Topoisomerase IIalpha gene amplification in gastric carcinomas: correlation with the HER2 gene. An immunohistochemical, immunoblotting, and multicolor fluorescence in situ hybridization study

Expression of the Topoisomerase II Alpha (TOP2A) Gene in Lung Adenocarcinoma Cells and the Association with Patient Outcomes

Background

This study was carried out to analyze TOP2A expression in lung adenocarcinoma (LUAD) and to assess its value in clinical diagnosis and prognosis.

Material/Methods

The Cancer Genome Atlas (TCGA) database was used to study the relationship of TOP2A expression with the progression and prognosis of LUAD. For a further elucidation of the value of TOP2A in LUAD, the effect of TOP2A knockout on cell viability and related protein expression of LUAD cell line A549 in vitro was investigated by using RNA interference, MTT, flow cytometry, RT-PCR, and western blot analysis.

Results

According to the results of database analysis, TOP2A expression in LUAD was higher than that in normal lung tissues. There was a strong correlation of TOP2A expression with clinicopathological and epidemiological parameters of LUAD. The survival rate of LUAD patients with high TOP2A expression was lower than that of patients with low expression (P<0.001). The expression of TOP2A in A549 cells was higher than that in Beas-2B cells. After decreased expression of TOP2A in A549 cells, the proliferation of A549 cells was downregulated and the apoptosis rate was increased. It was further verified that TOP2A low expression exerts a role in LUAD through activation of the ERK/JNK/p-P38/CHOP signaling pathway.

Conclusions

The findings from this study showed that TOP2A expression was upregulated in a human lung adenocarcinoma cell line, and this finding was supported by bioinformatics analysis. Further studies are required to determine whether TOP2A expression is a prognostic biomarker and potential therapeutic target in patients with lung adenocarcinoma.

Screening key genes and signaling pathways in colorectal cancer by integrated bioinformatics analysis

The aim of the present study was to identify potential key genes associated with the progression and prognosis of colorectal cancer (CRC). Differentially expressed genes (DEGs) between CRC and normal samples were screened by integrated analysis of gene expression profile datasets, including the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis was conducted to identify the biological role of DEGs. In addition, a protein‑protein interaction network and survival analysis were used to identify the key genes. The profiles of GSE9348, GSE22598 and GSE113513 were downloaded from the GEO database. A total of 405 common DEGs were identified, including 236 down‑ and 169 upregulated. GO analysis revealed that the downregulated DEGs were mainly enriched in 'detoxification of copper ion' [biological process, (BP)], 'oxidoreductase activity, acting on CH‑OH group of donors, NAD or NADP as acceptor' [molecular function, (MF)] and 'brush border' [cellular component, (CC)]. Upregulated DEGs were mainly involved in 'nuclear division' (BP), 'snoRNA binding' (MF) and 'nucleolar part' (CC). KEGG pathway analysis revealed that DEGs were mainly involved in 'mineral absorption', 'nitrogen metabolism', 'cell cycle' and 'caffeine metabolism'. A PPI network was constructed with 268 nodes and 1,027 edges. The top one module was selected, and it was revealed that module‑related genes were mainly enriched in the GO terms 'sister chromatid segregation' (BP), 'chemokine activity' (MF), and 'condensed chromosome (CC)'. The KEGG pathway was mainly enriched in 'cell cycle', 'progesterone‑mediated oocyte maturation', 'chemokine signaling pathway', 'IL‑17 signaling pathway', 'legionellosis', and 'rheumatoid arthritis'. DNA topoisomerase II‑α (TOP2A), mitotic arrest deficient 2 like 1 (MAD2L1), cyclin B1 (CCNB1), checkpoint kinase 1 (CHEK1), cell division cycle 6 (CDC6) and ubiquitin conjugating enzyme E2 C (UBE2C) were indicated as hub genes. Furthermore, survival analysis revealed that TOP2A, MAD2L1, CDC6 and CHEK1 may serve as prognostic biomarkers in CRC. The present study provided insights into the molecular mechanism of CRC that may be useful in further investigations.

Heterogeneity of COX-2 and Multidrug Resistance between Primary Tumors and Regional Lymph Node Metastases of Gastric Cancer

Aims and background

Cyclooxygenase-2 (COX-2) is involved in the progression of gastric cancer; however, the role of COX-2 in multidrug resistance (MDR) is still unclear. This study aimed to elucidate the relationship between COX-2 and MDR so as to show the heterogeneity of gastric primary tumors and regional lymph node metastases.

Methods

Between 2008 and 2009, 56 primary tumor samples and paired metastatic lymph node tissues from gastric cancer patients confirmed by surgery and pathological examination in our hospital were collected. The expression levels of COX-2 and MDR-associated factors such as P-glycoprotein (P-gp), glutathione S-transferase pi (GST-π) and topoisomerase II alpha (Topo-II-α) were determined by immunohistochemical staining. Tumor cells from these tissues were cultured and the cell chemosensitivities for 11 chemotherapeutic agents were measured by sulforhodamine B assay.

Results

The expression levels of COX-2, P-gp and GST-π were significantly higher in metastatic lymph node tissues than in primary tumors, while the expression level of Topo-II-α was lower in metastatic lymph node tissues than in primary tumors (all P <0.05). In primary tumors, COX-2 and GST-π were positively correlated and COX-2 and Topo-II-α were negatively correlated; in metastatic lymph node tissues, a positive correlation was found between COX-2 and P-gp (all P <0.05). The inhibition rates of eADM, VP-16, THP and MMC on cells from primary tumors were significantly lower than those on cells from metastatic lymph nodes, while the inhibition rates of HCPT, L-OHP and VCR on cells from metastatic lymph nodes were lower than those on cells from primary tumors.

Conclusion

The expression of COX-2 and MDR-associated factors as well as cell chemosensitivities are different in primary tumors and regional lymph node metastases of gastric cancer, and this may be an indication of their heterogeneity.

Assessment of HER2 status in patients with gastroesophageal adenocarcinoma treated with epirubicin-based chemotherapy: heterogeneity-related issues and prognostic implications

BACKGROUND

HER2 and topoisomerase 2 alpha (TOP2A) genomic status was previously reported to predict benefit from anthracyclines in breast cancer. We sought to define the prognostic impact and possible pitfalls related to these biomarkers in resectable gastroesophageal adenocarcinoma.

METHODS

HER2 and TOP2A gene amplification by fluorescent in situ hybridization and HER2 protein expression by immunohistochemistry (IHC) were assessed on whole tissue sections from 101 patients receiving peri- or postoperative epirubicin-based chemotherapy. In a subgroup of patients, at least two matched tumor blocks, originating either from surgical procedures (n = 88) or diagnostic biopsies (n = 32), were available for HER2 analyses by IHC.

RESULTS

Eighteen of 101 patients (17.8 %) were HER2 positive, whereas TOP2A was amplified in 4 of 84 patients (4.7 %). HER2 positivity was significantly associated with improved disease-free survival [HR = 0.47 (95 % CI 0.22-0.99), P = 0.046] and overall survival [HR = 0.33 (95 % CI 0.13-0.83), P < 0.018], independent of clinical-pathologic features. HER2 expression in matched tumor blocks from the same resection specimen was discordant in up to 11.8 % of pairs, while this rate increased up to 27.2 % when diagnostic biopsies and paired surgical samples were compared.

CONCLUSIONS

HER2 status is an independent prognostic biomarker in gastroesophageal adenocarcinomas receiving epirubicin-based chemotherapy. Compared to diagnostic biopsies, HER2 assessment in multiple resection specimens might lower the risk of sampling errors. These findings have several implications with respect to the optimal choice of the sample to be submitted to IHC testing of HER2.

Association of Topoisomerase II (TOP2A) and Dual-Specificity Phosphatase 6 (DUSP6) Single Nucleotide Polymorphisms with Radiation Treatment Response and Prognosis of Lung Cancer in Han Chinese

Background

Mutations of DNA topoisomerase II (TOP2A) are associated with chemotherapy resistance, whereas dual-specificity phosphatase 6 (DUSP6) negatively regulates members of the mitogen-activated protein (MAP) kinase superfamily to control cell proliferation. This study assessed TOP2A and DUSP6 single nucleotide polymorphisms (SNPs) in non-small cell lung cancer (NSCLC) patients for association with chemoradiotherapy responses and prognosis.

Material/Methods

A total of 140 Chinese patients with histologically confirmed NSCLC were enrolled and subjected to genotyping of TOP2A rs471692 and DUSP6 rs2279574 using Taqman PCR. An independent sample t test was used to analyze differences in tumor regression after radiotherapy versus SNP risk factors. Kaplan-Meier curves analyzed overall survival, followed by the log-rank test and Cox proportional hazard models.

Results

There were no significant associations of TOP2A rs471692 and DUSP6 rs2279574 polymorphisms or clinicopathological variables with response to chemoradiotherapy (p>0.05). Comparing overall survival of 87 patients with stage I–III NSCLC treated with radiotherapy or chemoradiotherapy to clinicopathological variables, the data showed that tumor regression, weight loss, clinical stage, and cigarette smoking were independent prognostic predictors (p=0.009, 0.043, 0.004, and 0.025, respectively). Tumor regression rate >0.34 was associated with patent survival versus tumor regression rate ≤0.34 (p=0.007).

Conclusions

TOP2A rs471692 and DUSP6 rs2279574 SNPs were not associated with chemoradiotherapy response, whereas tumor regression, weight loss, clinical stage, and cigarette smoking were independent prognostic predictors for these Chinese patients with NSCLC.

TOP2A copy number and TOP2A expression in uterine benign smooth muscle tumours and leiomyosarcoma

AIMS

To examine TOP2A copy number, TOP2A expression, and its prognostic value in uterine leiomyosarcoma (LMS) and other benign smooth muscle tumours.

METHODS

We analysed 37 patients treated for uterine LMS with immunohistochemistry for protein expression and fluorescence in situ hybridisation (FISH) for copy number. Twelve cases of leiomyoma variants (LMVs), 4 smooth muscle tumours of uncertain malignant potential (STUMP) and 23 leiomyomas (LMs) were also included.

RESULTS

Eighteen patients with LMS (48.6%) were International Federation of Gynecology and Obstetrics (FIGO) stage I, six (16.2%) were stage II, four (10.8%) were stage III, and nine (24.3%) were stage IV. Twenty-one (56.8%) patients with LMS showed high expression of TOP2A. Greater TOP2A levels were found in patients with stage ≥II disease compared with stage I and also in high mitotic index tumours (>20/10 HPF (high power field)). Eleven (36.7%) cases had abnormal TOP2A copy numbers. There was no link between TOP2A copy number and TOP2A expression. All patients with benign smooth muscle tumours had low TOP2A immunohistochemical expression and one (7.7%) patient had TOP2A amplification. TOP2A expression and TOP2A copy number had no impact on disease outcomes. Only the presence of disease outside of the uterus negatively impacted survival compared with early disease (53.4 vs 15.8 months; p<0.001).

CONCLUSIONS

TOP2A is highly expressed in advanced LMS but not in non-malignant diseases. TOP2A expression does not correlate with FISH results and does not predict outcome. TOP2A levels are higher in high-mitotic index tumours and in more advanced stages of disease.

Evaluation of HER2 by automated FISH and IHC in gastric carcinoma biopsies

PURPOSE

The use of trastuzumab (Herceptin) to target HER2 has been applied in breast carcinoma and gastric carcinoma (GC). Previous studies have tested trastuzumab's effectiveness by assessing HER2 expression or HER2 amplification by means of immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). In this work we aimed to evaluate automated FISH and IHC technologies for HER2 detection in GC biopsies to be used in routine pathology practice.

METHODS

The study used an Oracle HER2 IHC System and an LSI HER2/CEP17 Dual Probe on an automated Bond system (Leica Microsystems). One hundred GC biopsies were evaluated including 44 intestinal type, 38 diffuse type and 18 indeterminate type according to Lauren's classification.

RESULTS

The overall concordance rate between the automated FISH and IHC methods was 94% (κ = 0.87), as 6 samples were scored as equivocal (4 in IHC and 2 in FISH). Moreover, HER2 positivity was significantly different between the 3 types of GC (p<0.05), being more frequent in intestinal-type GC (23%) than in the other 2 histological types (5% and 0%). Finally, the HER2/CEP17 FISH ratio was significantly different (p<0.01) between disomic and polysomic samples, being higher in polysomic samples (mean 1.633 ± 0.509) than in disomic samples (mean 1.231 ± 0.675).

CONCLUSIONS

Automated HER2 testing of GC biopsies using the Leica Bond system was useful and efficient. This method allowed us to improve normal routine procedures, minimizing time and costs as well as handling and observation errors.

Multiplex Ligation-dependent Probe Amplification Can Clarify HER2 Status in Gastric Cancers with "Polysomy 17"

Therapy with trastuzumab confers a survival benefit in HER2 positive advanced gastric and gastroesophageal adenocarcinoma. HER2 status is evaluated by immunohistochemistry (IHC) and in situ hybridization (ISH). An ISH ratio of HER2 to centromere 17 (CEP17) ≥2.0 is considered amplified. This assumes that CEP17 reflects chromosomal copy number. Cases where CEP17 exceeds 3 are classified as polysomic, but it's unknown if they represent true polysomy or centromeric amplification. This has implications on the validity of current ISH criteria. Multiplex ligation-dependent probe amplification (MLPA) allows simultaneous quantification of multiple loci and can distinguish between true polysomy and centromeric amplification. We selected 13 gastric cancers with CEP17 counts ≥3.0 (polyCEP17), and 8 non-polyCEP17 gastric cancer controls. Silver ISH for HER2 and CEP17 were performed and scored by manufacturer guidelines. We also performed an MLPA HER2 assay that evaluates 22 genes on chromosome 17. MLPA identified HER2 amplification in 7 polyCEP17 cases compared to 2 identified by ISH. Overall, 9 of 13 polyCEP17 cases had amplification of the peri-centromeric gene WSB1, compared to 1 of 8 non-polyCEP17 controls (p=0.02). This could account for ISH CEP17 counts ≥3.0. MLPA did not show any cases of complete chromosome 17 duplication and peri-centromeric amplification can explain most cases of ISH polyCEP17. Current ISH criteria may under-diagnose HER2 amplification in polyCEP17 cases due to flawed assumptions about polysomy. MLPA can detect HER2 amplification missed by IHC and ISH, and thus may be an effective ancillary technique in evaluating HER2 status.

TOP2A amplification and overexpression in hepatocellular carcinoma tissues

Hepatocellular carcinoma (HCC) is the leading cause of cancer death in men worldwide owing to limited insights into pathogenesis and unsatisfactory efficacy of current therapies. HER2 and TOP2A genes are coamplified in breast and some other cancers. In this study, we investigated gene aberrations of HER2 and TOP2A and protein expressions of HER2, TOP2A, Ki-67, and p53 in tumor and matched nontumor tissues, as well as their associations with clinicopathological features. Gene aberrations were evaluated by FISH and protein expressions by IHC. Neither HER2 overexpression nor HER2 gene amplification was observed in both tumor tissues and matched nontumor tissues. By contrast, TOP2A overexpression was detected in 72.5% of tumor tissues but not detected in matched nontumor tissues. However, TOP2A gene amplification was not observed in both tumor and matched nontumor tissues. TOP2A overexpression was significantly associated with HCC tumor tissues (P < 0.001), hepatitis B surface antigen (HBsAg) in the serum (P = 0.004), and Ki-67 (P = 0.038) but not with age, tumor size, alpha-fetoprotein, TP53, and copy number of TOP2A gene and chromosome 17 centromere. In conclusion, TOP2A overexpression in HCC was not secondary to gene amplification. In addition, neither HER2 amplification nor overexpression could be used as prognostic and predictive marker in HCC.

High-level copy number gains of established and potential drug target genes in gastric cancer as a lead for treatment development and selection

PURPOSE

The overall survival rate of patients with advanced gastric cancer is poor. Therefore, there is an urgent need for new treatment options for these patients. The identification of drug target genes located on DNA regions exhibiting high-level copy number gains (CNG) may be an effective approach, as has e.g. previously been shown for HER2. The aim of the present study was to identify putative drug targets in patients with gastric cancer by applying this strategy.

METHODS

Genome-wide array comparative genomic hybridization (array CGH) data available from 183 primary gastric cancer samples were analyzed through Ingenuity Pathway Analysis (IPA) to assess whether any established or potential anticancer drug target genes showed high-level CNG, including focal amplifications.

RESULTS

A total of 147 high-level gained regions were identified in the gastric cancer samples, harboring 167 genes that had previously been annotated as drug target genes. Thirty (18 %) of these genes showed high-level gains in at least 2 % of the tumors. The identified drug target genes included those for drugs known to be active in advanced (gastric) cancer, targets for targeted therapies in clinical development, as well as targets for drugs currently used for other indications but of potential interest for anticancer treatment. In addition, 12 potential drug target genes were identified, including genes involved in growth factor signaling and cell cycle regulation.

CONCLUSION

The majority of gastric cancers carried one or more high-level CNGs or focal amplifications encompassing putative drug target genes. A number of the associated drugs are currently not being considered for treatment of gastric cancer. Based on these results we hypothesize that DNA copy number profiling may be a useful tool to identify new drug targets and to guide individualized treatment strategies in patients with gastric cancer.

Level of HER2 gene amplification predicts response and overall survival in HER2-positive advanced gastric cancer treated with trastuzumab

PURPOSE

Previous studies have highlighted the importance of an appropriate human epidermal growth factor receptor 2 (HER2) evaluation for the proper identification of patients eligible for treatment with anti-HER2 targeted therapies. Today, the relationship remains unclear between the level of HER2 amplification and the outcome of HER2-positive gastric cancer treated with first-line chemotherapy with trastuzumab. The aim of this study was to determine whether the level of HER2 gene amplification determined by the HER2/CEP17 ratio and HER2 gene copy number could significantly predict some benefit in overall survival and response to therapy in advanced gastric cancer treated with trastuzumab-based chemotherapy.

PATIENTS AND METHODS

Ninety patients with metastatic gastric cancer treated with first-line trastuzumab-based chemotherapy were studied. The optimal cutoff values for HER2/CEP17 ratio and HER2 gene copy number (GCN) for discriminating positive results in terms of response and prolonged survival were determined using receiver operating characteristic curves analyses.

RESULTS

In this study, a median HER2/CEP17 ratio of 6.11 (95% CI, 2.27 to 21.90) and a median HER2 gene copy number of 11.90 (95% CI, 3.30 to 43.80) were found. A mean HER2/CEP17 ratio of 4.7 was identified as the optimal cutoff value discriminating sensitive and refractory patients (P = .005). Similarly, the optimal cutoff for predicting survival longer than 12 months was 4.45 (P = .005), and for survival longer than 16 months was 5.15 (P = .004). For HER2 GCN, the optimal cutoff values were 9.4, 10.0, and 9.5, respectively (P = .02).

CONCLUSION

The level of HER2 gene amplification significantly predicts sensitivity to therapy and overall survival in advanced gastric cancer treated with trastuzumab-based chemotherapy.

Intratumoral heterogeneous amplification of ERBB2 and subclonal genetic diversity in gastric cancers revealed by multiple ligation-dependent probe amplification and fluorescence in situ hybridization

A humanized monoclonal antibody against ERBB2 is used in neoadjuvant therapy for patients with gastric cancer. A critical factor in determining patient eligibility and predicting outcomes of this therapy is the intratumoral heterogeneity of ERBB2 amplification in gastric adenocarcinomas. The aims of this study are to assess the underlying mechanisms of intratumoral heterogeneity of ERBB2 amplification; to characterize the diversity of coamplified oncogenes such as EGFR, FGFR2, MET, MYC, CCND1, and MDM2; and to examine the usefulness of multiple ligation-dependent probe amplification (MLPA) in the semicomprehensive detection of these gene amplifications. A combined analysis of immunohistochemistry and fluorescence in situ hybridization revealed ERBB2-amplified cancer cells in 51 of 475 formalin-fixed, paraffin-embedded gastric adenocarcinomas. The fraction of amplification-positive cells in each tumor ranged from less than 10% to almost 100%. Intratumoral heterogeneity of ERBB2 amplification, defined as less than 50% of cancer cells positive for ERBB2 amplification, was found in 41% (21/51) of ERBB2-amplified tumors. The combined analysis of MLPA and fluorescence in situ hybridization revealed that ERBB2 was coamplified with EGFR in 7 tumors, FGFR2 in 1 tumor, and FGFR2 and MET in 1 tumor; however, the respective genes were amplified in mutually exclusive cells. Coamplified ERBB2 and MYC coexisted within single nuclei in 4 tumors, and one of these cases had suspected coamplification in the same amplicon of ERBB2 with MYC. In conclusion, the amplification status of ERBB2 and other genes can be obtained semicomprehensively by MLPA and could be useful to plan individualized molecularly targeted therapy against gastric cancers.

TOP2A overexpression as a poor prognostic factor in patients with nasopharyngeal carcinoma

Despite the advances in diagnostic imaging and treatment modalities, the risk stratification and final outcomes in patients with nasopharyngeal carcinomas (NPC) still remain suboptimal. Through data mining from published transcriptomic database, topoisomerase IIα (TOP2A) was first identified as a differentially upregulated gene in NPC tissues, which implicates cell division via selective cleavage, rearrangement, and re-ligation of DNA strands. Given the roles of TOP2A in prognostication and in the frontline therapeutic regimen of common carcinomas, such as breast cancer, we explored TOP2A immunoexpression status and its associations with clinicopathological variables and survival in a well-defined cohort of NPC patients. TOP2A immunohistochemistry was retrospectively performed and analyzed using H-score method for biopsy specimens from 124 NPC patients who received standard treatment without distant metastasis at initial diagnosis. Those cases with H-score larger than the median value were construed as featuring TOP2A overexpression. The findings were correlated with the clinicopathological variables, disease-specific survival (DSS) and distant metastasis-free survival (DMFS). TOP2A overexpression was significantly associated with American Joint of Cancer Committee (AJCC) stages III-IV (p = 0.019) and univariately predictive of adverse outcomes for DSS (p = 0.0078) and DMFS (p = 0.0003). In the multivariate comparison, TOP2A overexpression remained prognostically independent to portend worse DSS (p = 0.047, hazard ratio = 1.732) and DMFS (p = 0.003, hazard ratio = 2.569), together with advanced AJCC stages III-IV. TOP2A expression is upregulated in a subset of NPCs and its increased immunoexpression significantly correlated with advanced stages and tumor aggressiveness, justifying the potentiality of TOP2A as a prognostic biomarker and a novel therapeutic target of NPC.

HER2 in gastric cancer: a digital image analysis in pre-neoplastic, primary and metastatic lesions

The assessment of human epidermal growth factor receptor 2 (HER2) status in gastric cancer is crucial in selecting patients who may benefit from targeted therapy, yet heterogeneous expression could represent an important drawback for HER2 testing. We aimed to analyze (i) HER2 heterogeneity in primary gastric cancers, pre-neoplastic and metastatic lesions and (ii) HER2 prognostic role. We studied 292 surgically resected primary gastric carcinomas and constructed 21 tissue microarrays including tumor tissue cores, invasive front, paired lymph node metastasis, low- and high-grade dysplasia. Microarrays were immunohistochemically stained with HER2 antibody and digitally scanned. Novel digital analysis algorithms were developed to score HER2 expression. Fluorescence in situ hybridization was performed on equivocal cases. HER2-positive cases were 13% and heterogeneous HER2 expression was observed in 71% of positive samples. Analysis of HER2 status in tumor and tumor invasive front demonstrate concordance in 177 cases (88%). Comparison of HER2 expression in primary cancer and synchronous lymph node metastasis exhibited discordant status in 14% of cases. Dysplastic epithelium surrounding the tumor showed immunohistochemical score 2 or 3 in 19% of high-grade and in 9% of low-grade dysplastic samples. HER2 status was significantly associated with intestinal-type carcinomas (P=0.018) and prognosis since patients with primary HER2-positive tumor showed decreased overall survival (P=0.006). Intratumoral HER2 expression heterogeneity and variable lymph node metastases status strongly suggest evaluating more than one sample and, if available, metastatic foci for routinely HER2 testing.

Prognostication of prostate cancer based on TOP2A protein and gene assessment: TOP2A in prostate cancer

Background

TOP2A encodes for topoisomerase IIα, a nuclear enzyme that controls DNA topological structure and cell cycle progression. This enzyme is a marker of cell proliferation in normal and neoplastic tissues; however, little information is available about its expression in prostate cancer (PCa).

Methods

Immunohistochemistry (IHC) was automated using mouse monoclonal antibody against TOP2A (clone SWT3D1; DAKO, Carpenteria, CA, USA) at dilution 1:800 and Flex Plus detection system in autostainer 48Ultra (DAKO). FISH was performed using TOP2A (17q21)/ CEP17 probe kit (Kreateck Biotechnology, San Diego, CA, USA). Biochemical and pathological data from 193 patients with PCa were retrieved for the analysis, whose significance was considered when p < 0.05. Also, fractal analysis was performed in a subset of 20 randomly selected cases.

Results

TOP2A protein expression correlated with higher Gleason scores and higher levels of preoperative PSA (p = 0.018 and p = 0.011). Patients with higher levels of TOP2A presented shorter biochemical recurrence-free survival (BRFS) (p = 0.001). In multivariate analysis, we found that TOP2A remained an independent prognostic factor of BRFS, with a relative risk of 1.98 (p = 0.001; 95% CI, 1.338–2.93); thus, cases that expressed high levels of this enzyme had a shorter BRFS compared with TOP2A-negative or TOP2A-low cases. No alterations in TOP2A gene status nor correlation between FISH and IHC results were observed. Concerning fractal analysis, patients who expressed higher levels of TOP2A have angiolymphatic invasion and presented higher Gleason scores (p = 0.033 and p = 0.025, respectively). Also, patients with higher expression of TOP2A presented shorter BRFS (p = 0.001).

Conclusions

This is the first study to perform TOP2A protein and gene digital assessment and fractal analysis in association with BRFS in a large series of PCa. Also, we show that TOP2A gene copy number alterations are not observed in this type of tumor. So, higher protein expression of TOP2A is not related to gene amplification in PCa. Furthermore, TOP2A protein assessment has prognostic importance and, due to its relation with poor outcome, TOP2A IHC evaluation in the biopsy can represent an important tool for selecting the most suitable surgical and clinical approach for patients with PCa.

A clinical-biological risk stratification model for resected gastric cancer: prognostic impact of Her2, Fhit, and APC expression status

BACKGROUND

To obtain a prognostic stratification model for resected gastric cancer patients.

PATIENTS AND METHODS

Clinicopathological and molecular data (expression of Cdx2, Apc, β-catenin, E-cadherin, Fhit, p53, and human epidermal growth factor receptor-2 (Her2); HER2 and TOPO2A gene copy number; PIK3CA mutations; microsatellite instability) were correlated to cancer-specific/overall survival (CSS/OS) using a Cox model. Individual patient probability (IPP) was estimated by logistic equation. A continuous score to identify risk-classes was derived according to the model ratios.

RESULTS

Two-hundred eight patients were studied (median follow-up 20 months). At multivariate analysis, sex, stage, margins, location, nodes, Apc, and Fhit were independent predictors for CSS; the same factors (and age and Her2, except Fhit) predicted OS. Multivariate model predicted IPP with high prognostic accuracy (0.90 for CSS; 0.91 for OS). A two-class model significantly separated low- and high-risk patients for CSS (23.4% and 85.6%, P < 0.0001) and OS (21.4% and 82.0%, P < 0.0001). A three-class model differentiated low-, intermediate-, and high-risk patients for CSS (6.3%, 35.3%, and 88.0%, P < 0.0001) and OS (6.1%, 34.6%, and 86.5%, P < 0.0001).

CONCLUSIONS

A risk classification system comprising the immunohistochemical expression of three proteins (Apc, Fhit, and Her2) and five clinicopathological parameters (stage, resected nodes, margins, location, and sex) accurately separates the resected gastric cancer patients into three classes of risk.

A novel five gene signature derived from stem-like side population cells predicts overall and recurrence-free survival in NSCLC

Gene expression profiling has been used to characterize prognosis in various cancers. Earlier studies had shown that side population cells isolated from Non-Small Cell Lung Cancer (NSCLC) cell lines exhibit cancer stem cell properties. In this study we apply a systems biology approach to gene expression profiling data from cancer stem like cells isolated from lung cancer cell lines to identify novel gene signatures that could predict prognosis. Microarray data from side population (SP) and main population (MP) cells isolated from 4 NSCLC lines (A549, H1650, H460, H1975) were used to examine gene expression profiles associated with stem like properties. Differentially expressed genes that were over or under-expressed at least two fold commonly in all 4 cell lines were identified. We found 354 were upregulated and 126 were downregulated in SP cells compared to MP cells; of these, 89 up and 62 downregulated genes (average 2 fold changes) were used for Principle Component Analysis (PCA) and MetaCore™ pathway analysis. The pathway analysis demonstrated representation of 4 up regulated genes (TOP2A, AURKB, BRRN1, CDK1) in chromosome condensation pathway and 1 down regulated gene FUS in chromosomal translocation. Microarray data was validated using qRT-PCR on the 5 selected genes and all showed robust correlation between microarray and qRT-PCR. Further, we analyzed two independent gene expression datasets that included 360 lung adenocarcinoma patients from NCI Director's Challenge Set for overall survival and 63 samples from Sungkyunkwan University (SKKU) for recurrence free survival. Kaplan-Meier and log-rank test analysis predicted poor survival of patients in both data sets. Our results suggest that genes involved in chromosome condensation are likely related with stem-like properties and might predict survival in lung adenocarcinoma. Our findings highlight a gene signature for effective identification of lung adenocarcinoma patients with poor prognosis and designing more aggressive therapies for such patients.

Identification of novel candidate oncogenes in chromosome region 17p11.2-p12 in human osteosarcoma

Osteosarcoma is the most common primary malignancy of bone. The tumours are characterized by high genomic instability, including the occurrence of multiple regions of amplifications and deletions. Chromosome region 17p11.2–p12 is amplified in about 25% of cases. In previous studies, COPS3 and PMP22 have been identified as candidate oncogenes in this region. Considering the complexity and variation of the amplification profiles for this segment, the involvement of additional causative oncogenes is to be expected. The aim of the present investigation is to identify novel candidate oncogenes in 17p11.2–p12. We selected 26 of in total 85 osteosarcoma samples (31%) with amplification events in 17p11.2–p12, using quantitative PCR for 8 marker genes. These were subjected to high-resolution SNP array analysis and subsequent GISTIC analysis to identify the most significantly amplified regions. Two major amplification peaks were found in the 17p11.2–p12 region. Overexpression as a consequence of gene amplification is a major mechanism for oncogene activation in tumours. Therefore, to identify the causative oncogenes, we next determined expression levels of all genes within the two segments using expression array data that could be generated for 20 of the selected samples. We identified 11 genes that were overexpressed through amplification in at least 50% of cases. Nine of these, c17orf39, RICH2, c17orf45, TOP3A, COPS3, SHMT1, PRPSAP2, PMP22, and RASD1, demonstrated a significant association between copy number and expression level. We conclude that these genes, including COPS3 and PMP22, are candidate oncogenes in 17p11.2–p12 of importance in osteosarcoma tumourigenesis.

Human epidermal growth factor receptor-2 gene amplification in gastric cancer using tissue microarray technology

AIM: To assess human epidermal growth factor receptor-2 (HER2)-status in gastric cancer and matched lymph node metastases by immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH).

METHODS: 120 cases of primary gastric carcinomas and 45 matched lymph node metastases from patients with full clinicopathological features were mounted onto multiple-punch and single-punch tissue microarrays, respectively, and examined for HER2 overexpression and gene amplification by IHC and CISH.

RESULTS: Twenty-four tumors (20%) expressed HER2 immunohistochemically. An IHC score of ≥ 2+ was observed in 20 tumors (16.6%). HER2 amplification was detected by CISH in 19 tumors (15.8%) and in their matched lymph node metastases. A high concordance rate was found between HER2 positivity (as detected by IHC) and HER2 gene amplification (as detected by CISH), since 19 of the 20 IHC positive cases were amplified (95%). All amplified cases had 2+ or 3+ IHC results. Amplification was associated with intestinal phenotype (P < 0.05). No association with grading, staging or survival was found.

CONCLUSION: In gastric cancer, HER2 amplification is the main mechanism for HER2 protein overexpression and is preserved in lymph node metastases.

Hybridization for human epidermal growth factor receptor 2 testing in gastric carcinoma: a comparison of fluorescence in-situ hybridization with a novel fully automated dual-colour silver in-situ hybridization method

Aims:

Amplification of the human epidermal growth factor receptor 2 (HER2) gene has been reported in gastric carcinoma (GC). Accordingly, trastuzumab plus chemotherapy has recently become the new standard treatment for HER2-positive advanced GCs. The aim was to compare the alleged gold standard for hybridization [fluorescence in-situ hybridization (FISH)] with a novel, fully automated brightfield dual-colour silver-enhanced in-situ hybridization (SISH) method.

Methods and results:

The studies series was comprised of 166 GC samples. Additionally, tumours with discordant results obtained by FISH and SISH were analysed by real-time quantitative polymerase chain reaction (PCR) with the LightMix kit HER-2/neu. Of the samples, 17.5% and 21% were amplified by FISH and SISH, respectively. Heterogeneity was identified in up to 52% of cases. In 96.4% of cases, FISH showed the same results as SISH. All six discordant cases were positive by SISH and negative by FISH. On review of the FISH slides, all contradictory cases were polysomic and were confirmed to be negative for amplification by real-time PCR. Interestingly, all ratios in this latter group were between 2.06 and 2.50, so setting the cut-off for amplification at ≥3 resulted in perfect concordance.

Conclusions:

Dual-colour SISH represents a novel method for the determination of HER2 status in GC.

Global molecular dysfunctions in gastric cancer revealed by an integrated analysis of the phosphoproteome and transcriptome

We integrated LC-MS/MS-based and protein antibody array-based proteomics with genomics approaches to investigate the phosphoproteome and transcriptome of gastric cancer cell lines and endoscopic gastric biopsies from normal subjects and patients with benign gastritis or gastric cancer. More than 3,000 non-redundant phosphorylation sites in over 1,200 proteins were identified in gastric cancer cells. We correlated phosphoproteome data with transcriptome data sets and reported the expression of 41 protein kinases, 5 phosphatases and 65 phosphorylated mitochondrial proteins in gastric cancer cells. Transcriptional expression levels of 190 phosphorylated proteins were >2-fold higher in gastric cancer cells compared to normal stomach tissue. Pathway analysis demonstrated over-presentation of DNA damage response pathway and underscored critical roles of phosphorylated p53 in gastric cancer. This is the first study to comprehensively report the gastric cancer phosphoproteome. Integrative analysis of the phosphoproteome and transcriptome provided an expansive view of molecular signaling pathways in gastric cancer.

Gene expression signature-based prognostic risk score in gastric cancer

PURPOSE

Despite continual efforts to develop a prognostic model of gastric cancer by using clinical and pathologic parameters, a clinical test that can discriminate patients with good outcomes from those with poor outcomes after gastric cancer surgery has not been established. We aim to develop practical biomarker-based risk score that can predict relapse of gastric cancer after surgical treatment.

EXPERIMENTAL DESIGN

Microarray technologies were used to generate and analyze gene expression profiling data from 65 gastric cancer patients to identify biomarker genes associated with relapse. The association of expression patterns of identified genes with relapse and overall survival was validated in independent gastric cancer patients.

RESULTS

We uncovered two subgroups of gastric cancer that were strongly associated with the prognosis. For the easy translation of our findings into practice, we developed a scoring system based on the expression of six genes that predicted the likelihood of relapse after curative resection. In multivariate analysis, the risk score was an independent predictor of relapse in a cohort of 96 patients. We were able to validate the robustness of the six-gene signature in an additional independent cohort.

CONCLUSIONS

The risk score derived from the six-gene set successfully prognosticated the relapse of gastric cancer patients after gastrectomy.

HER2 status in gastro-oesophageal adenocarcinomas assessed by two rabbit monoclonal antibodies (SP3 and 4B5) and two in situ hybridization methods (FISH and SISH)

AIMS

HER2 gene amplification has been detected in 10-20% of gastric adenocarcinomas. In view of the recently demonstrated clinical benefit of the anti-human epidermal growth factor receptor 2 (HER2) drug trastuzumab in the treatment of advanced gastric cancer, reliable HER2 testing is of key importance. The aim of this study was to examine HER2 status in gastro-oesophageal adenocarcinomas comparing SP3 and 4B5 immunohistochemistry (IHC) with dual probe HER2 [fluorescence in situ hybridization (FISH) and silver in situ hybridization (SISH)].

METHODS AND RESULTS

IHC and SISH were carried out on biopsy specimens of 146 patients with adenocarcinomas of the oesophagus and stomach. All SP3-IHC-positive cases and 91% of 4B5-IHC-positive cases were amplified. Sensitivity of SP3-IHC-positivity and 4B5-IHC-positivity for amplification was 77% and 96%, respectively. Results of FISH performed in 42 cases were identical to SISH. Amplification was heterogeneous in 73% of the adenocarcinomas; 24% of the oesophago-gastric carcinomas and 7% of distal stomach tumours were amplified.

CONCLUSIONS

HER2-positivity is present in a significant proportion of oesophago-gastric adenocarcinomas (24%), but at a lower rate in the distal stomach (7%). Sensitivity for amplification is higher with 4B5 IHC than with SP3. FISH and SISH yield identical results, but assessment is much easier with SISH. Our findings provide important guidance for HER2-testing in gastro-oesophageal adenocarcinomas for patients in whom anti-HER2 treatment is considered.

TOPOIIalpha and HER-2/neu overexpression/amplification in Barrett's oesophagus, dysplasia and adenocarcinoma

Rossi E, Villanacci V, Bassotti G, Donato F, Festa A, Cengia G, Grisanti S & Cestari R (2010) Histopathology57, 81–89 TOPOIIα and HER-2/neu overexpression/amplification in Barrett’s oesophagus, dysplasia and adenocarcinoma

Topoisomerase II alpha as a universal tumor antigen: antitumor immunity in murine tumor models and H-2K(b)-restricted T cell epitope

Topoisomerase II alpha (Top2alpha) is an attractive candidate to be used as a tumor antigen for cancer immunotherapy, because it is abundantly expressed in various tumors and serves as a target for a number of chemotherapeutic agents. In this study, we demonstrated the immunogenicity of Top2alpha, using dendritic cells (DC) electroporated with RNA encoding the Top2alpha C-terminus (Top2alphaCRNA/DC). Top2alphaCRNA/DC were able to demonstrate in vitro stimulation of T cells from mice that were previously vaccinated with Top2alpha-expressing tumor lysate-pulsed DC. Vaccination with Top2alphaCRNA/DC induced Top2alpha-specific T cell responses in vivo as well as antitumor effects in various murine tumor models including MC-38, B16F10, and GL26. DC pulsed with p1327 (DSDEDFSGL), defined as an epitope presented by H-2K(b), also induced Top2alpha-specific immune responses and antitumor effects. Based on these data, Top2alpha is suggested to be a universal target for cancer immunotherapy.

Role of Polysomy 17 in Transitional Cell Carcinoma of the Bladder: Immunohistochemical Study of HER2/neu Expression and FISH Analysis of c-erbB-2 Gene and Chromosome 17

This study investigates the potential clinical significance of c-erbB-2 gene and chromosome 17 alterations by fluorescence in situ hybridization (FISH) analysis and HER2/neu overexpression by immunohistochemical staining in transitional cell carcinoma (TCC) of urinary bladder correlating the results with tumor stage and grade categories and with clinical behavior. Sixty-three cases of TCC retrieved from the files of 2 institutions were analyzed for chromosome 17 aberrations and c-erbB-2 amplification by FISH analysis and evaluated immunohistochemically for HER2/neu overexpression. Five tumors were G1, 29 intermediate grade (G2), and 29 tumors high grade (G3); 32 tumors had stage Ta, 18 tumors T1, and 13 tumors T2. We found polysomy of chromosome 17 in 58.7% of TCC with average chromosome copy number >2.26; increased number of HER2/neu gene copy was observed in 66.7% of tumors. C-erbB-2 amplification occurred in 6.3% of tumors. Immunohistochemically, 60.3% of TCC overexpressed HER2/neu and 39.7% of tumors were negative. All tumors with polysomy showed simultaneously increase of HER2/neu gene copy number of which 34/37 with protein overexpression. A statistically significant correlation between polysomy of chromosome 17 and tumor stage ( P = .0003) and tumor grade ( P < .0001) was found; polysomy was not seen in G1 tumors; however, 8/29 G2 tumors and 29/29 G3 tumors revealed polysomy of chromosome 17; in 8/32 Ta tumors, 14/18 T1 and 13/13 of deeply invasive tumors (T2) polysomy 17 was observed. Moreover, it was found that 7 superficial tumors (1 Ta and 6 T1) showed high polysomy with average of chromosome 17 copy number ≥3.76 as observed in all invasive tumors. The data suggest that although HER2/neu amplification, found in high grade and invasive tumors, is a rare event in TCC, polysomy of chromosome 17 is an important factor correlated with tumor stage and grade categories and could be considered a molecular marker of tumor progression with interesting diagnostic implications.

Increased topoisomerase IIalpha expression in colorectal cancer is associated with advanced disease and chemotherapeutic resistance via inhibition of apoptosis

Topoisomerase IIalpha is a nuclear enzyme that regulates the tertiary structure of DNA. The influence of topoisomerase IIalpha gene (TOP2A) or protein alterations on disease progression and treatment response in colorectal cancer (CRC) is unknown. The study investigated the clinical relevance of topoisomerase IIalpha in CRC using in vivo and in vitro models. Differentially expressed genes in early and late-stage CRC were identified by array comparative genomic hybridization (CGH). Cellular location of gene amplifications was determined by fluorescence in situ hybridization (FISH). Topoisomerase IIalpha levels, proliferation index, and HER2 expression were examined in 228 colorectal tumors by immunohistochemistry. Overexpression of topoisomerase IIalpha in vitro was achieved by liposome-based transfection. Cell growth inhibition and apoptosis were quantified using the crystal violet assay and flow cytometry, respectively, in response to drug treatment. Amplification of TOP2A was identified in 3 (7.7%) tumors using array CGH and confirmed using FISH. At the protein level, topoisomerase IIalpha staining was observed in 157 (69%) tumors, and both staining and intensity levels were associated with an aggressive tumor phenotype (p values 0.04 and 0.005, respectively). Using logistic regression analysis, topoisomerase IIalpha remained significantly associated with advanced tumor stage when corrected for tumor proliferation (p=0.007) and differentiation (p=0.001). No association was identified between topoisomerase IIalpha and HER2. In vitro, overexpression of topoisomerase IIalpha was associated with resistance to irinotecan (p=0.001) and etoposide chemotherapy (p=0.03), an effect mediated by inhibition of apoptosis. Topoisomerase IIalpha overexpression is significantly associated with alterations in tumor behavior and response to drug treatment in CRC. Our results suggest that gene amplification may represent an important mechanism underlying these changes.

Expression analysis of Barrett's esophagus-associated high-grade dysplasia in laser capture microdissected archival tissue

PURPOSE

Identifying genes differentially expressed in nondysplastic BE (NDBE) from those expressed in high-grade dysplasia (HGD) should be of value in improving our understanding of this transition and may yield new diagnostic and/or prognostic markers. The aim of this study was to determine the differential transcriptome of HGD compared with NDBE through gene microarray analysis of epithelial cells microdissected from archival tissue specimens.

EXPERIMENTAL DESIGN

Laser capture microdissection was used to isolate epithelial cells from adjacent inflammatory and stromal cells. Epithelial mRNA was extracted from areas of NDBE and HGD in matched biopsies from 11 patients. mRNA was reverse transcribed and applied on Affymetrix cDNA microarray chips customized for formalin-exposed tissue. For a subset of these genes, differential gene expression was confirmed by real-time PCR and immunohistochemistry.

RESULTS

There were 131 genes overexpressed by at least 2.5-fold in HGD versus NDBE and 16 genes that were underexpressed by at least 2.5-fold. Among the overexpressed genes are several previously shown to be increased in the neoplastic progression of BE, as well as novel genes such as lipocalin-2, S100A9, matrix metallopeptidase 12, secernin 1, and topoisomerase IIalpha. Genes decreased in dysplastic epithelium include MUC5AC, trefoil factor 1 (TFF1), meprin A, and CD13. Real-time PCR validated the changes in expression in 24 of 28 selected genes. Immunohistochemistry confirmed increased protein expression for topoisomerase IIalpha, S100A9, and lipocalin-2 and decreased expression of TFF1 across the spectrum of BE-associated dysplasia from NDBE through adenocarcinoma.

CONCLUSIONS

This is the first study to identify epithelial genes differentially expressed in HGD versus NDBE in matched patient samples. The genes identified include several previously implicated in the pathogenesis of BE-associated dysplasia and new candidates for further investigation.

Analysis of EGFR, HER2, and TOP2A gene status and chromosomal polysomy in gastric adenocarcinoma from Chinese patients

BACKGROUND

The EGFR and HER2 genes are located on chromosomes 7 and 17, respectively. They are therapeutic targets in some tumors. The TOP2A gene, which is located near HER2 on chromosome 17, is the target of many chemotherapeutic agents, and co-amplification of HER2 and TOP2A has been described in several tumor types. Herein, we investigated the gene status of EGFR, HER2, and TOP2A in Chinese gastric carcinoma patients. We determined the rate of polysomy for chromosomes 7 and 17, and we attempted to clarify the relationship between EGFR, HER2, and TOP2A gene copy number and increased expression of their encoded proteins. Furthermore, we tried to address the relationship between alterations in EGFR, HER2, and TOP2A and chromosome polysomy.

METHODS

One hundred cases of formalin fixed and paraffin embedded tumor tissues from Chinese gastric carcinoma patients were investigated by immunohistochemistry and fluorescence in situ hybridization (FISH) methods.

RESULTS

Forty-two percent of the cases showed EGFR overexpression; 16% showed EGFR FISH positive; 6% showed HER2 overexpression; and 11% showed HER2 gene amplification, including all six HER2 overexpression cases. TOP2A nuclear staining (nuclear index, NI) was determined in all 100 tumors: NI values ranged from 0.5-90%. Three percent of the tumors showed TOP2A gene amplification, which were all accompanied by HER2 gene amplification. Nineteen percent of the tumors showed chromosome 7 polysomy, and 16% showed chromosome 17 polysomy. Chromosome 7 polysomy correlated significantly with EGFR FISH-positivity, but was not associated with EGFR overexpression. HER2 overexpression associated significantly with HER2 gene amplification. TOP2A gene amplification was significantly associated with HER2 gene amplification. No relationship was found between alterations in the EGFR, HER2, and TOP2A genes and clinicopathologic variables of gastric carcinoma.

CONCLUSION

The data from our study suggest that chromosome 7 polysomy may be responsible for increased EGFR gene copy number in gastric carcinomas, and that HER2 gene amplification may be the major reason for HER2 protein overexpression. A combined investigation of the gene status of EGFR, HER2, and TOP2A should facilitate the identification of a target therapeutic regimen for gastric carcinoma patients.

Signal transduction proteins in tumors from Puerto Rican and Caucasian gastric adenocarcinoma patients: expression differences with potential for specific targeted therapies

Overexpression of the HER2/NEU gene is associated with aggressive behavior and poor prognosis in breast cancer, making the Her2/neu protein a directed-therapy target. Tumors of two Puerto Rican (PR) patients overexpressed Her2/neu and resulting partial clinical responses motivated us to compare Her2/neu expression in PR (n = 101) and Caucasian non-Hispanic (n = 95) patients. Immunohistochemistry of tumors showed overexpression of p-Stat3, Cyclin D1, and Her2/neu, compared to non-neoplastic mucosa. Her2/neu and EGF-R protein levels were statistically significantly different with higher levels of both proteins in the PR group. Importantly, Her2/neu expression was strong and diffuse in tumors with signet-ring morphology, while other histo-pathological subtypes showed higher intra-tumoral Her2/neu heterogeneity than typically observed in breast cancer. Targeted therapies in gastric cancer directed at EGF-R and Hers-2/neu pathways warrant further investigation. These therapies may be especially effective in PR patients and in patients with signet-ring cell morphologies with a dismal prognosis.

Non-incidental coamplification of Myc and ERBB2, and Myc and EGFR, in gastric adenocarcinomas

This study was conducted to assess the frequencies of protein overexpression and gene amplification of Myc and to identify the mechanisms of Myc gene amplification, especially with regards to its possible coamplification with ERBB2 or EGFR in gastric adenocarcinomas. By immunohistochemical analysis of a total of 300 formalin-fixed and paraffin-embedded gastric adenocarcinomas, the nuclear overexpression of MYC was found in 47 tumors (16%). A fluorescence in situ hybridization (FISH) analysis revealed that nine (19%) of the 47 tumors with protein overexpression had cancer cells with high levels of Myc amplification, whereas only seven (6%) of the 122 tumors without protein overexpression showed high-level Myc gene amplification. Such Myc amplification was significantly correlated with positive nuclear protein overexpression. The coamplification of ERBB2 or EGFR with Myc that was found in six and four cases, respectively, is believed to be non-incidental because those frequencies were significantly higher than the individual frequencies observed for the total examined cases (ERBB2: 7%; EGFR: 4%). The high levels of gene amplification of these three genes, as visualized by FISH, could be broadly classified into two typical types, namely, 'multiple scattered signals' and 'large clustered signals'. Using two-color FISH, the coexistence of coamplified Myc and ERBB2, or Myc and EGFR, within single nuclei in various combinations of amplification types and copy numbers, could be ascertained in all nine cases, including one in which the synchronous 'multiple scattered type' coamplification of Myc and ERBB2 was observed. In three tumors, coamplification of ERBB2 and EGFR was found; however, ERBB2- and EGFR-amplified cell populations were separate and mutually exclusive. We propose that the non-incidental coamplification of Myc and either ERBB2 or EGFR occurred through translocation and subsequent rearrangement.