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.

[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.

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.

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.

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.

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.

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.

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