[Show abstract][Hide abstract] ABSTRACT: Glucocorticoids are universally used in the treatment of acute lymphoblastic leukemia (ALL), and resistance to glucocorticoids in leukemia cells confers poor prognosis. To elucidate mechanisms of glucocorticoid resistance, we determined the prednisolone sensitivity of primary leukemia cells from 444 patients newly diagnosed with ALL and found significantly higher expression of CASP1 (encoding caspase 1) and its activator NLRP3 in glucocorticoid-resistant leukemia cells, resulting from significantly lower somatic methylation of the CASP1 and NLRP3 promoters. Overexpression of CASP1 resulted in cleavage of the glucocorticoid receptor, diminished the glucocorticoid-induced transcriptional response and increased glucocorticoid resistance. Knockdown or inhibition of CASP1 significantly increased glucocorticoid receptor levels and mitigated glucocorticoid resistance in CASP1-overexpressing ALL. Our findings establish a new mechanism by which the NLRP3-CASP1 inflammasome modulates cellular levels of the glucocorticoid receptor and diminishes cell sensitivity to glucocorticoids. The broad impact on the glucocorticoid transcriptional response suggests that this mechanism could also modify glucocorticoid effects in other diseases.
[Show abstract][Hide abstract] ABSTRACT: Azathioprine (AZA), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are antimetabolite drugs, widely used as immunosuppressants and anticancer agents. Despite their proven efficacy, high incidence of toxic effects in patients during the standard-dose therapy is recorded. The aim of this study is to explain, from a mechanistic point of view, the clinical evidence showing a significant role of glutathione-S-transferase (GST)-M1 genotype on AZA toxicity in inflammatory bowel disease patients. To this aim, the human non-tumor IHH and HCEC cell lines were chosen as predictive models of the hepatic and intestinal tissues, respectively. AZA, but not 6-MP and 6-TG, induced a concentration-dependent superoxide anion production that seemed dependent on GSH depletion. N-acetyl-cysteine reduced AZA anti-proliferative effect in both cell lines and GST-M1 overexpression increased both superoxide anion production and cytotoxicity, especially in transfected HCEC cells. In this study, an in vitro model to study thiopurines metabolism has been set up and helped us to demonstrate, for the first time, a clear role of GST-M1 in modulating AZA cytotoxicity, with a close dependency on superoxide anion production. These results provide the molecular basis to shed light on the clinical evidence suggesting a role of GST-M1 genotype in influencing the toxic effects of AZA treatment.
Chemical Research in Toxicology 04/2015; DOI:10.1021/acs.chemrestox.5b00019 · 4.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To evaluate variation of the concentration of thiopurine metabolites after 5-aminosalicylate (5-ASA) interruption and the role of genetic polymorphisms of N-acetyl transferase (NAT) 1 and 2.
Concentrations of thioguanine nucleotides (TGN) and methymercaptopurine nucleotides (MMPN), metabolites of thiopurines, were measured by high performance liquid chromatography in 12 young patients (3 females and 9 males, median age 16 years) with inflammatory bowel disease (6 Crohn's disease and 6 ulcerative colitis) treated with thiopurines (7 mercaptopurine and 5 azathioprine) and 5-ASA. Blood samples were collected one month before and one month after the interruption of 5-ASA. DNA was extracted and genotyping of NAT1, NAT2, inosine triphosphate pyrophosphatase (ITPA) and thiopurine methyl transferase (TPMT) genes was performed using PCR assays.
Median TGN concentration before 5-ASA interruption was 270 pmol/8 x 10(8) erythrocytes (range: 145-750); after the interruption of the aminosalicylate, a 35% reduction in TGN mean concentrations (absolute mean reduction 109 pmol/8 × 10(8) erythrocytes) was observed (median 221 pmol/8 × 10(8) erythrocytes, range: 96-427, P value linear mixed effects model 0.0011). Demographic and clinical covariates were not related to thiopurine metabolites concentrations. All patients were wild-type for the most relevant ITPA and TPMT variants. For NAT1 genotyping, 7 subjects presented an allele combination corresponding to fast enzymatic activity and 5 to slow activity. NAT1 genotypes corresponding to fast enzymatic activity were associated with reduced TGN concentration (P value linear mixed effects model 0.033), putatively because of increased 5-ASA inactivation and consequent reduced inhibition of thiopurine metabolism. The effect of NAT1 status on TGN seems to be persistent even after one month since the interruption of the aminosalicylate. No effect of NAT1 genotypes was shown on MMPN concentrations. NAT2 genotyping revealed that 6 patients presented a genotype corresponding to fast enzymatic activity and 6 to slow activity; NAT2 genotypes were not related to thiopurine metabolites concentration in this study.
NAT1 genotype affects TGN levels in patients treated with thiopurines and aminosalicylates and could therefore influence the toxicity and efficacy of these drugs; however the number of patients evaluated is limited and this has to be considered a pilot study.
[Show abstract][Hide abstract] ABSTRACT: Juvenile idiopathic arthritis (JIAs) is the most common chronic rheumatic disease of childhood and is an important cause of disability. The folic acid analog methotrexate is the first choice disease-modifying anti-rheumatic drug in this disease, however, 35-45% of patients fail to respond. Molecular elements, such as variants in genes of pharmacological relevance, influencing response to methotrexate in JIA, would be important to individualize treatment strategies. Several studies have evaluated the effects of candidate genetic variants in the complex pathway of genes involved in methotrexate pharmacodynamics and pharmacokinetics, however, results are still contrasting and no definitive genetic marker of methotrexate response useful for the clinician to tailor therapy of children with JIA has been identified. Recently, genome-wide approaches have been applied, identifying new potential biological processes involved in methotrexate response in JIA such as TGF-beta signaling and calcium channels. If these genomic results are properly validated and integrated with innovative analyses comprising deep sequencing, epigenetics, and pharmacokinetics, they will greatly contribute to personalize therapy with methotrexate in children with JIA.
Frontiers in Pharmacology 03/2015; 6:52. DOI:10.3389/fphar.2015.00052 · 3.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: For children with juvenile idiopathic arthritis (JIA) who fail to respond to methotrexate, the delay in identifying the optimal treatment at an early stage of disease can lead to long-term joint damage. Recent studies indicate that relevant variants to predict methotrexate response in JIA are those in 5-aminoimidazole-4-carboxamide ribonucleotide-transformylase (ATIC), inosine-triphosphate-pyrophosphatase (ITPA) and solute-liquid-carrier-19A1 genes. The purpose of the study was, therefore, to explore the role of these candidate genetic factors on methotrexate response in an Italian cohort of children with JIA. Clinical response to methotrexate was evaluated as clinical remission stable for a 6-month period, as ACRPed score and as change in Juvenile Arthritis Disease score. The most relevant SNPs for each gene considered were assayed on patients' DNA. ITPA activity was measured in patients' erythrocytes. Sixty-nine patients with JIA were analyzed: 52.2 % responded to therapy (ACRPed70 score), while 37.7 % reached clinical remission stable for 6 months. ATIC rs2372536 GG genotype was associated with improved clinical remission (adjusted p value = 0.0090). For ITPA, rs1127354 A variant was associated with reduced clinical remission: (adjusted p value = 0.028); this association was present even for patients with wild-type ITPA and low ITPA activity. These preliminary results indicate that genotyping of ATIC rs2372536 and ITPA rs1127354 variants or measuring ITPA activity could be useful to predict methotrexate response in children with JIA after validation by further prospective studies on a larger patient cohort.
[Show abstract][Hide abstract] ABSTRACT: Azathioprine is a purine antimetabolite drug commonly used to treat inflammatory bowel disease (IBD). In vivo it is active after reaction with reduced glutathione (GSH) and conversion to mercaptopurine. Although this reaction may occur spontaneously, the presence of isoforms M and A of the enzyme glutathione-S-transferase (GST) may increase its speed. Indeed, in pediatric patients with IBD, deletion of GST-M1, which determines reduced enzymatic activity, was recently associated with reduced sensitivity to azathioprine and reduced production of azathioprine active metabolites. In addition to increase the activation of azathioprine to mercaptopurine, GSTs may contribute to azathioprine effects even by modulating GSH consumption, oxidative stress and apoptosis. Therefore, genetic polymorphisms in genes for GSTs may be useful to predict response to azathioprine even if more in vitro and clinical validation studies are needed.
World Journal of Gastroenterology 04/2014; 20(13):3534-3541. DOI:10.3748/wjg.v20.i13.3534 · 2.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study aims at evaluating the association between seven single nucleotide polymorphisms (SNPs) in five genes involved on antiretroviral pharmacokinetic pathways and virological failure in first line highly active antiretroviral therapy. Seven candidate polymorphisms (rs3842 and rs1045642 in ABCB1, rs212091 and rs3743527 in ABCC1, rs3745274 in CYP2B6, rs628031 in SLC22A1 and rs1517618 in SLCO3A1) were evaluated if they were associated with virological failure through logistic regression analysis. The study design was a retrospective cohort, analyzing 187 patients from Recife metropolitan region (Pernambuco, Brazil): among these 160 obtained complete suppression of HIV-1 replication (responders) and were compared to 27 non-responders, which underwent virological failure. There was no association between CYP2B6, SLC22A1 and SLCO3A1 SNPs and virological failure. Using logistic regression analysis, a significant association was detected between rs1045642 (3435C > T, ABCB1) and rs212091 (198217T > C; 3'-UTR, ABCC1) with virological failure of first-line antiretroviral regimens containing protease inhibitors, when controlled by clinical factors, such as sex, age and race. The present results could contribute to unravel the influence of genetic background in anti-HIV-1 therapy outcome and help in treatment personalization of Northeast Brazil HIV infected patients.
The Journal of Clinical Pharmacology 12/2013; 53(12). DOI:10.1002/jcph.165 · 2.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To investigate, in young patients with inflammatory bowel disease (IBD) treated with azathioprine, the association between genetic polymorphisms of thiopurine-S-methyl-transferase (TPMT), inosine-triphosphate-pyrophosphatase (ITPA), and glutathione-S-transferases (GST), involved in azathioprine metabolism, the concentration of the main metabolites of azathioprine, thioguanine nucleotides (TGNs) and the methylated nucleotides (MMPN), and the dose of the medication.
Azathioprine is widely used in IBD as an immunosuppressive agent, particularly to maintain remission in patients with steroid refractory disease. Azathioprine is a prodrug and requires conversion to its active form mercaptopurine, which has no intrinsic activity, and is activated by the enzymes of the purine salvage pathway to TGNs. Polymorphisms in genes of enzymes involved in azathioprine metabolism influence the efficacy and toxicity of treatment.
Seventy-five young patients with IBD treated with azathioprine at least for 3 months were enrolled and genotyped for the selected genes; for these patients, TGN and MMPN metabolites were measured by high performance liquid chromatography in erythrocytes.
GST-M1 deletion was associated with lower TGN/dose ratio (P=0.0030), higher azathioprine dose requirement (P=0.022), and reduced response to therapy (P=0.0022). TPMT variant genotype was associated with lower MMPN concentration (P=0.0064) and increased TGN/dose ratio (P=0.0035). ITPA C94A polymorphism resulted in an increased MMPN concentration (P=0.037).
This study describes the effect of candidate genetic polymorphisms in TPMT, ITPA, and GST-M1 on azathioprine pharmacokinetics in IBD patients, showing, for the first time, relevant effects of GST-M1 genotype on azathioprine metabolites concentration.
[Show abstract][Hide abstract] ABSTRACT: Objectives: Etiological periodontal therapy is effective in reducing cyclosporin A-induced gingival overgrowth, but a high variability among subjects has been observed. This study aimed to evaluate the role of polymorphisms in PAI-1 and A BCB1 genes on the course of this side effect following periodontal therapy. Method and Materials: Forty-five transplant patients were subjected to nonsurgical periodontal therapy and evaluated for hypertrophy index, probing depths, bleeding, and plaque scores at baseline, and after 3 and 6 months. A BCB1 (C3435T and G2677T) and PAI-1 (4G/5G) polymorphisms were studied with polymerase chain reaction-restriction fragment length polymorphism and allele-specific polymerase chain reaction respectively. Results: All the monitored periodontal indexes decreased significantly during the six months. Modeling of hypertrophy index by linearmixed- effect models (allowing non-normal distribution of the outcome variable hypertrophy index) resulted in the selection as the most significant model, of the one comprising the independent variables: time, C 3435T genotype, and their interaction term. This model indicated that C 3435T-mutated patients had significantly higher baseline hypertrophy index values (90% Markov chain Monte C arlo empirical confidence intervals: 5.08, 30.00). The decrease in hypertrophy index values over time showed a trend toward being faster in mutated than nonmutated patients (interaction time: C 3435T nonmutated, 90% Markov chain Monte C arlo empirical confidence interval: -11.08, -0.40). When hypertrophy index values were normalized, the significance and trend were lost. No effect of the A BCB1 G2677T and PAI-1 4G/5G polymorphisms was observed. Conclusion: These preliminary results suggest that C 3435T polymorphism is a genetic factor that could influence the course of cyclosporin A-induced gingival overgrowth in transplant patients subjected to periodontal therapy.
[Show abstract][Hide abstract] ABSTRACT: Several lympholytic and cytotoxic agents are used in acute lymphoblastic leukemia (ALL) polychemotherapy. Genetic variants for any of the cellular components involved in the pharmacokinetics and pharmacodynamics of these drugs can influence the pharmacological response, and molecular characterization of these genetic variants could be helpful for the comprehension of the mechanism of resistance or increased sensitivity. The purpose of this review is to carry out an update of recent publications on genes that might influence ALL treatment in terms of outcome and/or toxicity and to underlie the role of genetic variants, particularly single nucleotide polymorphisms (SNP), in predicting clinical response, with particular reference to the current protocol for ALL therapy used in Italy, AIEOP-BFM ALL 2009.
Current Medicinal Chemistry 02/2013; DOI:10.2174/0929867311320170008 · 3.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Treatment-related toxicity can be life-threatening and is the primary cause of interruption or discontinuation of chemotherapy for acute lymphoblastic leukemia (ALL), leading to an increased risk of relapse. Mercaptopurine is an essential component of continuation therapy in all ALL treatment protocols worldwide. Genetic polymorphisms in thiopurine S-methyltransferase (TPMT) are known to have a marked effect on mercaptopurine metabolism and toxicity; however, some patients with wild-type TPMT develop toxicity during mercaptopurine treatment for reasons that are not well understood. To identify additional genetic determinants of mercaptopurine toxicity, a genome-wide analysis was performed in a panel of human HapMap cell lines to identify trans-acting genes whose expression and/or single-nucleotide polymorphisms (SNPs) are related to TPMT activity, then validated in patients with ALL. The highest ranking gene with both mRNA expression and SNPs associated with TPMT activity in HapMap cell lines was protein kinase C and casein kinase substrate in neurons 2 (PACSIN2). The association of a PACSIN2 SNP (rs2413739) with TPMT activity was confirmed in patients and knock-down of PACSIN2 mRNA in human leukemia cells (NALM6) resulted in significantly lower TPMT activity. Moreover, this PACSIN2 SNP was significantly associated with the incidence of severe gastrointestinal (GI) toxicity during consolidation therapy containing mercaptopurine, and remained significant in a multivariate analysis including TPMT and SLCO1B1 as covariates, consistent with its influence on TPMT activity. The association with GI toxicity was also validated in a separate cohort of pediatric patients with ALL. These data indicate that polymorphism in PACSIN2 significantly modulates TPMT activity and influences the risk of GI toxicity associated with mercaptopurine therapy.
Human Molecular Genetics 07/2012; 21(21):4793-804. DOI:10.1093/hmg/dds302 · 6.68 Impact Factor