乳腺癌和导管增生病变与1p染色体不稳定的关系

目的检测乳腺普通型导管增生(usual dutal hyperplasia,UDH)、乳腺不典型增生(atypical dutal hyperplasia,ADH)、乳腺导管原位癌(dutal carcinoma in situ,DCIS)及乳腺浸润性导管癌(invasive dutal carcinoma,IDC)中染色体1p微卫星杂合性缺失(loss of heterozygosity,LOH)/微卫星不稳定(microsatellite instability,MSI)的改变规律,探讨乳腺导管增生病变进展为IDC的遗传学改变特征。方法应用PCR法检测20例UDH、7例ADH、25例DCIS、25例IDC石蜡包埋组织,8%尿素变性聚丙烯酰胺凝胶电泳后银染检测染色体1p区间微卫星位点D1S193、D1S463、D1S2881、D1S2885、D1S234、D1S252的LOH/MSI。结果染色体1p的每个位点均发生LOH/MSI,其发生的频率UDH为55.0%、ADH为42.9%、DCIS为64.0%、IDC为72.0%,各组间差异无显著性(P0.05);微卫星位点D1S193、D1S2881、D1S2885、D1S252、D1S234在各组中LOH/MSI的频率差异均无显著性(P0.05)。D1S463的频率在UDH组为5.0%、ADH组为0、DCIS组为45.0%、IDC组为40.0%,其中UDH组与ADH组明显低于DCIS组、IDC组(P0.008)。结论 1p染色体遗传学不稳定是乳腺癌发生的早期事件,D1S463位点的改变可能在乳腺导管增生性病变进展为乳腺癌中起关键作用。     

肝细胞癌8号染色体微卫星变异及其与临床病理特征的关系

目的　探讨肝细胞癌 (HCC)微卫星变异的特点及其与临床病理表现的相关性。方法采用毛细管电泳DNA分析系统 ,对 5 6例HCC中 8号染色体上 10个微卫星的杂合子丢失 (LOH)、微卫星不稳定性 (MSI)和等位基因失衡 (AI) 3种变异特征进行检测。结果　 5 6例HCC在 8号染色体上 10个基因位点发生LOH的总频率为 6 6 1% (37/ 5 6 ) ,LOH以D8S2 6 1最高为 5 3 5 % (2 3/ 4 3) ,其次为D8S172 1(5 2 5 % )和D8S1771(5 2 5 % )。D8S2 77基因位点 ,血清HBsAg阳性患者的LOH频率显著高于HBsAg阴性者 (P <0 0 1) ,D8S2 6 1、D8S2 98和D8S1733基因位点 ,血清HBsAg阴性患者的LOH频率显著高于HBsAg阳性者 (P <0 0 1) ;D8S2 98和D8S1771基因位点 ,直径 >3cm肿瘤的LOH率明显高于≤ 3cm组 (P <0 0 5和P <0 0 1) ;在D8S172 1基因位点 ,无包膜或包膜不完整的肿瘤的LOH显著高于包膜完整的肿瘤 (P <0 0 1) ;D8S2 98和D8S1771基因位点 ,肝内转移者的LOH明显高于无肝内转移者 (P <0 0 5 )。MSI的频率为 12 5 % (7/ 5 6 ) ,AI的频率为 19 6 % (11/ 5 6 )。结论HCC在 8号染色体上存在广泛的微卫星变异 ,其中LOH方式在HCC的发生和发展过程中起重要作用 ,MSI的作用次之。特定基因位点的LOH与临床和病理学参数有一定的相关性     

中国人肝癌分泌型卷曲相关蛋白1基因遗传的不稳定性

目的 研究8号染色体上D8S532位点的杂合性缺失(LOH)和微卫星不稳定性(MSI)对分泌型卷曲相关蛋白1基因(sFRP1)蛋白表达的影响,阐明 sFRP1 基因遗传不稳定性与肝癌进展的关系,为揭示sFRP1 基因作用机制和肿瘤发生发展机制提供实验依据. 方法 采用石蜡包埋组织抽提DNA,聚合酶链-单链构象多态性(PCR-SSCP)分析,常规银染检测D8S532位点的LOH和MSI,采用Envision免疫组织化学染色,Leica-Qwin计算机图像分析系统采图和Image-Pro P1uS(IPP)Version5.0专业图像分析软件分析蛋白表达. 结果 在36例肝癌中,D8S532位点LOH和MSI检出率分别为11.11%(4/36)和8.33%(3/36),D8S532位点MSI发生率在60岁以上年龄组(≥60) 26.67%(4/15),高于60岁以下年龄组(<60)0.00%(0/21, P <0.05).相比较于正常组织,86.11%(31/36)的sFRP1蛋白有不同程度表达下降,在肝癌组织中,sFRP1表达阳性率为52.78%(19/36),蛋白表达阴性组LOH阳性率为23.53%(4/17),明显高于蛋白阳性组的0.00%(0/19)( P <0.05). 结论 在中国人肝癌发生进展中,sFRP1蛋白表达下降甚至缺失是普遍现象, sFRP1 基因的遗传不稳定性可能是导致该抑癌基因突变、肿瘤发生的一个机制,LOH在sFRP1表达缺失的过程中起了重要作用.     

软组织平滑肌肉瘤染色体3p位点特异性的杂合性缺失

目的 对软组织平滑肌肉瘤(LMS)染色体3p上的5个特异性位点进行微卫星多态性分析,以明确这些位点染色体等位基因杂合性缺失(LOH)情况。方法 采用微卫星DNA-聚合酶链反应—银染法分析22例LMS 3p14．2-pter范围内的5个特异性位点LOH状态。结果 45．4％LMS至少在一个位点出现LOH,以D3s1295最高(36．8％),其次为D3s1289(10．5％),而D3s1293末检测到LOH。不同组织学分级、大小及不同部位的LMS其LOH发生差异无显著性。结论 LMS3p14．2—23范围发生杂合性缺失率较高,D3s1295及D3s1289位点所在的染色体区域及附近可能隐含与平滑肌肉瘤有关的抑癌基因。     

原发性胃癌中19p部分微卫星多态位点杂合性缺失分析

目的 筛选胃癌19p部分微卫星多态位点的杂合性缺失（loss of heterozygosite,LOH)频率,以初步确定19p上与胃癌相关基因连锁最密切的微卫星多态位点。方法 采用聚合酶链反应-单链长度多态（polymerase chain reaction-single strand length polymorophism,PCR-SSLP)-银染法选取19p上9对微卫星多态标记（D19S424,D19S216,D19S406,D19S413。D19S221,D19S226,D19S411,D19S883,D19S886）,对43例原发性胃癌的杂合性缺失情况进行了分析。结果 43例中22例至少在1个位点发生LOH,总缺失率为48.88%,这9个位点的LOH频率分别为29.63%,11.53%,33.33%,8.57%,13.15%,8.00%,6.45%,6.89%,10.71%,在D19S886也同时出现微卫星不稳定性（microsatellite instability,MSI)17.85%。结论 提示19p上的LOH缺失频发区域可能涉及与人类原发性胃癌发生发展相关基因的存在。     

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。     

子宫颈癌FHIT基因表达与杂合性丢失

目的　探讨抑癌基因FHIT基因在子宫颈癌发生中的作用及其失活的可能机制。方法　选取FHIT基因内 2个微卫星位点D3S130 0和D3S12 34,对 5 6例经显微切割分离肿瘤组织的原发性子宫颈癌进行杂合性丢失 (LOH)分析 ,同时采用免疫组化方法 (S P法 )检测FHIT的表达情况。结果　D3S130 0和D3S12 34的LOH发生率分别为 36 2 % (17/ 4 7)、32 7% (16 /4 9) ,5 2 % (2 9/ 5 6 )的子宫颈癌组织至少在一个位点存在LOH。 5 7 1%的子宫颈癌FHIT表达减弱或缺失 ,其中 71 9%存在FHIT基因LOH ,FHIT低表达与FHIT基因LOH之间有相关性 (P <0 0 1)。子宫颈鳞癌组织的LOH发生率及FHIT低表达率均高于腺癌 (6 4 3%vs 14 3% ,6 9 0 %vs 2 1 4 % ,P <0 0 5 )。子宫颈鳞癌LOH发生率及FHIT低表达与组织学分级、FI GO分期均不相关 (P >0 0 5 )。结论　FHIT基因可能在子宫颈鳞癌发生中起重要作用 ,杂合性丢失可能是FHIT基因失活的重要机制     

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。     

食管鳞癌及其前驱病变基因杂合子缺失的研究

目的 通过对食管黏膜高级别上皮内瘤变和鳞状细胞癌中的等位基因杂合子缺失(LOH)的检测,以期发现与食管鳞状细胞癌关系密切的抑癌基因。方法 应用显微切割,PCR扩增、凝胶电泳、放射自显影等技术,对照分析正常体细胞、食管鳞状上皮高级别上皮内瘤变和食管鳞状细胞癌组织中LOH的变化,并就各位点杂合子缺失率与患者的临床病理参数分别进行单因素分析。结果 高级别上皮内瘤变中7个位点的LOH依次为D13S802(40%)、D9S171(33%)、D13S267(320%)、D13S221(31%)、D9S942(30%)和D17S520(240%),而D17S1798在本组上皮高级别上皮内瘤变中未发现杂合子缺失。在食管鳞状细胞癌组织中,上述7个位点的LOH率依次为D13S267(71%),D13S802(58%),D17S520(55%)、D13S221(45%)、D9S942(43%)、D9S171(33%)和D17S1798(11%)。应用SPSS软件对7个微卫星序列的等位基因LOH率与患者的病理学分级、临床病理分期及是否有淋巴结转移进行单因素分析,差异均无显著性(P>0.05)。结论 (1)从正常黏膜到上皮内瘤变再到食管鳞癌的发生过程中,同时伴随基因异常的逐步积累。(2)13q12.12上的D13S802附近可能存在着主要与食管鳞状细胞癌早期发生有关的抑癌基因。(3)13q12.3上的D13S267附近、17p13.1上的D17S520和17p13.3上的D17S1798附近的基因可能与食管     

Loss of heterozygosity on chromosome 10p14-p15 in colorectal carcinoma.

High frequencies of loss of heterozygosity (LOH) on chromosome 10p14-p15 have been reported in various tumors, including gliomas, pulmonary carcinoid tumors and cervical, hepatic, prostatic and esophageal carcinomas. However, LOH on chromosome 10p14-p15 in colorectal tumors has not been reported. Therefore, we examined LOH on chromosome 10p14-p15 in 60 colorectal carcinomas (21 superficial and 39 advanced types) by microsatellite assay. Three microsatellite loci, D10S191 (10p14), D10S558 and D10S249 (10p15) were examined by polymerase chain reaction [early colorectal carcinomas, LOH of markers D10S191 (36%), D10S558 (7%) and D10S249 (11%), and in advanced colorectal carcinomas, LOH of markers D10S191 (20%), D10S558 (13%) and D10S249 (33%)]. There were no significant associations between LOH on chromosome 10p14-p15 and clinicopathologic features, including patient age, sex, tumor location, depth of invasion, histologic type, lymph node metastasis and prognosis. These data suggest that a putative tumor suppressor gene associated with colorectal carcinogenesis may be located on chromosome 10p14-p15 and that alteration of this gene may be involved in the development but not progression of colorectal tumors.     

Genome-wide analyses on loss of heterozygosity in head and neck squamous cell carcinomas

Head and neck squamous cell carcinoma (HNSCC) is a frequent malignancy with a poor survival rate. Identifying the tumor suppressor gene (TSG) loci by genomic studies is an important step to uncover the molecular mechanisms involved in HNSCC pathogenesis. We therefore performed comprehensive analyses on loss of heterozygosity (LOH) using a genome-wide panel of 191 microsatellite markers in 22 HNSCC samples. We found 53 markers with significantly high LOH (>30%) on 21 chromosomal arms; the highest values of those were observed on 3p, 9p, 13q, 15q, and 17p, corresponding to D3S2432 (67%), D9S921-D9S925 (67%) and GATA62F03 (86%), D13S1493 (60%), D15S211 (62%), and D17S1353 (88%), respectively. Fifteen hot spots of LOH were defined in 13 chromosomal arms: 2q22-23, 4p15.2, 4q24-25, 5q31, 8p23, 9p23-24, 9q31.3, 9q34.2, 10q21, 11q21-22.3, 14q11-13, 14q22.3, 17p13, 18q11, and 19q12 as loci reported previously in HNSCCs. Furthermore, we identified five novel hot spots of LOH on three chromosomal arms in HNSCC at 2q33 (D2S1384), 2q37 (D2S125), 8q12-13 (D8S1136), 8q24 (D8S1128), and 15q21 (D15S211). In conclusion, our comprehensive allelotype analyses have unveiled and confirmed a total of 20 possible TSG loci that could be involved in the development of HNSCC. These results provide useful clues for identification of putative TSGs involved in HNSCC by fine mapping of the suspected regions and subsequent analysis for functional genes.     

Low microsatellite instability and high loss of heterozygosity rates indicate dominant role of the suppressor pathway in squamous cell carcinoma of head and neck and loss of heterozygosity of 11q14.3 correlates with tumor grade

Loss of heterozygosity (LOH) and microsatellite instability (MSI) have been recognized as important events in squamous cell carcinoma of the head and neck (HNSCC), suggesting involvement of both suppressor and mutator pathways. We analyzed 153 HNSCC with 8 Bethesda reference panel markers and 14 microsatellite markers selected from chromosomal regions known to harbor either tumor-suppressor genes or oncogenes. A combination of multiplex fluorescence-based polymerase chain reaction and automatic fragment analysis was performed. LOH was observed in 78% of all tumors. 2% to 17% LOH frequency was observed with Bethesda reference panel markers comparing to higher 8% to 48% LOH in chromosomal areas 3p, 9p, 11q, and 17p. LOH of 11q14.3 correlated with tumor grade. The proportions of high- and low-MSI tumors were 3% and 10%, respectively, but no mutation was identified in MLH1 and MSH2 mismatch repair genes. These results indicate the dominant role of the suppressor in comparison with the mutator pathway in HNSCC carcinogenesis.     

No evidence of microsatellite instability but frequent loss of heterozygosity in primary resected lung cancer

We examined microsatellite instability and loss of heterozygosity (LOH) in primary lung tumors from 93 cancer patients, using 16 microsatellite markers. The cases studied included 87 non-small-cell lung cancers (NSCLC) and six small-cell lung cancers (SCLC). All the patients except two were current or former smokers. The microsatellite markers were all dinucleotide repeat sequences from chromosomal locations 1p, 3p, 5q, 8p, 9p, 10p, 11p, 13q, and 17q. None of the tumors showed microsatellite instability (0/93). In NSCLC, 28% (24/87) of the cases showed LOH in at least one locus, whereas, in SCLC, 67% (4/6) had allelic losses. The frequency of LOH differed between the various cell types of NSCLC. The highest frequency was seen in large cell carcinoma (3/6, 50%) followed by squamous cell carcinoma (16/43, 37%) and adenocarcinoma (5/35, 14%). The most common site of LOH was 3p, where markers D3S1284, D3S659, D3S1289, D3S966, D3S647, and D3S1038 were studied. LOH, studied with 9p markers (D9S126, D9S171, D9S162), was less common. The present results, together with earlier reports, suggest that smoking-related primary lung cancers seldom show microsatellite instability but are characterized by frequent LOH. Environ. Mol. Mutagen. 30:217–223, 1997. © 1997 Wiley-Liss, Inc.     

Molecular characterization of head and neck tumors by analysis of telomerase activity and a panel of microsatellite markers

Head and neck cancer is a frequent malignancy with a complex, and up to now not clear etiology. The reactivation of telomerase activity and losses or gains of specific chromosomal regions, which point to deletions of tumor suppressor genes or amplification of oncogenes are supposed to be the molecular processes during the development and progression of head and neck cancer. Therefore, we analyzed telomerase activity and microsatellite markers using a genome wide panel of 28 microsatellite markers in 38 head and neck squamous-cell carcinomas (HNSCC). Our microsatellite marker set included distinct chromosomal areas that all likely harbor genes contributing to the carcinogenesis of HNSCC. DNA or protein lysates were obtained from primary tumors and compared to peripheral lymphocytes or corresponding normal tissue. At least one genomic alteration [loss of heterozygosity (LOH), or microsatellite instability (MSI)] was found in 31 of the 38 cases (82%). Most frequently we detected an LOH in the chromosomal region 9p12-21 where at least the tumor suppressor genes (TSG) p16INK4A, p14ARF and p15INKB are localized. The comparison between grade two and grade three tumors showed a highly changed frequency of LOH in the chromosomal region 7q31, where a putative TSG is predicted. Telomerase activity was present in 31/37 (83.8%) tumor samples independent of the histopathological staging and grading of the tumors. These molecular characterizations of HNSCC may be a further hint for the involvement of additional, so far unknown, TSGs in the tumor progression and will elucidate the regulation of telomerase.     

Abnormalities of chromosome 17 in oesophageal cancer

BACKGROUND: Oesophageal cancer is the most common malignancy encountered in South African males, especially in the Eastern Cape and surrounding region of South Africa. There are a number of risk factors and predisposing conditions that have been implicated in the aetiology of the disease. The tylosis oesophageal cancer (TOC) gene, localised to a small region on chromosome 17q25, has been shown to be associated with oesophageal squamous cell carcinoma. AIM: To investigate loss of heterozygosity (LOH) and microsatellite instability (MSI) in the region of the TOC locus. METHODS: In 74 oesophagectomy specimens for squamous cell carcinoma, microsatellite PCR was performed using five fluorescently labelled TOC markers. The PCR products were analysed and the data correlated with clinicopathological findings. RESULTS: LOH ranged from 25% to 60%. LOH for the individual markers was as follows: D17S1839, 25%; D17S1864, 36%; D17S1817, 38%; D17S785, 47.8%; and D17S579, 60%. MSI ranged from 4.1% to 6.8% for the five loci in the 17q region. MSI was 4.1% for the markers D17S579, D17S785 and D17S1817. Marker D17S1864 showed MSI to occur in 4 cases (5.4%) and marker D17S1839 in 5 cases (6.8%). CONCLUSION: No significant relationship between genetic and clinical parameters was observed; however, aberrations in poorly differentiated tumours were high for markers D17S579 and D17S1864 (25% and 37%, respectively), indicating that these markers may have an underlying role in the molecular pathogenesis of oesophageal squamous cell carcinoma. In addition, 63% of patients who died showed LOH for the markers D17S579, D17S1864 and D17S1817.     

Allelic imbalance at chromosome 11 in head and neck squamous cell carcinoma in an Indian patient population

BACKGROUND: Genetic instability of chromosome 11 is a frequent event in many solid tumours, including head and neck squamous cell carcinoma (HNSCC). AIMS: To perform allelic imbalance analysis of cytogenetically mapped altered regions of human chromosome 11 in patients with HNSCC from eastern India. METHODS: Genomic alterations were investigated using highly polymorphic microsatellite markers in both HNSCC and leukoplakia tissues. RESULTS: Microsatellite markers D11S1758 from 11p13-15 and D11S925 from 11q23.3-24 had the highest frequency (38% and 32%, respectively) of loss of heterozygosity among all the markers analysed. Allelic loss at the marker D11S925 was seen in both leukoplakia and in all stages of HNSCC tumour tissues suggesting that it is an early event in HNSCC tumorigenesis. Microsatellite size alteration was also found to be high (> 20%) in several markers. In leukoplakia samples microsatellite instability was seen at a higher frequency than loss of the allele, indicating such alterations might initiate the process of tumorigenesis in HNSCC. CONCLUSIONS: The high rate of chromosomal alterations at 11q21-24 in HNSCC suggests the presence of a putative tumour suppressor gene in this region.     

Loss of heterozygosity on chromosome 1 and 9 and hormone receptor analysis of metastatic malignant melanoma presenting in breast

Malignant melanoma (MM), the most common metastatic solid tumor to involve the breast, may present as a diagnostic problem, frequently requiring the use of ancillary studies for accurate diagnosis. The implication of hormonal interplay is strong since metastatic MM to the breast is seen nearly always in women. However, the role of hormonal status as a predisposing factor in the development of this entity is largely unresolved. A number of chromosomal loci, including 1p36 and 9p21-22, appear to harbor critical genes important to melanoma tumorigenesis, and additionally chromosome 9q22.3-31. We wanted to know if metastatic MM in breast showed chromosome 1p and 9p genetic alterations (loss of heterozygosity) similar to those that occur in primary cutaneous MM, and whether additional 9q LOH changes are present. Hormonal receptor status of the metastatic MM was also determined. We identified 20 patients with known MM metastatic to the breast, which we analyzed with the following genetic markers: D9S12 (9q22.3), D9S171 (9p21), IFNA (9p22), and D1S450 (1p). Visually directed microdissection was performed on archival histologic slides containing both tumor and adjacent normal breast epithelium, followed by single-step DNA extraction and polymerase chain reaction (PCR) amplification for evaluation of loss of heterozygosity (LOH) for the above-listed markers. Immunohistochemical (IHC) stains for estrogen receptor (ER) and progesterone receptor (PR) was performed on 10 of the cases. Twelve of the 20 cases contained DNA suitable for PCR amplification following direct visualization microdissection. Four of 8 (50%) informative cases showed LOH at 9p21 with D9S171. Ten cases were heterozygous for IFNA, with 2 cases (20%) showing LOH at this locus. These particular cases also showed LOH at 9p21. One of 9 (11%) informative cases showed LOH for D1S450 (1p36). Five cases were heterozygous for D9S12, and 2 (40%) showed LOH in the tumor at 9q22.3. IHC stains for ER and PR were negative in the 10 tumors studied. Metastatic MM presenting as a breast mass is an interesting entity often requiring IHC studies for diagnosis, particularly when the histologic features simulate breast carcinoma or when no primary tumor is known. These tumors are ER and PR negative. Metastatic MM involving the breast shows similar genetic allelic losses on chromosome 9p21-22 (50%) and 1p36 (11%), as previously described in primary cutaneous MM. Additional LOH was observed at the 9q22.3-31 locus (40%). We suggest this locus to be investigated for harboring potential genes important in the tumorigenesis of cutaneous MM.     

Microsatellite instability in ovarian and other pelvic carcinomas

Twenty-six cases of ovarian carcinoma and six cases of other pelvic neoplasms were analyzed for microsatellite instability (MSI) using frozen specimens, fluorescence technology, and four selected markers (D2S123 on chromosome 2, D18S58 on chromosome 18, BAT26 on chromosome 2, and BAT40 on chromosome 1). This procedure also allowed the detection of loss of heterogeneity (LOH) at the four selected loci. One of the cases of ovarian carcinoma exhibited MSI and this was evident at three loci. Of 44 informative loci, 7 exhibited LOH representing 3 cases of ovarian carcinoma, 3 of 4 cases of primary peritoneal carcinoma, and one case of unknown primary. These data support other findings that MSI is not a frequent occurrence in ovarian cancer; however, LOH is a more frequent event and may be a target for the development of diagnostic/prognostic procedures for ovarian and primary peritoneal carcinoma.