Biomedical subjects

Irene Larripa

Publications and source records attributed to Irene Larripa.

12 recordsLinked to original sources

PubMed2006

cDNA microarray study to identify expression changes relevant for apoptosis in K562 cells co-treated with amifostine and imatinib.

PURPOSE: Chronic myeloid leukemia is a clonal myeloproliferative disorder characterized by the presence of the fusion gene BCR/ABL. We had previously demonstrated an increased proapoptotic effect of imatinib (STI571) in combination with amifostine (AMI) in K562 cell line. In this study, we used genomic scale gene expression profiling to monitor changes at transcriptional level in K562 cells during the treatment with AMI + STI571. MATERIALS AND METHODS: cRNA from Control and treated K562 cells were mixed in equal amounts and incubated with a microarray slide for hybridization. RNA from six independent paired experiments was subjected to transcriptional profiling. With the aim to automate the process of biological theme determination, selected genes were further analyzed by EASE. Validation of the expression was carried out by quantitative real-time PCR and western blotting. RESULTS: As expected, a small percentage of genes accounts for the effects of the combined drug treatment. We identified 61 sequences corresponding to known genes; 17 of the 61 genes were up regulated, such as RHO6, PPP2R5E, PPM1E and BTF that appear to reflect favorable events for apoptosis induction. Between down regulated genes, API5, TUBB2 and TLK1 are also of considerable interest. CONCLUSION: We identified a transcriptional repressor of survival genes, known as BTF, which triggers a proapoptotic signal, potentially helpful to overcome the resistance to STI571. This finding could be particularly useful to design novel therapeutic strategies for leukemia patients. This study demonstrates the importance of in vitro testing of a novel drug combination most likely to predict its potential usefulness for in vivo application.

Amifostine↗

PubMed2005

Additive apoptotic effect of STI571 with the cytoprotective agent amifostine in K-562 cell line.

PURPOSE: To study the apoptotic effect of the 2-phenylaminopyrimidine derivative STI571 in combination with antioxidant agents on K-562 cell line derived from a Philadelphia chromosome-positive chronic myeloid leukemia patient. MATERIALS AND METHODS: K-562 (BCR/ABL+), U-937, and HL60 (BCR/ABL-) leukemic cell lines were incubated with STI571 and the antioxidant agents catalase, glutathione, superoxide dismutase, and amifostine (AMI). Apoptotic effect was analyzed by morphological and flow cytometric criteria. RESULTS: STI571 at concentrations higher than 0.25 mumol L(-1) produced apoptosis (P<0.05) in K-562 cells only after treatment for 72 h. At the mentioned concentrations, STI571 also induced an increase in the loss of mitochondrial transmembrane potential from 24.6 to 40%. Combination of STI571 (0.5 micromol L(-1)) with antioxidant agents showed that the cytoprotective agent AMI (0.75 mg mL(-1)) produced an additive effect in the proapoptotic activity of STI571 in K-562 cells at nuclear (58.8%+/-2.0 vs. 28.9%+/-3.3) and mitochondrial (53.3%+/-3.6 vs. 29.5%+/-1.2) levels. CONCLUSIONS: Our results show that only AMI in combination with STI571, at submicromolar concentration, has an additive effect in K-562 cell line, and it does not have severe toxic effects on Philadelphia chromosome negative cells.

Amifostine↗

PubMed2005

Chronic lymphocytic leukemia developing in a patient with chronic myeloid leukemia: evidence of distinct lineage-associated genomic events.

We describe the cytogenetic, fluorescence in situ hybridization (FISH), and molecular findings in a patient who developed a typical chronic lymphocytic leukemia (CLL) 20 months after the diagnosis of a Philadelphia (Ph)-positive chronic myeloid leukemia. Unstimulated bone marrow culture showed a 46,XX,t(9;22)(q34;q11) karyotype, and interphase FISH detected the presence of a BCR/ABL fusion signal in 13% of cells. On stimulated bone marrow culture, a normal karyotype and a 13q14 deletion by interphase FISH with D13S319 probe in 14% of the cells were found. Molecular studies detected the chimeric BCR/ABL messengers by nested reverse-transcriptase polymerase chain reaction. The B-cellular clone was documented by the presence of a clonal heavy chain immunoglobulin rearrangement. The coexistence of these two hematologic malignancies leads to questions about their cell(s) of origin. We provide evidence that CLL arose in a Ph-negative clone. The implications of these findings are discussed.

Aged↗

PubMed2004

Insertion (4;11)(q27;q24q21) in a patient with essential thrombocythemia with progression to myelofibrosis.

We report a case of essential thrombocythemia (ET) in a 39-year-old woman who developed myelofibrosis at follow-up. The cytogenetic and fluorescence in situ hybridization analyses revealed a pathologic clone with the following previously unreported karyotype: 46,XX,ins(4;11)(q27;q24q21). We cannot conclude that the presence of this inverted insertion was associated with the overproduction of platelets, but documentation of more cases with chromosomal abnormalities and ET should lead to identifying different candidate genes involved in the neoplastic growth.

Adult↗

PubMed2004

Feasibility of a cost-effective approach to evaluate short tandem repeat markers suitable for chimerism follow-up.

BACKGROUND: Precise chimerism monitoring is important for the prediction of the success of allogeneic bone marrow transplantation (BMT). Most of the current procedures employed for chimerism follow-up with short tandem repeat (STR) markers are either time-consuming, labor-intensive, or use expensive assays, making it burdensome to perform large-scale studies of transplanted patients. AIM: To set-up a simple nonradioactive method to investigate a set of STR markers that could be used in the evaluation of chimerism status after allogeneic BMT. METHOD: Six dinucleotide STRs (D2S123, D5S107, CRTL1, D7S500, D11S1356, and TP53) were analyzed by touchdown (TD)-PCR followed by medium size non-denaturing polyacrylamide gel electrophoresis and silver staining. The sensitivity of the approach was evaluated by dilution competition assays. Peripheral blood samples were taken from a group of 50 healthy Argentinean donors, two transplanted patients, and their respective bone marrow donors. Buccal mucosa samples were also obtained from the BMT recipients. RESULTS: Four markers, D2S123, D7S500, D11S1356, and TP53, presented the highest heterozygosities (0.67-0.88) under our experimental system. A sensitivity of 0.8-1.6% for chimerism detection was consistently found for the different STR. The usefulness of these STR in chimerism analysis was illustrated with the screening of related siblings analyzing two transplanted patients with persistent mixed chimerism, which were previously studied by fluorescence in situ hybridization (FISH). Similar proportions of mixed chimerism were obtained with STR analysis compared with those estimated by FISH. DISCUSSION: To our knowledge, this was the first study of mixed chimerism using TD-PCR to achieve a highly specific STR amplification. This approach allows simple and accurate chimerism quantification because it avoids slippage of Taq polymerase on repeat stretches and prevents the differential amplification of the shorter allele. STR heterozygosities and the high level of sensitivity of this method demonstrated that this approach is not only very informative in this population, but is also rapid (taking less than 14 hours) and cost-efficient. CONCLUSION: The data confirms that this method is a useful tool applicable to routine large-scale STR genotyping and mixed chimerism analysis in low-complexity laboratories worldwide.

Bone Marrow Transplantation↗

PubMed2004

A single, multiplex analysis for all relevant activating NRAS gene mutations using heteroduplex generators.

We describe a multiplex polymerase chain reaction (PCR)-based test that detected all relevant NRAS activating mutations using a single PCR followed directly by electrophoresis. The test uses a Universal Heteroduplex Generator (UHG) to detect exon-2 (codon 61) NRAS mutations in multiplex with an UHG for exon-1 (codons 12 and 13). The method differentiated all 19 relevant mutations in these exons and showed a mutation independent sensitivity of approximately 6%. The sensitive, specific detection of all NRAS activating mutations using this single rapid test represents a minimum workload and could be applied readily for large-scale screening and for routine analysis.

Base Sequence↗

PubMed2003

Rapid detection of exon 1 NRAS gene mutations using universal heteroduplex generator technology.

Specific NRAS oncogene missense mutations have been frequently found in some tumors and several hematological diseases, especially in those of myeloid origin. There is a wide range of PCR-based methods for screening and detection of NRAS exon 1 single-base substitutions. However, there are disadvantages and ambiguities associated with these techniques because all of them require either separate probes, separate PCR amplifications, or complicated post-PCR manipulations. This report describes a new approach for detection of NRAS gene mutations at codon 12 and 13 based on the DNA heteroduplex analysis method. The strategy relies upon differential electrophoretic behavior of induced heteroduplex molecules formed by cross-hybridization of two PCR-amplified species, the sample under analysis and the synthetic universal heteroduplex generator (UHG). The screening of a panel of all codon 12 and 13 NRAS mutant DNA variants indicated that this approach discriminates all 12 relevant mutations. The sensitivity of the method was estimated by a competitive assay where mutant alleles could be detected at a dilution level of 1 to 16 wild-type alleles. This UHG technology was tested on some clinical samples previously studied by PCR-ASO. This methodology is highly specific, sensitive, and achieves an appreciable reduction in workload and time because it requires one PCR amplification followed by polyacrylamide gel electrophoresis in standard conditions. We propose that this new approach may be applied as an alternative strategy for codon 12-13 NRAS mutations and it could be easily incorporated into the range of routine assays performed in oncology laboratories.

Codon↗

PubMed2002

Evaluation of constitutional chromosome aberrations in hematologic disorders.

We have reviewed 4164 patients with various hematologic disorders cytogenetically studied in our laboratory during the last 25 years to analyze the frequency of constitutional chromosome aberrations (CCA) and to evaluate their association with hematologic malignancies. Our population of patients included 1133 pediatric patients and 3031 adults. Twenty-four (0.58%) cases showed CCA. They included four patients with Robertsonian translocations, one patient with a balanced translocation, two patients with sex chromosome abnormalities, and 17 cases with Down syndrome (DS). Nonsignificant differences among the frequency of patients with CCA from our hematologic series and those observed in the two largest combined surveys of livebirth published (0.65-0.84%) were found. The incidence of DS patients in our population (0.41%) was approximately three times higher than of that observed at birth (0.12-0.17%; P<0.001). The total incidence of constitutional chromosome abnormalities in the non-DS hematologic patients was 0.168% (7 of 4164) lower than of that observed in the newborn population (0.51-0.67%; P<0.001). Nonsignificant differences were found when the incidences of structural aberrations and sex chromosome anomalies were individually compared with the data of the overall population. Our results suggest that the presence of a CCA, other than DS, would not predispose patients to hematologic malignancies.

Adolescent↗

PubMed2002

Correlation between chromosome damage and apoptosis induced by fludarabine and idarubicin in normal human lymphocytes.

Fludarabine (FLU, a fluorinated purine analog) and idarubicin (IDA, a DNA-topoisomerase II poison) are frequently used in cancer chemotherapy. The effects of these drugs on cultured normal human lymphocytes were studied to establish the possible involvement of chromosome damage in the apoptotic program. Chromosome aberrations (CA) were evaluated in first division metaphases and the apoptotic process was measured by morphological and electrophoretical techniques. The percentage of abnormal cells was increased from the doses of FLU 1.0 microg/ml and IDA 0.005 microg/ml (P<0.0001) with an important decrease in the mitotic index (MI) for the highest doses assayed. A significant dose-dependent induction of abnormal cells was observed for both drugs. An increase of apoptotic cells was found at 5.0 and 10.0 microg/ml of FLU (P<0.001) while IDA activated apoptosis at 0.05 microg/ml (P<0.01) and markedly from 0.1 microg/ml (P<0.001). These increments were dose dependent. Apoptotic cell morphology was associated with DNA fragmentation at the highest doses. The increased induction of abnormal cells and the decreased MI were in correlation with the apoptotic index for FLU and IDA, suggesting the role of CA in drug-induced cell death.

Antibiotics, Antineoplastic↗

PubMed2002

Differential antigenotoxic and cytoprotective effect of amifostine in idarubicin-treated mice.

In this study we evaluated the antigenotoxic and cytoprotective capabilities of WR-2721 [S-2-(3-aminopropylamino)-ethylphosphorothioic acid (amifostine)] in different normal tissues of BALB/c mice treated with idarubicin [4-demethoxydaunorubicin (IDA)]. The aminothiol WR-2721 is a pro-drug that requires dephosphorylation to its active metabolite WR-1065, to produce selectively cytoprotective activity in normal tissues exposed to radio- and chemotherapeutic agents, without protecting malignant tissues. IDA is an effective chemotherapeutic agent against hematological diseases, but produces a broad spectrum of toxicity in nontumoral cells. Animals were injected intravenously with WR-2721 (250 mg/kg) or IDA (6 mg/kg) and WR-2721/IDA. Micronuclei frequency in bone marrow was measured 24 and 48 hr after initiation of the treatments. The IDA-treated group showed increased levels of micronuclei. However, the WR-2721- and WR-2721/IDA-treated groups did not show differences from the controls. Genetic damage was evaluated by alkaline single-cell gel electrophoresis at 24-hr posttreatments. Important DNA damage was observed in liver, spleen, and peripheral blood cells of mice treated with IDA. The presence of WR-2721 diminished that damaging effect only in liver cells. The apoptotic index was measured in liver and spleen tissues by the TUNEL assay 14 and 24 hr after treatment. In liver we observed an increased percentage of apoptotic cells at 24 hr for the IDA-treated group, whereas the WR-2721 and WR-2721/IDA groups remained at low levels. Splenic cells treated with IDA and WR-2721/IDA showed increased DNA fragmentation levels at any time. In conclusion, WR-2721 has a tissue-specific antigenotoxic and cytoprotective effect in IDA-treated mice using these experimental conditions.

Amifostine↗

PubMed2002

Enhanced uptake of antisense oligonucleotides using cationic liposomes and the apoptotic effect of idarubicin in K-562 cell line.

We have evaluated the apoptotic and DNA damaging activity of Idarubicin (IDA) on K-562 cells alone and following the uptake of modified antisense-oligodeoxynucleotides (AS-ODNs) targeting b3a2 mRNA of bcr/abl hybrid gene, after treatment with AS-ODNs/DCChol-DOPE (liposomes) complexes. The uptake of FITC-labeled oligonucleotide-liposomes complexes (FITC-ODNs/DCChol-DOPE) was analyzed by flow cytometry and fluorescence microscopy. Both techniques indicated cytoplasmic accumulation of labeled liposome complexes following 24h of exposure. In absence of liposomes, AS-ODNs uptake was minimal. Pre-treatment of cells with AS-ODNs/DCChol-DOPE increased the capability of IDA to induce apoptosis as determined by morphology and the comet assay. In contrast, the use of a non-sense oligodeoxynucleotide conjugated with liposomes, in the presence of IDA, did not increase K-562 cell apoptosis. Nevertheless, DNA damage in IDA treated cells was not related to ODNs/liposomes pre-treatment, as determined by the comet assay. Our data suggests that DCChol-DOPE increases the uptake of ODNs in K-562 cells, and these modified AS-ODNs increase IDA induced apoptosis by decreasing p210(bcr/abl) levels in K-562 cells.

Apoptosis↗

PubMed2002

Detection of risk groups in myelodysplastic syndromes. A multicenter study.

BACKGROUND AND OBJECTIVES: Myelodysplastic syndromes (MDS) comprise a group of heterogeneous hematologic disorders with risk of leukemic evolution (LE). The French-American-British (FAB) co-operative group classifies them into five morphologic entities and the International Prognostic Scoring System (IPSS) proposes four groups of risk on the basis of clinical and cytogenetic variables. The aim of this study was to evaluate the application of the IPSS in our Argentine population, to test the prognostic value of its variables and to determine whether this score helps to associate prognostic subgroups of risk into FAB subtypes. DESIGN AND METHODS: Two hundred and thirty-four patients with primary MDS and a median follow-up of 28 months were evaluated using univariate analyses to determine median survival (SV) and the time to LE. The variables analyzed were FAB classification, IPSS, percentage of myeloblasts, cytogenetic groups of risk and number of cytopenias. RESULTS: Univariate analyses showed that all variables analyzed were predictive for SV and for LE in our MDS population. Application of the IPSS allowed discrimination into the 4 groups of risk and helped to identify prognostic subclasses among the FAB classification, associating 5%, 15% and 19% of cases with worse prognosis within the FAB classification of refractory anemia (RA), RA with ringed sideroblasts and RA with excess of blasts (RAEB), respectively. The IPSS was not informative for RAEB in transformation cases and would not be applied to patients with chronic myelomonocytic leukemia. INTERPRETATION AND CONCLUSIONS: This score could be applied to our MDS population, showing no geographic differences. Stratification of FAB patients according to IPSS would be helpful to develop risk-adapted therapeutic strategies.

Adolescent↗