腺病毒介导的NT4p53(N15)Ant异源融合基因对肝癌细胞的杀伤作用

目的 构建包括神经营养因子4(NT4)信号肽,p53氨基端短活性肽(12～26位氨基酸)及蛋白质转导结构域-黑腹果蝇触足肽(Ant)序列在内的异源融合基因,并以腺病毒作为基因转移载体观察NT4p53(N15)Ant基因在体外对肝癌细胞系HepG2的杀伤效应.方法 应用互为模板的引物PCR技术及T载体克隆法获得p53(N15)Ant基因克隆,经酶切后连入pBV220/NT4质粒,再将融合基因NT4p53(N15)Ant亚克隆至腺病毒的穿梭质粒内,与辅助质粒pJM17共转染HEK293细胞,通过同源重组获得重组腺病毒,经PCR鉴定后,NT4p53(N15)Ant重组腺病毒感染HepG2细胞,用MTT比色法和PI染色流式细胞计数仪分析Ad.NT4p53(N15)Ant对肿瘤细胞和正常细胞的杀伤效应及凋亡率.结果 克隆出NT4p53(N15)Ant基因,得到高滴度的重组腺病毒,提取病毒DNA经PCR证实含目的基因.MTT测定结果显示,与平行对照病毒Ad.GFP相比,Ad.NT4p53(N15)Ant对HepG2细胞有强烈的杀伤效应,且以病毒感染后48 h作用最为明显,对肿瘤细胞抑制率达到63.3%,而对正常细胞NIH3T3的影响很小.Ad.NT4p53(N15)Ant感染HepG2细胞30 h后的流式细胞仪分析结果显示:Ad.NT4p53(N15)Ant可使HepG2细胞发生凋亡,凋亡率为18.16%.结论 通过分子克隆体外重组技术我们首次成功制备了NT4p53(N15)Ant复制缺陷型重组腺病毒;初步的研究发现Ad.NT4p53(N15)Ant对HepG2细胞有强烈的杀伤效应,这种效应部分是通过诱导HepG2细胞的凋亡而实现的.     

shRNA沉默COX-2基因表达对人肝癌细胞生物学特性的影响

背景与目的:环氧合酶-2(cyclooxygenase-2,COX-2)在肝癌组织中呈高表达,参与肝癌的发生发展.本研究探讨COX-2短发夹状RNA(shrt hairpin RNA,shRNA)对人肝癌细胞株HepG2中COX-2表达及细胞粘附侵袭力的影响.方法:以人COX-2 mRNA编码区中两条不同序列作为RNA干扰靶点,分别构建两个以绿色荧光蛋白GFP为报告基因的shRNA真核表达载体质粒WBH1和WBH2,应用阳离子脂质体转染HepG2细胞,分别观察转染后24 h、48 h、72 h和96 h COX-2 mRNA和蛋白表达的变化,检测抑制效果.MTT法观察HepG2细胞与Matrigel胶粘附性的变化.Transwell小室实验以穿过人工基底膜的细胞数量评估HepG2细胞体外侵袭力的变化.结果:质粒在HepG2细胞的转染率约为60%.质粒WBH1导人细胞24 h、48 h、72 h和96 h后,COX-2mRNA表达抑制率分别为18.5%、88.6%、52.8%和42.4%(P＜0.01),蛋白表达抑制率分别为10.3%、80.5%、45.3%和39.0%(P＜0.01).转染WBH2质粒的HepG2细胞COX-2表达无明显变化(P＞0.05).转染后48 h,转染WBH1质粒的HepG2细胞与Matrigel胶的粘附率为(6.0±0.4)%,与空白对照组(11.4±0.2)%相比明显下降(P＜0.01),抑制率为47.4%.转染WBH1质粒的细胞穿膜数为(8.2±1.5),与空白对照组(22.8±1.7)相比有显著性差异(P＜0.01),抑制率为63.7%.转染WBH2质粒的HepG2细胞粘附率和穿膜细胞数均无明显变化(P＞0.05).结论:shRNA真核表达载体明显干扰HepG2细胞的COX-2表达,能有效抑制HepG2细胞的体外粘附侵袭力.     

肝细胞癌中血管生成拟态的三维细胞培养及组织学研究

背景与目的:血管生成拟态(vasculogenic mimicry,VM)是新近发现的一种存在于恶性肿瘤中的血液供应方式.拟态血管由肿瘤细胞围成,无内皮细胞衬覆的管道样结构,其间有血液通过.目前对拟态血管的研究多局限在高侵袭性、双向分化的恶性肿瘤,对上皮来源的肿瘤很少涉及.本研究通过细胞三维培养,免疫组织化学方法观察肝细胞癌(hepatocellular carcinoma,HCC)中是否存在血管生成拟态,并探讨其形成过程及结构特点.方法:建立肝癌细胞株HepG2的三维培养模型,并收集15例肝癌石蜡包埋样本进行过碘酸雪夫氏(PAS)及CD31免疫组织化学双重染色以及PAS与Ferritin免疫组织化学双重染色,观察肝细胞肝癌中的血管生成拟态.结果:肝癌细胞三维培养两天时伸出细长突起,培养7天时彼此之间相互连接形成网络样、环状结构.15例肝癌免疫组织化学染色可见血管内皮CD31染色均为阳性,肝癌细胞Ferritin染色均为阳性.其中7例免疫组织化学与组织化学双重染色可见CD31阴性Ferritin阳性的肝癌细胞围成管道样结构,一层PAS阳性物质将肿瘤细胞同管腔分隔,肿瘤细胞构成的管腔中可见红细胞存在.并观察到分化良好的肝癌中血管生成拟态的形成少于分化差的肝癌,随着分化程度的降低肝癌细胞逐渐出现CD31着色阳性倾向.结论:肝癌细胞具有进行自身变形并与胶原蛋白相互作用,形成血管样通道的能力.肿瘤细胞可以通过血管生成拟态结构获得血液供应.     

Hepatocellular carcinoma HepG2 cell apoptosis and caspase-8 and Bcl-2 expression induced by injectable seed extract of Coix lacryma-jobi

BACKGROUND:Many Chinese herbs,especially herbal injections,have been shown to have anti-tumor effects in recent years.However,since most reports focus on the clinical effectiveness of these herbs,their mechanisms of action are not well understood.In this study,we assessed apoptosis in the hepatocellular carcinoma (HCC) cell line HepG2 induced by an injectable extract from the seed of Coix lacryma-jobi (Semen coicis,SC),and monitored the expression of Bcl-2 and caspase-8.METHODS:Injectable SC was applied to ...     

Hepatoprotective activity of punarnavashtak kwath,an Ayurvedic formulation,against CCl4-induced hepatotoxicity in rats and on the HepG2 cell line

Objective: Punarnavashtak kwath (PNK) is a classical Ayurvedic formulation, mentioned in Ayurvedic literature Bhaishajya Ratnavali, for hepatic disorders and asthma. This study investigated the hepatoprotective activity of PNK to validate the traditional use of this formulation.

Materials and methods: PNK was prepared in the laboratory according to the method given in Ayurvedic literature. Phytochemical screening was performed to determine the presence of phytoconstituents. Hepatoprotective activity was evaluated against CCl₄-induced hepatotoxicity in rats and by its effect on the HepG2 cell line.

Results: Preliminary phytochemical screening revealed the presence of alkaloids, tannins, flavonoids, saponins, and a bitter principle in PNK. Administration of PNK produced significant hepatoprotective effect as demonstrated by decreased levels of serum liver marker enzymes such as aspartate transaminase, serum alanine transaminase, serum alkaline phosphatase, and serum bilirubin and an increase in protein level. Thiopentone-induced sleeping time was also decreased in the PNK-treated animals compared with the CCl₄-treated group. It also showed antioxidant activity by increase in activity of glutathione, superoxide dismutase, and catalase and by a decrease in thiobarbituric acid reactive substance level compared with the CCl₄-treated group. Results of a histopathological study also support the hepatoprotective activity of PNK. Investigation carried out on the HepG2 cell line depicted significant increase in viability of cells exposed to PNK as compared with CCl₄-treated cells.

Discussion and Conclusion: It can be concluded that PNK protects hepatocytes from CCl₄-induced liver damages due to its antioxidant effect on hepatocytes. An in vitro study on HepG2 cell lines also supports its protective effect.     

人甲胎蛋白基因启动子siRNA表达载体的构建及效应鉴定

目的：探索基于人甲胎蛋白基因启动子构建的siRNA表达载体介导目的基因RNA干扰的可行性，为实现肝癌细胞靶向RNAi治疗作一初步研究。方法：PCR法扩增获得人甲胎蛋白基因启动子并插入pSilencer1．0-U6中以置换其U6启动子；依据hLRH-1基因RNAi靶位点设计出siRNA模板DNA，体外合成相应寡核苷酸片段后经退火形成短双链，再克隆构建成靶向人hLRH-1基因siRNA表达载体；脂质体转染法将上述重组质粒转入HepG2细胞中，实时定量PCR法初步分析所建系统在AFP表达细胞中触发靶基因hLRH-1的RNAi效应，以及hLRH-1调控下游靶基因的表达改变。结果：获得人甲胎蛋白基因启动子驱动的siRNA表达载体pSiAFP。所建的RNAi载体系统可在表达AFP的HepG2细胞中有效诱导靶基因hLRH-1表达下调，抑制率约达85％；同时调控hLRH-1下游靶基因CyclinE 1与Oct4的表达相应下调。结论：人甲胎蛋白基因启动子驱动的siRNA表达载体可在表达AFP的HepG2细胞中有效介导靶基因的RNAi效应。     

Study of inducibility and mechanism of phase 2 enzymes by quercetin and rutin

Objective The increasing recognition of the role for oxidative stress in hepatic disorders has led to extensive investigation on the protection by exogenous antioxidants against hepatic injury.In this study,we choose two typical polyphenol,quercetin and rutin,to investigate the mechanism of induction of cellular antioxidants and phase 2 enzymes in human HepG2 cells.Methods The HepG2 cells were treated with various concentrations of quercetin and rutin for 6 h and 24 h.The activities of NAD(P)H:quinone oxidoreductase(NQO1)in HepG2 cells were measured by 2,6-dichloroindophenol reduction method.The content of superoxide dismutase(SOD)was determined with the method of chemical colorimetry.The protein expressions of NQO1 and NF-E2-related factor 2(Nrf2)in HepG2 cells were detected by Western blotting.Results Incubation of HepG2 cells with quercetin and rutin resulted in a marked concentration-and time-dependent induction of a number of cellular antioxidants and phase 2 enzymes,including NQO1,SOD.Quercetin and rutin treatment of HepG2 cells also caused increase in protein expressions of NQO1 and Nrf2.Conclusions This study demonstrates that a series of phase 2 enzymes in HepG2 cells can be induced by quercetin and rutin in a concentration-and time-dependent fashion by upregulation the protein expression of nrf2.     

黄连提取物对肝细胞生长因子受体的特异性抑制作用

目的:观察黄连提取物对HepG 2细胞生长的影响,探讨黄连提取物的作用机制。方法:HepG 2细胞培养基中加入肝细胞生长因子,形成过量表达受体酪氨酸激酶(RTK)的HepG 2细胞,加入黄连提取物,测定细胞生长活性、HGFR和P-HGFR的表达水平(活性)。结果:黄连提取物对HepG 2细胞生长、HGFR和P-HGFR的表达水平(活性)均有不同程度的抑制作用。结论:黄连提取物通过抑制RTK而抑制肿瘤细胞的生长。     

Study of cytotoxic and apoptogenic properties of saffron extract in human cancer cell lines

Saffron (dried stigmas of Crocus sativus L.) has been used as a spice, food colorant and medicinal plant for millennia. In this study cytotoxic effect of saffron extract was evaluated in HepG2 and HeLa cell lines. Meanwhile role of apoptosis and ROS were explored. Malignant and non-malignant cells (L929) were cultured in DMEM medium and incubated with different concentrations of ethanolic saffron extract. Cell viability was quantitated by MTT assay. Apoptotic cells were determined using PI staining of DNA fragmentation by flow cytometry (sub-G1 peak). ROS was measured using DCF-DA by flow cytometry analysis. Saffron could decrease cell viability in malignant cells as a concentration and time-dependent manner. The IC50 values against HeLa and HepG2 were determined 800 and 950 μg/ml after 48 h, respectively. Saffron induced a sub-G1 peak in flow cytometry histogram of treated cells compared to control indicating apoptotic cell death is involved in saffron toxicity. This toxicity was also independent of ROS production. It might be concluded that saffron could cause cell death in HeLa and HepG2 cells, in which apoptosis or programmed cell death plays an important role. Saffron could be also considered as a promising chemotherapeutic agent in cancer treatment in future.