Fluorescence in situ hybridization is necessary to detect an association between chromosome aberrations and polycyclic aromatic hydrocarbon exposure in utero and reveals nonrandom chromosome involvement

Chromosome aberrations are associated with environmental exposures in infants and children. Recently we reported that prenatal exposure to airborne polycyclic aromatic hydrocarbons (PAHs) was significantly (P < 0.01) associated with stable aberration frequencies in cord blood from a subset of 60 newborns from the Columbia Center for Children's Environmental Health Prospective Cohort Study (Bocskay K et al. [ 2005]: Cancer Epidemiol Biomarkers Prev 14:506-511). To determine whether the environmental exposures may be targeting specific chromosomes and to compare various methods for measuring chromosome aberrations, we further evaluated this same subset of subjects composed of African-American and Dominican nonsmoking mother-newborn pairs residing in low-income neighborhoods of New York City, and exposed to varying levels of airborne PAHs. Chromosome aberrations were measured in cord blood lymphocytes, both by whole chromosome probe (WCP) fluorescence in situ hybridization (FISH) and traditional Giemsa-staining. Prenatal exposures were assessed by personal air monitoring. Breaks in chromosomes 1-6, as detected by WCP FISH, were nonrandomly distributed, underscoring the importance of appropriate chromosome probe selection to capture cytogenetic damage in response to exposure. FISH for stable aberrations was found to be a more sensitive method for detecting aberration frequencies associated with environmental exposures, when compared with FISH for unstable aberrations or Giemsa-staining for aberrations. Together, these results suggest that PAHs may be targeting specific chromosomes and highlight the importance of using the more sensitive detection methods to assess risk in populations with low levels of exposure.     

Evaluation of oncogene amplification in intact and truncated cell nuclei of gastro-esophageal cancer cell lines by DNA in situ hybridisation

Adenocarcinoma arising around the gastro-esophageal junction (GEJ) is a highly malignant form of cancer. Its incidence is rising sharply. The study of oncogenes in these carcinomas may give information concerning treatment and prognosis. In the present study, the fluorescence in situ hybridisation (FISH) technique was optimised for genetic characterisation of oncogenes in archival cancer specimens. Three cell lines derived from GEJ adenocarcinomas were investigated, i.e. JROECL 19, JROECL 33 and OACM5.1C, both in fresh and paraffin-embedded preparations. Furthermore, paraffin-embedded material of three xenografts was studied, i.e. JROECL 19, JROECL 33, and OACM4.1X. We focussed on the oncogenes MYC and HER2/neu, since they are frequently involved in intestinal cancers. Firstly, our results indicate that it is feasible to detect oncogene-specific probes with the FISH technique in formalin-fixed, paraffin-embedded material. Secondly, it appeared that the optimal section thickness for analysis was 2 microm. This thickness resulted in minimal nuclear overlap, which facilitates counting of FISH spots. Due to the truncation phenomenon, however, the sensitivity of the technique is less than FISH on intact nuclei. Importantly, (high level) oncogene amplifications were easily recognised in 2 microm thick sections. Finally, counting of the individual copy number of the MYC and HER2/neu oncogenes was feasible enabling an arbitrary assessment of low- and high-level amplification. In conclusion, FISH is an accurate technique for detecting amplification of oncogenes in paraffin-embedded patient material.     

18例闭经患者的分子-细胞遗传学研究

目的探讨荧光原位杂交（fluorescencein situhybridization,FISH）和高分辨比较基因组杂交（highresolution-comparative genomic hybridization,HR-CGH）技术在闭经研究中的应用价值。方法17例原发闭经和1例继发闭经患者经常规妇科检查、B超及内分泌功能检查后,应用染色体核型分析,部分染色体异常患者采用FISH和HR-CGH技术相结合的分子-细胞遗传学检查诊断结果,并对其临床症状及发病机制进行了探讨。结果17例原发闭经患者中,7例为46,XX的正常女性核型;10例携带有异常染色体核型,所占比例为58.8%,其中3例为46,XY的女性患者,2例为45,X及45,X/46,XX的Turner＇s患者;其余5例均为携带有X染色体结构异常,包括X染色体部分单体、X等臂染色体和X/Y嵌合体等异常核型患者;1例继发性闭经患者为X染色体与常染色体易位的异常核型。结论应用FISH和HR-CGH技术与高分辨染色体显带技术,精确诊断患者的染色体核型,可为临床的诊断和治疗提供医学遗传学依据。     

Numerical aberrations of chromosomes 1 and 7 in renal cell carcinomas as detected by interphase cytogenetics

Alcohol-fixed single cell suspensions of 37 renal cell carcinomas (RCCs) were assessed by both flow cytometry (FCM) and the fluorescence in situ hybridization (FISH) technique, using chromosome 1- and chromosome 7-specific centromere DNA probes. DNA diploidy or near-diploidy was observed in 30 of the 37 RCCs and only 12 of these (near-)diploid tumours were disomic for both chromosomes 1 and 7. Numerical aberrations of chromosome 1 and/or chromosome 7 were present in 18 of the 30 (near-)diploid RCCs and five of these cases showed monosomy for chromosome 1 in more than 50 per cent of the tumour cells. A double target FISH, with a centromeric and a telomeric specific probe for 1p36, excluded misinterpretation on the basis of clustering of 1q12, and suggested a complete loss of chromosome 1. All these five (near-)diploid RCCs with monosomy for chromosome 1 were eosinophilic chromophilic cell carcinomas, according to the Thoenes classification of RCC. This observation is of special interest, because it was recently concluded from cytogenetic studies that the diagnosis of chromophilic renal cell carcinoma must be considered as obsolete. Monosomy for chromosome 1 seems to be a non-random numerical aberration of (near-)diploid eosinophilic chromophilic cell carcinomas, and a gain of one or more chromosomes 1 appeared to be a common phenomenon in RCCs, especially in the DNA aneuploid tumours. As these chromosomal abnormalities were not found in the earlier classical cytogenetic studies, we conclude that in situ hybridization techniques are required in addition to chromosome banding techniques to obtain a complete characterization of the chromosome imbalances in RCCs.     

HER2 status in gastric cancer: A comparison of two novel in situ hybridization methods (IQ FISH and dual color SISH) and two immunohistochemistry methods (A0485 and HercepTest™)

In contrast to breast HER2 testing, the optimal ISH method and antibody for gastric HER2 testing are unclear. The aim of this study was to find out gastric HER2 positivity rates in our institutional data, and to compare the two novel ISH methods with A0485 antibody and HercepTest™. IHC and ISH were carried out on gastrectomy specimens of 88 patients up to the standardly advised procedure protocols, and interpretations were also carried out up to widely accepted international protocols., HER2 expression was (−) in 65, (+) in 5, (++) in 6, and (+++) in 12 cases by A0485 IHC. IHC (+) 4 cases and (++) 3 cases were (−) by HercepTest™. One IHC (−) amplified case was (++) by HercepTest™. All A0485 and HercepTest™ (+++) 12 cases were amplified by ISH. HER2 amplification was detected in 18 (20.4%) and in 15 (17.2%) cases by SISH and FISH, respectively. Of the 18 cases, 4 showed focal heterogeneous low level amplification by SISH. Focal amplification was noted in only 2 cases by FISH. The HER2 status of our gastric cancer file is 17.2% by FISH, 20.4% by SISH. The concordance between HercepTest™/A0485 IHC and ISH is perfect in (+++) cases. Equivocal results (++) with any IHC method should be clarified by one of the molecular methods (SISH and FISH). Probably up to the higher level of heterogeneity of gastric carcinomas, there is a 4.5% dilemma of cases that are negative or weakly positive by conventional IHC methods. Therefore, regarding HER2 status in gastric carcinoma, the reliability of IHC methods should be checked.     

The assessment of HER2 status in breast cancer: the past,the present,and the future

Humanized monoclonal anti‐human growth factor receptor 2 (HER2) antibody trastuzumab was approved for HER2 positive breast cancer patient treatment 11 years after the demonstration of HER2 gene amplification associated with the HER2 protein overexpression in breast cancer in 1987. HER2 positive status of breast cancer patients is assessed by HER2 gene amplification with in situ hybridization (ISH) and/or HER2 protein overexpression with immunohistochemistry (IHC). Because the discordance between quantitative HER2 ISH and subjective, semi‐quantitative HER2 IHC assay results is a well‐recognized issue of HER2 testing, we developed an assay combining HER2 ISH and HER2 IHC assays (HER2 gene‐protein assay; HER2 GPA) as one test on the same tissue section. HER2 GPA allows pathologists to score the HER2 gene and HER2 protein status simultaneously at the individual cell level. The possibility that HER2 GPA may become the next generation of HER2 testing is discussed, particularly for cases in which it is difficult to assess the HER2 status of breast cancer patients due to the HER2 heterogeneity.     

High <Emphasis Type="BoldItalic">PRL-3</Emphasis> expression in human gastric cancer is a marker of metastasis and grades of malignancies: an in situ hybridization study

Phosphatase of regenerating liver (PRL)-3, encoding a 22-kD low molecular weight tyrosine phosphatase, has been reported to be associated with metastasis of colorectal carcinoma. We assessed the levels of PRL-3 mRNA expression to know whether its up-regulation was involved in progression and metastasis of gastric carcinoma. Levels of PRL-3 expression in 94 human gastric adenocarcinomas and 54 matched lymph node metastases were detected by in situ hybridization and compared with clinicopathological characteristics including prognosis. High PRL-3 expression was detected in 36.2% of primary gastric carcinoma (with nodal metastasis, 55.6%; without nodal metastasis, 10%; P < 0.001) and in 74.1% of lymph node metastases. The incidence of high PRL-3 expression in lymph node metastasis was significantly higher than in primary tumors (P < 0.044). Moreover, high expression of PRL-3 was closely associated with tumor size, lymphatic invasion, venous invasion, extent of lymph node metastasis, and tumor stage. These results suggest that high PRL-3 expression may participate in the progression and metastasis of gastric carcinoma. PRL-3 might be a novel molecular marker for aggressive gastric cancer.