5-氮-2’脱氧胞苷诱导肺癌细胞系CDH13基因去甲基化及其表达

目的 观察去甲基化制剂5-氮-2’脱氧胞苷(5-aza-2’-deoxycytidine,5-Aza-dC)对人肺癌细胞系A549和LTEP-a2中CDH13基因启动子区甲基化状态及表达的影响,探讨肺癌细胞CDH13基因失活的机制及去甲基化制剂对CDH13基因表达的调控作用. 方法 5-Aza-dC处理体外培养的肺癌细胞A549、LTEP-a2及正常肺细胞系HFL1后,用甲基化特异性 PCR( MSP) 法检测处理前后细胞中CDH13基因的甲基化状态,半定量逆转录 聚合酶链反应(RT PCR)法检测用药前后细胞中CDH13 mRNA表达的变化. 结果 正常肺细胞中未见CDH13启动子甲基化,肺癌细胞A549、LTEP a2均发现CDH13启动子甲基化现象;应用 5-Aza-dC能使 CDH13基因启动子区 CpG 岛发生去甲基化. 肺癌细胞A549、LTEP-a2均可见CDH13 mRNA表达,但与正常肺细胞比较表达较弱,经药物处理癌细胞后其CDH13 mRNA的表达较前明显增强. 结论 启动子区异常甲基化是肺癌细胞CDH13基因失活的主要原因之一,去甲基化制剂5-Aza-dC能完全逆转CDH13基因甲基化状态,从而调控CDH13基因表达.     

5-Aza-dC及TSA对人小细胞肺癌细胞系中hMLH-1基因表达的影响

目的：探讨5-Aza—dC及TSA对人小细胞肺癌细胞系中抑癌基因基因表达的影响。方法：5-Aza—C及TSA处理体外培养的人小细胞肺癌细胞系NCI—H446,应用逆转录PCR（RT-PCR）方法检测人小细胞肺癌细胞系NCI—H446药物干预前后抑癌基因hMLH-1表达情况的变化。结果：NCI-H446细胞系经TSA,5-Aza—dC及联合作用后使原来不表达的抑癌基因hMLH-1重新表达或表达增强。结论：hMLH-1基因的异常甲基化是肺癌发生、发展过程中的频繁事件。肺癌细胞系中抑癌基因hMLH-1启动子甲基化可能是导致其基因失活的主要原因,5-Aza-dC单独作用和5—Aza—dC及TSA联合应用效果相似,均能显著增强甲基化的肿瘤抑制基因的重新表达。     

FHIT基因在宫颈癌细胞中的表达及其甲基化调控

目的探讨脆性组氨酸三联体(FHIT)基因在宫颈癌中的表达及其甲基化的调控。方法培养4株宫颈癌细胞C-33A、HeLa、CasKi、SiHa及1株人脐静脉血管内皮细胞ECV-304,分别用不同浓度5-氮脱氧胞苷(5-aza-dC)作为干预细胞。提取细胞的RNA,采用逆转录聚合酶链反应(RT-PCR)方法检测FHIT基因在干预前后表达变化情况;用直接记数法和四甲基偶氮唑盐(MTT)显色法检测细胞生长曲线与细胞增殖实验;以流式细胞仪分析干预前后细胞周期及凋亡率变化。结果①宫颈癌细胞在干预前均未见明显FHIT表达,用5-aza-dC干预后FHIT mRNA表达不同程度增强,尤其以1×10-6及2×10-6mmol.L-1浓度干预24 h可诱导FHIT表达显著增强;正常对照组细胞在干预前后均见到较强FHITmRNA表达(P<0.05)。②5-aza-dC干预后宫颈癌细胞生长曲线明显下降,而正常对照组细胞生长曲线无明显变化(P<0.05)。③MTT显色法结果提示,经过化学干预的宫颈癌细胞增殖速度及细胞存活率明显降低,正常细胞则无明显变化(P<0.05)。④5-aza-dC干预的宫颈癌细胞凋亡率增高,细胞周期阻滞在G1期,其中CasKi、C-33A细胞在干预浓度为2×10-6及10-6mmol.L-1时的变化最明显;而正常对照组细胞的细胞周期和凋亡率无明显变化(P<0.05)。结论FHIT基因的甲基化是FHIT基因表达下调的重要机制,FHIT基因可能作为抑癌基因在宫颈癌的发生发展中起重要作用;而通过人为抑制FHIT的甲基化,有可能抑制肿瘤的进展。     

脆性组氨酸三联基因与肿瘤

随着分子生物学的发展,发现了许多癌基因和抑癌基因。在肿瘤的发生发展和转移中,癌基因的激活和抑癌基因的失活有十分重要的作用。目前认为肿瘤是一种基因性疾病,多种癌基因和抑癌基因协同作用而导致肿瘤的发生和发展。脆性组氨酸三联基因(FragileHistidineTriad ,FHIT)是1996年被分离出来的一种新的肿瘤抑制基因,在多种肿瘤中发现它有异常改变。1　FHIT的发现抑癌基因的改变在肿瘤的病理形成过程中具有重要作用。细胞遗传学和分子生物学的研究揭示了染色体经常丢失的部位很有可能存在着抑癌基因,这些部位包括3p、5q、8p、9p、11p、13q…     

DNA甲基化治疗的抗肿瘤研究

DNA甲基化作为重要的表观遗传学调控方式近年来备受人们关注.肿瘤中存在的DNA甲基化异常,主要表现在癌基因的去甲基化和抑癌基因的甲基化.针对癌基因的甲基化治疗是目前抗肿瘤研究的新思路,其通过靶向诱导癌基因的甲基化可抑制癌基因表达及肿瘤细胞生长.本文综述癌基因甲基化治疗的I临床前研究进展.     

膀胱移行细胞癌中FHIT基因异常甲基化及其与临床病理学的关系

目的检测FHIT基因在膀胱移行细胞癌中的异常甲基化及其表达,探讨其与膀胱移行细胞癌临床病理学的关系。方法收集膀胱移行细胞癌新鲜组织标本共49例和10例正常膀胱组织,采用免疫组织化学的方法(S-P法)检测FHIT蛋白表达,用甲基化特异性聚合酶链反应PCR(MS-PCR)方法研究膀胱移行细胞癌组织、正常膀胱组织中FHIT基因启动子区CpG岛甲基化状态。结果FHIT蛋白在正常膀胱组织均为阳性;FHIT蛋白在膀胱移行细胞癌中阳性表达率为47%(23/49),肿瘤不同分级中随恶性程度的增高,表达减少,Ⅰ级与Ⅲ级比较,差异有统计学意义(P<0.05),不同临床分期中随分期的增高,表达减少,Tis～T1期与T2～T4期比较,差异无统计学意义(P>0.05)。49例膀胱移行细胞癌组织中,有8例发生了甲基化,阳性率为16%(8/49)。FHIT基因的异常甲基化和蛋白表达无相关性。正常膀胱组织FHIT基因启动子甲基化频率0(0/10)。结论FHIT基因与膀胱移行细胞癌的发生发展有关,FHIT蛋白异常表达可作为膀胱移行细胞癌肿瘤标志物。FHIT基因甲基化及表达缺失参与膀胱移行细胞癌的发生发展,且与其临床病理有一定关系,可能是影响膀胱移行细胞癌预后的重要因素。     

5-Aza-dC对硫酸铍诱导A549细胞中TβRⅡDNA甲基化的作用CSCD

目的探讨5-氮杂-2’-脱氧胞苷(5-Aza-2’-deoxycytidine,5-Aza-dC)对BeSO_(4)诱导人肺腺癌A549细胞中转化生长因子-βⅡ型受体(TβRⅡ)DNA甲基化的作用。方法建立BeSO_(4)染毒的A549细胞培养实验模型,采用CCK-8法检测细胞增殖活性,荧光定量聚合酶链反应(Quantitative Real-time PCR)检测TβRⅡ、α-平滑肌肌动蛋白(α-SMA)、胶原蛋白Ⅲ(COL-Ⅲ)和胶原蛋白Ⅰ(COL-Ⅰ)的mRNA表达;用5-Aza-dC进行干预,采用巢式降落式甲基化特异性PCR法检测TβRⅡDNA甲基化水平,用蛋白质印迹法(Western blot)检测TβRⅡ蛋白相对表达水平。结果根据细胞增殖结果建立低、中、高剂量组(终浓度分别为1、10和100μmol/L);BeSO_(4)可以诱导细胞形态变化,从椭圆形紧密连接的上皮细胞到纺锤形松散连接的间质细胞,并且随着暴露时间的延长,形态变化更加明显,BeSO_(4)在不同时间内诱导的细胞存活率随暴露时间延长而降低,最终选用细胞存活相对较多且低、中、高剂量组差异均有统计学意义的48 h作为干预时间;PCR结果显示:与对照组相比,BeSO_(4)各剂量组α-SMA、COL-Ⅲ和COL-Ⅰ的mRNA表达水平升高,这提示A549细胞胶原过量形成;与对照组相比,BeSO_(4)中、高剂量组的TβRⅡDNA甲基化水平分别增加77.52%和96.71%(P<0.05),5-Aza-dC干预组TβRⅡDNA甲基化水平较中剂量组降低28.60%(P<0.05);与对照组相比,BeSO_(4)低、中剂量组TβRⅡmRNA表达水平升高,中、高剂量组TβRⅡ蛋白相对表达水平分别升高117.49%、203.08%(P<0.05);5-Aza-dC干预后,TβRⅡ蛋白的表达水平较中剂量组降低15.22%,差异有统计学意义(P<0.05)。结论5-Aza-dC干预可导致BeSO_(4)诱导的A549细胞TβRⅡDNA甲基化程度降低。     

肺癌细胞株抑癌基因启动子甲基化与转录的关系

目的 通过测定3例非小细胞肺癌(NSCLC)细胞株中7个抑癌基因启动子甲基化与mRNA转录之间的关系,探讨启动子甲基化在NSCLC发生中的作用.方法 应用甲基化特异性的多聚酶链反应(MSP)和RT-PCR分别检测甲基化状态和mRNA的转录水平.结果 肺癌细胞株A549发生甲基化的基因包括p16INK4a、RASSF1α、CDH1、MGMT和CDH13,而DAPK和RAR-β为去甲基化状态;SH-77发生甲基化的基因包括p16INK4a、RASSF1α、CDH1和MGMT,而DAPK、CDH13和RAR-β为去甲基化状态;SPC-A1发生甲基化的基因包括p16INK4a、CDH1、 CDH13和RAR-β,而RASSF1α、MGMT和DAPK为去甲基化状态.RASSF1α、MGMT和RAR-β等3个基因发生甲基化的细胞株其mRNA转录失活,而去甲基化状态的细胞株则存在转录活性.结论 NSCLC细胞株中抑癌基因经常发生启动子CpG岛的甲基化,并且甲基化可能与抑癌基因mRNA转录失活相关.     

5-氮-2'脱氧胞苷对食管癌细胞系KYSE220中CDH13基因甲基化的影响

目的观察去甲基化制剂5-氮-2’脱氧胞苷(5-Aza-dC)对人食管癌细胞系KYSE220中CDH13基因启动子区甲基化影响,探讨KYSE220中CDH13基因失活机制及5-Aza-dC对CDH13基因表达调控作用。方法 5-Aza-dC处理体外培养的KYSE220细胞,用甲基化特异性PCR(MSP)法检测处理前后细胞中CDH13基因甲基化状态,半定量RT-PCR法检测用药前后细胞中CDH13 mRNA表达变化。结果 KYSE220中CDH13启动子区发现甲基化现象,应用5-Aza-dC使CDH13基因启动子区CpG岛去甲基化,经药物处理癌细胞后其CDH13 mRNA表达较前明显增强。结论去甲基化制剂5-Aza-dC能逆转CDH13基因甲基化状态,从而调控CDH13基因表达。     

重组天花粉蛋白高表达对人宫颈癌Caski细胞p73基因甲基化影响的机制研究

目的 探索重组天花粉蛋白(recombinant trichosanthin,rTCS)高表达对人宫颈癌Caski细胞p73基因甲基化影响的机制.方法 RT-PCR、QT-PCR、Western blot检测rTCS高表达后Caski细胞中DNA甲基化转移酶I(DNMT1)的表达变化,甲基化特异性PCR(MSP)法检测p73基因5′端启动子区CpG岛甲基化状态的改变.结果 宫颈癌Caski细胞p73为低表达,其启动子呈部分甲基化状态.高表达rTCS的细胞株其DNMT1mRNA及蛋白水平的表达均降低,其中mRNA水平降低0.56倍(P<0.01),p73基因启动子甲基化程度亦有所降低,p73mRNA水平表达升高.结论 高表达rTCS可能通过抑制DNMT1的表达,致使抑癌基因p73启动子去甲基化而重新表达,最终发挥抑癌基因功能抑制宫颈癌Caski细胞增殖.     

Nitric oxide, cell signaling and cell death

Nitric oxide (NO) is an important bioregulatory molecule in the nervous, immune and cardiovascular systems. NO participates in the regulation of the daily activities of cells as well as in cytotoxic events. It possesses a controversial effect on cell viability by acting both as a protection against apoptogenic stimuli, or by inducing apoptosis when produced at elevated concentrations. The mechanisms of NO in regulating these biological functions can be either through cyclic guanylate cyclase (cGMP)-dependent or cGMP-independent pathways. The purpose of this review is to highlight the implication of NO in cell signalling, synaptic transmission, and cell death. We focus also on the protective role as well as the toxicity of NO. Finally, the adverse effects of inhaled nitric oxide are also depicted in this review.     

树突状细胞对肿瘤细胞株的直接杀伤活性

目的 对比分析干扰素－γ（Interferon-γ,IFN-γ)或脂多糖（lipoplysaccharide,LPS)刺激后的树突状细胞（dendritic cell,DC)对肿瘤细胞杀伤活性的差异。方法 分离健康供者外周血单核细胞，用粒单细胞集落刺激因子和白介素－4诱导为DC。于培养液中加入LPS或IFN－γ培养12h，作为LPS激活的DC（LPS－DC）及IFN－γ激活的DC（IFN－DC）。用流式细胞仪检测DC表面共刺激分子的改变，以明确LPS或IFN－γ对DC的不同刺激作用；同时，以恶性血液病细胞株HL－60 Jurkat及Daudi为靶细胞，用不同效靶比与DC共同培养18h，采用^51Cr释放试验检测LPS－DC及IFN－DC抗肿瘤活性的差异。结果 ①LPS及IFN－γ可不同程度的上调DC表面CD86、CD80、CD83及CD1a的表达，以LPS刺激组明显。②IFN－γ和LPS可分别增强DC对HL60及Daudi的杀伤活性，在效靶比为20：1及10：1时杀伤率与未加刺激因子对照组（medium-DC)相比差异有显著意义（P＜0．05）。相反，IFN－γ－DC对Daudi、LPS－DC对HL－60无明显杀伤活性，但两者对Jurkat均具杀伤作用。结论 LPS及IFN－γ激活的DC对肿瘤细胞的杀伤活性具有相对肿瘤特异性。     

Pharmacotherapy for treating metastatic clear cell renal cell carcinoma

Introduction: Over the past decade metastatic renal cell carcinoma (RCC) treatment landscape has dramatically evolved from the era of cytokines-based immunotherapy (which benefited very few patients, at the expenses of high toxicities) to the present era of targeted agents and novel immunotherapeutics, greatly improving the prognosis of our patients.

Areas covered: Here we have reviewed the present status of the medical treatment of metastatic RCC. To do this, we interrogated the Medline database, as well as the proceedings of the main Oncological and Urological conferences for the relevant trials coducted so far.

Expert opinion: Despite all the advances made in these relatively few years, further improvements are needed, since none of the available agents proved able to cure even a sigle metastatic RCC patient. In particular, advances are awaited from the results of ongoing trial of combinations of different immune checkpoint inhibitors and of immune checkpoint inhibitors with anti-VEGF/VEGFRs agents. Furthermore, a better understanding of the molecular escape pathways used by the tumor to overcome VEGFR blockade or immune activation will hopefully bring soon to the clinic more active, tailored treatments, to be used in second line and beyond.     

Mast cell regulatory effect on lymphoid cell proliferation.

It has been shown rat mast cells (MC) can modulate lymphocyte proliferation in vitro. Depending on concentrations tested both serosal MC and their supernatants enhanced the spontaneous and T-mitogen-induced proliferation of spleen and lymph node cells. In addition T-mitogen-induced thymocyte proliferation was also increased. The enhancing effect of MC on lymphoid cell proliferation appeared after MC and lymphocytes were cocultured for 24, 48 or 72 h. The highest enhancing action of MC was observed when MC and lymphocytes were plated simultaneously. In contrast, when MC were added 24 or 48 h after the start of lymphocyte culture, the enhancing action of MC decreased or was abolished, respectively. No dependence was found between histamine concentration in MC supernatants and the enhancing activity of supernatants. After chromatographic separation of MC supernatants the fractions with molecular weights between 1-6 KDa augmented lymphoid cell proliferation.     

Rapid fluorometric assay for cell viability and cell growth using nucleic acid staining and cell lysis agents

The purpose of this study was to establish a new method for rapidly and simply assessing cell viability and growth with objective validation if the assay system proceeded under suitable conditions of cell culture. In this method, a cell lysis agent was combined with a fluorescent probe for nucleic acid which exclusively passes through the disrupted membranes of dead cells but not intact membranes of viable cells. The distinctive feature of this probe is to possess a large fluorescence enhancement (460-fold) on binding to nucleic acid despite very low intrinsic fluorescence. In this fluorometric assay based on cell lysis and staining (FACLS), the fluorescence intensity was linearly related to total tumour cell number. This FACLS was also used to evaluate the chemosensitivity of MOLT-4 human leukaemia cells and to measure cell viability. The results were similar to those obtained by MTT colorimetric and trypan blue exclusion assays. The main advantage of this assay is its ability to measure simultaneously both cell viability and cell growth rapidly (within about 5 min) and simply (two steps) with validation of cell culture conditions in each microplate. This method could be widely applicable to cytotoxic evaluation of anticancer drugs and other chemicals.     

T cell targeted immune enhancement yields effective T cell adjuvants

Given the critical role of cell-mediated immunity (CMI) in defense against attack from pathogens that establish chronic infections, it has become abundantly clear that current vaccine methodology will not be sufficient to develop the appropriate immune response for protection and/or clearance of infection. By extension, this logic also applies to cancer vaccines where T cell immune-mediated destruction is a critical mechanism for control of the disease. This review describes our current thoughts on the events associated with immune activation and evaluates the various approaches to achieve successful immune activation with defined or targeted antigens as opposed to using inactivated or attenuated organisms. The advantages and disadvantages of the current adjuvants for antigens that focus on mimicking the infection events via the innate immune system or antigen uptake are described in the context of generation of T cell specific responses. A central theme of the discussions is the importance of cytokines in modulating the immune response towards T cell immunity, either by adjuvant modulation or use of natural cytokine mixtures targeted towards the site of immune activation. Also discussed is the possibility that thymomimetic agents such as thymosin alpha1, levamisole and methyl inosine monophosphate (MIMP) may be useful in enhancing the T cell mediated arm of the immune response.     

Programmed cell death

Developmentally programmed cell death in animals is accomplished by the activation of a protease of the caspase family. Caspase activation is an essential feature of apoptosis. In Caenorhabditis elegans, this protease is CED-3, which corresponds to mammalian caspase-3. Caspases comprise a distinct family of cysteine aspartases that are activated by interaction with a co-factor and/or proteolytic processing. Once activated, they cleave targets containing the exposed consensus sequences, including other caspases, protein kinases and structural elements, to achieve the death of the cell. Apoptotic cells undergo a dramatic volume loss accompanied by ionic shifts and cytoplasmic acidification. The cytoskeleton rearranges and the cell membrane undergoes blebbing and phosphatidylserine externalization, thus marking the dying cell for ingestion by phagocytes. In addition to structural changes, mitochondria cease to synthesize ATP, release cytochrome c and other constituents, and lose membrane potential. DNA undergoes endonucleolytic cleavage first into 50-kb fragments, followed by cleavage to oligonucleosomes. Together these biochemical processes achieve the noninflammatory destruction of the cell.