Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

P-glycoprotein overexpression is an important adverse prognostic marker for osteosarcoma (OS) patients, which is associated with higher risk for developing metastases as a consequence of the limited responsiveness to standard treatments of P-glycoprotein overexpressing OS cells. The use of cytokines has been advocated as a possible therapeutic approach to overcome multidrug resistance (MDR), being active on cell lines that are resistant to conventional drugs. In this study, we evaluated in vitro effects of interferons (IFNs) on MDR P-glycoprotein overexpressing OS cells. Type I IFNs, but not IFNgamma, showed tangible inhibitory effects on OS cell growth, which were higher in MDR cell lines compared to parental cells. The higher sensitivity of P-glycoprotein overexpressing cells to Type I IFNs correlates with higher expression of the activator of the transcription (STAT)-2 and (STAT)-3, two intracellular mediators of the IFNalpha and IFNbeta signaling pathways, whereas no differences were observed with respect to the expression or activation of the Type I IFN receptor and STAT-1. Exposure of OS MDR cells to Type I IFN decreased the expression of P-glycoprotein. This effect resulted in a significantly increased chemosensitivity of MDR cells to doxorubicin. Therefore, our data support the use of IFNalpha or IFNbeta in the treatment of osteosarcoma patients who overexpress P-glycoprotein in their primary tumors, and respond insufficiently to current therapeutic regimens.
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PMID:Effectiveness of Type I interferons in the treatment of multidrug resistant osteosarcoma cells. 1471 13

Aim of present review is to provide an evidence-based update of mechanisms responsible for the onset of resistance to drug therapy by EGFR inhibitors, particularly with regards to TKIs. Among ABC transporters involved in MDR, P-glycoprotein and BCRP have been considered the pumps responsible for TKIs treatment failure. Moreover, two subtypes of EGFR mutations have been described: mutations of the exons coding for tyrosine kinase domain (18 to 21) and truncating mutations (exons 2 to 7) that involve downstream effectors such as MAPK, PI3K/Akt, STAT. The first group of mutations can be considered as a hallmark of NSCLC and are responsible for the failure of TKIs while the second group of mutations leads to resistance. The strategies to overcome MDR and to bypass the kinase domain mutations have been addressed. Finally, for some first generation TKIs some perspectives as radiotracers for PET/SPECT diagnosis in tumor displaying P-gp and BCRP overexpression have been suggested.
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PMID:EGFR tyrosine kinase inhibitors and multidrug resistance: perspectives. 2119 66

Resistance to 5-fluorouracil (5-FU), an important anticancer drug, is a serious challenge in the treatment of pancreatic cancer. Equilibrative nucleoside transporter 1 and multidrug-resistance protein (MRP) 5 and MRP8, rather than P-glycoprotein, play important roles in 5-FU transport. Thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase and thymidine phosphorylase are four key enzymes involved in 5-FU metabolism. Other metabolic enzymes, including uridine monophosphate synthetase, also contribute to chemoresistance. Intracellular signaling pathways are an integrated network, and nuclear factor kappa-light-chain-enhancer of activated B cells, AKT and extracellular signal-regulated kinases are signaling pathways that are particularly relevant to 5-FU resistance. In addition, recent reports indicate that STAT-3 is a crucial survival protein. Proteomic assays provide a powerful tool for identifying target proteins and understanding the role of microRNAs and stromal factors to facilitate the development of strategies to combat 5-FU resistance.
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PMID:Recent studies of 5-fluorouracil resistance in pancreatic cancer. 2540 Apr 52

Natural killer/T-cell (NK/T-cell) lymphomas are rare in children and adolescents and consist predominantly of nasal-type extranodal NK/T-cell lymphomas. More than half of pediatric/adolescent patients with NK/T-cell lymphomas present with localized nasal/sinus involvement, but the disease may involve many organs. NK/T-cell lymphoma cells are cytotoxic and associated with necrosis and angioinvasion; they express CD56, CD2, cytoplasmic CD3 epsilon, and to a variable degree CD30. The cells contain Epstein-Barr virus (EBV)-encoded RNA. Loss of chromosome 6q is frequent, and multiple other genetic changes may occur. The Janus kinase/signal transducers and activators of transcription (JAK/STAT) and other pathways are activated in NK/T-cell lymphoma. Adults with stage I/II disease receive radiation with or without chemotherapy, whereas adults with advanced disease receive multiagent chemotherapy, including asparaginase and drugs not affected by P-glycoprotein-mediated resistance. Outcomes data for pediatric patients come from retrospective reviews and retrospective case series. The overall survival of pediatric patients is 77% for those with stage I/II disease and 36% to 59% for those with advanced disease. Bone marrow transplant (BMT) is used in children, but with little evidence regarding the indications and rationale for type of transplant. BMT achieves better outcomes for adult patients in remission, but with high levels of morbidity and mortality. Improved understanding of the biology of this disease will allow the development of targeted approaches, including JAK/STAT inhibitors, checkpoint inhibitors, anti-CD30 agents, epigenetic modifiers, and reduced-intensity conditioning for BMT, to improve outcomes in pediatric patients.
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PMID:Natural killer/T-cell lymphomas in pediatric and adolescent patients. 2839 75

Objective: To summarize the abnormal location of FLT3 caused by different glycosylation status which further leads to the distinguishing signaling pathways and discuss targeting on FLT3 glycosylation by drugs reported in recent literatures. Methods: We review FLT3 glycosylation in endoplasmic reticulum. The abnormal signal of mutant FLT3 with different glycosylation status is discussed. We also address potential FLT3 glycosylation-targeting strategies for the treatment. Results: Inhibition of FLT3 mutant cells by drugs reported in recent literatures involves the influence of glycosylation of FLT3: 2-deoxy-D-glucose, Tunicamycin and Fluvastatin are reported to inhibit N-glycosylation of FLT3; Pim-1 inhibitors are proved to block the inhibition of Pim-1 on FLT3 Oglycosylation; HSP90 inhibitors and Tyrosine Kinase Inhibitors are shown to increase fully glycosylated form of FLT3. Discussion: The FMS-like tyrosine kinase 3 (FLT3) gene expressed only in CD34+ progenitor cells in bone marrow is located on chromosome 13q12 encoding FLT3 protein. FLT3 is initially synthesized as a 110 KD protein, which glycosylated in the endoplasmic reticulum to a 130 KD immature protein rich in mannose, and further processed into a mature 160 KD protein in the Golgi apparatus, which could be transferred to the cell surface. Therapy targeting on FLT3 glycosylation is a promising direction for AML treatment. Conclusions: The abnormal location of FLT3 caused by different glycosylation status leads to the distinguishing signaling pathways. Targeting on FLT3 glycosylation may provide a new perspective for therapeutic strategies. Abbreviations: ABCG2: ATP-binding cassette transporter breast cancer resistance protein; ATF: activating transcription factor; AML: acute myeloid leukemia; CHOP: CCAAT-enhancer-binding protein homologous protein; 2-DG: 2-deoxy-D-glucose; EFS: event free survival; EPO: erythropoietin; EPOR: erythropoietin receptor; ERS: endoplasmic reticulum stress; FLT3: FMS-like tyrosine kinase 3; GPI: glycosylphosphatidylinositol; HSP: heat shock protein; ITD: internal tandem duplication; IRE1a: inositol-requiring enzyme 1 alpha; JNK: c-Jun N-terminal kinase; JMD: juxtamembrane domain; JAK: janus kinase; MAPK/ERK: mitogen activated protein kinase/extracellular signal-regulated protein kinase; OS: overall survival; PI3K/AKT: phosphatidylinositide 3-kinases/protein kinase B; PERK: RNA-activated protein kinase-like endoplasmic reticulum kinase; Pgp: P-glycoprotein; PTX3: human pentraxin-3; STAT: signal transducer and activator of transcriptions; TKD: tyrosine-kinase domain; TKI: tyrosine kinase inhibitor; TM: Tunicamycin; UPR: unfolded protein reaction.
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PMID:Targeting on glycosylation of mutant FLT3 in acute myeloid leukemia. 3153 45