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Results for “MYC amplification”

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PubMed1987

N-myc amplification in an infant with stage IVS neuroblastoma.

N-myc amplification is most frequently found in neuroblastoma from patients with stage III and IV disease. Recently a significant association between genomic amplification and poor prognosis has been demonstrated. The primary tumors studied from patients with stage IVS disease have reportedly had a single copy of N-myc, and these patients are alive without progressive disease. We report a patient with stage IVS neuroblastoma with N-myc amplification who developed widespread metastasis within 6 months of diagnosis. The same correlation between oncogene copy number and progressive disease that has been seen in those patients with stage II, III, and IV disease was seen in this patient with stage IVS neuroblastoma.

Gene Amplification↗

PubMed1996

N-MYC amplification, loss of heterozygosity on the short arm of chromosome 1 and DNA ploidy in retinoblastoma.

Recurrent genetic alterations different from the alteration of the RB1 gene on chromosome 13q14 have been described in retinoblastoma, including structural alterations on the short arm of chromosome 1 and amplification of the N-MYC oncogene. These two genetic alterations are major prognostic factors in neuroblastoma, another embryonic neuro-ectodermal tumour. In order to assess the frequency of these alterations and their possible association with clinical parameters in retinoblastoma, we studied a series of 46 retinoblastoma tumour samples. Ploidy was assessed by flow cytometry, N-MYC copy number was evaluated by a spot-blot procedure using the pNb-1 probe and loss of heterozygosity was investigated by PCR analysis at mini- and microsatellites located on the short arm of chromosome 1. Most tumours were in the diploid or near diploid range; only one case exhibited tetraploidy. N-MYC amplification was observed in only one of the 45 tumours. Loss of heterozygosity on the short arm of chromosome 1 was observed in 9/43 tumours (21%); in particular, its incidence was higher in metastatic than in localised disease (P < 0.05). We suggest that alterations of one or several genes on chromosome 1p might play a role in the oncogenesis or progression of retinoblastoma. Analysis of the long term follow-up of these and additional patients should determine the prognostic value of this parameter.

Child, Preschool↗

PubMed1992

Inverse relationship between trk expression and N-myc amplification in human neuroblastomas.

We examined the expression of the trk protooncogene in a series of 82 neuroblastomas to determine its relationship to N-myc amplification and expression, disease stage, patient age, and survival. We found that virtually all stage I, II, and IV-S patients had moderate to high levels of trk expression, whereas most advanced stage neuroblastomas had low or absent levels. All but one tumor with N-myc amplification had low or absent trk expression, and the one exception was regressing at the time it was resected. Conversely, all neuroblastomas identified by mass screening had moderate to high expression of trk, and all these patients are surviving. Thus, trk expression was associated with an absence of N-myc amplification, lower disease stage, lower patient age, and favorable outcome. Tumors with high trk expression may be more likely to differentiate, regress spontaneously, or respond well to therapy.

Gene Amplification↗

PubMedDate not supplied

Fish detected p53 deletion and N-MYC amplification in colorectal cancer.

BACKGROUND/AIMS: Data about p53 condition in sporadic colorectal cancer and its impact on clinical features is controversial, and studies regarding N-myc gene in colorectal cancer are limited in number. Our aim was to determine the frequency of p53 deletion and N-myc amplification by fluorescence in situ hybridization method in colorectal cancer and their relationship with clinical parameters. METHODOLOGY: The study was prospectively derived from 40 patients who were diagnosed as having colorectal cancer (Dukes' stages: 11 B, 18 C, 11 D) and went to surgery. Fresh tumor samples from all patients and adjacent normal tissue from 16 patients as control specimens were obtained. Locus specific fluorescence in situ hybridization probes was used for p53 and N-myc gene. For each sample, hundred interphase nuclei were analyzed based on their fluorescence phenotype. RESULTS: Both p53 allelic loss and N-myc amplification were found in 21 cancer tissues, while p53 allelic loss was not observed in any of control tissue, and N-myc amplification only in 1 (p<0.001, p<0.01). Mutations were significantly related with metastasis. CONCLUSIONS: Our study indicates that p53 and N-myc mutations are frequently found in tumor tissue of colorectal cancer and both gene alterations are correlated with the more aggressive tumor phenotype.

Adenocarcinoma↗

PubMed2003

Association of C-MYC amplification with progression from the in situ to the invasive stage in C-MYC-amplified breast carcinomas.

Human carcinoma in situ of the breast already demonstrates genomic changes found in invasive lesions. However, no specific genetic alterations have previously been identified that are associated with progression from the in situ to the invasive stage. By comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH) analysis of an invasive breast carcinoma with a large associated in situ component, high-level amplification of C-MYC was found in the invasive component only. To determine the frequency of this correlation in a panel of 188 invasive breast carcinomas, 18 additional cases with C-MYC amplification were identified. Nine of these cases had a detectable adjacent in situ component. FISH analysis demonstrated increased (>5) C-MYC signals per nucleus in seven invasive components and increased (>4) C-MYC/centromere 8 signal ratios in five of these. None of the associated in situ components demonstrated these increases. The minimal amplified region was defined at 8q24.13-8qter. C-MYC amplification was correlated with overexpression of C-MYC and two of its target genes, TERT and FBL. Thus, C-MYC amplification is the first identified genetic alteration that is associated with progression from the in situ to the invasive stage of breast carcinoma.

Adult↗

PubMed1994

Integrin expression in human neuroblastoma cells with or without N-myc amplification and in ectopic/orthotopic nude mouse tumors.

Three human neuroblastoma cell lines, with or without N-myc amplification, were evaluated for their integrin expression patterns as cultured cells, as well as their nude mouse-borne tumors obtained after subcutaneous (ectopic) or adrenal gland (orthotopic) injection. IMR-32 and LaN1 cells (with amplified N-myc) do not express any of the common integrin subunits that recognize fibronectin or collagens, as determined by immunoprecipitation of cell extracts with specific monoclonal antibodies; the same was true for all subcutaneous or adrenal tumors from IMR-32 or LaN1, indicating that they are not essential during primary tumor formation at either site. SK-N-SH cells (with diploid N-myc) express beta 1, alpha 2, and alpha 3 subunits of expected sizes (with alpha 2 uncleaved at 145 kDa) but do not express alpha 1, alpha 4, alpha 5, alpha V, or beta 3. This expression pattern was conserved in all first-round subcutaneous and adrenal tumor cell populations, as well as in second-round subcutaneous tumors derived from a first-round subcutaneous tumor (no tumors expressed beta 3). One significant difference was noted between subcutaneous and adrenal tumor populations: all first- and second-round subcutaneous tumors expressed high levels of alpha V subunit, while adrenal tumors did not express any alpha V. This result suggests some essential function for alpha V beta 1 during subcutaneous primary tumor formation. Integrin patterns were also evaluated by fluorescence-activated cell sorting. SK-N-SH and its derivative tumors expressed heterogeneous amounts of beta 1 and alpha 2 at the cell surface, while only subcutaneous tumor cells expressed alpha V. Parental SK-N-SH cells contained two subpopulations, half of which expresses alpha 3, while the other half does not; all subcutaneous tumor cells retained this two-subpopulation pattern, indicating that primary tumor formation does not lead to clonal dominance of alpha 3- or alpha 3+ cell types in larger primary tumors. While these results suggest a correlation between N-myc amplification and down-regulation of integrin expression in neuroblastoma, they demonstrate conservation of integrin expression during two rounds of primary tumor formation at ectopic or orthotopic sites in a mouse model system, induction and/or selection for alpha V beta 1 expression at the subcutaneous site, and clonal heterogeneity in alpha 3 beta 1 expression throughout primary tumor development.

Animals↗

PubMed1990

Down-regulation of MHC class I antigens is not a general mechanism for the increased tumorigenicity caused by c-myc amplification.

Previous studies have shown that increased expression of oncogenes from the myc-family can down-regulate the level of MHC class I antigens in tumor cells. This has suggested a mechanism by which amplification/overexpression of myc-genes may contribute to the malignancy development of certain tumors. Earlier published data from the murine SEWA tumor, a polyomavirus-induced osteosarcoma, have correlated the degree of tumorigenicity of different sublines to their level of c-myc amplification. Here I present a quantitative and qualitative analysis of MHC class I antigens from five sublines of this tumor system. No differences could be found, between sublines with different degrees of tumorigenicity, regarding MHC class I antigen expression. Thus, in the SEWA tumor, the enhancement of the tumorigenicity caused by c-myc amplification is not mediated through down-regulation of MHC class I antigens.

Animals↗

PubMed2000

Comparative polymerase chain reaction analysis of c-myc amplification on archival breast fine-needle aspiration materials.

The oncogene c-myc is a key regulator of cell cycle progression (from G1 to S phase). The amplification of c-myc can either induce cell proliferation or apoptosis. As a part of our ongoing effort to develop methods for multiple tumor marker analysis, this study was carried out to determine whether biomarkers such as c-myc amplification could be analyzed on genetic materials collected from archival fine-needle aspiration (FNA) smears. A novel comparative PCR analysis was used to analyze c-myc amplification semiquantitatively. Genomic DNA was prepared using cells obtained from archival FNA materials that had undergone quantitative fluorescence image analysis (QFIA) for other biomarkers. Of the 72 cases selected from 1995 for this study, 53 had an adequate amount of DNA for analysis. A novel comparative PCR analysis was used to analyze c-myc amplification quantitatively. For each batch of experiments, DNA from the high c-myc expressing cells, HL-60, and DNA from the low expressing cells, K562, were served as positive and negative controls, respectively. c-myc amplification was observed in 16 (94.1%) of 17 malignant lesions, 5 (41.7%) of 12 proliferative breast diseases with nuclear atypia, and 4 (16.7%) of 24 other benign lesions (fibroadenoma or fibrocystic disease). The overall difference of c-myc expression among these groups was highly significant by chi2 analysis (P = 0.0002). We conclude that multiple phenotypic markers and genotypic markers may be combined in a risk assessment biomarker profile on small FNA samples that can be obtained on multiple occasions relatively noninvasively from the patient. The results of this study suggest that c-myc amplification may be a biomarker of breast cancer risk. However, additional large, prospective studies are needed to confirm the current observation.

Adult↗

PubMedDate not supplied

Association of near-diploid DNA content and N-myc amplification in neuroblastomas.

Seventeen neuroblastomas at different clinical stages were analysed for their N-myc copy number and flow cytometrically determined DNA content. Aneuploidy was found in 11 patients (65 per cent), whereas the remaining were near-diploid. N-myc amplification was found significantly (P less than 0.05) confined to near-diploid tumors (3 out of 6 cases). This finding indicates a very selective mechanism of oncogene amplification which is independent of gross chromosomal imbalance and limited to specific loci in the human genome. Association of near-diploidy and age at diagnosis older than 24 months was also demonstrated (P less than 0.05). Thus, flow cytometric analysis of DNA content together with N-myc gene dosage allowed us to distinguish two different subsets of neuroblastoma tumors: the first one aneuploid, with single-copy N-myc, usually observed in patients younger than 24 months with localized or IV-S clinical stages; the second one near-diploid, with frequent N-myc amplification, usually observed in patients older than 24 months with advanced clinical stages.

Child↗

PubMed1993

Mutation of the p53 gene in neuroblastoma and its relationship with N-myc amplification.

Mutation of the p53 tumor suppressor gene frequently occurs in a variety of tumors including lung, breast, gastrointestinal, and brain, as well as lymphomas-leukemias. Neuroblastoma, one of the most common solid tumors in childhood, often has amplification of the N-myc gene. We examined for mutations of the p53 tumor suppressor gene by single-strand conformational polymorphism using polymerase chain reaction products and direct sequencing method in neuroblastoma; in addition, we assessed the relationship between p53 mutation and N-myc gene amplification in the disease. Of 86 DNA samples from patients with neuroblastoma, two mutations (2%) were found in the coding region of the p53 gene. Each mutation caused a substitution of amino acid residues. One mutation was located in exon 5, and another was in exon 6. N-myc gene was amplified in 26% of the samples. No p53 mutations were found in neuroblastoma samples with N-myc amplification. In the two individuals, p53 mutations appeared as their disease became more progressive. The neurofibromatosis 1 (NF1) gene is frequently abnormal in another neural disorder, neurofibromatosis type 1; in addition, a potential mutational hot spot of NF1 at lysine at codon 1423 has been identified in several types of tumors. Using single-strand conformational polymorphism, we were unable to detect an abnormality in this region of NF1 in 50 samples of neuroblastoma. The data suggest that p53 mutations occasionally are associated with progression of neuroblastomas, and tumorigenetic influences of mutant p53 may differ from those of N-myc.

Gene Amplification↗

PubMed1995

Evidence for two tumour suppressor loci on chromosomal bands 1p35-36 involved in neuroblastoma: one probably imprinted, another associated with N-myc amplification.

Previous reports on possible genomic imprinting of the neuroblastoma tumour suppressor gene on chromosome 1p36 have been conflicting. Here we report on the parental origin of 1p36 alleles lost in 47 neuroblastomas and on a detailed Southern blot analysis of the extent of the 1p deletions in 38 cases. The results are remarkably different for tumours with and without N-myc amplification. In the N-myc single copy tumours we show that the lost 1p36 alleles are of preferential maternal origin (16 of 17 cases) and that the commonly deleted region maps to 1p36.2-3. In contrast, all N-myc amplified neuroblastomas have larger 1p deletions, extending from the telomere to at least 1p35-36.1. These deletions are of random parental origin (18 of 30 maternal LOH). This strongly suggests that different suppressor genes on 1p are inactivated in these two types of neuroblastoma. Deletion of a more proximal suppressor gene is associated with N-myc amplification, while a distal, probably imprinted, suppressor can be deleted in N-myc single copy cases.

Chromosome Deletion↗

PubMed2006

c-myc amplifications in primary breast carcinomas and their local recurrences.

OBJECTIVE: To evaluate the role of c-myc oncogene amplifications in the progression of invasive breast carcinomas. METHODS: c-myc gene copy number was evaluated in a series of 49 primary breast carcinomas and the corresponding local recurrences using fluorescence in situ hybridisation. RESULTS: 11 of the primary carcinomas (22%) harboured c-myc amplifications; these tumours typically were hormone receptor negative and occurred in younger patients (43 v 53 years). At the time of relapse, six additional tumours had acquired a c-myc amplification. The mean recurrence-free survival was 24 months; c-myc amplified tumours relapsed significantly earlier than carcinomas without amplification (18 v 27 months). Univariate analysis showed a worse overall survival in these patients. CONCLUSIONS: While c-myc amplifications can be observed in early stage breast cancer, especially in younger patients, they often occur later in tumour development and appear to be associated with disease progression.

Adenocarcinoma↗

PubMed1993

Expression of the apoptosis-suppressing protein bcl-2, in neuroblastoma is associated with unfavorable histology and N-myc amplification.

Survival rate in neuroblastoma, a tumor of post-ganglionic sympathetic neuroblasts, correlates with disease stage, tumor histology, and N-myc gene amplification. N-myc amplification is associated with rapid tumor progression and poor survival, but is not present in all cases of poor prognosis neuroblastoma. Moreover, overexpression of N-myc is not sufficient to cause cellular transformation. These data suggest that other genetic factors are important for neuroblastoma development. We investigated the expression of the, bcl-2 proto-oncogene in untreated cases of neuroblastoma. bcl-2 is a novel proto-oncogene that promotes cell growth by inhibiting programmed cell death (apoptosis), a form of cellular demise common during normal neurogenesis. Immunocytochemical localization using a monoclonal anti-bcl-2 antibody revealed that 16 of 40 patient specimens stained positive for bcl-2. bcl-2 was strongly associated with unfavorable histology (P = 0.002) and N-myc gene amplification (P = 0.002) and marginally associated with poor stage disease (P = 0.06). A logistic regression model evaluating the simultaneous association of stage, histology, and N-myc revealed that bcl-2 was most associated with unfavorable histology and N-myc gene amplification. These results support the notion that bcl-2 may play an important role in the genesis or progression of malignant neuroblastoma.

Adolescent↗

PubMed2005

c-myc amplification is associated with HER2 amplification and closely linked with cell proliferation in tissue microarray of nonselected breast cancers.

C-myc and HER2 amplification were analyzed on 214 consecutive breast cancers by fluorescence in situ hybridization using tissue microarray technology. The frequencies of amplification were 15.4% (33/214) and 23.3% (49/210), respectively. c- myc amplification was significantly associated with HER2 amplification ( P < .001) and closely linked with cell proliferative activity, measured by Ki67 labeling index ( P = .010). In univariate survival analysis, lymph node status, tumor size, and histological grade were significant prognostic factors, but in multivariate analysis, lymph node status was the only significant factor. Patient survival did not differ according to c- myc amplification status, and c- myc amplification showed no significant correlation with clinicopathologic features of the tumors. A strong correlation between c- myc and HER2 amplification and proliferative activity indicates a biological link between these genes in breast cancer cell.

Adult↗

PubMed1989

c-erbB-2/c-erbA co-amplification indicative of lymph node metastasis, and c-myc amplification of high tumour grade, in human breast carcinoma.

A panel of 73 samples, including 52 primary breast carcinomas, 10 normal breast tissues and 11 axillary lymph nodes, has been analysed for the presence of amplifications and gross structural alterations, in the oncogenes c-erbB-2, c-erbA, c-myc, N-myc, c-mos and c-Ha-ras. The tumours were also classified, graded and staged histopathologically and their DNA ploidy (42 samples) was determined by flow cytometry. Three breast cancer cell lines (MCF7, ZR-75-1 and T47D) were also included in the study. Amplification of c-erbB-2 was detected in 28% of the tumours, of which 91% had an increased steady-state level of c-erbB-2 mRNA. Amplification of c-erbA was found in 23% of tumours and was always associated with the amplification of c-erbB-2. Ten out of 12 (83%) tumours which had c-erbB-2 and c-erbA co-amplification had metastasised to axillary lymph nodes (P less than 0.006). However, the human thymidine kinase gene, which is present at the same chromosomal location as these two oncogenes (17q21-22), was amplified in only tw tumours. Amplification of c-myc was detected in 21% of the tumours studied, of which 82% (P less than 0.005) were of histopathological grade 3 and none were of grade 1. Flow cytometry showed that 90% (P less than 0.01) of the analysed tumours with c-erbB-2 and c-erbA co-amplification, and 70% (P less than 0.1) of those with c-myc amplification were DNA aneuploid. This study demonstrates the potential value of c-myc amplification in the assessment of the tumour grade, rather than metastatic potential; and of the co-amplification of c-erbB-2 and c-erbA as a strong indicator of metastatic potential, rather than tumour grade.

Breast Neoplasms↗

PubMed1988

Characterization of N-myc amplification units in human neuroblastoma cells.

A set of DNA clones comprising 48 independent HindIII fragments (215 kilobases of sequence) was derived from the N-myc amplification unit of the neuroblastoma cell line NGP. These clones were used to investigate N-myc amplification units in NGP cells and 12 primary neuroblastoma tumors. Three parameters were evaluated: (i) the number of rearrangements from germ line configuration that had occurred during the amplification process; (ii) the homogeneity of amplification units within individual tumors; and (iii) the conservation of amplified sequences among different tumors. The results indicated that remarkably few rearrangements had occurred during amplification, that the amplification units within any one tumor were quite homogeneous, and that although each tumor contained a unique pattern of amplified DNA fragments, there was considerable similarity between the amplification units of different tumors. In particular, the amplification units were strikingly similar over a contiguous domain of at least 140 kilobases surrounding the N-myc structural gene.

Cell Line↗

PubMed1996

c-myc amplification in pre-malignant and malignant lesions induced in rat liver by the resistant hepatocyte model.

We have investigated by restriction fragment analysis genomic abnormalities involving the c-myc gene in DNA isolated from adenomas and hepatocellular carcinomas (HCCs). Adenomas and HCCs were induced by the "resistant hepatocyte" protocol in diethylnitrosamine-initiated male F344 rats. Southern-blot analysis of EcoRI-restricted DNA from normal liver, early and late adenomas, 12 weeks (EAs) and 30 weeks (LAs) after initiation, and HCCs, showed 2 bands of 18 and 3.2 kb hybridizing with c-myc, in all tissues. c-myc amplification occurred in almost all HCCs, and in the majority of EAs and LAs. These results were confirmed by dilution analysis. c-myc amplification was also seen in adenomas and HCCs by Southern analysis with HindIII-restricted DNA, and in HCCs by differential PCR. c-myc mRNA increase occurred in all adenomas and HCCs, but it was higher in the lesions showing gene amplification. Moreover, a 13-kb DNA extraband, hybridizing with c-myc, was found in the HindIII-restricted DNA from HCCs, but not in normal liver and adenomas, and a 7.1-kb extra band was present in EcoRI-digested DNA from one LA. EcoRI-restricted DNA from some adenomas exhibited a decrease in intensity of the 18-kb fragment, and an increase in intensity of the 3.2-kb fragment. No alteration in banding pattern occurred in the beta-actin gene in adenomas. These results provide evidence of amplification and some other rearrangements involving the c-myc gene, in pre-malignant and malignant liver lesions, induced by the RH protocol, and suggest a role of c-myc rearrangement in the progression of adenomas to malignancy.

Adenoma↗

PubMed1985

N-myc amplification in multiple homogeneously staining regions in two human neuroblastomas.

Molecular characterization of two human neuroblastoma cell lines has revealed that both contain multiple homogeneously staining regions (HSRs), each representing a chromosome site of N-myc amplification. The newly established cell line CHP-382/JK had two cytogenetically distinct populations with several identical chromosomal abnormalities, indicating a common progenitor cell. Each population had one HSR, one on chromosome 5 at q31-34 and the other on chromosome 2 at q31-32. Chromosomal in situ hybridization with the N-myc probe pNb-1 demonstrated that both HSRs contained amplified copies of N-myc. Southern blot analysis confirmed amplification of N-myc sequences in genomic DNA of CHP-382/JK. Chromosomal features of CHP-382/JK shared with other neuroblastoma cell lines were the deletion of 1p and the presence of extra 17q material. In addition, the cells were highly reactive to monoclonal antibody PI 153/3 used to identify human neuroblastoma. CHP-382/JK cells were further characterized as neuronal cells by the expression of neurotoxin-responsive Na+ channels. Another neuroblastoma cell line, CHP-134, contained a single cell population with three HSRs, one in the short arm of each chromosome 7 and one in the long arm of a chromosome 6. All three HSRs contained amplified copies of N-myc as shown by in situ hybridization with the N-myc probe pNb-1. One of the 7p HSRs was acquired during culture of CHP-134 cells, whereas the 2q HSR of CHP-382/JK was lost. Such findings highlight the continued process of N-myc amplification and transposition in vitro. To our knowledge, amplification of N-myc in multiple HSRs has not been documented previously in neuroblastoma cell lines.

Antibodies, Monoclonal↗