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M Negrini

Publications and source records attributed to M Negrini.

At least 55 records · Page 3Linked to original sources
PubMed1997

Chromosome aberrations in atypical chronic lymphocytic leukemia: a cytogenetic and interphase cytogenetic study.

To define better the chromosomal profile of atypical chronic lymphocytic leukemia (aCLL), cytogenetic and interphase cytogenetic studies were performed in 43 cases, using mitogen-stimulated cultures and DNA probes detecting the two most frequently occurring aberrations in CLL, ie +12 and 13q14 deletions. All cases showed monoclonal CD5/CD19-positive lymphocytosis, with more than 10% large lymphocytes and/or prolymphocytes in peripheral blood smears and reactivity with FMC7, or bright expression of surface immunoglobulins in a fraction of the cases. Karyotype aberrations were detected in 27 of 43 cases (62.8%). Recurrent chromosome changes were +12 (nine cases), 13q14 aberrations (five cases), 11q anomalies (three cases), 6q21-q23 abnormalities and 4q anomalies with different breakpoints (two cases each). Additional chromosome changes were seen in four cases with +12, in three cases with 13q14 anomalies, in two cases with 11q anomalies, in one case with 6q and 4q anomalies. Trisomy 12 was associated with 13q14 anomalies in three cases, one of which also had an 11q abnormality; other associations, found in one case each, were: 13q14 deletion with a 6q anomaly, 11q anomaly with 13q- and 7q-, a 6q anomaly with 7q- and +12. Interphase cytogenetics confirmed the results of chromosome banding analysis and showed that six patients with normal karyotype or no mitosis in fact had concomitant +12 and 13q14 deletion in four cases and isolated +12 or 13q14 deletion in one case each, with a resultant 76% overall incidence of cytogenetic abnormalities. The presence of +12, 13q14 deletions, 11q, and 6q21-q23 anomalies in 19 cases was associated with a 2-month median interval between diagnosis and start of treatment, as compared with a 24-month median interval in 14 cases with normal karyotype or non-recurrent chromosome changes (P = 0.003). We conclude that aCLL is characterized by a relatively high incidence of chromosome anomalies, with recurrent chromosome changes, involving chromosomes 12, 13q14, 6q21q23, 11q, and, possibly, 4q. The presence of complex karyotypes, with concomitant abnormalities of 13q, +12, 6q, 11q, suggests that the development of sequential chromosome changes, rather than any single specific anomaly, may underlie leukemogenesis in this cytologic subset of CLL, partially accounting for the relatively aggressive clinical course.

Adult↗
PubMed1997

Mapping of 22 new ESTs around a tumor suppressor gene and a senescence gene at 6q16-->q21.

Twenty two expressed sequence tags (ESTs) have been mapped at the border of 6q16-->q21 and at the proximal end of 6q21, a candidate for two tumor suppressor genes and a senescence gene. Use of a translocation and deletion hybrid panel together with a 4-Mb YAC contig allowed us to precisely define the position of the ESTs. Thirteen ESTs were placed within the 4-Mb interval at the proximal portion of 6q21 using a restriction map of the YAC contig, seven ESTs span a 2-Mb region on the 6q16-->q21 border, and two are distal to the contig. Refinement of the localization of these ESTs will provide substantial assistance in identifying new genes within the region 6q16-->q21.

Aging↗
PubMed1996

ATM mutations in cancer families.

Ataxia-telangiectasia (A-T) is a multisystem recessive disease characterized clinically by cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency, sensitivity to radiomimetic agents, and cancer predisposition. This pleiotropic disorder is caused by mutations in the ATM (mutated in A-T) gene, which is located in the human chromosomal region 11q22-q23. The ATM gene product is a member of a novel family of large proteins implicated in the regulation of the cell cycle and response to DNA damage. Heterozygosity for A-T was previously suggested to be associated with an increased risk of tumors, particularly female breast cancer. Because of loss of constitutional heterozygosity at 11q22-q23 is a frequent event in breast and other tumors, suggesting the presence of a tumor suppressor gene(s) in this region, we screened blood DNA samples from 88 unrelated breast cancer patients of Swedish cancer families for ATM mutations using single-strand conformation polymorphism analysis. All patients had a family history of tumors previously associated with A-T heterozygosity or homozygosity. We demonstrate the first three germ-line mutations in ATM identified by screening of breast cancer patients. Two mutations were previously found in A-T homozygotes and one mutation was a 1-bp insertion. All mutations were found in families with a large number of tumors, however, they did not cosegregate with malignancies. Although the proportion of A-T carriers in this sample seems to be higher than expected by chance, larger studies and pooled data sets will be required to establish that an A-T allele confers cancer susceptibility in heterozygotes.

Adenine↗
PubMed1996

Characterization of t(11;14) translocation in mantle cell lymphoma by fluorescent in situ hybridization.

Characterization of chromosome abnormalities in leukemia and lymphoma have contributed to the understanding of the molecular basis of these neoplastic diseases. In addition, specific chromosomal aberrations have acquired diagnostic or prognostic value. The t(11;14)(q13;q32) chromosome translocation has been detected in mantle cell lymphomas. However, possibly due to the limits of conventional cytogenetic analysis and the presence of different breakpoints at the molecular level, it is possible that the true percentage of association is underestimated. In our study, we used a yeast artificial chromosome, spanning the entire area where the rearrangements occur on chromosome 11q13, to detect the presence of translocations by fluorescent in situ hybridization experiments. We detected BCL-1 translocations in eight of eight patients with clinical and immunological features of mantle cell lymphoma, suggesting that the t(11;14) translocation is a critical event in the pathogenesis of MCL and may be a primary element for the diagnosis. Since this translocation is associated with poor prognosis, its detection may help to make a correct diagnosis as well as to evaluate residual disease, which is critical to plan a rational chemotherapy regimen.

Aged↗
PubMed1996

The FHIT gene at 3p14.2 is abnormal in breast carcinomas.

Chromosome 3p deletions in breast cancer have been detected at 3p12-p21 by cytogenetic and loss of heterozygosity studies. Recently, we have cloned the FHIT (fragile histidine triad) gene, located at 3p14.2. Abnormalities of the FHIT locus were found in many established cancer cell lines, and the gene was abnormally transcribed in primary tumors of the digestive tract and lung. In this report, we describe the analysis of breast cancer, cell lines, and primary tumors for alterations in transcription of the FHIT gene; about 20% of the samples exhibited altered transcripts. In most of the cases, aberrant transcripts were missing exons. Lack of expression of FHIT mRNA was observed in another 10% of primary tumor samples. These results suggest that alterations in the FHIT gene may play an important role in breast cancer tumorigenesis and suggest that the MIT gene product functions in the control of the tumorigenic phenotype in a large variety of human neoplasms.

Acid Anhydride Hydrolases↗
PubMed1996

Aberrant FHIT transcripts in Merkel cell carcinoma.

Merkel cell carcinoma is a rare neuroendocrine carcinoma of the skin which shares several features with small cell lung carcinoma. In a previous study, we reported a high frequency of abnormalities of the FHIT gene, located at 3p14.2, in small cell lung tumors. To determine the role of the FHIT gene in small cell neuroendocrine malignancies, 14 cases of Merkel cell carcinoma were analyzed by reverse transcription of FHIT mRNA followed by PCR amplification and sequencing of products. Eight of 14 tumors (57%) displayed abnormal FHIT products that lacked three or more exons of the FHIT gene. The pattern of abnormal transcripts was similar to that observed in small cell lung tumors, suggesting that FHIT abnormalities might be a common genetic marker of these two types of neuroendocrine tumors.

Acid Anhydride Hydrolases↗
PubMed1996

Complete exon structure of the ALL1 gene.

The ALL1 gene is found rearranged in approximately 10% of acute lymphoblastic leukemias and in over 5% of acute myeloid leukemias. The gene undergoes fusion with either a variety of partner genes located on different chromosomes or with itself. To further characterize the role of the ALL1 gene in the leukemogenic process, and possibly in solid malignancies, we defined its complete genomic structure. The gene, which spans a region on chromosome band 11q23 approximately 90 kb in length, consists of 36 exons, ranging in size from 65 bp to 4249 bp. The determination of intronic sequences flanking the exon boundaries will allow the determination of whether point mutations may be responsible for inactivation of the gene in solid tumors showing loss of heterozygosity at region 11q23.

Base Sequence↗
PubMed1996

The FHIT gene 3p14.2 is abnormal in lung cancer.

To determine the role of the FHIT gene, which encompasses the fragile site at 3p14.2, we analyzed 59 tumors of the small cell and non-small cell type by reverse transcription of FHIT mRNA, followed by PCR amplification and sequencing of products. Allelic losses affecting the gene were evaluated by microsatellite polymorphism analysis and genomic alterations by hybridization using cDNA and genomic probes. Small cell lung tumors (80%) and non-small cell lung cancers (40%) showed abnormalities in RNA transcripts of FHIT, and 76% of the tumors exhibited loss of FHIT alleles. Abnormal lung tumor transcripts lack two or more exons of the FHIT gene. Small cell lung cancer tumors and cell lines were analyzed by Southern blotting and showed rearranged BamHI fragments. These data suggest a critical role of the FHIT gene in lung carcinogenesis.

Amino Acid Sequence↗
PubMed1996

Potential gastrointestinal tumor suppressor locus at the 3p14.2 FRA3B site identified by homozygous deletions in tumor cell lines.

A number of DNA fragments, identified by representational difference analysis, which were homozygously deleted in various cancer cell lines were previously mapped to human chromosomal arms. One of these, BE758-6, which was homozygously deleted in a number of colon carcinoma cell lines, had been mapped to chromosome region 3p. We have further localized the probe to 3p14.2, approximately 350kbp telomeric to the 3p14.2 break of the t(3;8) hereditary renal cell carcinoma chromosome translocation, within or near the 3p14.2 FRA3B, the most common human fragile site. We determined the sizes of the homozygous deletions in a number of cancer cell lines after isolation of a yeast artificial chromosome contig and development of STS markers which fall between D3S1234 and D2S1481, which flank the deletions. Homozygous deletions were observed and sized not only in the cell lines originally reported but also in a number of nasopharyngeal carcinoma cell lines and a gastric carcinoma cell line. About 50% of uncultured stomach and colon carcinomas were then shown to lose heterozygosity for alleles in the same region, with a common region of loss between the D3S1234 and D3S1481 markers. Thus, it is likely that the homozygous deletion observed in these cancer cell lines harbors an important tumor suppressor gene for several tumor types.

Base Sequence↗
PubMed1996

The t(6;16)(p21;q22) chromosome translocation in the LNCaP prostate carcinoma cell line results in a tpc/hpr fusion gene.

Very little is known about the molecular and genetic mechanisms involved in prostate cancer. Previous studies have shown frequent loss of heterozygosity (40%) at chromosomal regions 8p, 10q, and 16q, suggesting the presence of tumor suppressor genes in these regions. The LNCaP cell line, established from a metastatic lesion of human prostatic adenocarcinoma, carries a t(6;16)(p21;q22) translocation. To determine whether this translocation involved genes important in the process of malignant transformation, we cloned and sequenced the t(6;16) breakpoint of this cell line. Sequence analysis showed that the breakpoint is within the haptoglobin gene cluster on chromosome 16, and that, on chromosome 6, the break occurs within a novel gene, tpc, similar to the prokaryotic S10 ribosomal protein gene. The translocation results in the production of a fusion transcript, tpc/hpr.

Amino Acid Sequence↗
PubMed1996

Loss of heterozygosity for chromosome 11 in adenocarcinoma of the stomach.

Loss of heterozygosity (LOH) at several chromosomal loci is a common feature of the malignant progression of human tumors. In the case of chromosome 11, LOH has been well documented in several types of solid neoplasms, including gastric carcinoma, suggesting the presence of suppressor gene(s) at 11p15 and 11q22-23. Little is currently known about the molecular events occurring during the development of gastric cancer. To define the regions of chromosome 11 involved in gastric cancer progression, we used high-density polymorphic markers to screen for LOH in matched normal and tumor tissue DNA from 60 primary gastric carcinomas. We found that 21% of the tumors showed LOH simultaneously at 11p15 and 11q22-23, 41% had LOH at 11p15, and 30% had LOH at 11q22-23. We confirm that the minimal critical area of LOH for 11p15.5 is the approximately 2-Mb region between loci D11S1318 and D11S988. However, when we analyzed the pattern of LOH according to the country of origin of the patient, LOH for 11q22-23 alone was found only in cases from Italy. The minimal critical region of LOH at 11q22-23 is identical to that identified for other solid tumors, suggesting that the same putative tumor suppressor gene(s) contained within this region is involved in the pathogenesis of several common human tumors.

Adenocarcinoma↗
PubMed1996

Exon-scanning mutation analysis of the ATM gene in patients with ataxia-telangiectasia.

Using a polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) assay, which amplifies individually all coding exons of the ATM gene deficient ataxia-telangiectasia (A-T), we have analyzed 10 patients with A-T for ATM mutations. Mutation were detected in 9 patients. We describe the first ATM mutation in the splice junction found in the 5' splice site of intron 17, leading to exon skipping. However, most mutations were small deletions or insertions resulting in premature termination of the translation product. The development of DNA-based methods for detection of unknown mutations and further characterization of ATM mutation pattern will facilitate identification of A-T carriers and assessment of their cancer risk.

Ataxia Telangiectasia↗
PubMed1995

Genomic organization of the ATM locus involved in ataxia-telangiectasia.

The ATM gene, involved in the genetic disorder ataxia-telangiectasia (AT), has been identified recently. This gene is suspected to predispose to malignancy and is located in a chromosomal region that we have recently found deleted in 50 to 60% of breast and lung carcinomas. Because of its location and its function, the ATM gene is a strong candidate tumor suppressor or modifier gene of chromosome region 11q23. In this study, we define its genomic structure. The aim was to establish the basis for the development of mutation scanning methods based on DNA instead of RNA. We found that the gene spans a region of approximately 70-80 kb and is composed of 37 exons, ranging in size from 64 to 324 bp. Nucleotide sequences of all exon/intron boundaries were determined. With this information, it will be possible to develop simple genetic tests for the identification of homozygotes and heterozygotes, as well as determine whether the gene is involved in the pathogenesis of breast and other carcinomas.

Ataxia Telangiectasia↗
PubMed1995

The human immunodeficiency virus type-1 Tat protein upregulates Bcl-2 gene expression in Jurkat T-cell lines and primary peripheral blood mononuclear cells.

The regulatory Tat protein of human immunodeficiency virus type-1 (HIV-1) exerts a pleyotropic activity on the survival and proliferation of different cell types in culture. In this report, we investigated the effect of either endogenous or exogenous Tat on Bcl-2 proto-oncogene expression and cell survival in Jurkat T-cell lines and primary peripheral blood mononuclear cells. Stable and transient transfections of Jurkat cells with the cDNA of tat and a plasmid containing Bcl-2 promoter in front of CAT (Bcl-2 Pr/CAT) stimulated CAT activity and showed an increase of Bcl-2 mRNA and protein expression. This effect was specifically related to tat, because Jurkat cells transfected with the cDNA of tat in antisense orientation, tat carrying a mutation in the amino acid cys22-gly22, or the control vector alone (pRPneo-SL3) did not show any significant difference in Bcl-2 promoter activity with respect to parental Jurkat cells. We also observed a specific correlation between tat-induced Bcl-2 gene expression and inhibition of apoptosis induced by serum withdrawal. Our results suggest that the structural integrity of the activation domain of Tat was required for the promotion of the Bcl-2 promoter and Jurkat cell survival, because a single mutation in the aminoacid cys22 was sufficient to completely block the upregulation of Bcl-2 and inhibition of apoptosis. Moreover, picomolar concentrations of native or recombinant Tat were able to upregulate Bcl-2 expression both in Jurkat and primary peripheral blood mononuclear cells, suggesting that extracellular Tat, actively released by infected cells, may also play a significant role in suppressing apoptosis. An aberrant cell survival of lymphoid cells consequent to the upregulation of Bcl-2 may represent an additional pathogenetic mechanism that could help explain both the dysregulated immune response and the frequent occurrence of hyperplastic/neoplastic disorders in HIV-1-seropositive individuals.

Apoptosis↗
PubMed1995

Loss of heterozygosity at chromosome 11q in lung adenocarcinoma: identification of three independent regions.

We examined the pattern of allelic loss in 76 adenocarcinomas of the lung using 14 highly informative microsatellite markers on the long arm of chromosome 11. Loss of heterozygosity was found in 48 of 76 tumors (63%). Three distinct regions of deletion were identified. The first region, the most centromeric, lies between markers D11S940 and CD3D: the second, delimited by markers D11S924 and D11S925, is estimated to be 4 Mb in length, and has never been previously described; a third, more telomeric region, the length of which is also estimated to be in the range of 4 Mb, is bracketed by loci D11S1345 and D11S1328. These findings suggest the presence of at least three tumor suppressor genes on the long arm of chromosome 11, and confirm the relevance of 11q22-24, a region frequently deleted in carcinomas of the breast, ovary, uterine, cervix, colon, and malignant melanoma in the pathogenesis of solid tumors. The characterization of minimal regions of loss could provide the basis for the identification and cloning of the critical genes.

Adenocarcinoma↗
PubMed1995

Definition and refinement of chromosome 11 regions of loss of heterozygosity in breast cancer: identification of a new region at 11q23.3.

Chromosome 11 is frequently altered in several types of human neoplasms. In breast cancer, loss of heterozygosity has been described in two regions of this chromosome, 11p15 and 11q22-23. In this report we have dissected the two regions using high-density polymorphic markers, and have found that there are at least two independent areas of loss of heterozygosity in each region, suggesting that multiple genes on chromosome 11 may be targets of genetic alteration during tumor establishment or progression. The regions defined are: at 11p15, between loci D11S576 and D11S1318 and between D11S988 and D11S1318; at 11q23, between D11S2000 and D11S897 and between D11S528 and D11S990. The narrowing of these regions of loss should facilitate the cloning of the regions in yeast artificial chromosomes to identify the critical tumor suppressor genes.

Base Sequence↗
PubMed1995

Seven megabase yeast artificial chromosome contig at region 11p15: identification of a yeast artificial chromosome spanning the breakpoint of a chromosomal translocation found in a case of Beckwith-Wiedemann syndrome.

Genetic alterations of chromosome region 11p15 have been detected in neoplastic diseases as well as in cancer-predisposing syndromes. The cloning of the entire chromosomal region will be important for the identification and characterization of critical tumor suppressor genes. We have developed a yeast artificial chromosome contig that covers up to 7 Mb of this chromosome band. The most centromeric marker included in the contig is D11S932 and the most telomeric is D11S470. We have developed 18 new STS markers, which have been located in the contig in relation to 16 known markers. One of the yeast artificial chromosome clones was found to span the chromosome 11 breakpoint of the translocation t(11;18), associated with a case of Beckwith-Wiedemann syndrome. Cloning the regions in proximity to this translocation might reveal the presence of a gene altered in association with the development of Beckwith-Wiedemann syndrome.

Base Sequence↗