髓母细胞瘤8号染色体短臂的杂合性丢失

目的研究髓母细胞瘤8号染色体的遗传学异常,寻找与该肿瘤发病机制有关的杂合性丢失位点。方法通过微卫星分析（microsatellite analysis）方法,应用19个位于8号染色体短臂（8p）上的多态性标记物,检测髓母细胞瘤的杂合性丢失（loss of heterozygosity,LOH）。结果在所检测的23例髓母细胞瘤中,21例为原发肿瘤,2例为复发肿瘤。染色体8p总的LOH比率为51%（124个LOH/243个可分析位点）。我们在8p22-23.2之间发现了一个高比率的共同丢失区,其长度为18.14 cM。结论染色体8p22-23.1上很可能存在重要的抑癌基因,该基因的丢失可能与髓母细胞瘤发病有关。     

人胶质母细胞瘤等位基因谱分析的研究

目的 探讨胶质母细胞瘤（glioblastoma,GBM)发病的分子遗传学机理，确定GBM的发生发展主要和哪些染色体或染色体区域有关，哪些染色体区域上可能存在与GBM相关的肿瘤抑制基因（tumor suppressor gene,TSG)。方法 应用聚合酶链反应技术，采用荧光标记的引物和377型DNA序列自动分析仪，对21例GBM的所有22对常染色体上共计382个微卫星位点进行了杂合性丢失（loss of heterozygosity,LOH)分析，相邻2个微卫星位点之间的平均遗传学距离为10cM。结果 在所有被检测的染色体臂上都观察到LOH，其中以染色体10q、10p、9p、17p和13q的LOH率最高（＞50％），这些染色体臂上已知的肿瘤抑制基因PTEN、DMBT1、p16、p53和Rb所在区域LOH率都较高；14q、3q、22q、11p、9q、19q上也存在较高的LOH率（＞40．5％）；首次发现多个共同微小丢失区域：9p22-23、10p12.2-14、10q21.3、13q12.1-14.1、13q14.3-31、17p11.2-12、17p13、3q24-27、11p12-13、14q31-32.3、14q21-24.1、22q13.2-13.3、4q35、4q31.1-31.2、6qtel、6q16.3。结论 GBM存在复杂的遗传学异常，涉及多条染色体臂。以10q、10p、9p、17p和13q的异常与GBM发生发展的关系最为密切。除了已知的肿瘤抑制基因PTEN、DMBT1、p16、p15、p53和Rb外，首次所发现的多个微小共同丢失区域上可能存在GBM相关的多个未知TSG。     

胶质母细胞瘤14号染色体杂合性丢失的初步研究

目的 寻找胶质母细胞瘤（glioblastoma,GBM)14号染色体上可能存在肿瘤抑制基因的杂合性丢失（loss of heterozygosity,LOH)aqfa,为发现和定位肿瘤抑制基因提供线索和依据。方法 应用聚合酶链反应方法,采用荧光标记引物和377型DNA序列自动分析仪,分析了20例GBM患者14号染色体上14个微卫星多态性标记的LOH。结果 在50％（10／20）GBM患者的14号染色体上观察到LOH,在38．2％（81／212）可提供信息位点存在LOH。14p和14q的LOH率分别为32％（6／19）、50％（10／20）。在位于14q31-32．3的D14S65位点、14q21-24.1的D14S63－D14S74位点间区域检测到了较高LOH率,分别为57．1％、46．7％－47．1％。在所测位点均未检测到微卫星不稳定（microsatellite instability,MI)。结论 染色体14q上等位基因的丢失可能在GBM分子水平发病机理中起着重要作用,14q31-32.3的D14S65位点、14q21-24.1的D14S63－D14S74位点间区域可能存在与GBM相关的肿瘤抑制基因。     

髓母细胞瘤比较基因组杂交分析及ERBB-2异常表达的意义

目的研究髓母细胞瘤全基因组的遗传学异常,探讨癌基因的异常表达在髓母细胞瘤发病机制中的作用以及与预后的关系。方法应用比较基因组杂交（comparative genomic hybridization,CGH）技术检测14例髓母细胞瘤全基因组的遗传学改变;同时,在扩大系列的29例髓母细胞瘤中,应用荧光原位杂交（fluorescence in situ hybridization,FISH）和免疫组化染色分别检测ERBB-2在基因水平和蛋白水平的表达。结果（1）CGH结果显示,在所有14例髓母细胞瘤标本中,每一条染色体臂上都检测到了染色体的失衡（获得或丢失）,最常见的染色体异常为17q（85．7％）和7q（35．7％）的获得,以及8p（50％）、16q（28．6％）和17p（35．7％）的丢失;（2）FISH检测中,44．5％（13／29例）的肿瘤细胞有ERBB-2基因的异常表达;（3）免疫组化结果显示,37．9％（11／29例）的病例有抗体c-erbB-2的阳性表达;（4）在预后较差的16例患者中,56％（9／16例）的病例有ERBB-2的过度表达。结论CGH研究发现了髓母细胞瘤全基因组的染色体失衡。在染色体17q特异性位点上ERBB-2基因的异常改变很可能在髓母细胞瘤的发病机制中起着重要的作用,其过度表达与患者的预后密切相关。     

肾集合管癌染色体1q上的最小缺失区域

最近研究已证实了肾脏恶性肿瘤的遗传异质性，对其分子水平的研究显示57％的肾集合管癌的染色体1q具有杂合性丢失（LOH）。提示1q上的基因对肾集合管癌的发生和发展起重要作用。为了证实这种假设，作者应用PCR微卫星DNA分析技术对13例肾集合管癌的染色体1q进行高密度图谱分析。结果在5例肿瘤标本中发现LOH贯穿整个染色体lq。9／13例肿瘤至少在一个标记上观察到LOH。肿瘤10中标记DIS237、DIJS389和DIS251上观察到LOH，并描绘出了这个最小缺失区域的着丝粒侧和端粒侧界限。该区域的着丝粒侧界限在两个保留杂合性的标记DIS225和D…     

复发前后多形性胶质母细胞瘤的等位基因谱分析

目的：研究多形性胶质母细胞瘤（glioblastoma multiforme,GBM)复发前后的分子遗传学变化，了解基因组范围内哪些染色体区域可能与GBM复发有关。方法：应用聚合酶链反应技术为基础的杂合性丢失（loss of heterozygosity,LOH)分析法，采用荧光标记的引物和377型DNA序列自动分析仪，检测了1例复发前后GBM所有22对常染色体上多达382个微卫星位点。相邻2个微卫星位点之间的平均距离为10cM。结果：对原发肿瘤标本的等位基因谱分析显示，染色体9p21上D9S157位点和10q21.3-26.3上D10S537、D10S185、D10S192、D10S597、D10S587、D10S217位点存在LOH。对复发肿瘤标本的研究显示，不但9p21和10q21.3-26.3上LOH的范围扩大，而且在其它多条染色体上也出现了LOH（包括1q,7p,7q,21q,20p,20q,10p,19p,19q)。结论：染色体9p和10q可能在该例GBM的发生中起着重要作用。尽管该病例复发前后的病理诊断相同，复发后GBM存在着更广泛的分子遗传学异常改变，可能伴随着更多肿瘤抑制基因的失活。     

DPC4──在人类染色体18q21.1上的一个候补肿瘤抑制基因

人类胰腺癌表现出一致的遗传学改变，包括Ki－ras突变（＞80％），p53突变（50％～70％）和p16突变或纯合型缺失（＞85％）。等位基因型资料支持附加肿瘤抑制基因在其它区域的存在，最显著地位于18q上。约有90％的胰腺癌显示出这一区带的杂合性丢失（LOH），许多肿瘤抑制基因通过基因内突变而失活，称为LOH，即一个等位基因及其附近包括其它等位基因的染色体区域的丢失。在出现频率高的LOH区域内对纯合型缺失作图已成为发现肿瘤抑制基因的关键性步骤。为了证明候补肿瘤抑制基因在18q上，作者对纯合型缺失的集中部位进行了胰腺癌嵌板分析…     

少突胶质细胞瘤中PTEN基因突变和10q 染色体的杂合性缺失分析

目的 探讨PTEN基因突变和10q染色体的杂合性缺失(LOH)在少突胶质细胞瘤发生和发展中的意义。方法 以55例少突胶质细胞瘤和混合性胶质细胞瘤为研究对象，PCR扩增PTEN基因所有9个外显子，其产物经变性梯度凝胶电泳(DGGE)后，DNA序列分析检测PTEN基因突变。应用不同颜色荧光标记10q微卫星标志物引物，PCR扩增后，其产物在自动测序仪上进行聚丙烯酰胺凝胶电泳，用Gene Scan软件分析LOH。结果 2／55例有PTEN基因突变，1例是PTEN的第9外显子的20号T碱基缺失导致终止密码351易位至347，另1例在139位发生C到A的转换，使得Phe变成Leu。23／55(42％)例出现染色体10q的LOH，其中15／55例位于10q^23.3(D10S541)，其为PTEN基因位点，12／55例10q微卫星标志物位点完全缺失。结论 在少突胶质细胞瘤中PTEN突变较少见，而10q LOH较频繁，尤其在恶性度高的少突胶质细胞瘤中表现明显，提示10q LOH与少突胶质细胞瘤恶性进展有关，且10q上可能存在其他抑癌基因。     

前列腺癌及前列腺上皮内瘤6号染色体等位基因杂合子丢失分析

目的：检测原发性前列腺癌及高级别前列腺上皮内瘤（PIN）6号染色体等位基因杂合子丢失（LOH）及其意义。方法：经显微切割技术切获取前列腺癌及PIN各10例患者DNA,采用聚合酶链反应（PCR）及微卫星多态性技术,对6号染色体上的20个微卫星标志位点LOH进行检测。结果：10例原发性前列腺中有8例在6号染色上至少有1个位点检测到LOH,6p21-6q23及6q25-6q27为2个高频LOH区,10例高级别PIN检测6号染色体20个位点,有5例各有1个位点检测到LOH,结论：前列腺癌中存在6号染色体的高频LOH区,分别位于6q21-6q23,6q25-6q27区,编码细胞周期素C及胰岛素样生长因子Ⅱ受体的基因为此2区侯选的抑癌基因,它们可能与前列腺癌的发生发展有关。     

即时荧光定量PCR微卫星分析技术检测少突胶质细胞肿瘤染色体1p/19q杂合性缺失

目的研究少突胶质细胞肿瘤染色体1p／19q杂合性缺失（LOH）情况。方法采用即时荧光定量PCR微卫星分析技术对28例少突胶质细胞肿瘤进行染色体1p／19qLOH检测。结果28例少突胶质细胞肿瘤染色体中有24例（85．7％）发生1pLOH;有18例（64．3％）发生19qLOH;有17例（60．7％）发生1p／19q联合性LOH;25例有1P或19qLOH。结论即时荧光定量PCR微卫星分析技术特异性高、方便快捷,可以用于石蜡包埋组织标本染色体杂合性缺失的检测。大多数少突胶质细胞肿瘤发生了1p／19qLOH。     

Correlation of loss of heterozygosity at chromosome 9q with histological subtype in medulloblastomas.

Patients with the nevoid basal cell carcinoma syndrome (NBCCS) are at increased risk for medulloblastomas as well as for basal cell carcinomas. The gene for NBCCS has been mapped to chromosome 9q22.3-q31 by linkage analysis, and loss of heterozygosity (LOH) in this region has been demonstrated in approximately one-half of sporadic basal cell carcinomas. In the present study, LOH for chromosome 9q22.3-q31 microsatellite markers was investigated in medulloblastomas occurring among children with NBCCS and in sporadic medulloblastomas. Histologically, all 3 NBCCS medulloblastomas were noted to have a desmoplastic phenotype, and LOH was detected in both of the 2 cases for which microsatellite markers were heterozygous in normal tissues. LOH was also detected in a subset of sporadic medulloblastomas, each of which were found to display the desmoplastic phenotype. In all, 3 of the 6 sporadic desmoplastic tumors showed LOH, whereas LOH was not seen in any of the 11 sporadic, non-desmoplastic medulloblastomas studied. Additionally, desmoplastic tumors lacking detectable LOH each showed histological features of so-called cerebellar neuroblastoma, a subgroup of desmoplastic medulloblastoma with extensive neuroblastomatous differentiation. The data are consistent with a role for inactivation of a tumor suppressor gene at chromosome 9q in the development of medulloblastomas in patients with NBCCS and of sporadic medulloblastomas characterized by a desmoplastic phenotype similar to that found in patients with NBCCS. Restriction of chromosome 9q loss to non-neuroblastomatous desmoplastic tumors suggests that this variant of medulloblastoma maybe pathogenetically distinct from tumors having other histological phenotypes.     

Identification of two distinct regions of deletion at 6q in gastric carcinoma

Loss of heterozygosity (LOH) affecting the long arm of chromosome 6 has been found repeatedly in human cancers. Recently, our group reported that del(6)(q21-22→qter) was the most consistent structural cytogenetic abnormality in gastric carcinomas. To determine more precisely the deleted region, we studied 51 tumors with 9 polymorphic markers on this chromosome arm. LOH of one or more markers was found in 39% of the tumors. LOH at region 6q22.3 was detected in 50% of informative tumors and at 6q26-q27 in 37% of informative tumors. By comparative analysis of LOH regions, we identified two separate regions of overlapped deletions at 6q, one between 6q16.3-q21 and 6q22.3-q23.1, another distal to 6q23-q24. A comparison of clinicopathologic features of gastric carcinomas with and without LOH at 6q revealed statistically significant or suggestive differences between LOH and young age of the patients and proximal location of the tumors. The two informative early gastric carcinomas both showed LOH at 6q. The occurrence of LOH at 6q was similar in all histological types. We conclude that two distinct regions at 6q appear to be involved in the early stages of gastric carcinogenesis.     

Acquisition of the Glioblastoma Phenotype during Astrocytoma Progression Is Associated with Loss of Heterozygosity on 10q25-qter

Loss of heterozygosity on chromosome 10 (LOH#10) is the most frequent genetic alteration in glioblastomas and occurs in more than 80% of cases. We recently reported that PTEN (MMAC1) on 10q23.3 is mutated in approximately 30% of primary (de novo) glioblastomas but rarely in secondary glioblastomas that progressed from low-grade or anaplastic astrocytomas. Because secondary glioblastomas also show LOH#10, tumor suppressor genes other than PTEN are likely to be involved. We analyzed LOH on chromosomes 10 and 19, using polymorphic microsatellite markers in microdissected foci showing histologically an abrupt transition from low-grade or anaplastic astrocytoma to glioblastoma, suggestive of the emergence of a new tumor clone. When compared to the respective low-grade or anaplastic astrocytoma of the same biopsy, deletions were detected in 7 of 8 glioblastoma foci on 10q25-qter distal to D10S597, covering the DMBT1 and FGFR2 loci. Six of 8 foci showed LOH at one or two flanking markers of PTEN but did not contain PTEN mutations. LOH on 10p and 19q was found in only one case each. These data indicate that acquisition of a highly anaplastic glioblastoma phenotype with marked proliferative activity and lack of glial fibrillary acidic protein expression is associated with loss of a putative tumor suppressor gene on 10q25-qter.     

Loss of heterozygosity analysis of cutaneous melanoma and benign melanocytic nevi: laser capture microdissection demonstrates clonal genetic changes in acquired nevocellular nevi

The molecular pathology of the common nevocellular nevus (NCN) and its relationship to the genetic model of malignant melanoma (MM) progression has not been fully characterized. We used laser capture microdissection of archival formalin-fixed material to study 34 melanocytic lesions (19 MM and 15 NCN). Twelve of the 15 NCN were acquired, 3 of which were congenital; none had dysplastic features. Ten polymorphic markers on five chromosomal regions (1p36, 6q22-23.3, 8p22-24, 10q23, and 11q23) were selected for loss of heterozygosity (LOH) analysis, based on previous studies demonstrating involvement in MM pathogenesis and progression. Loss of heterozygosity at any allelic locus was observed in 18 of 19 (95%) MM and in 9 of 15 (60%) NCN. Of the three congenital nevi analyzed, none showed LOH at any informative locus. The frequency of allelic loss was highest in the MM at 6q22-23.3 (64%), followed by 10q23 (62%), 8p22-24 (43%), 11q23 (43%), and 1p36 (13%). In the 15 NCN, the most frequent allelic losses were detected at 6q22-23.3 (29%), 1p36 (27%), and 10q23 (25%), with lower frequencies of LOH at 11q23 (10%) and 8p22-24 (7%). LOH at a single polymorphic marker, D6S1038, was detected in 70% of the MM and in 36% of the NCN, suggesting the presence of putative tumor-suppressor genes (TSGs) critical in melanocytic neoplasia at 6q22-23.3. The presence of clonal genetic alterations in acquired NCN justifies their classification as a benign neoplasm. The pattern of LOH in NCN is not random; rather, the relative frequencies of LOH at the chromosomal regions examined are consistent with a multistep model of MM progression that begins with NCN. Molecular analysis of NCN reiterates established epidemiologic and morphologic notions that NCN are precursor lesions for MM.     

Delineation of two distinct deleted regions on chromosome 9 in human non-melanoma skin cancers

The mapping of the naevoid basal cell carcinoma syndrome (NBCCS) and the Ferguson-Smith syndrome to the same region on chromosome arm 9q has led to speculation that the two conditions may reflect different mutations within the same gene. Loss of heterozygosity of 9q alleles in both familial and sporadic basal cell carcinomas (BCCs) suggests that the NBCCS gene on 9q is acting as a tumour suppressor gene. Although LOH of 9q markers has not been studied in squamous cell neoplasms from patients with the Ferguson-Smith syndrome, chromosome 9 allele loss has been reported in sporadic squamous cell carcinomas (SCCs) of the skin. In order to characterise further the deleted region on chromosome 9 in BCCs and SCCs of the skin we have examined a series of non-melanoma skin cancers using a panel of highly informative microsatellite markers. Forty-four BCCs and 49 SCCs were studied. Loss of heterozygosity of one or more 9q markers was seen in 33 of the 44 BCCs. Only 4 of the 33 BCCs with 9q loss showed loss of 9p markers. Twenty-two BCCs showed loss of all informative 9q markers. Partial or interstitial 9q deletions were seen in 5 BCCs, and in 3 of these 5 BCCs the breakpoint occurred within the currently defined NBCCS locus. Chromosome 9 loss was seen in 16 of 49 SCCs. In contrast to the low frequency of 9p loss in BCCs, LOH of 9p markers was a common finding in SCCs, occurring in 15 of the 16 SCCs with chromosome 9 loss. In 5 SCCs 9p loss occurred with retention of 9q alleles. The different patterns of chromosome 9 loss in BCCs and SCCs and the failure to detect loss of markers at the Ferguson-Smith/NBCCS locus in 5 of 7 informative SCCs with partial chromosome 9 losses suggest that the targets for allelic deletion on chromosome 9 in BCCs and SCCs are different.     

Loss of heterozygosity on chromosome 22q in gastrointestinal stromal tumors (GISTs): a study on 50 cases

Mutational activation of KIT or PDGFRA is considered an early step in pathogenesis of gastrointestinal stromal tumors (GISTs); however, other nonrandom genetic changes have also been identified. At least three common regions of deletions on chromosome 22q, which may harbor putative tumor suppressor genes, have been defined. However, mapping of these regions has been inconsistent. It has also been speculated that GI autonomous nerve tumors (GANTs), GISTs with ultrastructural features suggestive of autonomic nerve differentiation, are characterized by a specific deletion involving 22q13 cytogenetic region. This study was undertaken to evaluate loss of heterozygosity (LOH) on chromosome 22q in 50 GISTs, including 10 GANTs. Four tumors were incidental minimal lesions 相似文献   

前列腺癌及高级别前列腺上皮内肿瘤10号染色体等位基因杂合性缺失分析

目的　检测原发性前列腺癌及高级别前列腺上皮内肿瘤 (prostatic intraepithelial neoplasia,PIN) 10号染色体等位基因杂合性缺失 (loss of heterozygosity,L OH)及其意义。方法　用显微切割技术获取 16个前列腺癌及 14个高级别 PIN样本 DNA,采用 PCR及微卫星多态性技术 ,对 10号染色体上的 2 0个微卫星位点 L OH进行检测。结果　 16个原发性前列腺癌样本在 10号染色体位点有不同的 L OH频率 ,从 0～ 4 6 .2 %不等 ,主要分布在 10 q2 3及 10 q2 4 - q2 5。 14个高级别 PIN,有 7个样本在 6个位点检测到L OH。结论　前列腺癌存在 10号染色体的高频 L OH区 ,主要位于 10 q2 3及 10 q2 4 - q2 5区 ,而高级别 PIN的 L OH率明显低于前列腺癌 ,PTEN及 MXI1为 10 q2 3及 10 q2 4 - q2 5区候选的肿瘤抑制基因 ,可能与前列腺癌的发生发展有关