Genetic variability profiling of the p53 signaling pathway in chronic lymphocytic leukemia. Individual and combined analysis of TP53, MDM2 and NQO1 gene variants.

TP53 gene disruption, including 17p13 deletion [del(17p)] and/or TP53 mutations, is a negative prognostic biomarker in chronic lymphocytic leukemia (CLL) associated with disease progression, treatment failure and shorter survival. Germline variants in p53 signaling pathway genes could also lead to p53 dysfunction, but their involvement in CLL has not been thoroughly evaluated. The aim of this study was to determine the association of TP53, MDM2 and NQO1 gene variability with clinical and genetic data of CLL patients. Individual genotype and haplotype data of CLL patients were compared with clinical prognostic factors, cytogenetic and molecular cytogenetic findings as well as IGHV and TP53 mutational status. The study included 116 CLL patients and 161 healthy blood donors. TP53 (rs1042522, rs59758982, rs1625895), NQO1 (rs1800566) and MDM2 (rs2279744, rs150550023) variants were genotyped using different PCR approaches. Analysis of genotype frequencies revealed no association with the risk of CLL. TP53 rs1042522, rs1625895 and MDM2 rs2279744 variants were significantly associated with abnormal karyotype and the presence of del(17p). Similarly, these two TP53 variants were associated with TP53 disruption. Moreover, TP53 C-A-nondel and G-A-del haplotypes (rs1042522-rs1625895-rs59758982) were associated with an increased likelihood of carrying del(17p) and TP53 disruptions. MDM2 T-nondel haplotype (rs2279744-rs150550023) was found to be a low risk factor for del(17p) (OR = 0.32; CI: 0.12-0.82; p = 0.02) and TP53 disruptions (OR = 0.41; CI: 0.18-0.95; p = 0.04). Our findings suggest that TP53 and MDM2 variants may modulate the risk to have chromosome alterations and TP53 disruptions, particularly del(17p). To our knowledge this is the first study of several germline variants in p53 pathway genes in Argentine patients with CLL.

Discrimination of the chemotherapy resistance status of human leukemia and glioblastoma cell lines by MALDI-TOF-MS profiling.

Chemotherapy mistreatment is partially due to a lack of rapid and reliable tools to discriminate between sensitive and resistant phenotypes. In many cases, the resistance mechanism is not fully understood, contributing to the diagnostic tools' absence. This work aims to determine the capacity of MALDI-TOF-MS profiling to discriminate between chemotherapy-resistant and sensitive phenotypes in leukemia and glioblastoma cells. A multivariate analysis of two therapy-resistant leukemia cell lines (Ki562 and Kv562) and two TMZ-resistant glioblastoma cell lines (U251-R and LN229-R) and their sensitive counterparts was performed. In this work, we first show MALDI-TOF-MS patterns analysis ability to differentiate these cancer cell lines by their chemotherapy-resistant status. We present a rapid and inexpensive tool that would guide and complement the therapeutic decision.

Avances en la genética de la hipertensión arterial pulmonar

La hipertensión arterial pulmonar (HAP) es un trastorno cardiopulmonar grave e incurable que conlleva una importante morbilidad y mortalidad. Se caracteriza por la oclusión y remodelación de las arteriolas pulmonares, insuficiencia respiratoria progresiva, disfunción ventricular derecha, insuficiencia cardíaca y muerte prematura. Puede presentarse en diferentes formas, entre ellas la idiopática (HAPI) en ausencia de una causa conocida y la hereditaria (HAPH) en caso de relacionarse con una alteración genética o si hay agregación familiar. Existen además de estas formas, otras causas de HAP asociadas a diversas condiciones médicas (drogas, toxinas, infección por virus de la inmunodeficiencia humana -VIH-, etc.). A pesar de los avances recientes sigue siendo una enfermedad difícil de diagnosticar y tratar. La investigación de las bases genéticas de la HAP ha contribuido significativamente a mejorar la comprensión de esta patología. Las alteraciones genéticas más frecuentes asociadas a la HAP son mutaciones inactivantes del gen que codifica el receptor de la proteína morfogenética ósea tipo 2 (BMPR2, bone morphogenic protein receptor type 2). Los pacientes con HAP y mutaciones en BMPR2 se presentan a una edad más temprana con una enfermedad más grave y tienen un mayor riesgo de muerte o trasplante, que aquellos sin mutaciones. Avances recientes han conducido al descubrimiento de nuevos genes relacionados con la HAP, tales como ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), entre otros. En este artículo de revisión resumimos el conocimiento sobre las variantes genéticas raras y comunes que subyacen al desarrollo y pronóstico de la HAP. Además, esbozamos la importancia de implementar el asesoramiento y el estudio genético en centros especializados. La comprensión de la genética de la HAP proporcionará nueva información sobre los mecanismos subyacentes a la patobiología, potencialmente, útiles para desarrollar nuevas estrategias terapéuticas en el marco de una medicina personalizada.

Pulmonary arterial hypertension (PAH) is a serious and incurable cardiopulmonary disorder with significant morbidity and mortality. It is characterized by the occlusion and remodeling of the pulmonary arterioles, progressive respiratory failure, right ventricular dysfunction, heart failure and premature death. PAH can occur in different forms, including idiopathic (IPAH) in absence of a known cause and hereditary (HPAH) if related to a genetic alteration or if there is familial aggregation. Besides these forms, there are other causes of PAH associated with various medical conditions (drugs, toxins, HIV infection, etc.). Despite recent advances in PAH, it remains a challenging disease to both diagnosis and management. Research about the genetic basis of PAH has contributed significantly to improve the understanding of this condition. The most common genetic alterations associated with PAH are inactivating mutations in the gene encoding a bone morphogenetic protein receptor type 2 (BMPR2). Patients with BMPR2 mutations present PAH at a younger age with more severe disease, and have an increased risk of death or transplantation, than those without mutations. Recent advances have led to the discovery of new genes related to PAH, such as ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), among others. In this review, we summarize the knowledge about rare and common genetic variants that underlie PAH development and prognosis. Additionally, we outline the importance of implementing genetic counseling and testing in specialized pulmonary hypertension centers. Understanding the genetics of PAH will provide new insights into the mechanisms underlying its pathobiology potentially useful for developing new therapeutic strategies within the scope of a personalized medicine.

A hipertensão arterial pulmonar (HAP) é um distúrbio cardiopulmonar grave e incurável, com morbidade e mortalidade significativas. É caracterizada pela oclusão e remodelação das arteríolas pulmonares, insuficiência respiratória progressiva, disfunção ventricular direita, insuficiência cardíaca e morte prematura. Pode acontecer em diferentes formas, incluindo a idiopática (HAPI) na ausência de uma causa conhecida e a hereditária (HAPH) no caso de estar associada a uma anomalia genética ou quando há agregação familiar. Adicionalmente a estas formas, existem outras causas de HAP associadas a várias condições médicas (toxinas, drogas, infecção por HIV, etc.). Apesar dos avanços recentes, continua a ser uma doença difícil de diagnosticar e tratar. A pesquisa sobre a base genética da HAP contribuiu significativamente para melhorar a compreensão desta doença. As alterações genéticas mais comuns associadas à HAP são as mutações no gene que codifica o receptor da proteína morfogenética óssea tipo 2 (BMPR2, bone morphogenic protein receptor type 2). Pacientes com HAP e mutações BMPR2 se apresentam em idade mais jovem com doença mais grave e têm maior risco de morte ou transplante do que aqueles sem mutações. Avanços recentes levaram à descoberta de novos genes relacionados à HAP, tais como ACVRL1 (activin A receptor like type 1), ENG (endoglin), CAV1 (caveolin-1), KCNK3 (potassium channel subfamily K, member 3), entre outros. Neste artigo de revisão resumimos o conhecimento sobre as variantes genéticas raras e comuns associadas à etiologia e prognóstico da HAP. Ademais, destacamos a importância de implementar o aconselhamento genético e o estudo genético em centros especializados. A compreensão da genética da HAP vai proporcionar novo informação sobre os mecanismos subjacentes à patobiologia potencialmente úteis para o desenvolvimento de novas estratégias terapêuticas no âmbito da medicina personalizada.

Gene polymorphism profiles of drug-metabolising enzymes GSTM1, GSTT1 and GSTP1 in an Argentinian population.

BACKGROUND: Glutathione S-transferases (GSTs) are drug-metabolising enzymes involved in biotransformation of carcinogens, drugs, xenobiotics and oxygen free radicals. Polymorphisms of GST genes contribute to inter-individual and population variability in the susceptibility to environmental risk factors, cancer predisposition and pharmacotherapy responses. However, data about GST variability in Argentina are lacking. AIM: The purpose was to determine the prevalence of GSTM1, GSTT1 and GSTP1 polymorphisms in the general population from a central region of Argentina and to perform inter-population comparisons. SUBJECTS AND METHODS: GSTM1 and GSTT1 gene deletions and GSTP1 c.313A > G were genotyped by PCR assays in 609 healthy and unrelated Argentinians. RESULTS: The frequencies of variant genotypes in Argentinians were GSTM1-null (45%), GSTT1-null (17%) and GSTP1-GG (11%). GSTM1-present genotype was significantly associated with GSTP1-AG or GSTP1-GG variants (p = 0.037; p = 0.034, respectively). Comparison with worldwide populations demonstrated that the GST distributions in Argentina are similar to those reported for Italy and Spain, whereas significant differences were observed regarding Asian and African populations (p < 0.001). CONCLUSION: This study has determined, for the first time, the normative profile of three pharmacogenetically relevant polymorphisms (GSTM1, GSTT1 and GSTP1) in the largest Argentinian cohort described to date, providing the basis for further epidemiological and pharmacogenetic studies in this country.

GSTM1 and GSTP1, but not GSTT1 genetic polymorphisms are associated with chronic myeloid leukemia risk and treatment response.

BACKGROUND: Chronic myeloid leukemia (CML) is associated to the BCR-ABL1 oncogene and can successfully be treated with tyrosine kinase inhibitors (TKIs). However, it remains still under investigation which molecular factors may influence CML risk or varying responses to TKIs. The aim of this study was to assess the role of Glutathione-S-transferases (GSTs) genetic polymorphisms in CML susceptibility and TKI clinical outcome. MATERIALS: Deletion polymorphisms in GSTM1 and GSTT1 genes and the single nucleotide polymorphism in GSTP1 c.319A>G (rs1695; p.105Ile>Val) were genotyped by PCR methods in 141 CML treated patients and 141 sex- and age-matched healthy individuals. RESULTS: Individual analysis of each GST gene showed no association with CML risk. A trend toward significance (p=0.07) for a recessive model was found for GSTP1 (OR: 2.04; CI: 0.94-4.4). However, the combined analysis showed that GSTM1-null/GSTP1-GG as well as GSTT1-null/GSTP1-GG were associated with CML development (p=0.03; OR: 3.54 CI: 1.2-14.57; p=0.05; OR: 12.65; CI: 1.17-21.5). The relationship with treatment outcome showed that the presence of GSTM1 gene was significantly linked with an inferior rate of major molecular response (p=0.048) and poor event free-survival (EFS) (p=0.02). Furthermore, a group of patients with GSTP1-GG genotype were significantly associated with reduced EFS comparing to those carrying other GSTP1 genotypes (p=0.049). GSTP1-GG genotypes had short time to treatment failure in a group of patients unresponsive to TKIs comparing to other GSTP1 genotypes (p=0.03). CONCLUSIONS: This study highlights the significance of GSTM1 and GSTP1 polymorphisms on CML susceptibility and response to TKIs in the Argentinean population.

TP53 codon 72 polymorphism predicts chronic myeloid leukemia susceptibility and treatment outcome.

BCR-ABL1 gene is a key molecular marker of chronic myeloid leukemia (CML), but it is still unclear which molecular factors may influence CML risk or lead to variable responses to tyrosine kinase inhibitors (TKIs). The aim of this study was to investigate the impact of TP53 c.213 G>C(Arg72Pro; rs1042522) polymorphism on CML risk and its correlation with clinical outcome. Peripheral blood samples from 141 treated CML patients and 141 sex- and age-matched healthy individuals were genotyped by PCR-RFLP. Standard genetic models for disease penetrance were evaluated by logistic regression analysis and Kaplan-Meier method was performed to estimate survival curves. Our study suggests that TP53 c.213 G>C polymorphism may be involved in CML development considering a recessive model (p=0.01; OR: 0.19; CI: 0.06-0.68). In addition, a non-homogenous distribution was found for this polymorphism in males and patients youngers than 50years (p=0.02). According to clinical response, TP53-GG genotype was associated with higher levels of BCR-ABL1 transcripts (p=0.04) and shorter event free survival (p=0.04). Moreover, a trend toward significance was found for failure free survival (p=0.06) and time to imatinib failure (p=0.08). In conclusion, our data suggest that a;TP53 c.213 G>C may be a potential biomarker of CML susceptibility and clinical outcome.

Glutathione S-transferase gene polymorphisms in celiac disease and their correlation with genomic instability phenotype.

BACKGROUND AND OBJECTIVE: Genomic instability and reduced glutathione S-transferase (GST) activity have been identified as potential risk factors for malignant complications in celiac disease (CD). In this study, we assessed the possible influence of GST polymorphisms on genome instability phenotypes in a genetically characterised group of celiac patients from previous studies. METHODS: The deletion polymorphisms in GSTM1 and GSTT1 genes and the single-nucleotide polymorphism GSTP1 c.313A>G were genotyped using PCR in a set of 20 untreated adult patients with a known genomic instability phenotype and 69 age- and sex-matched healthy individuals. RESULTS: The frequencies of variant genotypes in patients were GSTM1-null (30%), GSTT1-null (5%), GSTP1-AG (60%) and GSTP1-GG (15%), and they showed no differences from controls. No significant differences were found in the genotype distribution based on telomere length. Cases with GSTM1-null genotype (83%) and microsatellite stability were more frequent than those with genomic instability. Moreover, carriers of GSTP1-variant genotype (73%) and stable phenotype were significantly increased compared to unstable patients (27%) (P=0.031). No differences were found according to the clinical-pathological characteristics of celiac cases. CONCLUSIONS: No association between GST polymorphic variants and celiac-associated genomic instability was proven in our cohort. Future studies should explore the usefulness of other biomarkers to distinguish celiac patients who are susceptible to cancer development.

Glutathione S-transferase P1 mRNA expression in plasma cell disorders and its correlation with polymorphic variants and clinical outcome.

BACKGROUND: Glutathione S-transferase P1 (GSTP1) is an important phase II enzyme involved in detoxification of carcinogens. GSTP1 gene overexpression has been observed in a variety of human cancers but there are no studies in plasma cell disorders. The aim of this study was to examine GSTP1 mRNA expression level in multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS). In addition, we have determined GSTP1 polymorphic variants in order to estimate MM risk and their relationship with the expression level. Results were also correlated with laboratory parameters and clinical outcome. METHODS: Bone marrow mononuclear cells from 125 patients with plasma cell disorders were studied. Peripheral blood samples of 110 age and sex matched healthy controls were also evaluated. Real-Time Quantitative RT-PCR and PCR-RFLP assays were used. RESULTS: Upregulation of GSTP1 was observed in 37.7% MM and in 22.6% MGUS patients. A significant increase of GSTP1 expression in MM with respect to MGUS was detected (p=0.0427). Most MM patients that achieved complete remission had low transcription levels (77.8%) compared to those who did not reach this condition (44.4%) (p=0.0347). GSTP1 heterozygous carriers showed reduced expression compared to those with homozygous wild type genotype (p=0.0135). CONCLUSION: Our findings suggest, for the first time, a role for GSTP1 expression in development and/or progression of plasma cell disorders, and a probable influence of functional capacity of the enzyme on clinical outcome. These results and those of the literature support GSTP1 as an interesting tumor marker and a potential therapeutic target.

[Genetic alterations, genomic instability and cancer in celiac disease]. / Alteraciones genéticas, inestabilidad genómica y cáncer en enfermedad celíaca.

Celiac disease (CD) is a common autoimmune disorder characterized by intestinal inflammation and mucosal atrophy triggered by dietary gluten in genetically predisposed individuals. Although, most patients improve with a gluten-free diet, a small percentage (2-5%) develops refractoriness or pre- and malignant complications. Malignancies are the most serious complications of CD, including gastrointestinal carcinomas and non-Hodgkin lymphoma, particularly Enteropathy-type T-cell lymphoma, a rare high-grade T-cell non-Hodgkin lymphoma of the small intestine, almost exclusively observed in CD patients. The molecular basis behind cancer development in CD is not known. To really understand CD-cancer biology it is important to known all of its genetic and genomic alterations. Carcinogenesis involves the acquisition of multiple genetic changes that create a background of genetic instability which accelerate the accumulation of subsequent mutations. Two major modes of genome destabilization have been recognized: microsatellite instability and chromosome instability (CIN). A review of genetic abnormalities reported in CD, refractory sprue or CD-associated tumors, suggests that a CIN phenotype is implied in malignant transformation in CD. Moreover, our recent findings showing that a group of untreated CD patients exhibits genomic instability at nucleotide level, affecting specific microsatellite loci, provides evidence of molecular alterations in non-malignant CD cells. In conclusion, most genetic studies, point to the role of chronic inflammation in the induction of genomic instability and malignant emergence in at-risk individuals.

Analysis of genomic instability in adult-onset celiac disease patients by microsatellite instability and loss of heterozygosis.

BACKGROUND AND AIMS: Malignant complications of celiac disease (CD) include carcinomas and lymphomas. The genetic basis behind cancer development in CD is not known, but acquisition of genetic abnormalities and genomic instability has been involved. The aim of this study was to explore molecular characteristics of genomic instability in CD patients by analyzing microsatellite instability (MSI) and loss of heterozygosis (LOH) with carefully selected microsatellites. METHODS: We genotyped small bowel biopsies and peripheral blood samples from 20 untreated CD patients using five microsatellites related to MMR genes (panel A), and five repeats associated with tumor suppressor genes, chromosome instability, inflammation, and cancer (panel B). RESULTS: Genomic instability was found in seven out of 20 (35%) cases at: D5S107, D18S58, GSTP, TP53 or DCC, being TP53 the most frequently affected (five out of seven cases; 71%). Microsatellite alterations were significantly found using panel B markers (P=0.04). No cases with high frequency of MSI and replication error phenotype were detected. Only one case displayed MSI-L alone. Three patients exhibited LOH and three other cases showed LOH with low level of MSI, being classified as having chromosome instability phenotype. CONCLUSION: Two novel observations were found in this study: first, the finding that non-neoplastic cells from a group of untreated CD patients present genomic instability at nucleotide level; and second, the advantage to use carefully selected microsatellites to identify celiac patients with molecular instability. Our data support the existence of chromosome instability phenotype in CD, suggesting that stable and unstable patients are genomically distinct subtypes that may follow a different evolution.

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.

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.

Expresión de sitios frágiles en neoplasias mieloides / Fragile site expression in myeloid leukemias

El objetivo del presente trabajo fue evaluar la expresión de sitios frágiles (SF) en pacientes con leucemia mieloide crónica (LMC) y leucemia mieloblástica aguda (LMA) a fin de establecer si expresan SF constitucionales en los mismos puntos de ruptura de las alteraciones cromosómicas presentes en el tejido neoplásico. Se estudiaron 9 pacientes con LMA, 7 con LMC y 7 individuos sanos. Se determinó el cariotipo en médula ósea y se indujo la expresión de SF con FUDR (10 µg/ml) y BUDR (50 µg/ml) en sangre periférica. El estudio citogenético de médula ósea demostró que todos los casos de LMC presentaron la t(9;22)(q34;q11). En LMA se encontraron 4 individuos con cariotipo normal y los restantes presentaron las siguientes alteraciones clonales: t(3;8)(q11;q13), del (5)(p11), t(3;11)(q21;p15), inv(16)(p13;q22), t(9;22) y del (9q). En los pacientes con LMC no se encontraron SF en las bandas 9q34 ó 22q11, involucradas en el cromosoma Phû. Tampoco se identificaron SF en los puntos de ruptura implicados en AC estructurales de los pacientes con LMA. Estos resultados sugerirían que los SF no estarían involucrados con el origen de los marcadores cromosómicos hallados en estas neoplasias.

Expresión de sitios frágiles en neoplasias mieloides / Fragile site expression in myeloid leukemias

El objetivo del presente trabajo fue evaluar la expresión de sitios frágiles (SF) en pacientes con leucemia mieloide crónica (LMC) y leucemia mieloblástica aguda (LMA) a fin de establecer si expresan SF constitucionales en los mismos puntos de ruptura de las alteraciones cromosómicas presentes en el tejido neoplásico. Se estudiaron 9 pacientes con LMA, 7 con LMC y 7 individuos sanos. Se determinó el cariotipo en médula ósea y se indujo la expresión de SF con FUDR (10 Ag/ml) y BUDR (50 Ag/ml) en sangre periférica. El estudio citogenético de médula ósea demostró que todos los casos de LMC presentaron la t(9;22)(q34;q11). En LMA se encontraron 4 individuos con cariotipo normal y los restantes presentaron las siguientes alteraciones clonales: t(3;8)(q11;q13), del (5)(p11), t(3;11)(q21;p15), inv(16)(p13;q22), t(9;22) y del (9q). En los pacientes con LMC no se encontraron SF en las bandas 9q34 ó 22q11, involucradas en el cromosoma Ph¹. Tampoco se identificaron SF en los puntos de ruptura implicados en AC estructurales de los pacientes con LMA. Estos resultados sugerirían que los SF no estarían involucrados con el origen de los marcadores cromosómicos hallados en estas neoplasias.(AU)

Participacion de los sitios fragiles en cancer / Participation of fragile sites in cancer

La mayor parte de las neoplasias hematológicas y tumores sólidos presentan anomalfas cromosómicas especfficas, numéricas e estructurales, que podrían originarse debido a la existencia de ciertas zonas lábiles en el genoma, denominadas sitios frágiles (SF). Estos sitios se pueden definir como puntos específicos de los cromosomas con mayor susceptibilidad a rupturas y reordenamientos cromosómicos en las células somáticas levando a la activación de oncogenes o a la inactivación de genes supresores de tumor o antioncogenes, iniciando los primeros pasos del proceso oncogénico. En este trabajo se explica la calsificación y los mecanismos de inducción y se discute el significado biológico de estos sitios, principalmente su vinculación con el câncer.

Participacion de los sitios fragiles en cancer / Participation of fragile sites in cancer

La mayor parte de las neoplasias hematológicas y tumores sólidos presentan anomalfas cromosómicas especfficas, numéricas e estructurales, que podrían originarse debido a la existencia de ciertas zonas lábiles en el genoma, denominadas sitios frágiles (SF). Estos sitios se pueden definir como puntos específicos de los cromosomas con mayor susceptibilidad a rupturas y reordenamientos cromosómicos en las células somáticas levando a la activación de oncogenes o a la inactivación de genes supresores de tumor o antioncogenes, iniciando los primeros pasos del proceso oncogénico. En este trabajo se explica la calsificación y los mecanismos de inducción y se discute el significado biológico de estos sitios, principalmente su vinculación con el cÔncer. (AU)

Fragilidad cromosómica espóntanea y expresión de sitios frágiles en cáncer / Spontaneous chromosomic fragility and expression of fragile sites in cancer

La determinación de cambios cromosómicos específicos en diversas neoplásias confirmó que el rol de los cromosomas está predeterminado e intimimante asociado al desarrollo maligno. Se ha demostrado que la participación de los cromosomas no es al azar, diferentes cromosomas, regiones y bandas estan preferencialmente involucrados en diferentes neoplásias. Estos datos demostrarían que estas bandas contienen genes esenciales en la tumorigénesis. Los mecanismos básicos que originan los reordenamientos estructurales de las células cancerosas todavía son desconocidos. Se ha sugerido que los sitios frágiles [SF], que se localizan en las mismas bandas que los puntos de ruptura específicos de cáncer, podrían predisponer a los rearreglos cromosómicos que transforman la célula en maligna. Las anomalías estructurales también se podrían originar por una fragilidad cromosómica aumentada causada por una inestabilidad genómica inherente o constitutiva. Por consiguiente en el presente trabajo se estudió la fragilidad cromosómica espontánea e inducida en pacientes con neoplásias hematológicas y enfermedades hereditarias con predisposición al cáncer a fin de determinar si estas patologías presentan aumentos en las frecuencias de anomalías cromosómicas espontáneas, definir si las alteraciones espontáneas se ubican en sitios oncogénicos y finalmente, establecer la participación de los SF en el origen de las alteraciones cromosómicas adquiridas en las células neoplásicas. En este trabajo se demostró que las LMA poseen niveles incrementados de roturas espontáneas, localizadas en forma no aleatoria y se identificaron 11 SF específicos coincidentes con bandas involucradas en rearreglos cromosómicos en el tejido tumoral. En LMC se encontraron niveles duplicados o triplicados de roturas espontáneas sugiriendo que la inestabilidad podría predisponer al desarrollo neoplásico... (TRUNCADO)(AU)

Fragilidad cromosómica espóntanea y expresión de sitios frágiles en cáncer / Spontaneous chromosomic fragility and expression of fragile sites in cancer

La determinación de cambios cromosómicos específicos en diversas neoplásias confirmó que el rol de los cromosomas está predeterminado e intimimante asociado al desarrollo maligno. Se ha demostrado que la participación de los cromosomas no es al azar, diferentes cromosomas, regiones y bandas estan preferencialmente involucrados en diferentes neoplásias. Estos datos demostrarían que estas bandas contienen genes esenciales en la tumorigénesis. Los mecanismos básicos que originan los reordenamientos estructurales de las células cancerosas todavía son desconocidos. Se ha sugerido que los sitios frágiles [SF], que se localizan en las mismas bandas que los puntos de ruptura específicos de cáncer, podrían predisponer a los rearreglos cromosómicos que transforman la célula en maligna. Las anomalías estructurales también se podrían originar por una fragilidad cromosómica aumentada causada por una inestabilidad genómica inherente o constitutiva. Por consiguiente en el presente trabajo se estudió la fragilidad cromosómica espontánea e inducida en pacientes con neoplásias hematológicas y enfermedades hereditarias con predisposición al cáncer a fin de determinar si estas patologías presentan aumentos en las frecuencias de anomalías cromosómicas espontáneas, definir si las alteraciones espontáneas se ubican en sitios oncogénicos y finalmente, establecer la participación de los SF en el origen de las alteraciones cromosómicas adquiridas en las células neoplásicas. En este trabajo se demostró que las LMA poseen niveles incrementados de roturas espontáneas, localizadas en forma no aleatoria y se identificaron 11 SF específicos coincidentes con bandas involucradas en rearreglos cromosómicos en el tejido tumoral. En LMC se encontraron niveles duplicados o triplicados de roturas espontáneas sugiriendo que la inestabilidad podría predisponer al desarrollo neoplásico... (TRUNCADO)

Induccion de sitios fragiles por agentes quimicos y fisicos / Induction of fragile sites by chemical and physical agents

En la actualidad se acepta que muchas neoplasias humanas están causadas por factores y muchos mutágenos químicos inducen aberraciones cormosómicas (AC), las caules se cree que se origina por roturas en zonas cromosómicas específicas o sitios frágiles (SF). Los SF se estudiaron en cultivos de linfocitos expuestos a diversos inductores químicos, pero todavia no se conoce como influyen los factores ambientales en su expresión. Hasta ahora no hay estudios de SF inducidos con rayos X, ni se conoce la interacción de este agente con los inductores quimicos. Este es el primer trabajo que analiza la expresión de SF inducida por rayos X y por 3 inductores de SF: BUDR, FUDR y anfidicolina. Se identificaron 17 bandas cromosómicas significtivamente afectadas (p<0.oo1), que se definieron como SF. Los SF más frecuentes estaban localizados en las bandas 3p14 y 16q23. Se observó un aumento significativo (p<0.01) de AC y SF en el cultivo expuesto a rayos X y en el tratado con FUDR más radiación, indicando la conveniencia de emplear otro agente radiosensibilizador. Los resultados observados sugerirían que muchos SF pueden ser causados por factores ambientales tales como sustancias químicas o radiación. La alta correlación establecida entre los SF y la ubicación de AC inducidos por radiación, AC en cáncer y oncogenes demostraría la importante interacción entre SF, AC y oncogenes en el proceso neoplásico

Induccion de sitios fragiles por agentes quimicos y fisicos / Induction of fragile sites by chemical and physical agents

En la actualidad se acepta que muchas neoplasias humanas están causadas por factores y muchos mutágenos químicos inducen aberraciones cormosómicas (AC), las caules se cree que se origina por roturas en zonas cromosómicas específicas o sitios frágiles (SF). Los SF se estudiaron en cultivos de linfocitos expuestos a diversos inductores químicos, pero todavia no se conoce como influyen los factores ambientales en su expresión. Hasta ahora no hay estudios de SF inducidos con rayos X, ni se conoce la interacción de este agente con los inductores quimicos. Este es el primer trabajo que analiza la expresión de SF inducida por rayos X y por 3 inductores de SF: BUDR, FUDR y anfidicolina. Se identificaron 17 bandas cromosómicas significtivamente afectadas (p<0.oo1), que se definieron como SF. Los SF más frecuentes estaban localizados en las bandas 3p14 y 16q23. Se observó un aumento significativo (p<0.01) de AC y SF en el cultivo expuesto a rayos X y en el tratado con FUDR más radiación, indicando la conveniencia de emplear otro agente radiosensibilizador. Los resultados observados sugerirían que muchos SF pueden ser causados por factores ambientales tales como sustancias químicas o radiación. La alta correlación establecida entre los SF y la ubicación de AC inducidos por radiación, AC en cáncer y oncogenes demostraría la importante interacción entre SF, AC y oncogenes en el proceso neoplásico (AU)