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G Saglio

Publications and source records attributed to G Saglio.

At least 145 records · Page 8Linked to original sources
PubMed1993

Molecular defects associated with the acute phase CML.

Parts of the Bcr/Abl hybrid transcript supposed to be important for its transforming ability were sequenced in a series of CML blast crises, in order to evaluate the possible presence of alterations responsible for the disease transition from the chronic to the acute phase. In addition, the N- and Ki-ras as well as the p53 involvement was investigated by exploring their structure and expression in the same patients. We used traditional types of molecular analysis including Southern and Northern blot, together with methods that allow a rapid detection of point mutations and microdeletions, such as SSCP, single strand conformation polymorphism and direct sequencing. The results obtained may be summarized as follows: no alterations were found in the parts of the Bcr/Abl transcripts investigated in the present study (SH2, SH3 and the region surrounding codon 832); p53 alterations were observed in 5% and N- and Ki-RAS mutations in 5% of the cases examined. These molecular defects are therefore responsible for the clinical progression of the Ph1-positive CML only in a minority of cases.

Base Sequence↗
PubMed1993

Mutations in the P53 and RAS family genes are associated with tumor progression of BCR/ABL negative chronic myeloproliferative disorders.

We have investigated the involvement of the p53 tumor suppressor gene and RAS family proto-oncogenes in BCR/ABL-negative chronic myeloproliferative disorders (CMPD), including nine cases of myelosclerosis with myeloid metaplasia, four polycythemia vera, 10 essential thrombocythemia, one juvenile chronic myeloid leukemia, and eight BCR/ABL-negative chronic myeloid leukemia. Twenty-five samples were studied in the chronic phase, while seven samples were analyzed in the acute accelerated or blastic phase. The presence of mutations in p53 exons 5-9, as well as in N-, K-, H-Ras exons 1 and 2 (containing codons 12, 13, and 61) was tested by the polymerase chain reaction (PCR) single strand conformation polymorphism technique and by PCR direct sequencing. In addition, restriction analysis was performed to screen for gross rearrangements within the p53 locus. Alterations of the p53 tumor suppressor gene and Ras family proto-oncogenes were detected in 2/7 and 3/7 cases of acute phase BCR/ABL-negative CMPD, respectively, while consistently negative in all the chronic phase samples analyzed. These results suggest that p53 inactivation and/or Ras activation might play a role in acute transformation of BCR/ABL-negative CMPD.

Adolescent↗
PubMed1993

Molecular evidence of minimal residual disease after treatment for leukaemia and lymphoma: an updated meeting report and review.

The very rapid development in the last few years of techniques based on use of the polymerase chain reaction (PCR) for characterizing molecular lesions in leukaemia and lymphoma now offers the opportunity for monitoring residual disease at a sensitivity of one malignant cell in 10(5) or 10(6) normal cells. Maximal specificity is presumably achieved when the DNA sequences amplified are truly leukaemia-specific, such as BCR/ABL in chronic myelogenous leukemia, RARA PML/RARA in t(15;17) acute myelogenous leukemia, DEK/CAN in t(6;9) AML, PBX1/E2A in t(1;19) acute lymphoblastic leukemia (ALL), or TAL-1 deletions in other T-ALLs. Comparable sensitivity may be achieved by using immunoglobulin heavy chain (IGH) and T-cell receptor (TCR) gene rearrangements if a clonospecific probe can be generated. However, the presence of similar sequences in IgH genes from normal B lymphocytes may decrease the specificity. For clinical purposes the crucial issues are the following. Can PCR techniques be used for confirmation of diagnosis and evaluation of extent of disease? Can PCR data obtained in remission provide information about the probability of cure or of relapse? Can techniques be developed to quantitate the PCR product and thereby increase its predictive value? These and other issues were addressed at the 4th Workshop of the Molecular Biology/BMT Study Group that took place in Bristol UK on 9-10 May 1992.

Humans↗
PubMed1992

Karyotypic analysis of gastric carcinoma cell lines carrying an amplified c-met oncogene.

MKN 45 is a poorly differentiated gastric carcinoma cell line from which the subclone GTL 16 was obtained. Both lines carry an amplification unit derived from chromosome 7 sequences and containing an activated c-met oncogene. Karyotypic analysis showed that GTL 16 derived from a subclone of MKN 45 after endoreduplication. Several clonal abnormalities are evident in both lines; some are frequently observed in gastrointestinal tumors (loss of 17p and monosomy 18). Other consistent anomalies include 6q-, t(8;10) and t(5;8), and inv(16). A marker chromosome (M1), which was previously shown to contain the c-met amplification unit, is constantly duplicated in all GTL 16 metaphases; in contrast, most unidentified markers are retained in only a single copy in GTL 16 cells. These data are in agreement with the hypothesis that the c-met oncogene activation in these gastric cancer cell lines might be related to a gene dosage effect.

Adenocarcinoma↗
PubMed1992

Tumorigenic activity of a rearranged c-myc gene from a human T-cell leukemia line.

The T-lymphoma cell line Hut78 contains a rearranged c-myc oncogene derived from a translocation between the long arms of chromosomes 8 and 2; the event deletes the 3' end of the gene, causing the loss of the transcribed AT-rich sequence. It has recently been shown that the mutant c-myc mRNA is several-fold more stable than normal c-myc mRNA. We have assessed the tumorigenicity of the mutant c-myc allele by transfecting this gene and its normal counterpart into NIH3T3 cells, together with a neomycin resistance gene. Following selection for G-418 resistance, the cells were injected into nude mice. Tumors containing integrated c-myc arose in animals injected with cells transfected by the mutated, but not by the normal, allele. The results suggest that this rearranged c-myc bears a tumorigenic activity not observed in other naturally occurring mutated c-myc alleles and may have directly contributed to the tumorigenic event in the Hut78 cell line.

3T3 Cells↗
PubMed1992

Rapid identification by denaturing gradient gel electrophoresis of mutations in the gamma-globin gene promoters in non-deletion type HPFH.

We have outlined a fast, non-radioactive strategy to identify point mutations in the 5' flanking region of the gamma-globin genes using denaturing gradient gel electrophoresis (DGGE) of amplified DNA. In a sample of previously characterized carriers of non deletion-type hereditary persistence of fetal haemoglobin (HPFH) the different point mutations in both gamma gene promoters could be easily identified by DGGE of a 327 bp fragment. A 4 bp deletion at position -225 to -222 of the A gamma globin gene was unexpectedly found in several samples and shown to represent a frequent polymorphism. Analysis of a 681 bp fragment specific for the 5' region of the A gamma gene, showed that this can be used to determine the haplotype of the chromosome under study. This technique may be useful in the study of sequence variations associated with high Hb F expression in physiological and pathological conditions.

DNA Mutational Analysis↗
PubMed1992

Molecular pathogenesis of HIV-associated lymphomas.

The data presented here indicate that the pathogenesis of AIDS-NHL is variably associated with multiple genetic alterations including monoclonal EBV infection, oncogene activation (c-myc, N-, Ki-ras) and tumor suppressor gene (p53) inactivation. Up to three (3 cases) or four (1 case) different lesions have been observed in the same tumor. The distribution of these lesions among the various histotypes is heterogeneous, although some preferential associations have been found either between lesion and histotype or between lesions. The most notable case involves p53 mutations/loss that is exclusively associated with the SNCC lymphoma subtype. Since alterations of the c-myc gene occur at very high frequency in this same histotype it is possible that both lesions may be required for the pathogenesis of the BL phenotype. The consistent negativity of p53 lesions in other NHLs associated or non associated with HIV infection (18) reinforces this hypothesis. Finally, we note that the frequency of p53 mutations is significantly higher in AIDS-BL than in non HIV-related BL (18), although the significancy of this difference remains to be assessed. This study confirms the relatively low frequency of EBV infection in systemic AIDS-NHL in general, but reinforces the notion that EBV may be required for the pathogenesis of AIDS-LC-IBP, as recently suggested by the high frequency of EBV positivity in primary CNS AIDS-NHL which are mostly represented by LC-IBP (2). Conversely, the low frequency of EBV sequences in the AIDS-SNCC lymphomas appears similar to that observed in sBL. Only in a small minority of cases were ras oncogene mutations found, mostly associated with the BL type.(ABSTRACT TRUNCATED AT 250 WORDS)

Genes, myc↗
PubMed1992

Minimal residual disease status in transplanted chronic myelogenous leukemia patients: low incidence of polymerase chain reaction positive cases among 48 long disease-free subjects who received unmanipulated allogeneic bone marrow transplants.

Forty-eight long-term disease-free chronic myelogenous leukemia (CML) patients, who had received unmanipulated allogeneic bone marrow transplants (BMT) for eradication of the Philadelphia (Ph1)-positive clone were studied by polymerase chain reaction (PCR), using a very sensitive PCR procedure and very stringent criteria for preventing and revealing contamination. Nine patients (18%) were positive at the first PCR examination, but only one patient remained PCR positive four years after. However, a second PCR analysis performed on new bone marrow samples obtained at a median interval of 14 months (range 6-16) after the first specimen collection from six of nine originally positive cases, and from 16 of 39 originally negative cases, showed that only one of the six positive cases remained positive, whereas negativity was confirmed in all the originally negative patients. These data are evidence that the Ph1-positive clone is apparently completely eradicated in the majority of CML patients who survive disease-free long-term after an unmanipulated allogeneic BMT and that only sporadic cases remain PCR-positive four years post-BMT. The data also show that at least two sequential bone marrow samples for each patient must be analyzed before drawing conclusions regarding the stable persistence of BCR/ABL transcripts and the minimal residual disease status.

Adolescent↗
PubMed1992

Transient cytogenetic relapse in a Ph1-positive chronic myelogenous leukemia patient previously treated with alpha-interferon.

Therapy with alpha-interferon (IFN alpha) can suppress the Ph1-positive hemopoiesis in a percentage of patients with chronic myelogenous leukemia (CML). We used IFN alpha to treat a 30-year-old CML patient, characterized by favourable prognostic signs (such as low leukocytosis, absence of splenomegaly and no increase in bone marrow blasts) at diagnosis, and obtained a complete remission, as evaluated by Southern blot and cytogenetic analysis, after one year of treatment. However, the polymerase chain reaction (PCR) revealed the persistence of a minimal residual disease. The IFN alpha therapy was stopped and the hematological status remained stable until eighteen months later, when a cytogenetic analysis revealed the appearance of a clone characterized by t(9;22) and trisomy 8, accounting for 30% of bone marrow metaphases. This cell population spontaneously regressed in the following months, before any cytotoxic treatment. However, as leukemic cells, detected by PCR, were still present, the patient received a high dose chemotherapy, which induced the complete eradication of the Ph1-positive clone, as demonstrated by the absence of bcr-abl transcript at the PCR reaction. Molecular and cytogenetic remission persist one year later, without any further therapy.

Adult↗
PubMed1991

c-erbB-2 and ras expression levels in breast cancer are correlated and show a co-operative association with unfavorable clinical outcome.

c-erbB-2 and ras expression was measured on tumor extracts from 132 human primary breast carcinomas, by immunoblotting analysis. Expression of the c-erbB-2-encoded p185 protein was observed in 39% of the samples and found to correlate with c-erbB-2 gene amplification, detected by Southern analysis in 19 of the 77 available tumor DNAs. p185 expression was linked to the absence of progesterone receptors, but it was not related to lymph-node status or to other clinico-pathological parameters. Levels of the ras-encoded p21 proteins higher than in normal breast tissues were found in 71% of the samples. No significant correlation was seen between p21 level and the available clinical parameters. Conversely, there was a strong positive correlation between p21 and p185 levels. Analysis of follow-up data revealed that p185 expression was associated with a shorter time to relapse and death. Most notably, the contemporaneous expression of p185 and of high p21 levels was more effective than p185 expression alone in identifying cases with poor prognosis. The prognostic value of p185/p21 co-expression was particularly significant in progesterone-receptor-positive tumors. Our data suggest that c-erbB-2 and ras may act synergistically to endow breast-tumor cells with a highly aggressive phenotype.

Biomarkers, Tumor↗
PubMed1991

Analysis of N-ras gene mutations in medulloblastomas by polymerase chain reaction and oligonucleotide probes in formalin-fixed, paraffin-embedded tissues.

Precise data on the incidence of transforming ras oncogenes in pediatric tumors and the correlations with the histopathological properties of the tumors are very limited. Additionally the presence of ras activation in medulloblastomas has not been investigated so far. Using a combination of techniques including in vitro gene amplification by polymerase chain reaction (PCR) and detection of single base mutations by sequence-specific oligonucleotides we studied N-ras activation (mutations at codon 12, 13, and 61) in 32 medulloblastomas. DNA was isolated from 20 microns sections of formalin-fixed paraffin-embedded tissue. Mutations were found in 3 out of 32 examined medulloblastomas. In all cases only mutations of codon 61 were found: two of three mutations were C to A mutations at position 1 of the codon 61 (leading to a substitution of a glutamine residue for a lysine) and one was A to T mutation at position 3 in the same codon (glutamine-histidine). Our results indicate 10% incidence N-ras mutation in medulloblastoma, higher than in other CNS tumors studied so far. The main advantages of the procedure described are its greatly improved sensitivity, the increased speed with which tumor samples can be analyzed, and the possibility of using paraffin-embedded sections to analyze various rare tumors in retrospect.

Adolescent↗
PubMed1991

Trisomy 8 and an unbalanced t(5;17)(q11;p11) characterize two karyotypically independent clones in a case of idiopathic myelofibrosis evolving to acute nonlymphoid leukemia.

In a patient with idiopathic myelofibrosis (MFI) that had progressed to acute nonlymphoid leukemia (ANLL) after a long-lasting cytotoxic treatment, we observed two karyotypically independent cell populations, one showing trisomy of chromosome 8 as the only anomaly and one with an unbalanced translocation t(5;17)(q11) resulting in partial monosomy of 5q and 17p. The overall karyotypic configuration suggested that chromosome changes occurred as secondary events during the multistep process of leukemogenesis. The probable sequence of cytogenetic events in this patient and a review of the literature indicated that the t(5;17) may represent a therapy-induced abnormality nonrandomly related to the terminal phase of myeloid disorders.

Aged↗
PubMed1991

Effect of recombinant human IL-3 on the mitotic index and karyotype of hemopoietic cells.

The proliferative induction by hemopoietic growth factors may provide a useful tool to improve the mitotic yield of hemopoietic cells, allowing a more accurate cytogenetic analysis in hematologic malignancies. For such a purpose, we studied the effects of the recombinant human IL-3 (rhIL-3) on the mitotic index and the karyotype of bone marrow cells from 14 patients with myelodysplastic (MDS) and myeloproliferative syndromes (MPS). The mitotic response to IL-3 of normal bone marrow samples was also evaluated. Total bone marrow cells were cultured for 24 to 72 hours either in presence or absence of rhIL-3. In most cases, IL-3--stimulated samples showed a considerably higher (4-70 times) mitotic index than unstimulated controls. Although a great patient-to-patient variability was observed, a common pattern of mitogenic response to IL-3 emerged among MPS, MDS, and normal cases. At 48 hours of incubation, the mean mitotic index from MPS and MDS cases stimulated with IL-3 was significantly higher (p less than 0.01) than unstimulated controls, whereas the mean mitotic increase from normal samples did not reach statistical significance (p greater than 0.1). Even though not statistically evaluable, a similar trend of response was observed at 24 and 72 hours of culture. Chromosome studies of MPS and MDS cases showed the same karyotype either in stimulated and unstimulated samples.

Bone Marrow↗
PubMed1991

Simultaneous screening for beta-thalassemia mutations by chemical cleavage of mismatch.

We used the chemical cleavage of mismatch (CCM) method to screen the beta-globin gene simultaneously for Mediterranean beta-thalassemia mutations. The beta-globin gene was amplified in two segments encompassing the whole gene and hybridized to a corresponding labeled PCR product from a normal subject. All the known mutations tested were identified and discriminated. Three beta-thalassemic subjects with previously undiagnosed mutations were identified as carriers of two rare DNA changes. The inheritance of the mutations could be traced in family studies, showing the reliability of the method even for prenatal diagnosis. The beta-globin gene polymorphisms were also detected and the framework was determined for most alleles. Our results suggest further applicability of the CCM method as a means to screen a gene simultaneously for multiple mutations.

Base Sequence↗