甲醛致大鼠鼻腔癌与K-ras癌基因活化相关

为探讨甲醛致大鼠鼻腔癌的分子机制,对甲醛诱发的大鼠鼻腔癌细胞系FAT7中的转化序列进行检测.采用的实验方法,包括肿瘤细胞DNA与选择标志基因(neo)共转染、裸鼠成瘤性分析、Southern杂交、聚合酶链反应(PCR)和序列分析等.结果发现:在第二轮裸鼠肿瘤DNA中含有大鼠源性的K-ras基因序列,而无大鼠源性的H-ras、N-ras和p53基因序列.这表明甲醛诱发的大鼠鼻腔癌细胞系FAT7中所含的转化序列与H-ras、N-ras及p53基因无关,K-ras癌基因的活化可能参与甲醛致大鼠鼻腔癌.     

裸小鼠异向C型病毒侵染的大鼠肝癌(BERH-2)移植瘤超微结构的研究

在Swiss品系裸小鼠皮下接种传代的大鼠肝癌BERH-2移植瘤,从47代起作超微结构观察,发现移植瘤已受到裸小鼠异向C型病毒的严重侵染。病毒的平均直径为120±6 nm。从50代起,移植瘤从Swiss品系转移植到BALB/C品系生长,C型病毒的形态和出现率并无明显改变。本实验提示,BERH-2移植瘤生物学特性发生改变可能与裸小鼠异向C型病毒的侵染有关;已被侵染的移植瘤株是探讨异向C型病毒活化机理和生物危害颇有价值的实验模型。     

AFP表达调控载体对肝癌模型的靶向治疗作用

目的观察甲胎蛋白(AFP)表达调控载体pAFP-P53-EGFP对AFP表达阳性肝癌模型靶向治疗作用。方法以人肝癌HepG2(AFP阳性)、人肝癌SMMC7721(AFP阴性)细胞于BALB/c-nu裸小鼠右腋皮下荷瘤,14d成瘤,免疫组化检测AFP。将构建好的pAFP-EGFP和pAFP-P53-EGFP重组质粒于肿瘤内注射,观察肿瘤体积变化,通过免疫组化观察p53在HepG2肿瘤中的特异性表达及对肿瘤细胞的杀伤作用。结果荷HepG2、SMMC7721细胞株裸鼠14d皮下肿瘤生长良好,且肿瘤体积均为500mm3左右,经HE染色证实造模成功。同时,AFP免疫组化结果显示接种HepG2细胞的肿瘤组织AFP表达阳性,SMMC7721细胞的肿瘤组织AFP表达为阴性。经pAFP-EGFP和pAFP-P53-EGFP重组质粒治疗后,p53的免疫组化分析结果显示接种HepG2细胞的裸鼠pAFP-P53-EGFP治疗组p53表达量显著高于其他各组,可见明显细胞凋亡现象,且肿瘤体积较对照组减小。结论含AFP基因调控序列的pAFP-P53-EGFP载体可专一性地作用于AFP阳性肝癌细胞,引起肝癌细胞周期阻滞和凋亡。     

ras蛋白转译后的加工

至今已在哺乳动物基因组中至少鉴定出三个ras基因,即H-ras、K-ras和N-ras,人类的这三种ras基因分别位于11、12和1号染色体的短臂上。它们都编码分子量为21,000的ras蛋白即P21~(ras)。ras基因最初发现于Ha-MuSV和Ki-MuSV所转化的细胞,以后发现正常人细胞及人癌瘤细胞中也存在H、K、N-ras基因。ras基因的表达与膀胱癌、肾癌、肺癌、结肠癌、胆囊癌、胰腺癌、慢性淋巴细胞白血病及黑色素瘤等的发生有着密切关系。P21~(ras)蛋白合成后要经过转译后的加工过程,然后位于质膜的内面发挥作用。对此,研究ras基因的表     

杂合启动子HREAF的构建及其肝癌特异性分析

本研究将在几乎所有肝癌细胞中均有高特异性的杂合启动子HREAF用于构建肝癌特异性溶瘤腺病毒。根据献报道的缺氧应答元件(HRE)和人甲胎蛋白(AFP)核心启动子(AF0.3)基因序列,设计并合成2对引物,采用PCR方法从肝癌细胞基因组DNA中扩增获得大小分别约为560bp的HRE DNA片段和310bp的AF0.3DNA片段,连接到pGEM—T Easy载体进行测序,证明获得了HRE和AF0.3的基因片段。将HRE和AF0．3的PCR产物分别进行PstI和SspI酶切并末端补平后直接连接,将此约700bp的连接产物克隆到pGEM—T Easy载体进行测序,证明杂合启动子HREAF构建成功。将HREAF亚克隆至腺病毒穿梭载体pShuttle并在其后克隆入受其调控的腺病毒早期基因E1,构建成肝癌特异性溶瘤腺病毒穿梭载体pShuttle—HREAF—E1,经PCR及酶切鉴定。将pShuttle—HREAF—E1转染肺癌细胞株及AFP产量不等的不同人肝癌细胞株,经Ela的RT—PCR检测证实杂合启动子HREAF可调控目的基因在AFP产量不等的不同人肝癌细胞系中特异性高表达。杂合启动子HREAF及腺病毒穿梭载体pShuttle—HREAF—E1的构建为进一步研制肝癌特异性重组溶瘤腺病毒及其体内外肝癌特异杀伤作用的研究打下了基础。     

裸小鼠肝癌原位移植模型的建立

目的建立一种BALB/c裸小鼠肝癌原位移植模型。方法采用异氟烷气化对实验动物进行全身麻醉,分别用"包埋法"和"夹心法"建立BALB/c裸小鼠肝癌原位移植瘤模型。手术后用小动物活体成像系统对肿瘤组织的生长情况进行检测,4周后对肝及肿瘤组织进行组织病理学检查。结果采用夹心法建立的肝癌原位移植BALB/c裸小鼠模型,具有操作时间短,难度低,成瘤率高的特点,肿瘤组织生长良好,在腹腔内未出现肿瘤广泛种植现象,组织病理学检查无异常,动物死亡率低等特点。结论与包埋法相比,夹心法更具优势,可快速制备大批量小鼠肝癌原位移植模型,为肝癌原位药效学及其他研究提供更便利的平台。     

人肝癌裸小鼠常位移植实验研究

采用硫贲妥钠（３０ｍｇ／ｋｇ、３０％乙醇配制）麻醉和蘸上立止血（２５０ｋＩＵ／ｍｌ）的明胶海棉止血措施确保了人肝癌裸小鼠常位移植术能安全、可靠地进行。本中心建立的两株人肝癌裸小鼠移植瘤株（ＨＨＣ４、ＨＨＣ１５）已成功地移植于裸小鼠（ＳＰＦ级）肝脏内,移植瘤生长良好、传代稳定和持续分泌ＡＦＰ。荷瘤（ＨＨＣ１５）３～６周裸小鼠血清ＡＦＰ含量与瘤体积的增加呈正相关。常位移植前（７ｄ）裸小鼠皮下注射０．１ｍｌ０．５％ＣＣ１（Ｖ／Ｖ。橄榄油配制）能明显提高ＨＨＣ４常位移植的成功率（Ｘ２检验、Ｐ＜０．０１）;在微量ＣＣｌ４作用下,裸小鼠肝细胞受损伤,发生肝硬化,在此基础上所移植和生长的人肝癌常位移植瘤与大多数人肝癌病变发生的肝脏病理生理学特点相似,本模型的建立更适用于抗肝癌药物的模拟治疗和筛选。     

生理性及病理性人体甲种胎儿蛋白分子异质性研究

为阐明人体组织处于生理及病理状态时合成及分泌的各种甲种胎儿蛋白(AFP)分子中糖基组成上的差异,本文采用刀豆球蛋白A(ConA)及扁豆凝集素(LCA)亲和双向放射免疫电泳(Aff-RIEP)分析人体羊水、孕妇、急性肝炎及原发性肝癌患者血清中各种不同来源的AFP。实验表明孕妇及肝炎血清中AFP在ConA及LCA电泳中呈现相似的电泳图谱,但与肝癌AFP有显著差异。在ConA电泳中,肝癌血清显示二种分子变异体,其中以ConA结合型为主,兼有小部分非结合型AFP,而肝炎及孕妇AFP仅为一种ConA结合型分子。然而,在LCA电泳中,肝炎及孕妇血清AFP却以LCA非结合型为主,兼有小部分结合型,但肝癌AFP却与之相反,以结合型为主,非结合型为次。上述结果提示癌性与非癌性AFP分子之间存在糖基组成及结构上的差异。     

细小病毒H—1对人肝癌移植瘤的抑制及其组织学与组织化学的研究

本文用人肝癌裸小鼠ＱＧＹ－９２０４移植模型为材料,进行了细小病毒Ｈ－１抑瘤的组织学、组织化学及分子生物学研究所。     

荧光素酶标的人肝癌细胞裸鼠异种移植瘤模型的生物发光成像和PET-CT成像比较

目的利用荧光素酶基因标记的人肝癌细胞株BEL-7402建立裸鼠肝原位移植模型,及小鼠肝原位移植模型的生物发光和小动物PET-CT成像的比较。方法构建表达荧光素酶基因的真核表达载体并将其转入人肝癌细胞BEL-7402,经梯度浓度G418筛选获得稳定表达荧光素酶基因的细胞克隆并扩大培养。BALB/cA-nu裸鼠肝门静脉接种5×105个发光细胞使其成瘤,活体荧光成像和小动物PET-CT成像系统观察肿瘤的生长情况。结果获得了稳定表达Luc的人肝癌细胞株,将其接种到裸鼠体内,活体荧光成像系统观察发现能够成瘤,小动物PET-CT影像观察发现小鼠肝脏边缘对18 F-FDG有高摄取区域。结论利用荧光素酶基因标记的人肝癌细胞BEL-7402成功建立了原位肝癌裸鼠模型,小动物活体成像结合小动物PET-CT技术为原位肿瘤模型的建立提供了一种新的可靠的技术,为进一步研究肝癌生长转移机制和药物开发提供了新的有用工具。     

Targeted genomic disruption of H-ras and N-ras, individually or in combination, reveals the dispensability of both loci for mouse growth and development

Mammalian cells harbor three highly homologous and widely expressed members of the ras family (H-ras, N-ras, and K-ras), but it remains unclear whether they play specific or overlapping cellular roles. To gain insight into such functional roles, here we generated and analyzed H-ras null mutant mice, which were then also bred with N-ras knockout animals to ascertain the viability and properties of potential double null mutations in both loci. Mating among heterozygous H-ras(+/-) mice produced H-ras(-/-) offspring with a normal Mendelian pattern of inheritance, indicating that the loss of H-ras did not interfere with embryonic and fetal viability in the uterus. Homozygous mutant H-ras(-/-) mice reached sexual maturity at the same age as their littermates, and both males and females were fertile. Characterization of lymphocyte subsets in the spleen and thymus showed no significant differences between wild-type and H-ras(-/-) mice. Analysis of neuronal markers in the brains of knockout and wild-type H-ras mice showed that disruption of this locus did not impair or alter neuronal development. Breeding between our H-ras mutant animals and previously available N-ras null mutants gave rise to viable double knockout (H-ras(-/-)/N-ras(-/-)) offspring expressing only K-ras genes which grew normally, were fertile, and did not show any obvious phenotype. Interestingly, however, lower-than-expected numbers of adult, double knockout animals were consistently obtained in Mendelian crosses between heterozygous N-ras/H-ras mice. Our results indicate that, as for N-ras, H-ras gene function is dispensable for normal mouse development, growth, fertility, and neuronal development. Additionally, of the three ras genes, K-ras appears to be not only essential but also sufficient for normal mouse development.     

人膀胱癌中某些癌基因的研究

本实验应用Northern和斑点印渍杂交技术探测了人膀胱癌细胞株中c-myc、c-fos、erbB等癌基因的表达,以及TPA对这些癌基因表达的调控,发现BIU-87细胞有这些癌基因的表达,并能被TPA所增强,同时也发现人膀胱癌组织有c-myc、c-fos、erbB、N-ras基因的高表达。提示蛋白激酶C的激活可以诱导某些癌基因的表达。多种癌基因的表达异常可能在膀胱癌中起重要作用。     

维生素E和微量元素Se对人肝癌细胞生长、分化及其癌基因表达的影响

本工作观察了体外环境中不同水平的维生素Ｅ和微量元素Ｓｅ对人肝癌细胞株（ＳＭＭＣ－７７２１）生长、分化和其癌基因（Ｎ－ｒａｓ、ｃ－ｍｙｃ）表达水平的影响。实验结果表明：高水平维生素Ｅ（２．４、９．２、２４．０ｎｍｏｌ／Ｌ）和Ｓｅ（０．１５、０．３０、０．６０ｎｍｏｌ／Ｌ）对肝癌细胞的集落形成率具有明显的抑制作用;生化分析显示高水平维生素Ｅ和微量元素Ｓｅ均可明显抑制环境中脂质过氧化的水平,Ｓｅ对癌细胞甲胎蛋白的分泌有明显的抑制作用,而维生素Ｅ作用不明显。细胞原位杂交发现维生素Ｅ浓度为２．４和９．２ｎｍｏ１／Ｌ时对细胞癌基因Ｎ－ｒａｓ的表达具有明显抑制作用;Ｓｅ浓度为０．１５和０．３０ｎｍｏｌ／Ｌ时对癌基因ｃ－ｍｙｃ的表达明显抑制。实验还观察了维生素Ｅ和Ｓｅ之间的叠加效应,结果显示除对环境中脂质过氧化的抑制作用具有叠加效果外,对其他指标没有明显作用。     

Structure and activation of the human N-ras gene

The normal human N-ras gene has been cloned. In structure and sequence it closely resembles the human H-ras and K-ras genes. The three genes share regions of nucleotide homology and nucleotide divergence within coding sequences and have a common intron/exon structure, indicating that they have evolved from a similarly spliced ancestral gene. The N-ras gene of SK-N-SH neuroblastoma cells has transforming activity, while the normal N-ras gene does not, the result of a single nucleotide change substituting lysine for glutamine in position 61 of the N-ras gene product. From previous studies we conclude that amino acid substitutions in two distinct regions can activate the transforming potential of ras gene products.     

The different activation of int genes in mammary carcinomas developed in three mouse strains harboring mouse mammary tumor viruses derived from DD/Tbr.

RNA expressions of common integration site (int) genes and several oncogenes were investigated in mammary carcinomas spontaneously developed in different three strains of mice; DD/Tbr, NIH Swiss and BALB/c which harbor DD-MMTV derived from DD/Tbr mouse. Latter two strains of mice were designated NIH/Mtv+ and BALB/Mtv+, respectively. An increased expression of int-1 (wnt-1) and int-2 genes was observed in 56% (9/16) and 50% (8/16) of mammary carcinomas of DD/Tbr mice, respectively. Either int-1 or int-2 RNAs were expressed in 81% (13/16) of the carcinomas of DD/Tbr mice. IN NIH/Mtv+ mice, activation of int-1 and int-2 was observed in 41% (7/17) and 24% (4/17) of mammary carcinomas, respectively. Either int-1 or int-2 RNAs were expressed in 47% (8/17) of the carcinomas examined in this strain. In BALB/Mtv+ mice, on the other hand, either int-1 or int-2 gene were transcribed into RNAs at low frequency (33%: 3/9). These results suggest that the frequency of activation of int genes in mammary carcinomas induced by the same DD-MMTV in three strains of mice is genetically defined characteristics of these strains, and that the involvement of int-1 and int-2 genes in virus-induced mammary carcinogenesis may be influenced by genetic properties of animals. The activation of int-1 and int-2 genes did not clearly correlate with an increase in the expression of oncogenes examined; H-ras, K-ras, N-ras, myc, raf, fgr, fms, erB, mos, and src genes.     

外源性神经节苷脂GM_3影响人肝癌细胞生长的可能机制的初步研究

通过苔酚蓝染色细胞发现,外源性GM3（10μg/ml）能明显抑制人肝癌细胞株SMMC-7721细胞生长,在GM3处理3d时,出现明显差异．通过NorthernBlot分析发现,外源性GM3可明显影响人肝癌细胞株SMMC-7721细胞中c-fos、c-jun、c-myc和N-ras这四种癌基因的mRAN表达．未经GM3处理的细胞中没有检测到c-fosmRNA,但c-jun微量表达,并有c-myc和N-rasmRNA的高水平表达而GM3可在短时间内快速大量地诱导c-fos、c-junmRNA的生成．GM3处理的细胞,c-myc和N-rasmRNA的表达均明显减少．GM3处理45min时,c-myc基因表达只为对照组的39．55％;GM3处理24h时,N-ras基因表达为对照组的30.48％．以上结果提示：GM3抑制SMMC-7721细胞生长很可能是通过改变癌基因表达来实现的．     

Highly frequent detection of transforming genes in acute leukemias by transfection using in vivo selection assays

DNAs from nine out of ten acute leukemia cases that were negative by in vitro focus forming assays exhibited transforming activity tested by in vivo selection assays in nude mice using transfected NIH3T3 cells. Of the nine cases, six cases contained activated N-ras genes, and one case exhibited activation of the c-K-ras gene. None of the ras gene family showed homology with the transforming genes derived from the other two cases. Our observations indicate that in vivo selection assays detect transforming genes including ras oncogenes at high frequency, and that activated N-ras genes are frequently detected in human acute leukemias.