抗人肝癌单克隆抗体轻链可变区基因的体外扩增、克隆及序列测定

我们应用一对引物利用聚合酶链反应（ＰＣＲ）技术从小鼠抗人肝癌单克隆抗体杂交瘤细胞株ＨＡｂ２７ＲＮＡ中扩增出了抗体轻链可变区基因，将此基因重组λＭ１３噬菌体ＤＮＡ中，测定了此可变区基因的全序列，经计算机分析，结果表明基因长度为３２４ｂｐ编码１０８个氨基酸，是具有功能性的抗体轻链可变区基因，在核苷酸序列上与鼠胚系基因ＶｋＯＸ１具有８５％同源性，所得基因为Ｖｋ与Ｊｋ４重排。     

抗人脑胶质瘤基因重组单抗的研究

苏州医学院附二院神经外补脑肿瘤研究室黄强等（215004）从该室先前建立的鼠原性抗人脑胶质瘤单抗SZs。杂交瘤细胞中抽提总RNA，RTPCR扩增VH和VL基因，测序结果分别为348hP（116个氨基酸）和318bp（106个氨基酸），证实为SZ39。重、轻键可变区基因后，采用重组技术，分别将VH和VL基因片断与人免疫球蛋白IgG1重链CH1和轻链K恒定区基因拼接，构建表达载体PHEN1SZ39Fab／Hu，又将SZ39VH和VL基因片断，以通用Linker进行连接，构建表达载体PHEN1SZ39SoFv，尔后分别在抑制性大肠杆菌HB2151中表达。两者的表达产物均为可溶性…     

抗人膀胱癌单克隆抗体重链可变区基因的克隆及其原核表达载体的构建

目的 克隆抗人膀胱癌单克隆抗体重链可变区基因(VH)，并构建其原核表达载体。方法从能分泌抗人膀胱癌单克隆抗体的杂交瘤细胞BDI-1中提取总RNA，通过RT-PCR扩增出VHcDNA。用HindⅢ和XhoⅠ酶切纯化的RT-PCR产物和原核表达载体pET28a( )，在T4DNA连接酶作用下室温连接。重组质粒经酶切鉴定，阳性克隆测序并进行序列分析。结果扩增出VHcDNA片段，大小约为370bp，重组质粒的酶切鉴定结果与预期一致。VH基因序列长度为366bp，编码122个氨基酸。VH基因属于鼠免疫球蛋白重链11亚类。结论成功克隆出抗人膀胱癌单克隆抗体重链可变区基因，并成功构建其原核表达载体。     

抗CEA人鼠嵌合F(ah’)_2在昆虫细胞中的表达

癌胚抗原(CEA)是一种非特异性肿瘤标记(TW).在结肠癌,胃癌,肺癌,乳腺癌,宫颈癌等许多恶性肿瘤中均有较高表达.利用抗CEA单克隆抗体进行放免显像研究近年来发展较快,但都存在着放射性本底较高的问题,影响了显像结果.F(ab’)_2.由于分子量小,没有Fc段,从血液中清除较快,可减少非特异结合,而因显像效果较好,但仍然受HAMA反应的影响.为此,本研究利用昆虫杆状病毒表达系统在SF9细胞中表达了抗CEA人鼠嵌合F(ah’)_2,以利于临床肿瘤的放免显像.提取一株表达完整抗CEA嵌合抗体的CHO细胞的总RNA,分别用与人轻链k恒区基因及α1重链CH2基因互补的3’引物进行反转录,再以CDNA为模板,5’引物相同,都与鼠重链前导肽互补,3’引物与反转录相同分别进行PCR扩增,得到含有鼠重链前导肽,轻链可变区,完整的k恒区的680bp的轻链基因和含有鼠重链前导肽,重链可变区,     

非B淋巴细胞来源的恶性肿瘤细胞中存在Ig重链片段的表达

免疫球蛋白Ig是由两条重链及两条轻链组成的糖蛋白,分别由定位于不同染色体上的3个不连锁的Igc,Igλ,IgH基因所编码.目前的免疫学理论认为,在正常的机体内,Ig基因只有在B细胞来源的细胞中进行选择性重排及表达,是B淋巴细胞的特有产物.然而,我们曾用免疫学方法检测表明癌细胞可能表达免疫球蛋白.近期设计了23条PCR引物,分别位于Ig重链前导,肽区,FRIJ链区,恒定区,并用RTPCB的方法对4个来源于人的恶性肿瘤细胞系HT-29(大肠癌),MCF-7(乳腺癌),HeLaMR(宫颈癌),PC3M(前列腺癌)及来源于健康人外周血的单个核细胞的阳性对照进行了检测.     

基因工程抗体的研究

本文综述了本实验室近年来在基因工程抗体方面所做的工作：①从杂交瘤细胞基因组中筛选和鉴定出抗乙型脑炎病毒单克隆抗体的重链、轻链可变区基因，构建成人-鼠嵌舍基因并在骨髓瘤细胞中表达出抗乙型脑炎病毒的人-鼠嵌合抗体；②根据文献中抗CD3单抗的序列，进行了分子设计，设计出改形抗体的分子序列．用合成和PCR补齐的方法构建了改形的单域抗体（Vn)表达载体，并在大肠杆菌中表达；④构建了外分泌型-附着型的表达单链抗体的表达载体；④克隆和测序了抗人肺腺癌．膀胱癌、CD3的单抗重,轻链可变区基因，并正在构建鼠的抗体库。     

P185erbB2单抗可变区基因克隆及人鼠嵌合抗体真核高效表达载体构建

P185是erbB_2(HER2/neu)基因编码的具酪氨酸激酶活性的跨膜糖蛋白,在多种上皮细胞来源的恶性肿瘤中过表达,且与肿瘤的耐药、转移、复发有关.应用P185单抗进行肿瘤的诊断和判断预后已得到广泛应用,美国FDA已批准一株人化抗体应用于临床治疗erbB_2高表达的乳腺癌,但国内尚无人化抗体应用于临床治疗.为获得具有临床治疗价值的人化抗体,消除HAMA反应,本文从自制的10株抗P185胞外区的单抗中选出抑制erbB_2高表达的肿瘤细胞增殖活性最高的一株(C25)进行人化改造.C25单抗在体外对SKBR3细胞增殖的仰制率可达60.63%,属于小鼠IgG1亚类、к轻链.根据C25的IgG亚类选用Winter等设计的引物,以BT-PCR方法从杂交瘤细胞株中扩增轻、重链可变区基因.分别克隆     

反式二羟环氧苯并（a）芘相关新基因brg的全长克隆

背景与目的:在前期研究中发现,16HBE-C细胞表达变化的基因中有未知基因参与,因其与BPDE有关,所以命名为brg(anti-BPDErelatedgene)基因。本研究应用cDNA末端快速扩增法(rapidamplificationofcDNAends,RACE)扩增此未知基因的全长,以进行下一步的基因功能研究。材料与方法:应用cDNA末端快速扩增法(RACE技术),对3'和5'端分别设计了梯度PCR,巢式PCR等优化程序,以获得特异的产物,然后对特异产物直接测序,将测序结果进行生物信息学分析,基因拼接等获得新基因brg全长。结果:3'和5'端均成功获得特异性产物,3'RACE测序为394bp,有明显的PolyA加尾信号,有编码区的终止密码子;5'RACE测序为1017bp,有起始密码子ATG,其中197bp为3'和5'全长共有序列。将3'和5'序列拼接,结果全长1214bp,生物信息学分析brg基因阅读框1032bp,编码344个氨基酸。结论:所得结果与设计一致,说明所采用的技术路线是简便可行的,brg基因可能在反式二羟环氧苯并(a)芘的致癌机制中起重要作用。     

反式二羟环氧苯(a)芘相关新基因brg的全长克隆

背景与目的:在前期研究中发现,16HBE-C细胞表达变化的基因中有未知基因参与,因其与BPDE有关,所以命名为brg(anti-BPDE related gene)基因.本研究应用cDNA末端快速扩增法(rapid amplification of cDNA ends,RACE)扩增此未知基因的全长,以进行下一步的基因功能研究.材料与方法:应用cDNA末端快速扩增法(RACE技术),对3'和5'端分别设计了梯度PCR,巢式PCR等优化程序,以获得特异的产物,然后对特异产物直接测序,将测序结果进行生物信息学分析,基因拼接等获得新基因brg全长.结果:3'和5'端均成功获得特异性产物,3'RACE测序为394 bp,有明显的PolyA加尾信号,有编码区的终止密码子;5'RACE测序为1 017bp,有起始密码子ATG,其中197 bp为3'和5'全长共有序列.将3'和5'序列拼接,结果全长1 214 bp,生物信息学分析brg基因阅读框1 032 bp,编码344个氨基酸.结论:所得结果与设计一致,说明所采用的技术路线是简便可行的,brg基因可能在反式二羟环氧苯并(a)芘的致癌机制中起重要作用.     

抗人大肠癌单链抗体基因的克隆与表达

背景与目的：单链抗体相对于完整抗体具有免疫源性低、对肿瘤组织穿透力强的特点,日益成为肿瘤诊断和治疗的良好导向载体。本研究的目的是将抗人大肠癌单克隆抗体ND－1的重链可变区VH和轻链可变区VL基因借助一短肽序列（Gly4Ser)3进行重组,构建单链抗体基因ND－1scFv,并使其在大肠杆菌中表达。方法：采用RT－PCR技术从能够分泌ND－1单抗的鼠杂交瘤细胞中扩增VH和VL基因,通过重叠延伸拼接PCR在VH和VL基因间引入连接短肽,体外构建ND－lscFv基因,经过常规转化和筛选,将其克隆至PET－28a( )表达载体,由IPTG诱导在大肠杆菌BL21中表达为ND－lscFv与His-Tag的融合蛋白。表达产物用Ni-NTA resin亲和层析方法纯化,并采用ELISA方法检测其免疫活性。结果：序列分析表明,ND－lscFv基因全长732bp,VH354bp位于上游;VL330bp位于下游。SDS－PAGE显示,重组蛋白相对分子量30kDa,与预期结果一致。scFv表达产物以不溶性包涵体形式存在,经亲和层析纯化后蛋白纯度达94％。ELISA结果显示scFv保留了与亲本抗体ND－1相似的免疫活性。结论：成功地构建了抗人大肠癌单链抗体ND－lscFv,并在大肠杆菌中获得了较高水平的功能性表达。     

小细胞肺癌抗独特型单链抗体的表达及活性研究

目的:在大肠杆菌中高效表达小细胞肺癌(SCLC)抗独特型抗体3F6单链抗体(ScFv),并获得具有生物学活性的ScFv。方法:从SCLC抗独特型抗体3F6小鼠杂交瘤细胞中提取总RNA,反转录为cDNA。利用小鼠抗体骨架区共用引物,PCR扩增单抗重链可变区(VH)和轻链可变区(VL)。通过人工设计的柔性连接肽(Gly4Ser)3连接构建3F6ScFv。再将其重组到原核表达载体pQE31中,构建3F6ScFv表达载体。转化大肠杆菌M15,IPTG诱导表达,用NiNTA树脂对表达产物进行变性纯化。通过凝胶(SephacrylS200)柱上在位复性后,用竞争ELISA检测复性的3F6ScFv活性。结果:获得了SCLC抗独特型抗体3F6的VH和VL基因,构建了3F6ScFv表达质粒。在大肠杆菌中高效表达3F6ScFv,表达蛋白的相对分子质量为32×103,以包涵体形式存在。纯化后获得较纯的3F6ScFv蛋白,经复性后可竞争2F7抗体与SCLCNIHH128细胞结合。结论:成功构建、表达、纯化和复性了SCLC抗独特型抗体3F6ScFv,获得有活性的3F6ScFv,为SCLC抗独特型抗体的进一步研究奠定了基础。     

Identification of a 428-kb homozygously deleted region disrupting the SEZ6L gene at 22q12.1 in a lung cancer cell line

Frequent allelic losses on chromosome 22q in small cell lung carcinomas (SCLCs) and advanced non-small cell lung carcinomas indicate the presence of tumor suppressor gene(s) on this chromosome arm. We detected a homozygous deletion at 22q12.1 in a SCLC cell line, Lu24. Cloning of the breakpoints of the Lu24 deletion revealed that the deletion was interstitial and 428, 131 bp in size. The deleted region contained the SEZ6L (Seizure 6-like) gene, whose structure had been partially determined by the chromosome 22 sequencing project. We determined the full length cDNA sequence for the SEZ6L gene based on the genomic sequence for the SEZ6L locus using the GENSCAN program and the RT - PCR method. The deduced SEZ6L protein was a transmembrane protein of 1024 amino acids with multiple domains involved in protein - protein interaction and signal transduction. SEZ6L expression was detected in a variety of human tissues, including lung, while its expression was detected in 14 (30%) of 46 lung cancer cell lines examined. Missense mutations were detected in three (7%) of the 46 cell lines, and a 1 bp deletion in the polypyrimidine tract preceding exon 4 was detected in one (2%) of 46 primary lung cancers. Therefore, it is possible that genetic and/or epigenetic SEZ6L alterations are involved in the development and/or progression in a subset of lung cancer, although functional analysis of the SEZ6L gene as well as molecular analysis of other genes in the homozygously deleted region is necessary to understand the pathogenetic significance of 22q deletions in human lung carcinogenesis.     

L552S, an alternatively spliced isoform of XAGE-1, is over-expressed in lung adenocarcinoma.

Using a combination of cDNA subtraction and microarray analysis, we report here the identification and characterization of L552S, an over-expressed, alternatively spliced isoform of XAGE-1 in lung adenocarcinoma. Real-time RT-PCR analysis shows that L552S is expressed at levels greater than 10-fold in 12 of 25 lung adenocarcinoma tumors compared with the highest expression level found in all normal tissues tested. L552S is expressed in both early and late stages of lung adenocarcinoma, but it was not detected in large cell carcinoma, small cell carcinoma, or atypical lung neuroendocrine carcinoid. The full-length cDNA for L552S comprises 770 bp and encodes a polypeptide of 160 amino acids. C-terminal 94 amino acids of L552S are identical to a cancer testis antigen, XAGE-1, found in Ewing's sarcoma. Genomic sequence analysis has revealed that L552S and XAGE-1 are alternatively spliced isoforms, and expression of both L552S and XAGE-1 isoforms are present in lung adenocarcinoma. Immunohistochemistry analysis using affinity purified L552S polyclonal antibodies demonstrated specific nuclear staining in 10 of 12 lung adenocarcinoma samples. Furthermore, antibody responses to recombinant L552S protein were observed in seven of 17 lung pleural effusion fluids of lung cancer patients. These results strongly imply that L552S protein is immunogenic and suggest that it might have use as a vaccine target for lung cancer.     

DNA sequences of the immunoglobulin heavy chain variable region gene in pyothorax-associated lymphoma

B cell lymphoma develops in the pleural cavity of patients affected by long-standing pyothorax resulting from lung tuberculosis, thus termed pyothorax-associated lymphoma (PAL). PAL usually shows a diffuse large cell morphology, and constantly contains Epstein-Barr virus (EBV) genome. To investigate whether PAL cells proliferate in response to specific antigenic stimuli and its stage in B cell differentiation, immunoglobulin heavy chain gene in 7 cases and 2 cell lines from PAL, all confirmed by histological studies to be EBV-positive diffuse large B cell lymphoma, were examined by using polymerase chain reaction (PCR) method. Clonal rearrangement of the gene was detected in 4 cases of PAL tissues and one cell line. As for the usage of the V region gene (V(H)), the V(H)3 family gene was used in 3 of these 5 cases with different homologous germlines, suggesting that the origin of PAL cells from a repertoire of B lymphocytes responsive to specific antigenic epitope was unlikely. Compared to the homologous germline, the mutation frequency of PAL was 9% on average. Only one case might have more replacement mutations in the complementarity-determining regions than expected by chance, thus antigen-selected maturation might not take place in PAL. Intraclonal sequence heterogeneity in the V(H) gene was found in another case. From these findings, it is concluded that PAL is composed of B lymphocytes at the differentiation stage of the postgerminal center. Antigen-selected maturation might not take place in PAL, which is distinct from the majority of B cell lymphomas.     

DEVELOPMENT OF GENETICALLY ENGINEERED MOUSE/HUMAN CHIMERIC AND SINGLE CHAIN ANTIBODIES AGAINST HUMAN BRAIN GLIOMA:A PRELIMINARY REPORT

Thetargetingdiagnosisandtherapyofmalignanttumorbymeansoftumormonoclonalantibody(mAb)isoneofthehighlypopularresearchsubjectsinrecentyears.ThemurineoriginmAbSZ,,'againstmalignanthumanbraingliomageneratedinourlaboratoryin1988hasbeenconjugatedwithadriamycinandshowntopossessanincreasedtargetingactivitybothinvitroandinanimalmodels.Inaddition,ithasbeenlabeledwithisotopesandusedastargetingagentforthediagnosticpurposeinhumanbraingliomapatients.'However,themurineoriginmAbpossessedthedrawbackofpotentia…     

小细胞肺癌2F7单抗ScFv的高效表达及复性研究

目的 在大肠杆菌中高效表达小细胞肺癌单抗2F7的单链抗体（ScFv)，并获得具有生物学活性的ScFv。方法 利用PCR方法将2F7单抗重链可变区（VH）和轻链可变区（VL）通过一人工设计的柔性连接肽（Linker)连接，再将单链抗体基因重组到原核表达载体pQE31中，构建单链抗体高效表达载体pQE-2F7-ScFv。将pQE-2F7-ScFv质粒转化大肠杆菌M15后诱导表达，并对表达产物进行纯化和稀释复性。结果 获得了2F7单链抗体的高效表达，表达蛋白大小约27.4kD，以包涵体形式存在。包涵体蛋白在经过变性、纯化和稀释复性后，获得了有功能的单链抗体。结论 成功地构建和表达了小细胞肺癌单抗F27的单链抗体，并对其进行了纯化和复性，将进一步促进2F7单抗小分子抗体的应用。     

What is the current evidence for antigen involvement in the development of chronic lymphocytic leukemia?

For many years it has been evident that B-cell chronic lymphocytic leukemia (CLL) displays preferential usage of individual immunoglobulin (Ig) variable heavy chain (V(H)) genes. The V(H)1-69 gene was the first to be reported overrepresented in a large number of CLL patients, where the V(H)1-69(+) CLL rearrangements showed characteristic molecular features, such as unmutated V(H) genes, usage of specific diversity/joining gene segments, and a longer than average complementarity determining region (CDR) 3 with certain common amino acid motifs. Also, biased usage of the V(H)3-07 and V(H)4-34 genes with specific rearrangement characteristics was reported in CLL. These findings led to the speculation that antigens could be involved during CLL development by triggering proliferation of B-cells with specific B-cell receptors (BCRs) leading to an increased risk of transforming events. Recently, we characterized a subset of CLL utilizing the V(H)3-21 gene that also displayed peculiar Ig features, e.g. very short and homologous CDR3s, predominant lambda expression and preferential V(lambda)2-14 gene usage. This V(H)3-21(+) subgroup also had poor prognosis despite the fact that two-thirds of cases carried mutated V(H) genes. Moreover, we and others have thereafter described further CLL subsets with very similar heavy and light chain gene rearrangement features. These latter findings of subsets expressing restricted BCRs have emphasized the hypothesis that antigens could play a role during the pathogenesis of CLL. Interestingly, recombinant antibodies produced from these restricted subsets showed similar cytoplasmatic reactivity within each group, thus suggesting recognition of a limited number of autoantigens. Further characterization of antigens is now necessary in order to understand their nature and exact role in CLL development.