人胰腺癌中bcl—2基因和蛋白的过度表达

目的：分析胰腺癌中bcl-2基因的mRNA转录和蛋白翻译，探讨其在胰腺癌 发生、发展中的作用。方法：以50例胰腺癌组织、15例胰腺癌转移灶组织和10例慢性胰腺炎为研究对象，采用免疫组织化学（SP法）和原位分子杂交法检测bcl-2的表达。结果：Bcl-2蛋白表达与患年龄、性别、TNM分期无关，与肿瘤分化程度、有无转移病灶有关。在胰腺癌组织中的表达低于胰腺炎组织，但明显高于转移灶。免疫组织化学与原位杂交技术检测胰腺癌组织中的bcl-2基因表达结果一致。结论：Bcl-2蛋白可能作用于胰腺细胞癌变阶段，并与胰腺导管上皮癌变有关；bcl-2基因在mRNA和蛋白水平表达是相对稳定的。     

An immunohistochemical study of the expression of bcl-2 and p53 oncoproteins in pancreatic intraepithelial neoplasia and pancreatic cancer.

BACKGROUND: The bcl-2 and p53 gene deregulation is frequently involved in several types of malignancies. The purpose of this study was to evaluate the expression of bcl-2 and p53 genes in various types of pancreatic intraepithelial proliferation and in pancreatic cancer and to answer the question of whether they interact in the process of intraductal epithelial proliferation. METHODS: Immunohistochemical staining for p53 and bcl-2 was performed on paraffin embedded sections from 56 patients operated on for pancreatic carcinoma, chronic pancreatitis, and other conditions. RESULTS: Pancreatic cancer in 100% of cases showed p53 expression and in 27.7% bcl-2 expression. The p53 gene was expressed already in pancreatic intraductal neoplasia and its frequency was significantly rising with an increasing degree of hyperplasia. Normal epithelium of pancreatic ducts and ductules showed a high expression of bcl-2, which was decreasing in the process of intraductal proliferation. CONCLUSIONS: Pancreatic cancer is characterized by a high expression of p53 and a low expression of bcl-2. In pancreatic cancers and pancreatic intraepithelial neoplasia, there is an inverse relationship between the expression of bcl-2 and p53. Malignant behavior of pancreatic cancer may be associated with the phenotype bcl-2-/p53+.     

白细胞介素-1β小干扰RNA的设计、合成及筛选

目的设计和合成针对白细胞介素-1β（IL-1β）的特异性小干扰RNA（siRNA），研究其对体外培养的新西兰白兔膝关节滑膜成纤维细胞表达IL-1β mRNA的干扰作用，筛选出有干扰效果的IL-1β siRNA，为进一步构建IL-1β特异性双链RNA（dsRNA）质粒载体创造条件。方法参照siRNA的设计原则，采用Ambion公司提供的软件，利用Finder程序查找和设计针对IL-1β siRNA的正义和反义寡核苷酸链。体外转录法合成4个IL-1β siRNA，将合成的IL-1β siRNA分别转染体外培养的新西兰白兔膝关节滑膜成纤维细胞，并以未转染细胞作为空白对照，采用RT-PCR技术检测所合成的IL-1β siRNA对体外培养的兔滑膜成纤维细胞IL-1β mRNA表达的影响。结果转染48小时后，4条IL-1β siRNA链中有1条（L4）能够使兔滑膜成纤维细胞IL-1β mRNA的表达水平明显下调，其余3条IL-1β siRNAs链未见明显的干扰效果。结论不同的IL-1β siRNA对兔膝关节滑膜成纤维细胞IL-1β mRNA表达水平具有不同的干扰效能。成功筛选出1个有效的IL-1β siRNA，初步提示RNA干扰技术可用于抑制兔膝关节滑膜成纤维细胞IL-1β mRNA的表达。     

Infectivity enhanced, cyclooxygenase-2 promoter-based conditionally replicative adenovirus for pancreatic cancer

BACKGROUND AND AIMS: Pancreatic cancer is one of the most aggressive human malignancies. Conditionally replicative adenoviruses (CRAds) have shown some promise in the treatment of cancers. However, to date, their application for pancreatic cancer has met several obstacles: one is lack of a good control element to regulate replication, and the other is relatively low adenoviral infectivity. Thus, we constructed infectivity enhanced cyclooxygenase (COX)-2 promoter-based CRAds to develop a safe and effective therapeutic modality. METHODS: The CRAds were designed to achieve COX-2 promoter-controlled E1 expression for regulated replication (COX-2 CRAds). The infectivity-enhanced CRAds also have an RGD-4C motif in the adenoviral fiber-knob region. The selectivity and efficacy of these constructs were analyzed with cell lines in vitro. The in vivo therapeutic effect and viral replication were analyzed with a xenograft model. Pathology of the major organs and E1 RNA levels in the liver were also studied after systemic administration. RESULTS: The COX-2 CRAds showed a selective cytocidal effect in vitro in COX-2-positive cells and killed most of the pancreatic cancer cells. In vivo, intratumoral administration of the infectivity-enhanced COX-2 CRAds (10(9) particles) showed a strong antitumor effect comparable to wild-type virus, whereas the COX-2 CRAds without infectivity enhancement showed a limited effect. Viral replication was confirmed in the xenograft tumors. Systemic administration did not cause any detectable toxicity; the E1 RNA level in the liver after COX-2 CRAd administration was minimal. CONCLUSIONS: Infectivity-enhanced COX-2 CRAd is a promising agent for the treatment of pancreatic cancer.     

Clearance of hepatitis B virus from the liver of transgenic mice by short hairpin RNAs

Hepatitis B virus (HBV) causes acute and chronic hepatitis and hepatocellular carcinoma. Although a preventive vaccine is available, the therapeutic options for chronically infected patients are limited. It has been shown that RNA interference can prevent HBV gene expression and replication in vivo when HBV expression vectors are delivered simultaneously with small interfering RNA (siRNA) or siRNA expression constructs. However, the therapeutic potential of siRNAs to interrupt ongoing HBV replication in vivo has not been established. Here, we show that expression of HBV-specific siRNAs in the liver of HBV transgenic mice by recombinant adenoviruses can suppress preexisting HBV gene expression and replication to almost undetectable levels for at least 26 days. These results demonstrate that efficiently delivered siRNAs should be able to silence HBV in chronically infected patients.     

Sticky overhangs enhance siRNA-mediated gene silencing

siRNA delivery to cells offers a convenient and powerful means of gene silencing that bypasses several barriers met by gene delivery. However, nonviral vectors, and especially polymers, form looser complexes with siRNA than with plasmid DNA. As a consequence, exchange of siRNA for larger polymeric anions such as proteoglycans found outside cells and at their surface may occur and lower delivery. We show here that making siRNAs "gene-like," via short complementary A(5-8)/T(5-8) 3' overhangs, increases complex stability, and hence RNase protection and gene silencing in vitro up to 10-fold. After decomplexation in the cytoplasm, sticky siRNA (ssiRNA) concatemers fall apart. ssiRNAs are therefore not inducing antiviral responses, as shown by the absence of IFN-beta production. Finally, transfection experiments in the mouse lung show that ssiRNA should be particularly suited to silencing with linear polyethylenimine in vivo.     

RNAi沉默Polo-like kinase-1基因表达对胰腺癌细胞增殖的影响

目的:探讨polo-like kinase-1(PLK1)基因在胰腺癌细胞中的作用.方法:采用PLK1小干扰核糖核酸分子(small interfering RNA,siRNA)转染人胰腺癌Mi- aPaCa-2细胞后,分别采用实时定量PCR和Western blot检测PLK1基因mRNA和蛋白表达水平,观察PLK1 siRNA转染对胰腺癌细胞体内外增殖的影响.于转染不同时间后收集细胞,分别采用琼脂糖凝胶电泳和TUNEL方法检测胰腺癌细胞凋亡情况.结果:胰腺癌MiaPaCa-2细胞经siRNA转染处理后,PLK1 mRNA和蛋白表达水平明显下降(P<0.05).PLK1基因siRNA可明显抑制癌细胞体外生长(P<0.05)和体内裸鼠模型增殖(P<0.05).细胞凋亡检测发现,DNA电泳出现明显的梯度图谱,且与浓度相关(r=0.836,P<0.05).TUNEL结果显示,转染组癌细胞凋亡指数明显增加,且呈时间和浓度依赖性(r= 0.875,P<0.05).结论:PLK1 siRNA转染可明显抑制胰腺癌细胞增殖,其机制可能与诱导细胞凋亡有关.     

Detection of bcl-2 and bax expression and bcl-2／JH fusion gene in intrahepatic cholangiocarcinoma

AIM: To investigate the relationship between bcl-2 gene and its related protein bax and intrahepatic cholangiocellular carcinoma (CCC). METHODS: Semi-nested in situ PCR (SNISPCR) and immunohistochemistry were performed to detect bcl-2/JH fusion gene and bcl-2, bax protein expression in 29 cases of CCC. RESULTS: No bcl-2/JH fusion gene was found in all cases of CCC, 72.4% of 29 cases expressed bcl-2 protein. Bcl-2 protein expression was related to histopathological grades (P<0.05). There was no corresponding relationship between bcl-2/JH fusion gene formation and bcl-2 protein expression in CCC (P<0.05). Bax was expressed in 10.3% of 29 cases. The ratio of bcl-2 to bax in normal liver tissues (3.5 to 1) was different from that in tumor tissues (7.0 to 1). CONCLUSION: It is suggested that bcl-2/JH fusion gene formation is not a frequent event and may not play an important role in the pathogenesis of CCC. However, aberrant ratio of bcl-2 to bax protein expression may be involved in the course of tumorigenesis of CCC. Abnormal bcl-2 protein expression may not be solely resulted from bcl-2/JH fusion gene.     

Apoptosis, proliferation and differentiation patterns are influenced by Zebularine and SAHA in pancreatic cancer models

OBJECTIVE: Pancreatic cancer continues to be an urgent clinical problem. We used the novel DNA methyltransferase inhibitor Zebularine and the histone deacetylase inhibitor SAHA to investigate the epigenetic influence on viability and differentiation of the pancreatic cancer cell lines YAP C, DAN G and Panc-89 in vitro and in vivo. MATERIAL AND METHODS: Cell vitality, proliferation and expression of PDX-1, cytokeratin 7 and 20, chromogranin A, vimentin, bax and bcl-2 were determined on the protein and mRNA level in vitro and in a subcutaneous xenograft model. RESULTS: A time- and dose-dependent increase of apoptosis, paralleled by decreased proliferation, was observed after incubation with single agents or a combination therapy with lower concentrations. This was associated with up-regulation of pro-apoptotic bax and a phenotypic stabilization by the enhanced expression of cytokeratin 7. In vivo, growth of xenografts was delayed with the most pronounced effect in Panc-89 after 1 week of daily intraperitoneal injections of Zebularine paralleled with CK7 up-regulation and down-regulation of dedifferentiation markers. CONCLUSIONS: Epigenetic modulation via inhibition of DNA methyltransferase and histone deacetylase induces apoptosis in human pancreatic cancer cells in vitro and delays xenograft growth in vivo, which is associated with a morphological/molecular phenotypic stabilization. These compounds may therefore be suitable as adjunctive therapeutic agents in the treatment of pancreatic cancer.     

Activity of stabilized short interfering RNA in a mouse model of hepatitis B virus replication

To develop synthetic short interfering RNA (siRNA) molecules as therapeutic agents for systemic administration in vivo, chemical modifications were introduced into siRNAs targeted to conserved sites in hepatitis B virus (HBV) RNA. These modifications conferred significantly prolonged stability in human serum compared with unmodified siRNAs. Cell culture studies revealed a high degree of gene silencing after treatment with the chemically modified siRNAs. To assess activity of the stabilized siRNAs in vivo initially, an HBV vector-based model was used in which the siRNA and the HBV vector were codelivered via high-volume tail vein injection. More than a 3 log10 decrease in levels of serum HBV DNA and hepatitis B surface antigen, as well as liver HBV RNA, were observed in the siRNA-treated groups compared with the control siRNA-treated and saline groups. Furthermore, the observed decrease in serum HBV DNA was 1.5 log10 more with stabilized siRNA compared with unmodified siRNA, indicating the value of chemical modification in therapeutic applications of siRNA. In subsequent experiments, standard systemic intravenous dosing of stabilized siRNA 72 hours after injection of the HBV vector resulted a 0.9 log10 reduction of serum HBV DNA levels after 2 days of dosing. In conclusion, these experiments establish the strong impact that siRNAs can have on the extent of HBV infection and underscore the importance of stabilization of siRNA against nuclease degradation.     

Identification of effective siRNA against K-ras in human pancreatic cancer cell line MiaPaCa-2 by siRNA expression cassette

AIM: We shall construct the small interfering RNA (siRNA) expression cassette (SEC) targeting activated K-ras gene sequence, identify more effective siRNA sequence against K-ras gene in human pancreatic cancer cell line MiaPaCa-2 by SEC and reveal the anti-cancer effects of RNA interference (RNAi) and its therapeutic possibilities. METHODS: Three different sites of SECs were constructed by PCR. K1/siRNA,K2/siRNA and K3/siRNA are located at sites 194,491 and 327, respectively. They were transfected into MiaPaCa-2 cells by liposome to inhibit the expression of activated K-ras. In the interfering groups of sites 194 and 491, we detected the apoptosis in cells by FACS after they were incubated for 48 h, then we tested the alternation of K-ras gene in MiaPaCa-2 cells by RT-PCR immunofluorescence, respectively. RESULTS: Introduction of the Kl/siRNA and K2/siRNA against K-ras into MiaPaCa-2 cells leads to increased apoptosis, and the number of apoptotic cells is increased compared with control cells. The tests of RT-PCR immunofluorescence show the effects of inhibiting expression of activated K-ras gene by RNA interference in the Kl/siRNA and K2/siRNA groups. We also find that the introduction of K3/siRNA has no effect on MiaPaCa-2 cells. CONCLUSION: Kl/siRNA and K2/siRNA can inhibit the expression of activated K-ras but K3/siRNA has no effect, demonstrating that Kl/siRNA and K2/siRNA are effective sequences against K-ras gene and K3/siRNA are not. We conclude that specific siRNA against K-ras expression may be a powerful tool to be used therapeutically against human pancreatic cancer.     

An immunohistochemical study of the expression of bcl-2 and p53 oncoproteins in pancreatic intraepithelial neoplasia and pancreatic cancer

Background. The bcl-2 and p53 gene deregulation is frequently involved in several types of malignancies. The purpose of this study was to evaluate the expression of bcl-2 and p53 genes in various types of pancreatic intraepithelial proliferation and in pancreatic cancer and to answer the question of whether they interact in the process of intraductal epithelial proliferation. Methods. Immunohistochemical staining for p53 and bcl-2 was performed on paraffin embedded sections from 56 patients operated on for pancreatic carcinoma, chronic pancreatitis, and other conditions.     

Apoptosis of human pancreatic cancer cells induced by Triptolide

AIM： To investigate apoptosis in human pancreatic cancer cells induced by Triptolide （TL）, and the relationship between this apoptosis and expression of caspase-3＇ bcl-2 and bax. METHODS： Human pancreatic cancer cell line SW1990 was cultured in DMEM media for this study. MTT assay was used to determine the cell growth inhibitory rate in vitro. Flow cytometry and TUNEL assay were used to detect the apoptosis of human pancreatic cancer cells before and after TL treatment. RT-PCR was used to detect the expression of apoptosis-associated gene caspase-3＇ bcl-2 and bax. RESULTS： TL inhibited the growth of human pancreatic cancer cells in a dose-and time-dependent manner. TL induced human pancreatic cancer cells to undergo apoptosis with typically apoptotic characteristics. TUNEL assay showed that after the treatment of human pancreatic cancer cells with 40 ng/mL TL for 12 h and 24 h, the apoptotic rates of human pancreatic cancer cells increased significantly. RT-PCR demonstrated that caspase-3 and bax were significantly up-regulated in SW1990 cells treated with TL while bcl-2 mRNA was not. CONCLUSION： TL is able to induce the apoptosis in human pancreatic cancer cells. This apoptosis may be mediated by up-regulating the expression of apoptosisassociated caspase-3 and bax gene.     

bcl-2 expression in non-Hodgkin's lymphomas is not associated with bcl-2 gene rearrangements

Previous reports have associated bcl-2 gene rearrangements found in non-Hodgkin's lymphomas with an inappropriately elevated bcl-2 expression compared with the mature B-cell stage of development. This study investigates bcl-2 expression in non-Hodgkin's lymphomas (NHL) without bcl-2 gene rearrangements. Molecular analysis in 168 patients with NHL revealed 45 patients without bcl-2 gene rearrangements in which additional immunostaining for bcl-2 protein was possible. An unexpectedly high prevalence (39/45) of bcl-2 expression was found. The levels and patterns of bcl-2 expression were not specific for the histological type of NHL and were similar to those shown in comparable cases with bcl-2 gene rearrangements. In conclusion, bcl-2 expression is not specific for NHL bearing bcl-2 gene rearrangements. This finding implicates the existence of other deregulating control mechanisms of bcl-2 expression, more important than bcl-2 gene rearrangements.     

Relationship between expression and distribution of cyclooxygenase-2 and bcl-2 in human gastric adenocarcinoma

AIM: To explore expression and distribution features of COX-2 and bcl-2 in human gastric adenocarcinoma tissues and to study its biological significance. METHODS: Totally 36 human gastric carcinoma samples were enrolled in this study (cardiac adenocarcinoma 16 cases, distal gastric adenocarcinoma 20 cases). The expressions of COX-2 and bcl-2 in cancerous tissues and corresponding para-cancerous tissues were investigated by immunohistochemistry using COX-2 polyclonal antibody and bcl-2 monoclonal antibody. The normal gastric mucosa tissues were used as control. RESULTS: The expressions of COX-2 and bcl-2 in gastric carcinoma were significantly higher than that in the para-cancerous tissues (77.8% vs 47.2%, P<0.01, 80.56% vs 58.33%, P<0.05). The expression of COX-2 in cardiac adenocarcinoma was remarkably higher than that in the distal gastric carcinoma (93.8% vs 65.0%, P<0.01). The expression of COX-2 was mainly localized in the cytoplasm of tumor cells and partly in the nucleus. There is a transition of the COX-2 cytoplasmic positivity to nucleic in tumor cells with the increase of gastric carcinoma pathological grade. Interstitial macrophages, fibroblasts and vascular endothelial cells also expressed COX-2. The tissues with higher expression of COX-2 also expressed high level of bcl-2 protein. CONCLUSION: Abnormal expression pattern of COX-2 within the tissues of human gastric cancer is correlated with tumor location and lymph node metastasis. COX-2 may regulate expression of apoptosis suppressor gene (bcl-2) through interaction of tumor cells and stromal cells and play an important role in the generation and development of tumors, which will be of great help in developing new methods for antitumor therapy.     

RNA interference and the use of small interfering RNA to study gene function in mammalian systems

In the past 2 years, extraordinary developments in RNA interference (RNAi)-based methodologies have seen small interfering RNAs (siRNA) become the method of choice for researchers wishing to target specific genes for silencing. In this review, an historic overview of the biochemistry of the RNAi pathway is described together with the latest advances in the RNAi field. Particular emphasis is given to strategies by which siRNAs are used to study mammalian gene function. In this regard, the use of plasmid-based and viral vector-based systems to mediate long-term RNAi in vitro and in vivo are described. However, recent work has shown that non-specific silencing effects and activation of the interferon response may occur following the use of some siRNA and delivery vector combinations. Future goals must therefore be to understand the mechanisms by which siRNA delivery leads to unwanted gene silencing effects in cells and, in this way, RNAi technology can reach its tremendous potential as a scientific tool and ultimately be used for therapeutic purposes.     

Bcl-6 p53 mutations in lymphomas carrying the bcl-2/Jh rearrangement

BACKGROUND AND OBJECTIVES: The t(14;18)(q32;q21) chromosomal translocation is the hallmark of follicular lymphomas (FL). The translocation induces the overexpression of the Bcl-2 protein and prolongs the survival of clonogenic cells. Tumor cells may acquire additional molecular alterations that may be associated with histologic progression or with chemo-resistance. DESIGN AND METHODS: We analyzed the distribution and association of bcl-6 and p53 mutations in 55 consecutive bcl-2/Jh+ lymphoma samples derived from 43 patients obtained at the time of diagnosis and, in 5 of these patients, during follow-up. A total of 29 bcl-6 point mutations were detected in seventeen patients (40%) associated with major or minor breakpoints of the bcl-2/Jh fusion gene. In seven cases a p53 mutation was detected. Three cases corresponded to FL with the minor breakpoint in the bcl-2 gene and these patients had a favorable clinical evolution, whereas the 4 patients with p53 mutations and the major breakpoint had a bad clinical outcome with morphologic transformation to high-grade lymphoma in three cases. The sequential analysis of 5 patients showed a different timing in the acquisition of mutations: one patient showed bcl-6 and p53 mutations at diagnosis, another patient showed bcl-6 mutations at diagnosis and acquired a p53 mutation later whereas the third patient had a p53 mutation before the appearance of the bcl-6 mutation. RESULTS: We did not find significant differences in survival between patients with FL who showed exclusively bcl-6 mutations and those without bcl-6 mutations, but those patients with a high International Progostic Index score and p53 mutations showed the lowest overall survival (p = 0.002). INTERPRETATION AND CONCLUSIONS: These findings suggest that bcl-2/Jh lymphomas show molecular heterogeneity and that bcl-6 and p53 mutations may be acquired during the evolution of such lymphomas. Bcl-6 mutations, by themselves, do not seem to be associated with a bad prognosis. Rearrangements at the minor bcl-2 locus may have a different molecular evolution.