SEARCH · PubMed Health

Results for “amplification”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources

PubMed1992

Prognostic factors in human primary breast cancer: comparison of c-myc and HER2/neu amplification.

Amplification of oncogenes in primary tumours may have prognostic and/or therapeutic significance for patients with breast cancer. We have studied HER2/neu and c-myc amplification together with steroid receptors in human primary breast tumours and related the outcome with (relapse-free) survival. A strong inverse correlation was found between HER2/neu amplification and the presence of oestrogen and progesterone receptors. Actuarial 5-years survival showed that breast cancer patients with c-myc amplification in their primary tumours experience a shorter relapse-free survival, especially in node-negative and in receptor-positive tumours, whereas HER2/neu amplification may be of prognostic value for overall survival in receptor-negative tumours. Overall, in our hands, c-myc amplification appeared to be a more potent prognosticator than HER2/neu amplification in human primary breast cancer.

Breast Neoplasms↗

PubMed2006

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

Topoisomerase IIalpha (topoIIalpha) is an enzyme required for DNA replication and a molecular target for drugs called anthracyclines. The topoIIalpha gene (TOP2A) is located close to the HER-2/neu oncogene (HER2). We assessed gastric cancers to (1) clarify the relationship between gene amplification and protein overexpression of topoIIalpha and HER2; (2) evaluate the correlation between gene amplification and protein overexpression of topoIIalpha; and (3) examine the relationship between the results of immunohistochemistry and Western blot analysis for topoIIalpha. In a combined analysis of immunohistochemistry and fluorescence in situ hybridization on 552 formalin-fixed and paraffin-embedded gastric cancer tissues, 38 cases were found to have HER2 amplification. Further examination by fluorescence in situ hybridization revealed amplification of TOP2A in 13 of the 38 cases. No aberrations in the TOP2A gene were observed in cases without HER2 overexpression, except for one containing a gene deletion. The TopoIIalpha protein-labeling index was not correlated with TOP2A amplification. Fluorescence in situ hybridization was performed on nuclear imprint specimens obtained from 9 cases using simultaneous probes for TOP2A, HER2, and centromere 17. Of these 9 cases, 3 displayed coamplification of TOP2A and HER2, and only 1 of the 3 cases revealed a high expression of topoIIalpha in Western blot. Although patients having gastric adenocarcinoma with TOP2A amplification could be considered suitable for clinical trials, information involving anthracycline therapy is not firmly understood in regards to the status of TOP2A amplification or protein overexpression. Therefore, results of the current study will provide further insight for the clinical application of anthracycline in gastric cancers.

Adenocarcinoma↗

PubMed2006

Comparison of amplification methods for transcriptomic analyses of low abundance prokaryotic RNA sources.

Microarrays have established as instrumental for bacterial detection, identification, and genotyping as well as for transcriptomic studies. For gene expression analyses using limited numbers of bacteria (derived from in vivo or ex vivo origin, for example), RNA amplification is often required prior to labeling and hybridization onto microarrays. Evaluation of the fidelity of the amplification methods is crucial for the robustness and reproducibility of microarray results. We report here the first utilization of random primers and the highly processive Phi29 phage polymerase to amplify material for transcription profiling analyses. We compared two commercial amplification methods (GenomiPhi and MessageAmp kits) with direct reverse-transcription as the reference method, focusing on the robustness of mRNA quantification using either microarrays or quantitative RT-PCR. Both amplification methods using either poly-A tailing followed by in vitro transcription, or direct strand displacement polymerase, showed appreciable linearity. Strand displacement technique was particularly affordable compared to in vitro transcription-based (IVT) amplification methods and consisted in a single tube reaction leading to high amplification yields. Real-time measurements using low-, medium-, and highly expressed genes revealed that this simple method provided linear amplification with equivalent results in terms of relative messenger abundance as those obtained by conventional direct reverse-transcription.

Nucleic Acid Amplification Techniques↗

PubMed2004

Amplification of the cyclin D1 gene is associated with tumour subsite, DNA non-diploidy and high S-phase fraction in squamous cell carcinoma of the head and neck.

Amplification of CCND1 (cyclin D1 gene) in squamous cell carcinoma of the head and neck (SCCHN) is correlated to poor prognosis. The purpose of this study was to investigate whether CCND1 amplification is related to different subsites and also to DNA ploidy status and S-phase fraction (SPF). Biopsies from 67 patients with SCCHN were analysed for CCND1 amplification by fluorescence in situ hybridisation (FISH) and for ploidy status and SPF by flow cytometry (FCM). Twenty-one of 67 tumours (31%) showed CCND1 amplification and the frequencies differed significantly between different subsites (p = 0.01). Tumours from hypopharynx, larynx and oropharynx showed higher rates of amplification as compared to tumours from oral cavity and epipharynx. CCND1 amplification was also associated to DNA non-diploidy and high SPF (p = 0.002 and p = 0.002, respectively). In conclusion, the rate of CCND1 amplification differed between different subsites in SCCHN and was also associated to a more aggressive tumour phenotype, as defined by DNA non-diploidy and high SPF.

Adult↗

PubMedDate not supplied

Detection of C-erb B2 gene amplification in bilharzial associated bladder cancer using fluorescence in situ hybridization.

BACKGROUND: Gene amplifications are common events in different tumor types and may confer diagnostic, prognostic, or therapeutic information for patient management. Fluorescence in situ hybridization (FISH) represents a standard methodologic approach for testing for this genetic alteration, as it is rapid, reproducible and extremely reliable in detecting presence of C-erb-B2 gene amplification for clinical utility. PATIENTS AND METHODS: In this study, FISH is used in a series of archival human bilharzial bladder cancer specimens to evaluate for the presence of cerbB-2 gene alterations in the most common malignant tumor in bilharzial endemic areas, e.g., Egypt and some other countries. The study included 40 cases, 30 males and 10 females. Their ages ranged between 30 years and 76 years (median: 51 years). Twenty-one cases had squamous cell carcinoma, 16 had transitional cell carcinoma, two had adenocarcinoma, and one case had undifferentiated carcinoma. RESULTS: Thirteen out of 40 tumor samples (32.5%) show evidence of true C-erb-B2 gene amplification. Of the remaining samples, 24 (60%) show no gene amplification and three (7.5%) fall into the borderline category with a ratio between one and two C-erb-B2 genes/cell relative to chromosome 17 centromeres. No evidence of chromosome 17 polysomy was found in any cases scored as single copy with the C-erb-B2 probe. CONCLUSION: No significant association was found between gene amplification and any of the tested clinicopathologic parameters or tumor recurrence except for tumor grade where higher tumor grades tended to be associated with more C-erb-B2 gene amplification (P = 0.01) thus reflecting more tumor aggressiveness. So, the amplification of C-erb-B2 in bilharzial associated bladder cancer is probably not independently related to clinical outcome of patients.

Adult↗

PubMed2005

Amplification of EMSY, a novel oncogene on 11q13, in high grade ovarian surface epithelial carcinomas.

OBJECTIVES: Amplification of the 11q13 locus is commonly observed in a number of human cancers including both breast and ovarian cancer. Cyclin D1 and EMS1 have been implicated as candidate oncogenes involved in the emergence of amplification at this locus. Detailed analysis of the 11q13 amplicon in breast cancer led to the discovery of four regions of amplification suggesting the involvement of other genes. Here, we investigate the role of EMSY, a recently described BRCA2 interacting protein, as a key element of the 11q13 amplicon in ovarian cancer. EMSY maps to 11q13.5 and is amplified in 13% of breast and 17% of ovarian carcinomas. METHODS: EMSY amplification was assessed by fluorescent in-situ hybridization (FISH) in 674 ovarian cancers in a tissue microarray and correlated with histopathological subtype and tumor grade. A detailed map of the 11q13 amplicon in 51 cases of ovarian cancer was obtained using cDNA-array-based comparative genomic hybridization (aCGH). To further characterize the role of EMSY within this amplicon, we evaluated both the amplification profiles and RNA expression levels of EMSY and two other genes from the 11q13 amplicon in an additional series of 22 ovarian carcinomas. RESULTS: EMSY amplification was seen in 52/285 (18%) high grade papillary serous carcinomas, 4/27 (15%) high grade endometrioid carcinomas, 3/38 (8%) clear cell carcinomas, and 3/10 (30%) undifferentiated carcinomas. aCGH mapping of 11q13 in ovarian cancer showed that EMSY localized to the region with the highest frequency of copy number gain. Cyclin D1 and EMS1 showed a lower frequency of copy number gain. A highly significant correlation between EMSY gene amplification and RNA expression was also observed (P = 0.0001). This was a stronger correlation than for other genes at 11q13 including Cyclin D1 and PAK1. CONCLUSIONS: These findings support the role of EMSY as a key oncogene within the 11q13 amplicon in ovarian cancer.

Chromosome Mapping↗

PubMed2001

[CCND1 oncogene amplification and cellular DNA content in squamous cell carcinomas of the head and neck].

Cyclin D1 protein (encoded by the CCND1 gene) contributes to the progression of the cell cycle in the G1/S checkpoint. Cyclin D1 overexpression (for instance as a consequence of CCND1 amplification) might result in loss of control over genetic damage at this point and in an accumulation of chromosomal aberrations. In this work we analyze whether CCND1 amplification is associated with a higher incidence of alterations in cellular DNA content. 31 squamous cell carcinomas of the head and neck were studied. CCND1 amplification was determined by polymerase chain reaction. Cellular DNA content was determined by flow cytometry. CCND1 amplification was found in 6 (19%) cases. Thirteen (42%) cases were diploid and 18 (58%) were aneuploid. Two (33%) of the 6 cases with CCND1 amplification were aneuploid compared with 16 (64%) of the cases without CCND1 amplification (P = 0.36). We conclude that CCND1 amplification is not associated to a higher incidence of chromosomal aberrations in squamous cell carcinomas of the head and neck.

Adult↗

PubMed2000

Restricted 12p amplification and RAS mutation in human germ cell tumors of the adult testis.

Human testicular germ-cell tumors of young adults (TGCTs), both seminomas and nonseminomas, are characterized by 12p overrepresentation, mostly as isochromosomes, of which the biological and clinical significance is still unclear. A limited number of TGCTs has been identified with an additional high-level amplification of a restricted region of 12p including the K-RAS proto-oncogene. Here we show that the incidence of these restricted 12p amplifications is approximately 8% in primary TGCTs. Within a single cell formation of i(12p) and restricted 12p amplification is mutually exclusive. The borders of the amplicons cluster in short regions, and the amplicon was never found in the adjacent carcinoma in situ cells. Seminomas with the restricted 12p amplification virtually lacked apoptosis and the tumor cells showed prolonged in vitro survival like seminoma cells with a mutated RAS gene. However, no differences in proliferation index between these different groups of seminomas were found. Although patients with a seminoma containing a homogeneous restricted 12p amplification presented at a significantly younger age than those lacking it, the presence of a restricted 12p amplification/RAS mutation did not predict the stage of the disease at clinical presentation and the treatment response of primary seminomas. In 55 primary and metastatic tumors from 44 different patients who failed cisplatinum-based chemotherapy, the restricted 12p amplification and RAS mutations had the same incidence as in the consecutive series of responding patients. These data support the model that gain of 12p in TGCTs is related to invasive growth. It allows tumor cells, in particular those showing characteristics of early germ cells (ie, the seminoma cells), to survive outside their specific microenvironment. Overexpression of certain genes on 12p probably inhibits apoptosis in these tumor cells. However, the copy numbers of the restricted amplification of 12p and K-RAS mutations do not predict response to therapy and survival of the patients.

Adult↗

PubMed1996

Meanings of c-erbB and int-2 amplification in superficial esophageal squamous cell carcinomas.

BACKGROUND: Accumulation of genetic abnormalities is linked to the development and progression of cancer. We therefore analyzed the correlation between the clinical characteristics of superficial esophageal squamous cell carcinoma patients and oncogene amplifications. METHODS: Between 1980 and 1991, there were 63 cases of superficial esophageal carcinoma (Tis and T1 cancer) at Keio University Hospital. The T1 cases were divided into two groups: T1a cases, in which the tumor had invaded the lamina propria, and T1b cases, in which the tumor had invaded the submucosa. DNA was isolated from paraffin-embedded blocks. Oncogene amplification was determined by slot-blot hybridization. RESULTS: Amplification of int-2 and c-erbB was detected in 14 and 5, respectively, of the 54 cases. Three of 12 T1b patients with int-2 amplification died of distant organ metastasis. The survival rate for the group with int-2 amplification was significantly lower than that without int-2 amplification. All 4 T1b patients with c-erbB amplification had lymph node metastasis at operation. CONCLUSIONS: These findings mean that genetic abnormalities are a useful marker for treating patients with superficial esophageal squamous cell carcinomas.

Carcinoma, Squamous Cell↗

PubMed2001

Amplification of c-myc gene and overexpression of c-Myc protein in breast cancer and adjacent non-neoplastic tissue.

BACKGROUND: Deregulated c-Myc expression and alterations of c-myc oncogene have been reported to play an important role in breast cancer tumorigenesis. We examined the relationship between c-Myc protein level, amplification of c-myc oncogene and commonly used clinical and pathologic factors. METHODS: The studies were conducted on 94 ductal and lobular cancers. Amplification of c-Myc was assessed by the semiquantitative multiplex PCR assay. The amount of c-Myc protein was estimated by the densitometry analysis of Western blots. RESULTS: Amplification of c-Myc was found in 21% of examined cancers. There was no association of c-myc amplification with established risk factors. Overexpression of c-Myc protein without c-myc amplification was associated with negative status of axillary lymph node. The size of lobular carcinoma displaying overexpression of c-Myc and the normal copy number of c-myc gene was significantly smaller than the size of tumor with elevated c-Myc and amplification of c-myc gene (p < 0.01). Within tumors displaying overexpression of c-Myc protein and c-myc gene amplification the size of ductal carcinoma was smaller than the size of lobular carcinoma (p < 0.007). CONCLUSION: Data presented in this study suggest that alterations of c-myc gene and c-Myc protein level might be related to breast cancer progression. The prognostic utility of elevated level of c-Myc protein associated with normal status of c-myc gene for patients with lobular carcinoma requires further studies.

Breast↗

PubMed1987

N-myc oncogene amplification and prognostic factors of neuroblastoma in children.

The N-myc oncogene of 28 neuroblastic tumors obtained from 16 untreated and 12 pretreated children was clinically evaluated and compared with known prognostic factors. Significant amplification of the N-myc (more than ten copies) was observed in 0 of 2 tumors in stage I, 1 of 5 in stage II, 2 of 6 in stage III, 6 of 9 in stage IV, and 2 of 6 in stage IVS. In stages II, III, IV, and IVS, all 15 patients with low N-myc amplification (under ten copies) are alive without disease, while among 11 patients with the amplification, seven died with progressive disease and two have a recurrence (P less than .01). All tumors with N-myc amplification originated from the suprarenal region and the amplification appeared in 55% of those from that origin. The amplification also correlated with the age factor. These results suggest that the genomic amplification of N-myc seems to be correlated with known prognostic factors of neuroblastoma, and may be a reliable factor even in the case of preoperatively treated tumors.

Age Factors↗

PubMed2001

Analysis of p53 mutational events and MDM2 amplification in canine soft-tissue sarcomas.

Canine cancer is of major significance in terms of animal health and welfare and soft tissue sarcomas are an important group of tumours accounting for approximately 15% of all canine tumours presented. Abnormal p53 protein expression and gene mutations have been identified in a number of different canine tumour types. However, mdm2 gene amplification has only been investigated in a limited number of canine osteosarcomas. In this present study a series of canine soft-tissue sarcomas (STS) were examined for p53 mutations and/or mdm2 amplification. For p53 mutational studies polymerase chain reaction and direct DNA sequencing was used. Gene mutations were identified in 6 of 30 (20%) primary tumour cases including MPNST (n=3) leiomysarcoma (n=1), heamangiosarcoma (n=1) and sarcoma (n=1). mdm2 gene amplification was assessed by Southern Blot. Although there was no evidence for major gene rearrangements, gene amplification was detected in 4 of 35 (11.4 %) primary tumours including MPNST (n=2), rhabdomyosarcoma (n=2). A total of 33 cases were examined for both p53 mutations and mdm2 amplification. Seven of the tumours were positive for p53 mutations, while five were positive for mdm2 amplification. With the exception of one case, a reciprocal relationship between the presence of a p53 mutation and mdm2 gene amplification was demonstrated.

Animals↗

PubMed2003

Topoisomerase II-alpha (topoII) and HER2 amplification in breast cancers and response to preoperative doxorubicin chemotherapy.

A significant proportion of breast cancers with HER2 amplification have simultaneous amplification of topoisomerase II-alpha (topoII). Amplification of HER2 and topoII was assayed using a novel chromogenic in situ hybridisation (CISH) method. HER2 and topoII amplification status and the response to preoperative doxorubicin chemotherapy were analysed in 67 locally advanced breast cancer patients. Response to chemotherapy was increased in the cases with coamplification of HER2 and topoII (18/19), whereas the response rate was significantly decreased in the cases without HER2 and topoII amplification (17/36). The 12 cases with HER2 amplification alone showed an intermediate response rate (9/12). The findings of the current study indicate that topoII amplification may play a role in determining chemosensitivity of breast cancers to doxorubicin chemotherapy.

Adult↗

PubMed1992

Prevalence of amplification of the oncogenes c-myc, HER2/neu, and int-2 in one thousand human breast tumours: correlation with steroid receptors.

The frequency of oncogene amplification described in the literature shows a large fluctuation, which could be attributed to the study of relatively small series of tumours, to selection of subgroups of patients, or, especially in retrospective studies, to selection of tumour material from the tumour-bank. To address this question, we have studied amplification of c-myc, HER2/neu and int-2/bcl-1 genes in a series of 1052 collected human breast tumours. The retrospective and prospective subgroups in this collected series of tumours were of equal size. c-myc was amplified in 17.1%, HER2/neu in 18.7% and int-2/bcl-1 in 14.1%, of all breast cancer specimens studied. In the retrospective subgroup the prevalence of amplification was 18.1% for c-myc; 22.6% for HER2/neu and 11.6% for int-2/bcl-1, whereas in the prospective subgroup an incidence of amplification of 16.1%, 15.1% and 16.3% for c-myc, HER2/neu and int-2/bcl-1, respectively was observed. HER2/neu amplification was negatively correlated with oestrogen receptor (ER) and progesterone receptor (PR) status (P less than 0.0001; for both), c-myc amplification was more prevalent in the PR-negative subpopulation (P less than 0.05) and int-2/bcl-1 amplification was positively correlated with ER status (P less than 0.001).

Breast Neoplasms↗

PubMed1997

Amplification of 11q13 DNA markers in head and neck squamous cell carcinomas: correlation with clinical outcome.

This study was performed on 282 patients with primary head and neck squamous cell carcinomas to evaluate the prognostic importance of 11q13 amplification. Amplification of the 11q13 DNA markers, HST-1/FGF-4 and BCL-1, evaluated by Southern and slot blot hybridisation, was detected in 52% of tumours. 11q13 amplification was associated with tumour site since this alteration occurred in 76% of tumours arising in the hypopharynx, versus 40% in the other sites (P = 0.0007). 11q13 amplification was also significantly related to the presence of involved neck lymph nodes (P = 0.013). The relationship between 11q13 amplification and risk of progression was studied in two subgroups of head and neck cancer patients with regard to treatment modalities. The presence of 11q13 amplification in the tumour was not significantly associated with a shorter event-free survival (P = 0.82) and crude survival (P = 0.61) of the 201 patients treated by surgery and postoperative radiotherapy. Similarly, absence of a relationship was observed for the group of 79 patients treated by surgery alone. These results confirm that 11q13 amplification is a prominent event in head and neck squamous cell carcinoma, indicating that it may be a common genetic event in the development of these neoplasms, but is not a reliable prognostic marker.

Adult↗

PubMed2001

Frequent cyclin D1 gene amplification and protein overexpression in oral epithelial dysplasias.

Amplification of the cyclin D1 gene has been identified in 17-55% of head and neck squamous cell carcinoma. In some tumors, this alteration has been associated with decreased survival and increased recurrence rates. In precancerous lesions of the mouth, the frequency of cyclin D1 gene amplification is not known. In addition, it is unknown whether amplification of the gene translates to overexpressed cyclin D1 protein in these lesions. We examined 59 formalin-fixed, paraffin embedded tissue biopsies of oral epithelial dysplasias (OED) and 25 oral squamous cell carcinoma (SCC) from the floor of the mouth for cyclin D1 gene and protein levels. Genomic DNA was extracted from laser microdissected lesional tissue and a duplex, quantitative PCR assay was used to determine the amplification of the cyclin D1 gene relative to interferon-gamma. Cyclin D1 protein expression was determined using immunohistochemistry and counting positive nuclei by computer image analysis. We found cyclin D1 gene amplification in 41% of mild, 45% of moderate and 24% of severe OEDs. Cyclin D1 was amplified in 36% of SCC. Overexpression of cyclin D1 protein was identified in 29% of mild, 47% of moderate, 29% of severe OED's, and in 32% of SCC. Overexpression of cyclin D1 protein was identified in similar proportions of all grades of dysplasia and SCC. There were statistically significant correlations identified between gene and protein levels in all categories of disease. We concluded that amplification of the cyclin D1 gene is frequent in OED and that duplex, quantitative polymerase chain reaction is a reliable method to detect this change in routinely processed biopsies. The strong correlation between cyclin D1 gene amplification and protein levels suggests that this method may be suitable to assess cyclin D1 gene status in tissues not suitable for protein analysis.

Adult↗

PubMed2001

Quantitation of epidermal growth factor receptor gene amplification by competitive polymerase chain reaction in pre-malignant and malignant oral epithelial lesions.

Abnormal amplification of epidermal growth factor receptor (EGFR) gene has been reported widely in various human tumors. However, the status of amplification of this gene in the process of carcinogenesis is not clearly defined. We used competitive polymerase chain reaction (PCR) to study whether EGFR gene is amplified and the degree of amplification in pre-malignant and malignant oral epithelial lesions, and also examined the relationship between EGFR gene aberration and the development of squamous cell carcinoma (SCC). Genomic DNA was extracted from paraffin sections of 17 cases of oral epithelial dysplasia (ED), four cases of carcinoma in situ (CIS), and 20 cases of untreated primary SCC. The extracted DNA was subjected to competitive PCR to amplify EGFR gene. Amplification of the EGFR gene was observed in three cases (17%) of ED, one case of CIS and four cases (20%) of SCC. In cases showing EGFR gene amplification, the degree of amplification was low in ED and CIS cases, whereas it was extremely high in SCC cases. These results suggest that amplification of EGFR gene occurs in the relatively early stage of the development of oral SCC. However, a high level of EGFR gene accumulation probably plays an important role in the progression to invasive cancer.

Carcinoma in Situ↗

PubMed2003

Amplification and overexpression of the EMS 1 oncogene, a possible prognostic marker, in human hepatocellular carcinoma.

DNA amplification in cancer cells frequently involves oncogenes whose increased expression confers a selective advantage on tumor cell growth. In an attempt to identify novel oncogenes involved in hepatocarcinogenesis, representational difference analysis (RDA) was performed using DNA from a primary human hepatocellular carcinoma (HCC) that showed high-level DNA amplifications on chromosomes 1p32 and 11q13 by comparative genomic hybridization. Ten amplification fragments were isolated by RDA, and when used to probe Southern blots of tumor DNA, there was a 5- to 50-fold increase in hybridization intensity relative to normal DNA. The sequence of one amplification product matched that of the EMS1 oncogene, which is located on chromosome 11q13 and is amplified in other cancers. We detected EMS1 amplification in 3 of 17 primary HCC. Overexpression of EMS1 mRNA was observed in 12 of 14 HCC cell lines in the absence of gene amplification or an increased copy-number of the gene. The EMS1 gene encodes cortactin, a cortical actin-associated protein that is a substrate for Src kinase and is involved in cytoskeleton organization. Alterations of the EMS1 gene that lead to overexpression of cortactin may be associated with tumor development in HCC. EMS1 amplification and overexpresion is indicative of unfavorable prognosis in several cancers and may have similar prognostic implications in liver cancer.

Base Sequence↗