Early apoptosis and cell death induced by ATX-S10Na （ Ⅱ ）-mediated photodynamic therapy are Bax- and p53-dependent in human colon cancer cells

AIM： To investigate the roles of Bax and p53 proteins in photosensitivity of human colon cancer cells by using lysosome-localizing photosensitizer, ATX-S10Na （Ⅱ）. METHODS： HCT116 human colon cancer cells and Bax-null or p53-null isogenic derivatives were irradiated with a diode laser. Early apoptosis and cell death in response to photodynamic therapy were determined by MTT assays, annexin Ⅴ assays, transmission electron microscopy assays, caspase assays and western blotting. RESULTS： Induction of early apoptosis and cell death was Bax- and p53-dependent. Bax and p53 were required for caspase-dependent apoptosis. The levels of anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-xL, were decreased in Bax- and p53-independent manner. CONCLUSION： Our results indicate that eady apoptosis and cell death of human colon cancer cells induced by photodynamic therapy with lysosome-localizing photosensitizer ATX-S10Na （Ⅱ） are mediated by p53- Bax network and low levels of Bcl-2 and Bcl-xL proteins. Our results might help in formulating new therapeutic approaches in photodynamic therapy.     

β-catenin accumulation in nuclei of hepatocellular carcinoma cells up-regulates glutathione-s-transferase M3 mRNA

AIM: To identify the differentially over-expressed genes associated with β-catenin accumulation in nuclei of hepatocellular carcinoma (HCC) cells.METHODS: Differentially expressed genes were identified in radiation-induced B6C3 F1 mouse HCC cells by mRNA differential display, Northern blot and RT-PCR, respectively. Total glutathione-s-transferase (GST) activity was measured by GST activity assay and β-catenin localization was detected with immunostaining in radiation-induced mouse HCC cells and in HepG2 cell lines.RESULTS: Two up-regulated genes, glutamine synthetase and glutathione-s-transferase M3 (GSTM3), were identified in radiation-induced mouse HCC cells. Influence of β-catenin accumulation in nuclei of HCC cells on up-regulation of GSTM3 mRNA was investigated. The nearby upstream domain of GSTM3 contained the β-catenin/Tcf-Lef consensus binding site sequences [5’-(A/T)(A/T) CAAAG-3’], and the total GST activity ratio was considerably higher in B6C3F1 mouse HCC cells with β-catenin accumulation in nuclei of HCC cells than in those without β-catenin accumulation (0.353 ± 0.117 vs 0.071 ± 0.064, P < 0.001). The TWS119 (a distinct GSK-3β inhibitor)-induced total GST activity was significantly higher in HepG2 cells with β-catenin accumulation than in those without β-catenin accumulation in nuclei of HCC cells. Additionally, the GSTM3 mRNA level was significantly higher at 24 h than at 12 h in TWS119-treated HepG2 cells.CONCLUSION: β-catenin accumulation increases GST activity in nuclei of HCC cells, and GSTM3 may be a novel target gene of the β-catenin/Tcf-Lef complex.     

Transfection of p27^kip1 enhances radiosensitivity induced by ^60Co γ-irradiation in hepatocellular carcinoma HepG2 cell line

AIM: To study the cell cycle alterations of human hepatoma cell line HepG2 in vitro after ^60Co γ-irradiation and further to examine the mechanisms underlying the enhancement of radiosensitivity to γ-irradiation in HepG2 transiently transfected with wild type p27^kip1. METHODS: The proliferation of HepG2 cells was evaluated with MTT assay, and the cell cycle profile and apoptosis were assessed by cell morphology, DNA fragmentation analysis and flow cytometry. HepG2 cells were transfectedwith p27^kip1 wild type by using Lipofectamine (LF2000), and the expression and subcellular localization of p27^kip1 in HepG2 were detected by immunocytochemistry.RESULTS: ^60Co γ-irradiation inhibited the growth of HepG2 cells in a dose-dependent manner. Apoptosis of HepG2 cells was induced 48 h after ~, ray exposure. Furthermore research was carried out to induce exogenous expression of p27^kip1 in HepG2. The expression of p27^kip1 induced G0/G1 phase arrest in HepG2 cells. The overexpression of p27^kip1 enhanced ^60Co γ-irradiation-induced radiosensitivity in HepG2 cells. CONCLUSION: Overexpression of p27^kip1 is a rational approach to improve conventional radiotherapy outcomes, which may be a possible strategy for human hepatoma therapy.     

Changes of NF—kB,p53,Bcl—2 and caspase in apoptosis induced by JTE—522 in human gastric adenocarcinoma cell line AGS cells：role of reactive oxygen species

AIM:To identify whether JTE-522 can induce apoptosis in AGS cells and ROS also involved in the process,and to investigate the changes in NF-kB,p53,bcl-2 and caspase in the apoptosis process.METHODS:Cell culture,MTT,Electromicroscopy,agarose gel electrophoresis,lucigenin,western blot and electrophoretic mobility shift assay(EMSA)analysis were employed to investigate the effect of JTE-522 on cell proliferation and apoptosis in AGS cells and related molecular mechanisms.RESULTS:JTE-522 inhitied the growth of AGS cells and induced the apoptosis,Lucigenin assay showed thd generation of ROS in cells under incubation with JTE-522,The increased ROS generation might Contribute to the induction of AGS cells to apoptosis.EMSA and Western blot revealed that NF-kB activity was almost completely inhihbited by preventing the degradation of IKBα,Additionally,by using Western blot we confirmed that the level of bcl-2 was decreased,whtereas p53 showed a great inmcrease following JTE-522 treatment.Their changes were in a dose-dependent manner. CONCLUSION：These findings suggest that reactive oxygen species,NF-kB,p53,bcl-2 and caspase-3 may play an important role in the induction of apoptosis,in ags cells after treatment with JTE-522.     

Sequencing of p53 mutation in established human hepatocellular carcinoma cell line of HHC4 and HHC15 in nude mice

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Knockdown of survivin gene expression by RNAi induces apoptosis in human hepatocellular carcinoma cell line SMMC-7721

AIM: To investigate the survivin gene expression in human hepatocellular carcinoma cell line SMMC-7721 and the effects of survivin gene RNA interference (RNAi) on cell apoptosis and biological behaviors of SMMC-7721 cells. METHODS: Eukaryotic expression vector of survivin gene RNAi and recombinant plasmid pSuppressorNeo-survivin (pSuNeo-SW), were constructed by ligating into the vector, pSupperssorNeo (pSuNeo) digested with restriction enzymes Xba I and Sail and the designed double-chain RNAi primers. A cell model of SMMC-7721 after treatment with RNAi was prepared by transfecting SMMC-7721 cells with the lipofectin transfection method. Strept-avidin-biotin-complex (SABC) immunohistochemical staining and RT-PCR were used to detect survivin gene expressions in SMMC-7721 cells. Flow cytometry was used for the cell cycle analysis. Transmission electron microscopy was performed to determine whether RNAi induced cell apoptosis, and the method of measuring the cell growth curve was utilized to study the growth of SMMC-7721 cells before and after treatment with RNAi. RESULTS: The eukaryotic expression vector of survivin gene RNAi and pSuNeo-SW, were constructed successfully. The expression level of survivin gene in SMMC-7721 cells was observed. After the treatment of RNAi, the expression of survivin gene in SMMC-7721 cells was almost absent, apoptosis index was increased by 15.6%, and the number of cells was decreased in G2/M phase and the cell growth was inhibited. CONCLUSION: RNAi can exert a knockdown of survivin gene expression in SMMC-7721 cells, and induce apoptosis and inhibit the growth of carcinoma cells.     

Expression of p57(kip2) and its relationship with clinicopathology, PCNA and p53 in primary hepatocellular carcinoma

AIM: To investigate the expression of p57kip2 and its relationship with clinicopathology, PCNA and p53 in primary hepatocellular carcinoma (HCC). METHODS: Expression of p57kip2, PCNA and p53 in tumor tissues from 32 patients with HCC and 10 liver tissues of normal persons was detected with Elivision immunohistochemical technique. RESULTS: The p57kip2 protein positive-expression rate in HCC was 56.25%, lower than that in normal tissues (100%, P<0.05). The reduced expression of p57kip2 protein correlated significantly with moderate or low differentiation of tumor cells (P = 0.007 <0.05), high clinical stage (P= 0.041 <0.05) and poor prognosis (P= 0.036 <0.05), but did not correlate significantly with metastasis, tumor size, level of AFP and age (P>0.05). The PCNA positive-expression rate was 56.25%, which was correlated significantly with the expression of p57kip2 (P= 0.025<0.05). The p53 positive-expression rate was 46.88%, which was not correlated significantly with the expression of p57kip2 (P>0.05). CONCLUSION: There is a marked loss or absence of p57kip2 expression and high expression of PCNA in HCC, which are involved in carcinogenesis and development of HCC. The p57kip2 and p53 may induce apoptosis via different mechanisms.     

U6嵌和型Maxizyme对肝癌突变抑癌基因p53的抑制作用

目的探讨U6嵌和型Maxizyme对肝癌突变抑癌基因p53的抑制作用。方法应用计算机设计针对肝癌突变抑癌基因p53(mtp53)249位密码子(AGG→AGT)Maxizyme(Mz)的基因片段,构建其真核表达载体,使抗mtp53的Mz嵌于U6表达系统中,细胞外由T7 RNA聚合酶转录,细胞内由RNA聚合酶Ⅲ高效转录。检测Mz在细胞外对mtp53的切割效率。在LipofectamineTM2000介导下转染肝癌细胞MHCC97,应用逆转录聚合酶链反应(RT-PCR)检测Mz对肝癌细胞mtp53的抑制作用,western blot分析mtp53蛋白表达水平,并用四甲基偶氮唑盐(MTT)法观察肿瘤细胞的生长情况。结果在细胞外,Mz可特异性切割靶基因mtp53,切割效率为42%,而野生型p53(wtp53)没有被切割。RT-PCR和western blot检测结果提示转染Mz的MHCC97内mtp53 mRNA和蛋白(5.3 ×104)表达均明显下降,转染Mz的MHCC97增殖速度明显降低。结论U6表达系统能高效启动核酶等小分子RNA的转录,U6嵌和型Maxizyme在细胞内外均可特异性抑制mtp53表达,抑制肝癌细胞增殖,有望开发为肝癌基因治疗的新方法。     

肝细胞癌组织HSP70、p53和PCNA的表达及其意义

目的探讨热休克蛋白70（HSP70）、p53和增殖细胞核抗原（PCNA）在肝细胞癌（HCC）组织中的表达及其意义。方法采用免疫组化法检测正常人、慢性乙型肝炎、肝硬化和HCC肝或癌组织HSP70、p53和PCNA的表达情况。结果 HCC组织HSP70、p53和PCNA表达阳性率明显高于非癌组织（x1^2=27.16x2^2=67.6,x3^2=40.6,P〈0.01）;HSP70在正常人、慢性乙型肝炎、肝硬化和HCC中的表达逐步增强;HSP70和p53在分化较好的HCC中的阳性率明显低于分化不良者（x1^2=6.8,P1〈0.01x2^2=6.1,P2〈0.05）,而PCNA表达与HCC组织分化程度无关（x2=2.4,P〉0.05）;HSP70表达强度与p53和PCNA表达关系密切（x1^2=41.3,x2^2=41.4,P〈0.01）。结论 HCC是HSP70高表达肿瘤。HSP70表达与p53和PCNA表达密切相关,因而在HCC发生和发展中起重要作用。     

三氧化二砷对肾癌GRC-1细胞凋亡及p53、Survivin基因表达的影响

目的观察三氧化二砷(As_2O_3)对人肾癌GRC-1细胞凋亡及p53、Survivin基因表达的影响,探讨其作用机制。方法将体外培养的人肾癌GRC-1细胞分为对照组(N)和实验组,实验组根据加入As_2O_3浓度的不同分为A、B、C、D、E(2、4、6、8、10μmol/L)组。48h后,四甲基偶氮唑蓝(MTT)法测定细胞增殖,流式细胞仪检测细胞凋亡和细胞周期变化．免疫细胞化学和RT-PCR方法测定p53和Survivin基因表达。结果As_2O_3可抑制GRC-1细胞的增殖．当As_2O_3由2μmol/L增加到10μmol/L时,细胞增殖率由88．3%降低到18．7%(F= 7546．587,P＜0．01)。各实验组p53、Survivin基因表达均较对照组减少,且随着As_2O_3的增加表达呈递减改变(F=1120．741、F=6 296．535,P＜0．01)。结论As_2O_3能够抑制GRC-1细胞增殖,并且具有浓度依赖性。能将细胞阻滞在G_2/M期,诱导细胞凋亡,其作用机制与p53和Survivin基因表达水平下降有关。     

核苷(酸)类似物及干扰素治疗对慢性HBV感染者远期肝癌和死亡风险的影响

目的观察核苷(酸)类似物(NAs)和α干扰素(IFN-α)抗病毒治疗对慢性乙型肝炎(CHB)和代偿期肝硬化(LC)患者远期发生肝细胞癌(HCC)及死亡风险的影响。方法采用回顾性-前瞻性双向队列研究设计,自2008年1月起,对1998年8月至2007年12月间住院的慢性HBV感染者通过回顾性调查建立研究队列,并随访至2013年5月。共2 035例患者纳入队列研究,其中NAs治疗组380例,IFN-α治疗组153例,未治疗(对照)组1 502例。结果 IFN-α治疗组中位随访时间10.08(IQR:7.96~11.67)年,HCC发生率为2.70/1 000人年;NAs治疗组中位随访时间7.58(IQR:6.08~9.67)年,HCC发生率为6.76/1 000人年;对照组中位随访时间9.2(IQR:7.0~11.33)年,HCC发生率为13.02/1 000人年。在CHB患者中,IFN-α治疗组的HCC累积发生率显著低于对照组(P=0.008)和NAs治疗5年的患者(P=0.039),其累积肝病相关病死率亦显著低于对照组(P=0.001)和NAs治疗5年(P=0.007)的患者;NAs治疗≥5年患者的累积肝病相关病死率显著低于对照组(P=0.019)和NAs治疗5年的患者(P=0.034)。在基线代偿期LC患者中,NAs治疗≥5年的患者HCC累积发生率显著低于对照组(P=0.028)及NAs治疗5年患者(P=0.031);同时其累积肝病死亡率亦显著低于对照组(P=0.001)及NAs治疗5年患者(P=0.017)。结论 IFN-α治疗能显著降低CHB患者远期发生HCC和死亡的风险,而NAs长期治疗可以减少CHB患者的死亡风险,并显著降低代偿性肝硬化患者HCC的发生风险及死亡率。