-Ex-4 transfected cells exhibited lower caspase-3 activity than the pβ-Ex-4 transfected cells. Therefore, PEI25k/pβ-SP-Ex-4 complex may be useful to protect isolated β cells from apoptosis during transplantation.     

MAPK信号转导通路在糖皮质激素耐药白血病中的研究进展

丝裂原活化蛋白激酶(MAPK)信号通路作为信号传递网络中的重要途径之一,在细胞凋亡及生存中发挥重要作用,其中最主要的是ERK、JNK及p38 MAPK途径。近来研究发现,MAPK信号转导通路与白血病的发生发展及耐药的产生有密切关系,将有可能成为白血病治疗的新靶点。本文主要综述了MAPK信号转导通路与白血病发病、治疗作用机制及与糖皮质激素耐药的关系。     

Data mining for signals in spontaneous reporting databases: proceed with caution

PURPOSE: To provide commentary and points of caution to consider before incorporating data mining as a routine component of any Pharmacovigilance program, and to stimulate further research aimed at better defining the predictive value of these new tools as well as their incremental value as an adjunct to traditional methods of post-marketing surveillance. METHODS/RESULTS: Commentary includes review of current data mining methodologies employed and their limitations, caveats to consider in the use of spontaneous reporting databases and caution against over-confidence in the results of data mining. CONCLUSIONS: Future research should focus on more clearly delineating the limitations of the various quantitative approaches as well as the incremental value that they bring to traditional methods of pharmacovigilance.