Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Azathioprine Pharmacogenomics in Myasthenia Gravis Patients

ABSTRACT: Myasthenia gravis (MG) is an autoimmune disease affecting the neuromuscular junction, whose clinical hallmark is muscle weakness and early fatigability. Azathioprine (AZA) is commonly used in Myasthenia Gravis therapy. AZA is a purine antagonist, which inhibits the cell cycle in the resting and DNA synthesis phases. It is usually used as an immunosuppressant to block T- and B-cell proliferation. AZA, bioconverted to 6-mercaptopurine by glutathione S-transferase (GST), can be metabolized either through the hypoxanthine phosphoribosyl transferase pathway to active 6-thioguanine nucleotides (6-TGN) or through the thiopurine S-methyltransferase (TPMT) pathway to inactive methyl-thiopurine metabolites. The incorporation of active 6-TGNs into DNA, causing breaks in DNA strands resulting in interference with RNA production and thereby protein synthesis, is responsible for the drug effect. The response to AZA is determined by which metabolic pathway is being favored. While balanced use of both HPRT and TPMT pathways results in responsiveness to AZA, hyperactivity of TPMT skews the balance towards the TPMT pathway and results in unresponsiveness to AZA with no pharmacological effect. In contrast, low TPMT activity skews the balance towards the HPRT pathway, resulting in increasing side-effects due to the accumulation of 6-TGNs. Current treatments for MG therapy are often inadequate because less than 40% of patients achieve complete remission with available drugs. This reflects the lack of drugs acting on target sites for which there is strong evidence of pathogenicity and the inability to identify responder patients. No criteria for responsiveness are available, exposing patients to unpredictable failures and unpredictable side effects. These individuals are at particular risk for adverse drug reaction (ADRs) or therapeutic failure. Genetic profiling with the Affymetrix drug metabolizing enzymes and transports genotyping array offers the ability to determine 1,931 variants and 225 genes involved in drug metabolism and disposition. Accordingly, the study of well-known drug-metabolizing genes can be involved in the specific metabolic pathway of a drug, which is more likely to define genotype-phenotype association and thereby genotype profiles relevant to drug response that can be applied as predictive biomarkers for pharmacological treatment.

ORGANISM(S): Homo sapiens

SUBMITTER: Dimos Kapetis

PROVIDER: E-MTAB-4489 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Esophageal cancers (ECs) are highly aggressive tumors with poor prognosis and few treatment options. This study investigated the possibility of treating esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) cells by inhibitors of broad and specific histone deacetylases (HDACi; SAHA, MS-275, FK228) and/or of DNMT (Azacytidine, AZA). Drug targets (HDAC1,2,3 and DNMT1) were present in non-neoplastic (HET-1A), ESCC (OE21) and EAC (OE33) cell lines. All cell lines responded to HDACi by reduced HDAC activity and increased histone acetylation as well as to AZA by up-regulation of p21. Expression of drug targets remained largely unaffected by HDACi and AZA treatment. Importantly, cell viability, apoptosis, cell cycle dynamics and DNA damage were only affected by HDACi and/or AZA in ESCC and EAC, but not the non-neoplastic cells. This was specifically seen for the combination of MS-275 and AZA, leading to enhanced cancer cell selectivity and drug efficiency. By transcriptome analyses of MS-275, AZA and MS-275/AZA treated cells, known (e.g. p21) as well as novel regulated genes significantly associated with the cellular effects post HDACi and/or AZA treatment in ESCC and EAC cells were identified. Finally, human EC tissue specimens frequently expressed the actionable drug targets HDAC1/2/3 and DNMT1. In summary, a combined HDACi (MS-275)/AZA treatment is cancer cell selective and efficient in vitro. Since the majority of ECs express the drug targets in situ, this paves the way for further investigations of HDACi/AZA treatment in esophageal cancer cells and their translation into a clinico-pathological setting. To elucidate the transcriptome response to HDAC inhibitors of normal esophageal cells and esophageal tumor cells, total RNA was isolated from non-neoplastic esophageal epithelial cells (Het1A cells) a well as from two esophageal tumor cell lines (OE21 and OE33), respectively. Cells were treated with either MS-275, Azacytidine (AZA) or in combination of both. DMSO treatment was used as control in each case. Total RNA was isolated from cells 24 h after treatment and experiments were performed in biological triplicates.

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Azathioprine Pharmacogenomics in Myasthenia Gravis Patients

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