反义及正义表达癌基因c-Ha-ras重组质粒的构建

c-Ha-ras癌基因通过其产物p21蛋白的点突变或过量表达使细胞恶变。国外一些实验室的初步研究表明,导入一段与c-Ha-ras基因转录出的mRNA(sense RNA,正义RNA)顺序互补的RNA(anti-sense RNA,反义RNA),有可能通过阻断DNA复制,RNA转录或蛋白质翻译等过程,减少p21蛋白的合成,从而使转化细胞逆转。为了进一步系统研究反义c-Ha-ras RNA在转化细胞逆转中的     

lncRNA CBR3-AS1通过调控miR-145-5p影响胃癌HGC-27细胞的增殖、迁移、侵袭和凋亡

为探讨lncRNA CBR3-AS1靶向miR-145-5p对胃癌细胞HGC-27恶性生物学行为的影响,该研究先用实时荧光定量PCR(RT-qPCR)检测30例胃癌患者的癌组织及癌旁组织中CBR3-AS1和miR-145-5p的表达水平。然后,将CBR3-AS1干扰表达载体质粒、miR-145-5p模拟物、miR-145-5p抑制剂与CBR3-AS1干扰表达载体质粒转染至胃癌细胞HGC-27;用四甲基偶氮唑盐比色法(MTT)检测细胞活性;流式细胞术检测细胞凋亡流程;Transwell法检测迁移和侵袭的细胞数;双荧光素酶报告实验检测CBR3-AS1和miR-145-5p的靶向关系。实验结果显示,胃癌组织中CBR3-AS1表达水平高于癌旁组织,而miR-145-5p表达水平低于癌旁组织(P0.05)。过表达miR-145-5p或抑制lncRNA CBR3-AS1表达可降低HGC-27细胞活性,减少迁移侵袭细胞数,而提高细胞凋亡率(P0.05)。lncRNA CBR3-AS1靶向调控miR-145-5p;下调miR-145-5p逆转了抑制lncRNA CBR3-AS1表达对HGC-27细胞的作用。因此,抑制lncRNA CBR3-AS1表达可能通过上调miR-145-5p抑制HGC-27细胞的迁移侵袭、增殖,促进细胞凋亡。     

Mirtron类microRNA6894-5p过表达促进胃癌细胞的迁移、侵袭和增殖

该文主要探讨Mirtron类micro RNA6894-5p过表达对胃癌细胞迁移、侵袭和增殖的影响。将miRNA6894-5p的模拟物分别转染进入胃癌MGC803和SGC7901细胞中,构建miRNA6894-5p过表达的细胞系;实时荧光定量PCR测miRNA6894-5p的RNA表达;Transwell实验检测细胞迁移侵袭能力;Cell Counting Kit 8实验检测细胞的增殖能力;荧光素酶报告基因实验检测miRNA6894-5p与肝配蛋白A3的靶向关系;实时荧光定量PCR和蛋白质印迹法进一步检测miRNA6894-5p过表达后EFNA3的m RNA和蛋白的变化。结果显示,成功构建miRNA6894-5p过表达模型的胃癌细胞系;与相应阴性对照组相比,过表达miRNA6894-5p可提高细胞迁移侵袭能力(P0.05)和增强细胞增殖能力(P0.05);荧光素酶报告基因实验证实,miRNA6894-5p靶向作用于肝配蛋白A3,过表达miRNA6894-5p后肝配蛋白A3的m RNA及蛋白水平显著下降(P0.05)。该研究结果显示,Mirtron类miRNA6894-5p在人胃癌细胞中过表达可促进胃癌细胞的迁移、侵袭和增殖。     

大鼠胃炎癌转化模型建立与早期诊断方法探索

目的构建大鼠胃炎癌转化模型,探索新的胃癌早期血清学诊断指标。方法采用N-甲基-N'-硝基-N'-亚硝基胍饮水(MNNG)协同高盐饲料喂养的方法诱导大鼠胃炎癌转化模型。核磁共振成像及组织病理学观察大鼠胃部恶化过程。qRT-PCR检测不同时间点(造模第0,12,24,36,48周)大鼠血清miR-17-5p和miR-374-5p表达水平。结果 MNNG饮水协同高盐饲料喂养成功诱导大鼠胃炎癌转化,经历萎缩性胃炎(造模第24周)和不典型增生(造模第48周)的过程。血清中miR-17-5p和miR-374-5p的表达水平与大鼠胃部恶化程度正相关。与正常对照组相比,第36、48周时,miR-17-5p表达水平分别增加约8倍(t=4.12,P0.001)和10倍(t=5.33,P0.001);第48周时,miR-374-5p表达水平增加约6倍(t=3.62,0.001P0.002)。结论MNNG饮水协同高盐饲料喂养构建的大鼠胃炎癌转化模型为研究胃癌发病机理提供了良好的动物模型,血清miR-17-5p和miR-374-5p是潜在的胃癌早期无创诊断指标。     

miR-615-3p是胃癌诊断和预后的潜在标志物

miR-615-3p是miRNA家族的一员。为了探讨miR-615-3p在胃癌诊断和预后中的作用,我们应用实时荧光定量PCR(RT-qPCR)法检测了35例胃癌组织(13例低分化,22例中高分化)及良性胃病组织,以及此35例患者的治疗前血清及35例健康体检者血清中miR-615-3p的相对表达情况,分析了其和胃癌的临床病理因素之间的关系,计算其用于区分胃癌和健康人群的灵敏度、特异度。检测数据显示,低分化胃癌组中miR-615-3p的水平显著高于良性病变组及中高分化胃癌组(p0.01),而在中高分化胃癌组的表达水平与良性病变组比较差异无统计学意义(p0.05)。低分化和中高分化胃癌患者血清中miR-615-3p的水平均显著高于健康组(p0.01),低分化胃癌患者血清中miR-615-3p的水平显著高于中高分化胃癌血清组(p0.01)。miR-615-3p的表达水平与胃癌患者的性别、年龄无关(p0.05),与病理类型、TNM分期相关(p0.05)。miR-615-3p受试者的工作特征曲线下面积为0.803(95%CI(0.707,0.906)),与A=0.5比较,差异有统计学意义。以上结论表明,miR-615-3p的表达水平与胃癌组织的分化和分期呈正相关,检测组织和血清中miR-615-3p的水平对胃癌有较高的诊断价值。miR-615-3p可作为胃癌诊断、预后的潜在标志物。     

EB病毒潜伏性膜蛋白CTAR—2突变体的构建及功能分析

为了探讨EB病毒潜伏性膜蛋白 1(LMP1)的活性部位及细胞转化作用机制 ,采用PCR方法构建LMP1羧基末端活化区 2 (CTAR 2 )中 3 84～ 3 86位密码子对应的氨基酸YYD→ID突变的重组体 ,将此重组突变型LMP1(mt LMP1)与野生型LMP1(wt LMP1)分别与含有转录因子NF κB或AP 1启动子序列的荧光素酶表达质粒共转染 2 93细胞 ,单光子检测仪测定比较二者活化转录因子的功能 ;同时将mt LMP1和wt LMP1分别导入Rat 1细胞 ,接触抑制试验比较二者对细胞的转化作用。发现 :( 1)与wt LMP1相比 ,mt LMP1对转录因子NF κB的活化作用降低了 80 %左右 ,对AP 1的活化作用全部消失 ;( 2 )mt LMP1表达的Rat 1细胞集落形成数比wt LMP1表达的细胞显著降低[( 2 3± 3 ) /皿对 ( 3 5 7± 19) /皿 ;( 64± 8) /皿对 ( 40 8± 40 ) /皿 ;n =3 ,P <0 .0 0 1]。这些结果表明CTAR 2中最后 3位氨基酸 ( 3 84～ 3 86)是EB病毒LMP1的重要活性部位之一 ;LMP1致Rat 1细胞转化作用主要与其活化转录因子NF κB或 /和AP 1的功能有关     

外周血miR-17-92基因簇对于早期胃癌的诊断及预测价值

目的:探讨外周血mi R-17-92簇对早期胃癌的诊断价值,为胃癌的早期诊断及治疗提供参考依据。方法:收集胃癌125例(Ⅰ期35例,Ⅱ期28例,Ⅲ期39例,Ⅳ期23例)和癌前病变24例(包括肠化生及上皮内瘤变),同时选择65例慢性胃炎作为对照组。采用实时荧光定量PCR技术(Real-time quantitative PCR,RT-qPCR)检测患者血清中的mi R-17-92基因簇的表达水平。通过受试者工作曲线(Receiver Operating Curve, ROC)及曲线下的面积(Area Under the Curve,AUC)评估mi R-17-92基因簇表达水平诊断早期胃癌的敏感性和特异性。结果:(1)慢性胃炎与癌前病变mi R-17-92基因簇表达比较无显著差异(P0.05);(2)早期胃癌及进展期胃癌mi R-17-5p表达明显高于慢性胃炎(P0.05),mi R-19a-3p、mi R-19b-3p、mi R-20a-5p和mi R-92a-3p表达则显著低于慢性胃炎及进展期胃癌(P0.05);(3)miR-17-5p诊断早期胃癌的曲线下面积较mi R-19a-3p、mi R-19b-3p、mi R-20a-5p、mi R-92a-3p及CEA更高;(4)miR-19a-3p、mi R-19b-3p、mi R-20a-5p、mi R-92a-3p高低表达组与在胃癌的浸润深度间有显著性差异(P0.05),mi R-19b-3p高低表达组在胃癌的临床分期间有显著性差异(P0.05);(5)miR-17-5p、mi R-19a-3p、mi R-19b-p、mi R-20a-5p、mi R-92a-3p诊断早期胃癌的阳性率较CEA、CA199高。结论:外周血mi R-17-92基因簇对于早期胃癌的诊断价值明显优于CEA和CA199,这可能为胃癌的早诊早治提供新的策略。     

miR-1271-5p靶向PDK1促进胃癌细胞凋亡

目的 探讨miR-1271-5p在胃癌的作用和可能的作用机制。方法 RT-qPCR和原位杂交法检测胃癌组织和胃癌细胞株中miR-1271-5p的表达。Lipofectamine 2000转染miR-1271-5p mimics后,噻唑蓝（MTT）法和台盼蓝染色法检测SGC-790细胞的活性,Annexin V/PI染色检测细胞凋亡,JC-1探针检测线粒体膜电位,Western blot检测PDK1/Akt/凋亡信号相关蛋白的表达。荧光素酶法以及功能修复实验评估miR-1271-5p与PDK1的靶向关系。结果 胃癌组织和细胞中miR-1271-5p的表达降低。转染miR-1271-5p mimics后,SGC-790细胞的存活率下降,凋亡率上升,线粒体膜电位以及Bcl-2和p-AKT表达降低,Bax和Cleaved caspase-3表达增高。PDK1为miR-1271-5p的靶基因,过表达PDK1能逆转miR-1271-5p对胃癌细胞的促凋亡作用。结论 过表达miR-1271-5p可促进胃癌细胞凋亡,其机制可能与其靶向PDK1进而抑制AKT信号活性有关。     

癌基因Ha-ras在转化和未转化细胞中表达和调控的差异

以前的工作曾用人胃癌基因Ha-ras转化了大鼠全胚细胞系Ratl细胞,得到转化细胞Rat3-3。克隆了Ha-ras癌基因6.6kb及其上游区2.5kb DNA片段,并发现2.5kb有Alu重复顺序,说明这个片段是来源于人胃癌细胞,虽族观察到p21蛋白编码12位点突变,我们又发现转化的Rat3-3细胞的Ha-ras mRNA水平比未转化的Rat1高大约五倍;通过DNase I超敏感实验证明只有转化细胞核中的Ha-ras基因对DNaseI敏感,1μg/mL的DNaseI就有明显的降解,而未转化细胞Rat1细胞核的Ha-ras基因在15μg/mL的DNaseI中也未发现有任何降解;另外还发现转化细胞核有一种能为Ha-ras基因上游区2.5kb特异结合的核蛋白,分子量大约35kD,此核蛋白不能与6.6kb Ha-ras基因本身结合,在未转化细胞中未发现此蛋白。从这些结果推测,癌基因Ha-ras的活化,除了点突变外,还可能存在另一条活化途径,即它的上游区可能有类似增强子的调控区。     

P 7IkZP i、EF Z- 1在胃癌中的表达及其相关性研究

目的：研究p27^kip1蛋白、转录因子E2F-1在胃癌中的表达及其与胃癌病理参数乏问的关系,并探讨二者相关性。方法：应用免疫组化S-P法,对90例胃癌患者的癌组织、34例癌旁正常胃黏膜进行检测,分析p27^kip1、E2F-1蛋白表达及其与胃癌病理参数之间的关系。结果：p27^kip1在正常胃组织、胃癌组织中的阳性率分别为55．9％（19／34）、31．1％（28／90）,二者差异有统计学意义（p〈0．05）。其阳性表达率与胃癌组织的浸润深度（p〈0．05）、组织学分型（p〈0．01）、分化程度（p〈0．01）、淋巴结转移（p〈0．05）均相关;E2F-1在正常胃组织、胃癌组织中的阳性率分别为17．6％（6／34）、36．7％（33／90）,二者差异有统计学意义（p〈0．05）,其阳性表达率与胃癌的组织学分型相关。而与胃癌的浸润深度（p〉0．05）、分化程度（p〉0．05）、淋巴结转移无关（p〉0．05）。结论：p27^kip1在胃癌组织中的表达明显低于在正常组织,相反,E2F-1蛋白在胃癌组织中的表达却明显增强;p27^kip1蛋白表达与胃癌的浸润深度、组织学分型、分化程度、淋巴结转移等病理参数相关;E2F-1表达与胃癌的组织学分型相关;p27^kip1、E2F-1在胃癌中的表迭呈负相关。     

Oncogene-induced transformation of a rat embryo fibroblast cell line is enhanced by tumor promoters.

Rat embryo fibroblast cell line 6 was transfected with plasmid pT24, which contains the activated human bladder c-Ha-ras oncogene, and the cells were grown continuously in the absence or presence of the tumor promoters 12-O-tetradecanoyl phorbol-13-acetate (TPA) or teleocidin. The presence of TPA or teleocidin led to a 6- to 14-fold increase in the number of morphologically transformed foci. No transformed foci were seen when rat 6 cells were transfected with the normal c-Ha-ras oncogene in the absence or presence of TPA, or in cells simply treated with TPA or teleocidin. Enhancement of pT24-induced foci was seen even when the addition of TPA was delayed until day 16. In transfection studies with the drug resistance genes gpt and neo, TPA and teleocidin did not increase the number of Gpt+ or Neo+ colonies. When rat 6 cells were cotransfected with pT24 and neo genes and grown in the absence or presence of TPA, the presence of TPA did not increase the yield of Neo+ colonies but caused a fivefold increase in the number of Neo+ colonies that displayed a transformed morphology. Southern blot analyses of DNAs obtained from these clones indicated that TPA treatment did not influence the extent of integration of either the pT24 or neo gene. DNA samples from all of the morphologically transformed cells displayed a characteristic 2-kilobase SacI fragment homologous to pT24 DNA and expressed relatively high levels of the corresponding mRNA. Our findings indicate that in this system tumor promoters do not simply enhanced the process of DNA transfection per se. Thus, this model system may be useful for analyzing synergistic interactions between tumor promoters and activated oncogenes during multistage carcinogenesis. It may also serve as a simple screening test for detecting new tumor promoters.     

Modifications of sialylation in BHK 21/C13 cells after in vitro transfection by c-Ha-ras human oncogene

A Hamster kidney fibroblast cell line (BHK 21/C13) has been transfected by c-Ha-ras human oncogene. The expression of the oncogene significantly modified the global sialytransferase activity of the cell extract. This activity is enhanced on an average 2.5 fold whatever the acceptor. In addition, the proportion of cell-surface associated N-glycolylneuraminic acid is enhanced in transfectants, the ratio N-acetylneuraminic acid/N-glycolylneuraminic acid decreases from 7.10 to 2.80. These results suggest that a tight relationship exists, in c-Ha-ras transfected BHK cells, between the expression of the oncogene and the neuraminic acid metabolism as well as a gene regulation of glycoconjugate sialylation.     

p53-plus-ras-transformed rat embryo fibroblasts express tumor-specific transplantation antigen activity which is shared by independently transformed cells.

p53-plus-ras-transformed rat cell lines express a tumor-specific transplantation antigen that is common to a number (85%) of independently derived p53-plus-ras-transformed cell lines. This has been shown by immunizing rats with irradiated p53-plus-ras-transformed cells and demonstrating protection of these animals by subsequent live-cell tumor challenge. Several c-myc-plus-ras-transformed cell lines (54% of the lines tested) and one adenovirus E1a-plus-ras-transformed cell line (9% of those tested) were shown to share a common tumor-specific transplantation antigen by their ability to immunize a rat against a p53-plus-ras cell line challenge. Several experimental approaches have been used to fractionate and identify the antigen common to these cell lines. The experimental results reported here make it clear that the p53 protein common to most of these transformed cell lines is not likely to be the tumor-specific transplantation antigen.     

Neoplastic transformation and characterization of human fibroblasts by treatment with60Co gamma rays and the human c-Ha-ras oncogene

Summary Human fibroblasts (KMST-6) immortalized by treatment with⁶⁰Co gamma rays were further neoplastically transformed by transfection of the c-Ha-ras oncogene from human lung cancer. The ras-transfected cells formed undifferentiated fibrosarcoma in nude mice. One of the tumors was recultured and a neoplastic human fibroblast line, KMST-6/RAS, was established. To analyze multistep carcinogenesis of human cells, the cellular characteristics of these genetically matched immortalized (KMST-6) and neoplastic (KMST-6/RAS) cell lines were studied in detail. KMST-6/RAS cells showed an increased saturation density, colony formation on confluent monolayers of normal human fibroblasts, proliferation in neomycin-containing medium, anchorage-independent growth, and enhanced expression of the transfected c-Ha-ras oncogene, whereas the immortalized cells did not demonstate these characteristics. Unexpectedly, growth of KMST-6/RAS cells was serum-dependent, although they were neoplastic. Interestingly, the neoplastic cells did not show the criss-crossing or piling up growth pattern characteristic of transformed rodent fibroblasts.     

Dose effects of transfected c-Ha-rasVal 12 oncogene in transformed cell clones

We have examined the expression of the transformed phenotype in a series of clonal lines of NIH/3T3 cells transfected with the human c-Ha-rasVal 12 oncogene and the neomycin phosphotransferase gene. Cells from individual transformed foci were cloned and subjected to detailed analyses of the ras sequences. Three clones were found that expressed approximately one, 2-4, or 4-8 copies of the human c-ras oncogene, respectively. A fourth clone had multiple copies of the transfected sequences, and expressed abundant c-Ha-ras RNA. Analysis of the transformed phenotype of various clones indicated that cells expressing low levels of mutant c-Ha-ras had lost some of their extracellular fibronectin network, and were barely altered in their cytoskeleton. In contrast, cells expressing abundant c-Ha-ras had lost both their actin and fibronectin networks and showed an increase in plasminogen activator activity. Cells with amplified c-Ha-rasVal 12 grew better in low serum, formed large colonies in soft agar and showed enhanced activity of ornithine decarboxylase, the rate-controlling enzyme in polyamine biosynthesis. These results show that the dosage level of the mutant oncogene makes a significant contribution to the transformed phenotype of c-Ha-ras oncogene-transformed cells.     

Primary functional identification of gene TMSG-1

TMSG-1 (Tumor metastasis suppressor gene-1) is a cancer metastasis-related gene cloned by means of mRNA differential display from human prostate cancer cell lines with different metas-tatic potential[1], which has higher expression in non-metastatic cell line, whereas lower expres-sion in highly metastatic cell line. In samples of primary gastric carcinoma, the TMSG-1 expres-sion markedly decreased in gastric carcinoma with lymph node metastases. It was found that protein encoded by TMS…