@article {8319, title = {Thiopurine Biotransformation and Pharmacological Effects: Contribution of Oxidative Stress.}, journal = {Curr Drug Metab}, volume = {17}, year = {2016}, month = {2016}, pages = {542-9}, abstract = {

BACKGROUND: Thiopurine antimetabolites are important agents for the treatment of severe diseases, such as acute lymphoblastic leukemia and inflammatory bowel disease. Their pharmacological actions depend on biotransformation into active thioguanine-nucleotides; intracellular metabolism is mediated by enzymes of the salvage pathway of nucleotide synthesis and relies on polymorphic enzymes involved in thiopurines{\textquoteright} catabolism such as thiopurine-S-methyl transferase. Given the enzymes involved in thiopurines{\textquoteright} metabolism, it is reasonable to hypothesize that these drugs are able to induce significant oxidative stress conditions, possibly altering their pharmacological activity.

METHODS: A systemic search of peer-reviewed scientific literature in bibliographic databases has been carried out. Both clinical and preclinical studies as well as mechanistic studies have been included to shed light on the role of oxidative stress in thiopurines{\textquoteright} pharmacological effects.

RESULTS: Sixty-nine papers were included in our review, allowing us to review the contribution of oxidative stress in the pharmacological action of thiopurines. Thiopurines are catabolized in the liver by xanthine oxidase, with potential production of reactive oxidative species and azathioprine is converted into mercaptopurine by a reaction with reduced glutathione, that, in some tissues, may be facilitated by glutathione- S-transferase (GST). A clear role of GSTM1 in modulating azathioprine cytotoxicity, with a close dependency on superoxide anion production, has been recently demonstrated. Interestingly, recent genome-wide association studies have shown that, for both azathioprine in inflammatory bowel disease and mercaptopurine in acute lymphoblastic leukemia, treatment effects on patients{\textquoteright} white blood cells are related to variants of a gene, NUDT15, involved in biotransformation of oxidated nucleotides.

CONCLUSIONS: Basing on previous evidences published in literature, oxidative stress may contribute to thiopurine effects in significant ways that, however, are still not completely elucidated.

}, issn = {1875-5453}, author = {Pelin, Marco and De Iudicibus, Sara and Londero, Margherita and Spizzo, Riccardo and Dei Rossi, Sveva and Martelossi, Stefano and Ventura, Alessandro and Decorti, Giuliana and Stocco, Gabriele} } @article {8065, title = {Glucocorticoid pharmacogenetics in pediatric idiopathic nephrotic syndrome.}, journal = {Pharmacogenomics}, volume = {16}, year = {2015}, month = {2015 Sep}, pages = {1631-48}, abstract = {

Idiopathic nephrotic syndrome represents the most common type of primary glomerular disease in children: glucocorticoids (GCs) are the first-line therapy, even if considerable interindividual differences in thepir efficacy and side effects have been reported. Immunosuppressive and anti-inflammatory effects of these drugs are mainly due to the GC-mediated transcription regulation of pro- and anti-inflammatory genes. This mechanism of action is the result of a complex multistep pathway that involves the glucocorticoid receptor and several other proteins, encoded by polymorphic genes. Aim of this review is to highlight the current knowledge on genetic variants that could affect GC response, particularly focusing on children with idiopathic nephrotic syndrome.

}, issn = {1744-8042}, doi = {10.2217/pgs.15.101}, author = {Cuzzoni, Eva and De Iudicibus, Sara and Franca, Raffaella and Stocco, Gabriele and Lucaf{\`o}, Marianna and Pelin, Marco and Favretto, Diego and Pasini, Andrea and Montini, Giovanni and Decorti, Giuliana} } @article {8075, title = {Patients{\textquoteright} Induced Pluripotent Stem Cells to Model Drug Induced Adverse Events: A Role in Predicting Thiopurine Induced Pancreatitis?}, journal = {Curr Drug Metab}, volume = {17}, year = {2015}, month = {2015}, pages = {91-8}, abstract = {

Induced pluripotent stem cells (iPSC) can be produced from adult cells by transfecting them with a definite set of pluripotency-associated genes. Under adequate growth conditions and stimulation iPSC can differentiate to almost every somatic lineage in the body. Patients{\textquoteright} derived iPSC are an innovative model to study mechanisms of adverse drug reactions in individual patients and in cell types that cannot be easily obtained from human subjects. Proof-of concept studies with known toxicants have been performed for liver, cardiovascular and central nervous system cells: neurons obtained from iPSC have been used to elucidate the mechanism of chemotherapy-induced peripheral neuropathy by evaluating the effects of neurotoxic drugs such as vincristine. However, no study has been performed yet on pancreatic tissue and drug induced pancreatitis. Thiopurines (azathioprine and mercaptopurine) are immunosuppressive antimetabolite drugs, commonly used to treat Crohn{\textquoteright}s disease. About 5\% of Crohn{\textquoteright}s disease patients treated with thiopurines develop pancreatitis, a severe idiosyncratic adverse event; these patients have to stop thiopurine administration and may require medical treatment, with significant personal and social costs. Molecular mechanism of thiopurine induced pancreatitis (TIP) is currently unknown and no fully validated biomarker is available to assist clinicians in preventing this adverse event. Hence, in this review we have reflected upon the probable research applications of exocrine pancreatic cells generated from patient specific iPS cells. Such pancreatic cells can provide excellent insights into the molecular mechanism of TIP. In particular three hypotheses on the mechanism of TIP could be explored: drug biotransformation, innate immunity and adaptative immunity.

}, issn = {1875-5453}, author = {Stocco, Gabriele and Lanzi, Gaetana and Yue, Fengming and Giliani, Silvia and Sasaki, Katsunori and Tommasini, Alberto and Pelin, Marco and Martelossi, Stefano and Ventura, Alessandro and Decorti, Giuliana} } @article {7779, title = {Role of oxidative stress mediated by glutathione-s-transferase in thiopurines{\textquoteright} toxic effects.}, journal = {Chem Res Toxicol}, volume = {28}, year = {2015}, month = {2015 Jun 15}, pages = {1186-95}, 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, a high incidence of toxic effects in patients during 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 nontumor 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-Acetylcysteine reduced the AZA antiproliferative 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{\textquoteright} 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.

}, issn = {1520-5010}, doi = {10.1021/acs.chemrestox.5b00019}, author = {Pelin, Marco and De Iudicibus, Sara and Fusco, Laura and Taboga, Eleonora and Pellizzari, Giulia and Lagatolla, Cristina and Martelossi, Stefano and Ventura, Alessandro and Decorti, Giuliana and Stocco, Gabriele} } @article {3516, title = {Pharmacogenetics of azathioprine in inflammatory bowel disease: a role for glutathione-S-transferase?}, journal = {World J Gastroenterol}, volume = {20}, year = {2014}, month = {2014 Apr 7}, pages = {3534-41}, 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.

}, keywords = {6-Mercaptopurine, Animals, Apoptosis, Azathioprine, Glutathione, Glutathione Transferase, Humans, Immunosuppressive Agents, Inflammatory Bowel Diseases, Oxidative Stress, Pharmacogenetics, Polymorphism, Genetic}, issn = {2219-2840}, doi = {10.3748/wjg.v20.i13.3534}, author = {Stocco, Gabriele and Pelin, Marco and Franca, Raffaella and De Iudicibus, Sara and Cuzzoni, Eva and Favretto, Diego and Martelossi, Stefano and Ventura, Alessandro and Decorti, Giuliana} }