RESUMO
Several studies indicate that the short arm of chromosome 17 is one of the most frequently altered regions in sporadic breast carcinomas (45-60%). In the present report the 17p13.3-ter locus in tumour DNA of breast cancer patients, along with their matching normal lymphocyte DNA, have been mapped with four markers (D17S5, D17S379, ABR and D17S34), spanning nearly 3 cM of the telomer. Sixty-five of 143 heterozygous tumours had lost at least one of the markers at the minimum region of loss (45%). High levels of loss of these distal markers on 17p13.3 are independent of TP53 mutations and are associated with tumour cell proliferation. A follow-up period of over 7 years demonstrates that loss of these markers correlates both with disease-free (P = 0.004) and overall survival (P = 0.007). In addition we show that for disease-free survival the prognostic power of this genetic alteration is second only to axillary lymph node involvement (3.1 vs 6.3 relative risk), and is a better predictor than the mutational status of TP53 (1.6 relative risk). Our results are further evidence of the presence, within the region, of at least a second tumour suppressor gene distal to TP53, that might be targeted by deletions.
Assuntos
Neoplasias da Mama/genética , Carcinoma Ductal de Mama/genética , Cromossomos Humanos Par 17 , Genes Supressores de Tumor , Perda de Heterozigosidade , Alelos , Neoplasias da Mama/sangue , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/sangue , Carcinoma Ductal de Mama/patologia , DNA de Neoplasias/genética , Feminino , Genes p53 , Humanos , Análise Multivariada , Fenótipo , Mutação Puntual , Reação em Cadeia da Polimerase , Prognóstico , Análise de SobrevidaRESUMO
We have recently isolated a human gene, ROX, encoding a new member of the basic helix-loop-helix leucine zipper protein family. ROX is capable of heterodimerizing with Max and acts as a transcriptional repressor in an E-box-driven reporter gene system, while it was found to activate transcription in HeLa cells. ROX expression levels vary during the cell cycle, being down-regulated in proliferating cells. These biological properties of ROX suggest a possible involvement of this gene in cell proliferation and differentiation. The ROX gene maps to chromosome 17p13.3, a region frequently deleted in human malignancies. Here we report the genomic structure of the human ROX gene, which is composed of six exons and spans a genomic region of less than 40 kb. In an attempt to identify possible inactivating mutations in the ROX gene in human breast cancer, we performed a single-strand conformation polymorphism analysis of its coding region in 16 sporadic breast carcinomas showing loss of heterozygosity in the 17p13.3 region. No mutations were found in this analysis. Five nucleotide polymorphisms were identified in the ROX gene, three of which caused an amino acid substitution. These nucleotide changes were present in the peripheral blood DNAs of both the patients and the control individuals. In vitro translated assays did not show a significant decrease in the ability of the ROX mutant proteins to bind DNA or to repress transcription of a driven reporter gene in HEK293 cells. Despite experimental evidence that ROX might act as a tumor suppressor gene, our data suggest that mutations in the coding region of ROX are uncommon in human breast tumorigenesis.
Assuntos
Neoplasias da Mama/genética , Éxons , Íntrons , Proteínas Repressoras/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos , Linhagem Celular , Cromossomos Humanos Par 17/genética , Análise Mutacional de DNA , Proteínas de Ligação a DNA/metabolismo , Sequências Hélice-Alça-Hélice/genética , Humanos , Zíper de Leucina/genética , Perda de Heterozigosidade/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Repressoras/metabolismo , Fatores de Transcrição/metabolismoRESUMO
High levels of loss of distal markers on 17p13.3 in breast cancer suggested the presence within the region of at least one tumour-suppressor gene. Here we describe the derivation of two biallelic polymorphisms from the 17p telomeric yeast artificial chromosome (YAC) TYAC98. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and multiplex PCR analysis demonstrated that the high level of allelic imbalance observed in breast tumours represented loss of constitutional heterozygosity (LOH) and that this LOH extended to the telomere. Lung carcinoma (but not Wilms' tumour)-derived DNA again revealed a high level of loss of subtelomeric 17p sequences. Telomeric microsatellite polymorphisms from other chromosome arms did not show such elevated loss in either tumour type. This suggested that the 17p loss observed did not reflect a general telomeric instability and provided further evidence for the presence of a breast cancer tumour-suppressor gene in the distal region of 17p13.3.
Assuntos
Neoplasias da Mama/genética , Deleção Cromossômica , Cromossomos Humanos Par 17 , Telômero , Feminino , Genes Supressores de Tumor , Humanos , Polimorfismo de Fragmento de RestriçãoRESUMO
Colorectal and breast cancers account for a significant number of deaths due to malignant neoplasia. Laboratory medicine plays an important role in the diagnosis and management of these tumors through the application of histopathology, immunohistochemistry, and serologic identification of tumor markers. Approximately 5% to 10% of colorectal and breast cancers result from an inherited predisposition. The genes responsible for most genetically transmitted cancers have been identified, and the application of findings from molecular pathology are being evaluated. This article reviews the genetic changes that occur as a result of somatic mutation and inherited or germline mutations.
Assuntos
Neoplasias da Mama/genética , Neoplasias Colorretais/genética , Polipose Adenomatosa do Colo/diagnóstico , Polipose Adenomatosa do Colo/genética , Neoplasias da Mama/diagnóstico , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Neoplasias Colorretais Hereditárias sem Polipose/genética , Feminino , Genes Supressores de Tumor/genética , Doenças Genéticas Inatas/genética , Heterozigoto , Humanos , Pessoa de Meia-Idade , Biologia Molecular , Proto-Oncogenes/genéticaRESUMO
The chromosome region 17p13.3 is thought to encode a tumour suppressor gene involved in sporadic breast cancer and other malignancies. Physical ordering of markers has been carried out by a series of multicolour fluorescent in situ hybridisation (FISH) experiments, using isolated yeast artificial chromosomes (YACs) and cosmids. Eight polymorphic markers ordered within this new physical map and one external marker were used to investigate the pattern of loss of heterozygosity in a panel of 40 sporadic breast tumour patients. The data revealed a region of high loss (60%) within distal 17p13.3, defined by markers D17S926, D17S695 and D17S849 which mapped close together. A contig of YACs was constructed physically linking these three markers.
Assuntos
Neoplasias da Mama/genética , Deleção Cromossômica , Cromossomos Humanos Par 17 , Genes Supressores de Tumor , Sequência de Bases , Bandeamento Cromossômico , Mapeamento Cromossômico , Cromossomos Artificiais de Levedura , Feminino , Heterozigoto , Humanos , Hibridização in Situ Fluorescente , Dados de Sequência MolecularRESUMO
The short area of chromosome 17 is a frequent target for deletions in human tumors, including breast cancer. We have investigated by restriction fragment polymorphism analysis the pattern of loss of heterozygosity (LOH) at four loci on 17p13.1-17pter in a panel of 110 primary human breast carcinomas. A copy of the p53 gene was lost in 23% of the informative cases. Point mutations in the p53 gene were statistically associated with LOH at the same locus (p = 0.003) but not at other loci on 17p13.3-17pter. A second region bordered by the loci D17S5/D17S28 (17p13.3) and D17S34 (17pter) is also affected by LOH, independent of point mutations in the p53 gene. We propose the presence of a second tumor suppressor gene within this region. In support of this hypothesis is the significant association (p = 0.005) between LOH at the D17S5/D17S28, but not at the TP53 or D17S34 loci, and tumors having a high S-phase index.
Assuntos
Neoplasias da Mama/genética , Cromossomos Humanos Par 17 , Genes Supressores de Tumor/genética , Fase S/genética , Alelos , Deleção Cromossômica , Genes p53 , Heterozigoto , Humanos , Mutação Puntual/genética , Reação em Cadeia da PolimeraseRESUMO
The expression of three epidermal growth factor (EGF)-related peptides, transforming growth factor alpha (TGF-alpha), amphiregulin (AR) and cripto-1 (CR-1), was examined by immunocytochemistry (ICC) in 68 primary infiltrating ductal (IDCs) and infiltrating lobular breast carcinomas (ILCs), and in 23 adjacent non-involved human mammary tissue samples. Within the 68 IDC and ILC specimens, 54 (79%) expressed immunoreactive TGF-alpha, 52 (77%) expressed AR and 56 (82%) expressed CR-1. Cytoplasmic staining was observed with all of the antibodies, and this staining could be eliminated by preabsorption of the antibodies with the appropriate peptide immunogen. Cytoplasmic staining with all of the antibodies was confined to the carcinoma cells, since no specific immunoreactivity could be detected in the surrounding stromal or endothelial cells. In addition to cytoplasmic reactivity, the AR antibody also exhibited nuclear staining in a number of the carcinoma specimens. No significant correlations were found between the percentage of carcinoma cells that were positive for TGF-alpha, AR or CR-1 and oestrogen receptor status, axillary lymph node involvement, histological grade, tumour size, proliferative index, loss of heterozygosity on chromosome 17p or overall patient survival. However, a highly significant inverse correlation was observed between the average percentage of carcinoma cells that expressed AR in individual tumours and the presence of a point-mutated p53 gene. Likewise, a significantly higher percentage of tumour cells in the ILC group expressed AR as compared with the average percentage of tumour cells that expressed AR in the IDC group. Of the 23 adjacent, non-involved breast tissue samples, CR-1 could be detected by ICC in only three (13%), while TGF-alpha was found in six (26%) and AR in ten (43%) of the non-involved breast tissues. These data demonstrate that breast carcinomas express multiple EGF-related peptides and show that the differential expression of CR-1 in malignant breast epithelial cells may serve as a potential tumour marker for breast cancer.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias da Mama/química , Fator de Crescimento Epidérmico , Glicoproteínas/análise , Substâncias de Crescimento/análise , Peptídeos e Proteínas de Sinalização Intercelular , Glicoproteínas de Membrana , Proteínas de Neoplasias/análise , Fator de Crescimento Transformador alfa/análise , Anfirregulina , Família de Proteínas EGF , Feminino , Proteínas Ligadas por GPI , Genes p53/genética , Humanos , Mutação Puntual/genética , RNA Mensageiro/análise , RNA Neoplásico/análiseAssuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Cromossomos Humanos Par 17 , Genes p53 , Mutação Puntual , Southern Blotting , Mapeamento Cromossômico , Cromossomos Humanos Par 1 , Cromossomos Humanos Par 13 , Cromossomos Humanos Par 3 , Éxons , Feminino , Humanos , Reação em Cadeia da Polimerase , Fase SRESUMO
A series of 121 human breast tumors was screened for point mutations in exons 5 through 8 of the p53 gene, by SSCP analysis. On the same tumor samples, the S-phase index (SPI) was determined by the incorporation of BUdR in fresh tissue. p53 mutations were observed in 29% of the cases. The frequency of point mutations for the individual exons was: exon 5, 10.0%; exon 6, 9.9%; exon 7, 7.1% and exon 8, 5.5%. Two mutations detected by SSCP were confirmed by sequencing the p53 cDNA. The presence of a p53 mutation, irrespective of its location, correlates (p = 0.003) with a high SPI. This association appears to primarily reflect mutations in exon 5 (p = 0.0002) and exon 6 (p = 0.05), since mutations in exons 7 and 8 failed to show any association. These results indicate that mutations in the p53 gene identify highly proliferating tumors, and that the position of the p53 mutation may have different effects upon the proliferative activity of tumor cells in vivo.
Assuntos
Neoplasias da Mama/genética , Cromossomos Humanos Par 17 , Éxons/genética , Genes p53/genética , Mutação/genética , Fase S/genética , Sequência de Bases , Neoplasias da Mama/patologia , Divisão Celular/genética , Análise Mutacional de DNA , Feminino , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodosRESUMO
The prognostic value of breast cancer proliferative activity was evaluated in 385 women operated for primary, non-metastasised mammary carcinoma. Cell kinetics was measured using two immunohistochemical techniques. Cells in S-phase of cell cycle were labelled in vitro by incubation of fresh tissue fragments with 5-bromo 2-deoxyuridine (BrdU), a thymidine analogue. Nuclei of cells in active DNA synthesis were stained by an anti-BrdU monoclonal antibody (Mab). Cells in interphase and mitosis were detected with Ki-67, a Mab that is known to react with a nuclear antigen present in G1/S/G2/M phases of cell cycle, but not in resting cells. This reagent provides a means of evaluating the growth fraction of neoplastic cells. BrdU was incorporated in a proportion of tumour cells ranging from 0.1 to 65.5% (median 6.8%). In the panel of tumours presented in this report the median percentage of Ki-67 positive cells (Ki-67 score) was 9.0% (range 0.1-77%). The relationship between disease-free survival (DFS), BrdU labelling index, Ki-67 score and 13 different clinico-pathological variables was investigated by multivariate analysis, using the Cox proportional hazards model. Axillary node status (P = 0.009) and Ki-67 score (P = 0.038) emerged as independent prognostic factors. Nodal status and tumour growth fraction allowed division of patients into groups at different risk of relapse: tumours with a proliferative index below the median value showed a lower recurrence rate than tumours with a high proliferative activity (P < 0.001). In particular, no relapse occurred in pN0 patients bearing carcinomas with a Ki-67 labelling < 9.0% 4 years after surgery. These findings suggest that the evaluation of proliferative activity in breast cancer enhances the probability of correctly predicting outcome after surgery and could be of assistance in the planning of adjuvant therapies.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias da Mama/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/química , Bromodesoxiuridina/imunologia , Divisão Celular , DNA de Neoplasias/biossíntese , Feminino , Humanos , Antígeno Ki-67 , Linfonodos/patologia , Pessoa de Meia-Idade , Proteínas de Neoplasias/imunologia , Recidiva Local de Neoplasia , Proteínas Nucleares/imunologia , PrognósticoRESUMO
A systematic study of primary human breast tumor DNA demonstrated that three proto-oncogenes or regions of the genome (c-myc, int-2, and c-erbB2) are frequently amplified and that there is loss of heterozygosity (LOH) on chromosomes 1p(37%), 1q(20%), 3p(30%), 7(41%), 11p(20%), 13q(30%), 17p(49%), 17q(29%), and 18q(34%). Specific subsets of tumors can be defined based on the particular collection of mutations they contain. For instance, LOH on chromosomes 11p, 17p, and 18q frequently occurs in the same tumor. A search for putative tumor suppressor genes within the regions of the genome affected by LOH has been started. In a comprehensive molecular analysis of the p53 gene on chromosome 17p, 46% of the tumors contained a point mutation in the p53 gene.
Assuntos
Neoplasias da Mama/genética , DNA de Neoplasias/análise , Mutação , Humanos , Mutação/genética , Proto-Oncogenes/genéticaRESUMO
The capacity of breast tumor cells to proliferate is considered a potential prognostic factor together with other histopathologic parameters. The authors determined the proliferation index on a large panel of human primary breast tumors by measuring the levels of incorporation of bromodeoxyuridine (BrdU) by fresh tumor specimens in culture. Previous analysis showed that the percentage of cells entering the S-phase of the cell cycle strongly correlates with tumor grade, tumor size, and estrogen and progesterone receptor status. The capacity of tumor cells to proliferate might be associated with specific genetic mutations in primary tumors. To test this hypothesis, a panel of 96 human breast carcinomas, for which the BrdU labeling index (LI) was known, were tested for loss of heterozygosity (LOH) or increased copy number (ICN) at chromosomes 1q, 3p, 13q, 17p, and 18q. On chromosome 17p, LOH and ICN were observed in 27% and 12%, respectively, of the informative breast tumors. The LOH on chromosome 17p was significantly associated with tumors having an elevated BrdU proliferation index (P = 0.022). No association (P = 0.45) was observed between BrdU LI and tumor size (T2 + T3 compared with T1), tumor grade, and lymph node status. Increased copy number on chromosome 17p, LOH or ICN on 1q, and LOH on 13q14, 18q, and 3p also showed no significant correlation with cell kinetic parameters. These data are consistent with the presence of a gene or genes on chromosome 17p13 near the YNZ22.1 locus whose normal functioning is necessary for controlling breast tumor cells proliferation in vivo.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Cromossomos Humanos Par 17 , Heterozigoto , Southern Blotting , Bromodesoxiuridina/metabolismo , Divisão Celular , DNA de Neoplasias/genética , DNA de Neoplasias/metabolismo , Humanos , Índice Mitótico , Timidina/metabolismoRESUMO
Twenty-six primary breast tumors were examined for mutations in the p53 tumor suppressor gene by an RNase protection assay and nucleotide sequence analysis of PCR-amplified p53 complementary DNAs. Each method detected p53 mutations in the same three tumors (12%). One tumor contained two mutations in the same allele. Single strand conformation polymorphism analysis of genomic DNA and complementary DNA proved more sensitive in the detection of mutations. Combining this technique with the other two a total of 12 mutations in the p53 gene were demonstrated in 11 tumors (46%), and a polymorphism at codon 213 was detected in another tumor. Loss of heterozygosity on chromosome 17p was detected by Southern blot analysis in 30% of the tumor DNAs. Not all of the tumors containing a point mutation in p53 also had loss of heterozygosity of the remaining allele, suggesting that loss of heterozygosity may represent a later event.
Assuntos
Neoplasias da Mama/genética , Genes p53 , Mutação , Sequência de Bases , Mapeamento Cromossômico , DNA de Neoplasias/análise , Feminino , Heterozigoto , Humanos , Dados de Sequência Molecular , Polimorfismo de Fragmento de Restrição , RNA Neoplásico/análiseRESUMO
Transforming growth factor alpha (TGF alpha) is one growth factor that has been circumstantially implicated in regulating the autocrine growth of breast cancer cells. Expression of TGF alpha can be modulated by activated cellular protooncogenes such as ras and by estrogens. For example, the epidermal growth factor (EGF)-responsive normal NOG-8 mouse and human MCF-10A mammary epithelial cell lines can be transformed with either a point-mutated c-Ha-ras protooncogene or with a normal or point-mutated c-neu (erbB-2) protooncogene. In ras transformed NOG-8 and MCF-10A cells but not in neu transformed cells there is a loss in or an attenuated response to the mitogenic effects of EGF. This response may be due in part to an enhanced production of endogenous TGF alpha that is coordinately and temporally linked to the expression of the activated ras gene and to the acquisition of transformation-associated properties in these cells. TGF alpha mRNA and TGF alpha protein can also be detected in approximately 50-70% of primary human breast tumors. In addition, approximately 2- to 3-fold higher levels of biologically active and immunoreactive TGF alpha can also be detected in the pleural effusions from breast cancer patients as compared with the TGF alpha levels in the serous effusions of noncancer patients. Over-expression of a full-length TGF alpha cDNA in NOG-8 and MCF-10A cells is capable of transforming these cells. Finally, expression of TGF alpha mRNA and production of biologically active TGF alpha protein is also found in normal rodent and human mammary epithelial cells.
Assuntos
Neoplasias da Mama/metabolismo , Fator de Crescimento Transformador alfa/metabolismo , Animais , Transformação Celular Neoplásica , Células Cultivadas , Expressão Gênica , Humanos , Derrame Pleural/metabolismo , Proto-Oncogenes/fisiologia , Fator de Crescimento Transformador alfa/genéticaRESUMO
The int-2 protein is related to basic fibroblast growth factor (bFGF) by amino acid sequence homology. To assess its biological activity, we constructed retroviral vectors containing four variants of mouse int-2 complementary DNA under the transcriptional control of the beta-actin promoter and tested their effects on human SW13 adrenal cortical tumor cells. This cell line specifically requires bFGF, interleukin 1, or transforming growth factor e for anchorage-independent growth in soft agar. Despite encoding a signal sequence that should direct the protein to the secretory pathway, vectors containing unmodified int-2 complementary DNA, or a form optimized for translation initiation at the AUG codon, were incapable of inducing SW13 growth in soft agar. However, SW13 transfectants expressing a construct (pSP1), in which a mouse immunoglobulin signal peptide sequence is linked to the int-2 coding sequences, grew well in soft agar. The concentrated conditioned medium from these pSP1-transfected cells supported anchorage-independent growth of SW13 indicator cells and competed with bFGF for binding to receptors. Western blot analysis with an int-2-specific antiserum detected Mr 30,000-32,000 int-2 products in cell extracts and conditioned medium from pSP1-transfected clones, whereas the conditioned medium from these and other SW13 clones contained only low levels of bFGF as measured in a specific radioimmunoassay. These data suggest that the product of the int-2 gene can functionally replace bFGF in modulating the anchorage-independent growth of SW13 cells.
Assuntos
Fator 2 de Crescimento de Fibroblastos/genética , Fatores de Crescimento de Fibroblastos , Expressão Gênica/fisiologia , Proteínas Proto-Oncogênicas/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Meios de Cultura , Fator 3 de Crescimento de Fibroblastos , Vetores Genéticos , Camundongos , Dados de Sequência Molecular , Proteínas Proto-Oncogênicas/genética , Radioimunoensaio , Ensaio Radioligante , Proteínas Recombinantes/genética , Retroviridae/genética , Transfecção/genéticaRESUMO
Transforming growth factor-alpha (TGF alpha) has been implicated in the autocrine growth control of a number of different rodent and human tumor cells, including breast cancer cells. Although TGF alpha has been detected in a limited number of normal tissues, its distribution and physiological function in the mammary gland are relatively unknown. TGF alpha mRNA expression was detected by in situ hybridization with a labeled TGF alpha antisense RNA probe and quantitated by application of computer-assisted digital image processing in both the ductal and alveolar epithelial cells in the virgin rat and nulliparous and parous human mammary glands. During pregnancy and lactation, the level of TGF alpha mRNA expression in the ductal and alveolar epithelial cells increased two- to threefold, while a heterogeneous yet strong expression of TGF alpha mRNA could also be detected in approximately 10-15% of the surrounding stromal cells in the pregnant mammary gland.
Assuntos
Mama/metabolismo , Glândulas Mamárias Animais/metabolismo , RNA Mensageiro/biossíntese , Fatores de Crescimento Transformadores/biossíntese , Animais , Northern Blotting , Feminino , Expressão Gênica , Humanos , Técnicas In Vitro , Lactação/metabolismo , Hibridização de Ácido Nucleico , Gravidez , Sondas RNA , Ratos , Transcrição GênicaRESUMO
The gene for the human DF3 breast carcinoma-associated antigen contains a conserved (G + C)-rich 60-base pair tandem repeat and maps to chromosome 1q21-24. In the present study we isolated and characterized 1220 base pairs of nonrepetitive adjacent sequences. Multiple alleles were identified by fragment size. Signal intensity of hybrids with the tandem and unique sequence probes indicated that allelic variation is due to different numbers of repeats. Probes for both the tandem and the unique sequences were used to study the DF3 locus in human breast tumor DNAs. Seventy of 110 breast tumor DNAs were informative at the DF3 locus. Of these, 20 (29%) showed a loss of heterozygosity, while eight (11%) had an increased copy number of one allele. In some cases, the loss of heterozygosity or increased copy number did not extend to other markers on chromosome 1q or 1p. These data indicate that the chromosomal region around the DF3 locus is affected by mutations at high frequency.
Assuntos
Antígenos de Neoplasias/genética , Biomarcadores Tumorais , Neoplasias da Mama/genética , Carcinoma/genética , Sequência de Aminoácidos , Sequência de Bases , Mapeamento Cromossômico , Cromossomos Humanos Par 1 , Células Clonais , DNA/genética , DNA de Neoplasias/genética , Humanos , Dados de Sequência Molecular , Hibridização de Ácido NucleicoRESUMO
Gene amplification is a relatively frequent event in human malignant tumors and is believed to have an important function in neoplastic transformation and tumor progression. Our attention has been focused on the amplification and the expression of the int-2 gene for several reasons: (1) In the mouse mammary tumorigenesis int-2 is frequently activated by MMTV proviral integration. (2) The human homolog of int-2, located on chromosome 11q13, is frequently amplified in human primary tumors and is comprised in an amplification unit encompassing the hst gene, which is often coamplified; the amplification at the 11q13 locus in breast carcinomas correlates with a poor outcome of the disease. (3) int-2 and hst belong to the basic FGF gene family. All these observations raise the possibility that the human int-2 gene plays an active role in the neoplastic process, but this will prove to be true only if int-2 is expressed in human tumors. In the present study we used RNA:RNA in situ hybridization and Northern blot analysis to show that int-2 gene is expressed in a number of human carcinomas amplified at the same locus.
Assuntos
Amplificação de Genes , Neoplasias/genética , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/análise , Proteínas de Peixe-Zebra , Northern Blotting , Southern Blotting , Mapeamento Cromossômico , Humanos , Hibridização de Ácido Nucleico , Proteínas WntRESUMO
Transforming growth factor alpha (TGF alpha) mRNA expression was measured by Northern blot analysis in 18 human, primary, infiltrating, ductal breast carcinomas. Expression of a 4.8-kilobase TGF alpha mRNA transcript was detected in nine of 18 tumors. No evidence was observed of any gross amplifications or major rearrangements of the TGF alpha gene in the breast carcinoma specimens. Biologically active and immunoreactive TGF alpha was measured in the pleural effusions or in the ascitic fluids from 37 noncancer and 63 cancer patients. The TGF alpha activity detected ranged from 0.2 to 26 ng/mL in most effusions from both groups. However, 29 of 63 (46%) of the effusions from cancer patients exhibited TGF alpha levels that were 6 ng/mL or higher, whereas only seven of 37 (19%) of those from noncancer patients exceeded this level (P less than .03). In particular, effusions obtained from breast cancer patients showed a significantly higher level of TGF alpha, compared with those from noncancer patients (P less than .001). Effusions from 14 cancer patients also contained elevated levels of two tumor-associated antigens, CEA and/or TAG-72, and within this group, nine also had elevated levels of TGF alpha.