Comparison of fluorescence and chromogenic in situ hybridization for detection of HER-2/neu oncogene in breast cancer

Determination of HER-2/neu oncogene amplification has become clinically important in the present management of breast cancer and may have important applications in other areas of clinical oncology and scientific research. In situ hybridization is an extremely accurate and sensitive technique for assessing amplification of HER-2/neu. A new method using a chromogen-labeled probe offers numerous advantages, including the ability to view the morphologic features of the cells of interest using a light microscope, which can be found in every laboratory. We used both techniques to assay 31 cases of infiltrating breast carcinoma; assays were performed in laboratories at 2 institutions. Identical results for both methods were found in 26 cases (10 amplified, 16 nonamplified). One case was misinterpreted as overexpressed by chromogenic in situ hybridization (CISH) because of background precipitate. In 4 cases, CISH suggested low-level amplification. Three of these cases subsequently were found to have chromosome 17 polysomy. In the remaining case, the initial section chosen was suboptimal, showing weak signals by both methods. If a probe for chromosome 17 (now available for CISH) is used in cases of questionable HER-2/neu amplification, CISH seems to be as accurate and more practical than FISH.     

Immunocytochemical evaluation of HER-2/neu on fine-needle aspirates from primary breast carcinomas

Detection of HER-2/neu alterations is increasingly used in breast cancer patients for therapeutic purposes. This study examines the reliability of HER-2/neu immunocytochemical assessment on 66 cytospin smears obtained by fine-needle aspiration biopsy from breast cancer patients. Results were compared with those obtained by both fluorescence in situ hybridization (FISH) on fine-needle aspirate (FNA) and immunohistochemistry (IHC) on matched histologic section. Concordance between immunocytochemistry (ICC) and FISH was 78% and between ICC and IHC was 84%. Discordance mainly concerned seven unamplified cases that resulted positive by ICC and four cases scored negative by IHC but positive by ICC. Simultaneous assessment of HER-2/neu by ICC, IHC, and FISH was available in 24 cases; the concordance was 75%. In this study, the false positivity of immunocytochemical technique represents the major criticism. In our experience, FISH remains the most objective and powerful technique for HER-2/neu assessment on breast cancer FNAs.     

Quantitative evaluation of HER-2/neu status in breast cancer by fluorescence in situ hybridization and by immunohistochemistry with image analysis

We correlated quantitative results obtained in 40 invasive breast cancer cases for HER-2 gene amplification by fluorescence in situ hybridization with protein expression by immunohistochemical studies with computer-assisted image analysis. Fluorescence in situ hybridization (FISH) results were quantified as the mean number of fluorescent signals per nucleus, and immunohistochemical slides were read by semiquantitatively assessing membranous immunostaining intensity in tumor cells vs nonneoplastic breast tissue or quantitatively evaluated by image analysis. We found high correlation between immunohistochemical results by semiquantitative scoring and by image analysis. FISH results correlated with immunohistochemical results moderately when the staining intensity of only tumor cells was assessed and significantly better when the difference in staining intensity between tumor cells and nonneoplastic breast tissue was assessed. The correlation with FISH results was further improved when immunohistochemical study was combined with heat-induced epitope retrieval (HIER). Although FISH and immunohistochemical studies assess different aspects of the HER-2/neu gene (amplification vs overexpression), we found good correlation between the diagnostic techniques. The correlation was best when immunohistochemical studies were combined with HIER and assessed as the difference between tumor cells and nonneoplastic breast tissue.     

Chromogenic in situ hybridization: a practical alternative for fluorescence in situ hybridization to detect HER-2/neu oncogene amplification in archival breast cancer samples

Determination of HER-2/neu oncogene amplification has become necessary for selection of breast cancer patients for trastuzumab (Herceptin) therapy. Fluorescence in situ hybridization (FISH) is currently regarded as a gold standard method for detecting HER-2/neu amplification, but it is not very practical for routine histopathological laboratories. We evaluated a new modification of in situ hybridization, the chromogenic in situ hybridization (CISH), which enables detection of HER-2/neu gene copies with conventional peroxidase reaction. Archival formalin-fixed paraffin-embedded tumor tissue sections were pretreated (by heating in a microwave oven and using enzyme digestion) and hybridized with a digoxigenin-labeled DNA probe. The probe was detected with anti-digoxigenin fluorescein, anti-fluorescein peroxidase, and diaminobenzidine. Gene copies visualized by CISH could be easily distinguished with a x40 objective in hematoxylin-stained tissue sections. HER-2/neu amplification typically appeared as large peroxidase-positive intranuclear gene copy clusters. CISH and FISH (according to Vysis, made from frozen pulverized tumor samples) correlated well in a series of 157 breast cancers (kappa coefficient, 0.81). The few different classifications were mostly because of low-level amplifications by FISH that were negative by CISH and immunohistochemistry with monoclonal antibody CB-11. We conclude that CISH, using conventional bright-field microscopy in evaluation, is a useful alternative for determination of HER-2/neu amplification in paraffin-embedded tumor samples, especially for confirming the immunohistochemical staining results.     

HER-2/neu testing in breast carcinoma: a combined immunohistochemical and fluorescence in situ hybridization approach.

We evaluated 750 consecutive invasive breast carcinomas for HER-2/neu utilizing a combination of immunohistochemical (IHC) and fluorescence in situ hybridization (FISH) methodologies. IHC reactions of 3+ were considered HER-2/neu positive and 0 and 1+ IHC reactions were considered HER-2/neu negative. IHC reactions of 2+ were considered inconclusive and reflexed to FISH analysis. In addition, a 10% sampling and validation FISH analysis was performed on the positive and negative IHC tests. One hundred thirty-eight cases (18.4%) were HER-2/neu positive by IHC and/or FISH. One hundred twenty-three of the positive cases (89%) were 3+ IHC reactions and 14 positive cases were inconclusive by IHC and amplified by FISH. There was concordance with FISH in 77 of 78 (98.7%) of the positive or negative IHC cases that were tested (95% confidence interval [CI] = 93.1 to 100%). A single IHC-negative case showed HER-2/neu amplification by FISH. Thirty-nine cases were 2+ IHC (5.2%); 14 (36%) were amplified, 24 (62%) were not amplified, and one was not interpretable. HER-2/neu positivity was observed in 34% of grade 3 ductal carcinomas, 11.4% of grade 2 ductal carcinomas, 3.2% of grade 1 ductal carcinomas, and 3.2% of lobular carcinomas. Occasional cases with discordant IHC expression of HER-2/neu within the in situ and invasive carcinoma elements were also identified. IHC reliably characterized HER-2/neu in approximately 95% of the cases studied (95% CI = 93.0 to 96.2%) and was effective as a primary method for evaluating HER-2/neu status. In this study, 2+ IHC reactions were a heterogeneous group best regarded as indeterminate or inconclusive; in this series, only 36% were amplified by FISH analysis. Our findings suggest that a combination of IHC and FISH testing with FISH analysis performed reflexly on all 2+ IHC cases can optimize HER-2/neu testing.     

Examination of the increased speed of detection of HER-2/neu gene amplification in breast cancer by fluorescence in situ hybridization (FISH) using image analysis software

The time required to count signals in the detection of HER-2/neu gene amplification in breast cancer by fluorescence in situ hybridization (FISH) has been a problem. To assess whether the amount of time necessary for counting could be reduced, image analysis using computer software (Win ROOF) was tested. Five photographs from each FISH sample were arranged into ten composite photographs. All ten composite photographs were necessary when using the conventional method of manual counting. However, using only four of the composite photographs and the image analysis method, the 60 necessary nucleus numbers could be measured, and a constant ratio of HER-2/neu / CEP 17 was obtained. In all 58 samples used, in the presence or absence of HER-2/neu gene amplification, there was agreement in counts between the conventional and image analysis methods, and a good correlation of r=0.961 (p<0.001) was obtained. Using the image analysis method, the necessary scoring time was reduced, particularly when the HER-2/neu gene had been amplified, where it was completed in about 1/4 of the time normally required. These results indicate that this image analysis method can be applied when using FISH in other areas of research, and may increase the speed of examination.     

Fluorescence in situ hybridization (FISH) for detection of HER-2/neu amplification in breast cancer: a multicenter portability study

Amplification and/or overexpression of HER-2/neu has been shown to be both a prognostic and predictive marker in breast cancer. Recent studies have also confirmed the efficacy of Herceptin (trastuzumab) as adjuvant therapy for patients with overexpression of HER-2/neu. Therefore, it is critical that precise and reproducible assays be used in the clinical laboratory setting for determination of the HER-2/neu status in patients with breast cancer. The objective of this study was to determine the portability (reproducibility between different institutions) of the PathVysion HER-2 fluorescence in situ hybridization (FISH) assay used for detection of amplification of the HER-2/neu gene in formalin-fixed, paraffin-embedded tissue sections of invasive ductal carcinoma of the breast. Study specimens consisted of one breast tumor with a normal HER-2/neu copy number, two tumors with a low level, and one tumor with a high level of HER-2/neu amplification. The PathVysion HER-2 assay was shown to be highly reproducible on different assay days (n = 3) and between different institutions (n = 5) in the detection of amplification of the HER-2/neu gene in routinely processed clinical specimens of breast carcinoma. In addition, this study examined the feasibility of enumerating FISH signals in 20 nuclei in contrast to 60 nuclei per specimen. Although a modest increase in variation was observed when analyzing 20 compared to 60 nuclei, the mean ratios were similar. Therefore, analysis of as few as 20 nuclei with this FISH HER-2/neu assay may be sufficient for determining the amplification level of the HER-2/neu gene.     

Fluorescence in situ hybridization and immunohistochemical assays for HER-2/neu status determination: application to node-negative breast cancer

BACKGROUND: HER-2/neu (ERBB2) gene amplification and/or overexpression is a major event in human breast tumorigenesis. HER-2/neu gene alterations have been the most frequently assessed prognostic factors during the last 10 years in breast cancer and have recently emerged as a management decision tool and a therapeutic target. There is still controversy over the best method to determine whether a tumor is HER-2/neu positive. Because of the increasing demand for HER-2/neu gene status determination in clinical practice, we compared HER-2/neu gene alterations at the DNA level (gene amplification) and the protein level (overexpression) in a panel of patients with lymph node-negative breast cancer who had received local radiotherapy alone, with no adjuvant therapy. METHODS: We tested 100 excised lymph node-negative breast tumors, using fluorescence in situ hybridization (FISH) with a biotinylated HER-2/neu DNA probe and immunohistochemical assays (IHC) with 2 different antibodies. RESULTS: The FISH frequency of HER-2/neu gene amplification was 15%, and the IHC frequency of overexpression was 21%. CONCLUSION: Although HER-2/neu amplification by FISH and HER-2/neu overexpression by IHC correlated well in this panel of lymph node-negative breast carcinomas, there were a number of discordant cases, pointing to the important need for determining HER-2/neu alteration for the future management of HER-2/neu-based clinical applications.     

HER-2/neu oncogene amplification by fluorescence in situ hybridization in epithelial tumors of the ovary

HER-2/neu gene amplification and protein overexpression have been associated with prognosis in breast, lung and prostate cancers but have not been extensively studied in ovarian carcinoma. For the study, we selected 5-micron-thick, formalin-fixed, paraffin-embedded tissue sections from 74 cases of ovarian epithelial tumors of low malignant potential and ovarian carcinoma. Tumors were graded and staged and evaluated for amplification of the HER-2/neu gene by fluorescence in situ hybridization. HER-2/neu amplifications was present in 3 of 13 serous, mucinous, and endometrioid epithelial tumors of low malignant potential and in 40 of 61 epithelial carcinomas. In the carcinoma group, amplification did not correlate with stage, grade, or tumor type. Mean follow-up was 31 months; 1 patient with a low malignant potential tumor and 32 patients with carcinomas died of disease. On univariate and multivariate analysis, survival correlated with stage of disease but not with HER-2/neu amplification. HER-2/neu amplification by fluorescence in situ hybridization can be performed on tissue sections of ovarian neoplasms; amplification is uncommon in ovarian tumors of low malignant potential, but is present in 66% of ovarian epithelial carcinomas. HER-2/neu amplification did not predict outcome in ovarian epithelial neoplasia but may have an important role in tumor development.     

Fluorescence in situ hybridization analysis of HER-2/neu, c-myc, and p53 in endometrial cancer

Our objective was to evaluate the association between HER-2/neu, c-myc, p53, and clinicopathologic variables in endometrial cancer using fluorescence in situ hybridization (FISH) cytogenetic analysis. FISH analysis for HER-2/neu, c-myc, and p53 was performed on 47 endometrial cancer specimens. Amplification of HER-2/neu was seen in 4/47 (8.5%) cases and amplification of c-myc was seen in 7 of 47 (15%) cases; neither was associated with adverse clinicopathologic variables or survival. Deletion of p53 was seen in 31/47 (66%) cases and was associated with poor histologic grade (P = 0.008). There was no impact of genetic alterations on overall survival or disease-free interval. Grade 3 tumor was associated with poor overall survival (P = 0.032). This study found that p53 deletion is a common genetic alteration in endometrial cancer and is associated with poor-grade tumors.     

HER-2/neu gene amplification in breast imprint cytology analyzed by fluorescence in situ hybridization: direct comparison with companion tissue sections

Fluorescence in situ hybridization (FISH) is a validated method for detection of HER-2/neu gene amplification and was recently approved by the FDA for diagnostic use in paraffin-embedded tissue. Its use in cytologic specimens, however, has not been investigated. To see whether HER-2/neu gene amplification is detectable in cytologic specimens, we examined touch imprints and corresponding tissue sections of 27 breast carcinomas (20 invasive and 7 in situ) and 3 atypical epithelial hyperplastic lesions, using the FISH technique with the HER-2/neu DNA probe kit (Vysis, Inc., Downers Grove, IL). HER-2/neu gene amplification was determined, using the ratio of HER-2/neu:CEP 17 signal counts; a ratio of 2.0 or greater was considered amplified. Successful hybridization occurred in 55/60 (92%) slides. In all cases, at least one of the paired slides was adequate for evaluation. Whole-cell imprint and tissue section slides yielded comparable HER-2/neu:CEP 17 signal counts and ratios, including one case of low-level HER-2/neu gene copy numbers where the ratio was 2.0. Our findings indicate that whole-cell imprint cytology preparations are a reliable medium for HER-2/neu gene quantification by FISH, and may substitute for or complement tissue section analysis.     

Fluorescence in situ hybridization study of HER-2/neu oncogene amplification in prostate cancer.

Prostate cancer is a serious disease affecting men worldwide and treatment compromises the quality of life of prostate cancer patients. We conducted a study of 88 cases of prostate cancer in an attempt to identify prognostic biomarkers that can distinguish aggressive cases that must be treated immediately. HER-2/neu oncogene amplification was initially studied because amplification of this gene has been reported in many other cancers, including those studied in this laboratory. Fluorescence in situ hybridization (FISH) using a HER-2/neu gene probe with a chromosome 17 centromere control probe was performed on formalin-fixed, paraffin-embedded tissues. Of a total of 86 cases successfully analyzed, only 8 (9.3%) were found to be amplified. This frequency was lower than the frequency of amplification found in other cancers studied. Furthermore, no case was found where the level of amplification can be considered high. Only one case was found to have moderate amplification. The rest of the positive cases can all be classified as low amplification. Thus, while we have demonstrated that FISH is a sensitive technique for detecting oncogene amplification, the frequency and level of HER-2/neu amplification detected in prostate cancer seem to be lower than those in most cancers that we studied. In view of the fact that HER-2/neu amplification does not seem to play as significant a role, exploration of other biomarkers in prostate cancer is warranted.     

Fluorescence in situ hybridization analysis of HER-2/neu in brushings of normal oral mucosa

Oncogene alterations have been clearly demonstrated to be related to the carcinogenesis and progression of oral squamous cell carcinoma (OSCC). However, the analysis of these alterations for screening and early diagnostic purposes generally requires invasive techniques for surgical removal of pathological epithelium. The aim of the present study was to assess the feasibility of fluorescence in situ hybridization (FISH) analysis of HER-2/neu amplification in oral mucosa brushings and to compare the HER-2/neu status with the history and smoking and drinking habits of healthy subjects. Cells obtained by centrifugation of oral brushings from 21 subjects (overall no. of cells: 5125) were suspended in physiological saline and fixed onto two slides for cytological evaluation and FISH analysis (dual-target, dual-color fluorescence assay) of the HER-2/neu gene and CEP17 centromere. A mean of 89.8% of the cells showed two HER-2/neu signals and a mean of 94% had two CEP17 signals at fluorescent microscopy. Finally, a mean of 96% of cells with HER-2/neu / CEP17 had a ratio equal to 1. No association between smoking and drinking habits, age and the HER-2/neu and CEP17 characteristics evaluated by FISH was found.     

HER-2/neu oncogene expression and DNA ploidy analysis in breast cancer

This study was performed to evaluate the correlation between HER-2/neu gene expression and DNA ploidy patterns. Forty-five cases of breast-cancer were analyzed. Immunohistochemical staining of HER-2/neu protein on frozen sections was used to detect the HER-2/neu protein, and the Feulgen DNA staining method was used to assess DNA amounts in the same tumor cells. Positive HER-2/neu overexpression was evaluated visually, and quantitation of the HER-2/neu protein was measured by image analysis. Twenty-two of the 45 cases were visually scored to be positive for the overexpression of the HER-2/neu protein, and these cases also contained above 10% HER-2/neu protein compared with a standard control cell line. All 22 of these cases had near-tetraploid DNA content. In contrast, cells, derived from the 23 cases that did not overexpress the HER-2/neu protein, contained DNA amounts that ranged from euploid (diploid) to varying degrees of aneuploid. The results of this study indicated that tumors that overexpress the HER-2/neu protein have tetraploid or near-tetraploid DNA content. This pattern could relate to the biological behavior of these tumors.     

Detection of c-erbB-2 (HER-2/neu) amplification in breast carcinoma by fluorescence in situ hybridization on tissue sections and imprinted cells

Abnormalities in c-erbB-2 have attracted a great deal of attention. Treatment using an antibody against the c-erbB-2 gene product is effective against breast cancers with amplification and/or overexpression of c-erbB-2. There is an urgent need to establish methodology for selecting patients who would benefit from this therapy. A total of 235 breast carcinomas were examined for c-erbB-2 protein overexpression by immunohistochemistry. Tissue sections with discernible immunostaining from 52 tumors, 70 negative tumors and smear imprints from 35 patients were examined by dual-color fluorescence in situ hybridization (FISH) using probes specific for c-erbB-2 and the centromeric region of chromosome 17. The concordance between gene amplification and protein overexpression was 95.7%. When the findings of the two FISH preparation techniques were compared, no discrepancies were found in 24 of the tumors. However, differences were seen in eight cases. In six of these cases the differences did not affect the presence or absence of amplification, but in the other two cases, considered to show low-level amplification on paraffin sections, polysomy 17 was detected instead. It was concluded that FISH is an excellent tool to detect gene amplification in particular, and FISH on touch imprints is a useful adjunct to differentiate between low-level amplification and polysomy 17.     

Analysis of HER-2/neu amplification in endometrial carcinoma by chromogenic in situ hybridization. Correlation with fluorescence in situ hybridization, HER-2/neu, p53 and Ki-67 protein expression, and outcome.

Fluorescence in situ hybridization (FISH) is the most widely used technique to detect HER-2/neu gene amplification; however, it is only available in some institutions. In contrast, chromogenic in situ hybridization (CISH) can be evaluated by routine light microscopy. In endometrial carcinoma there are few data concerning HER-2/neu status and prognosis. Therefore, we determined HER-2/neu gene status by CISH using a digoxigenin-labelled probe on 60 formalin-fixed paraffin-embedded endometrial carcinomas. The data were compared with the immunohistochemistry of HER-2/neu (A0485, TAB250), p53, Ki-67, clinicopathological factors, and survival. By conventional light microscopy, HER-2/neu amplification (>/=6 copies >50% cancer cells) was detected in 14% (8/59) tumours, HER-2/neu overexpression (>10% cells moderate/strong complete membrane staining) in 22% (13/60) for A0485, and 18% (11/60) for TAB250, p53 (>10% +cells) in 61% (36/59), and Ki-67 (>50% +cells) in 50% (30/60). Discordant cases for CISH and immunohistochemistry, as well as all (2+) were further analysed by FISH (Vysis). Among 10 cases (2+) and not amplified by CISH, two showed low-level amplification by FISH. Significant correlation was found between amplification and protein overexpression (P相似文献   

Contribution of fluorescence in situ hybridization to immunohistochemistry for the evaluation of HER-2 in breast cancer

The main focus of the present study was to assess the efficacy of interphase cytogenetics using fluorescence in situ hybridization (FISH) as a valid alternative to immunohistochemistry (IHC) in paraffin-embedded tissue sections and/or the efficacy of the combination of the two methods, while, at the same time, aiming to provide additional information on the use of the two methods. For this study, selected breast cancer patients (n=66) were tested for HER-2 gene amplification by FISH. The probe contains DNA sequences specific for the HER-2 human gene locus and hybridizes to the 17q11.2 through q12 region of human chromosome 17. The same samples were tested previously for HER-2 overexpression by two monoclonal antibodies (300G9 and CB11), recognizing an extracellular and an internal domain of gp185(Her-2), respectively. HER-2 overexpression also was evaluated using the HerceptTest Kit (Dako, Milan, Italy). The HerceptTest was performed according to the manufacturer's standard procedures, and results were scored on a 0 to 3+ scale. A total of 34 (51%) of 66 breast tumors enrolled in this study were positive by FISH. Of the 34 cases amplified by FISH, 9 were negative by IHC using both monoclonal antibody (MoAb) 300G9 and MoAb CB11, with a concordance rate from 80.3% to 83.3%. A higher concordance was verified (92.4%) when we used the HerceptTest Kit. Of the 32 cases found negative with the HerceptTest, FISH analysis identified HER-2 gene amplification in more than 10%. Our results indicate that with the combined use of both methods, several amplified samples classified negative by IHC can be used thus improving therapeutic planning for specific therapy with the monoclonal antibody trastuzumab.     

HER-2/neu in breast cancer: interobserver variability and performance of immunohistochemistry with 4 antibodies compared with fluorescent in situ hybridization.

The immunohistochemistry (IHC) performance of 4 anti-HER-2/neu antibodies was compared with fluorescent in situ hybridization (FISH) analysis of HER-2/neu gene expression in breast cancer patients considered for Herceptin (Trastuzumab) therapy. Interobserver variability in IHC interpretation was measured. Formalin-fixed tissue was received from 24 provincial hospital laboratories. The following anti-Her-2 antibodies were used: DAKO A0485 (polyclonal), Novacastra CB11 (monoclonal), Zymed TAB250 (monoclonal), and DAKO HercepTest (polyclonal). Additional sections were analyzed by FISH (Vysis). Three pathologists blinded to FISH results independently interpreted invasive tumor cell membranous staining on a scale of 0 to +3. The HER-2/neu gene was considered amplified when the FISH signal ratio of HER-2/CEP-17 was > or =2.0. Blocks from all hospitals and of all ages were suitable for IHC and FISH analysis. No interlaboratory analysis variability was noted. The interobserver agreement (kappa) for stain intensity for each antibody was good for 0 and +3 but poor for +1 and +2. Reasonable concordance between IHC and FISH was found with three of the four antibodies. TAB250 was the most sensitive antibody. For the three pathologists, the IHC sensitivities and specificities compared with FISH using 0/+1 as negative and +2/+3 as positive were as follows: A0485, 63-84/95-98; CB11, 63-66/97-98; TAB-250, 82-100/94-95; HercepTest, 59-77/91-93. The positive and negative predictive values varied by stain intensity. Stain scores of 0 and +3 were highly predictive of gene status. Stain scores of +1 and +2 were not sufficiently predictive to classify cases as amplified versus nonamplified. IHC is a reasonable first test to assess HER-2/neu status in patients with breast cancer. For most cases, DAKO A0485, TAB250, and HercepTest adequately predicted gene status. In cases with stain intensity of +1 or +2, the interobserver agreement is poor, and the predictive value is unsatisfactory for clinical use. Additional testing, preferably with FISH, is recommended.     

Amplification of the c-erbB-2 (HER-2/neu) gene in gastric cancer cells. Detection by fluorescence in situ hybridization.

Amplification of the c-erbB-2 gene was examined in 120 gastric adenocarcinomas by dual-color fluorescence in situ hybridization (FISH) using probes for centromere 17 and the 17q11.2-12. The results were compared with Southern blot analysis and immunohistochemistry of c-erbB-2 overexpression. FISH was successful in 105 tumors, and the amplification was found in 19 tumors. FISH on 17 tumors revealed high-level amplification; in 15, the predominant cancer populations had amplified c-erbB-2 gene with the signals forming one or two clusters, indicating that the amplified gene was present in homogeneously staining regions. In two tumors, most cancer cells had multiple scattered c-erbB-2 signals, indicating that the amplicon was within double-minute chromosomes. The other two tumors had a few additional copies of the c-erbB-2 gene. Seventeen tumors had increased numbers of the gene probably due to polysomy 17, and sixty-nine tumors had no aberrations of chromosome 17. Immunohistochemically, distinct membrane staining was found only in the 17 tumors with the high-level amplification. It is concluded that, in gastric adenocarcinomas, high-level amplification produces the c-erbB-2 gene principally in homogeneously staining region form and occasionally in double-minute form and is thought to control the over-expression of the protein in the cytoplasmic membrane.     

Gold-facilitated in situ hybridization: a bright-field autometallographic alternative to fluorescence in situ hybridization for detection of Her-2/neu gene amplification

Fluorescence in situ hybridization (FISH) represents an excellent method for profiling gene amplification in situ, but correlation with tissue morphology is difficult because of dark-field visualization. Validation of a bright-field assay for assessment of HER-2/neu gene amplification was investigated. Streptavidin-Nanogold was used to generate bright-field gene copy signals using GoldEnhance gold-based autometallography, catalyzed reported deposition, and a biotin-labeled probe. One hundred cases of invasive breast carcinoma were evaluated for which FISH gene copy results, and mRNA and oncoprotein gene expression, were known. Autometallographic signals were qualitatively evaluable without the use of oil immersion microscopy. Results correlated well with indirect and direct label FISH. Autometallographic gold-based in situ hybridization represents a promising bright-field assay for the assessment of HER-2/neu gene amplification.