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GST Pi (gst + pi)
Selected AbstractsOrganometallic Ruthenium Inhibitors of Glutathione- S -Transferase P1-1 as Anticancer DrugsCHEMMEDCHEM, Issue 12 2007Han Ang Dr. Abstract Ruthenium,arene complexes conjugated to ethacrynic acid were prepared as part of a strategy to develop novel glutathione- S -transferase (GST) inhibitors with alternate modes of activity through the organometallic fragment, ultimately to provide targeted ruthenium-based anticancer drugs. Enzyme kinetics and electrospray mass spectrometry experiments using GST P1-1 and its cysteine-modified mutant forms revealed that the complexes are effective enzyme inhibitors, but they also rapidly inactivate the enzyme by covalent binding at Cys,47 and, to a lesser extent, Cys,101. They are highly effective against the GST Pi-positive A2780 and A2780cisR ovarian carcinoma cell lines, are among the most effective ruthenium complexes reported so far, and target ubiquitous GST Pi overexpressed in many cancers. [source] Glutathione- S -transferase pi as a model protein for the characterisation of chemically reactive metabolitesPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 2 2008Rosalind E. Jenkins Dr. Abstract Chemically reactive metabolites (CRMs) are thought to be responsible for a number of adverse drug reactions through modification of critical proteins. Methods that defined the chemistry of protein modification at an early stage would provide invaluable tools for drug safety assessment. Here, human GST pi (GSTP) was exploited as a model target protein to determine the chemical, biochemical and functional consequences of exposure to the hepatotoxic CRM of paracetamol (APAP), N -acetyl- p -benzoquinoneimine (NAPQI). Site-specific, dose-dependent modification of Cys47 in native and His-tagged GSTP was revealed by MS, and correlated with inhibition of glutathione (GSH) conjugating activity. In addition, the adaptation of iTRAQ labelling technology to define precisely the quantitative relationship between covalent modification and protein function is described. Multiple reaction monitoring (MRM)-MS of GSTP allowed high sensitivity detection of modified peptides at physiological levels of exposure. Finally, a bioengineered mutant cytochrome P450 with a broad spectrum of substrate specificities was used in an in vitro reaction system to bioactivate APAP: in this model, GSTP trapped the CRM and exhibited both reduced enzyme activity and site-specific modification of the protein. These studies provide the foundation for the development of novel test systems to predict the toxicological potential of CRMs produced by new therapeutic agents. [source] Protein expression profiling of glutathione S -transferase pi null mice as a strategy to identify potential markers of resistance to paracetamol-induced toxicity in the liverPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 2 2003Neil R. Kitteringham Abstract GST pi (GSTP) is a member of the glutathione S -transferase (EC 2.5.1.18; GST) family of enzymes that catalyse the conjugation of electrophilic species with reduced glutathione and thus play an important role in the detoxification of electrophilic metabolites. Deletion of GSTP in mice has previously been shown to lead to enhanced susceptibility to chemical-induced skin carcinoma, consistent with its known metabolic functions. A decreased susceptibility to paracetamol hepatotoxicity has also been observed, which has not been fully explained. One possibility is that deletion of the GSTP gene locus results in compensatory changes in other proteins involved in defence against chemical stress. We have therefore used complementary protein expression profiling techniques to perform a systematic comparison of the protein expression profiles of livers from GSTP null and wild-type mice. Analysis of liver proteins by two-dimensional electrophoresis confirmed the absence of GSTP in null mice whereas GSTP represented 3,5% of soluble protein in livers from wild-type animals. There was a high degree of quantitative and qualitative similarity in other liver proteins between GSTP null and wild-type mice. There was no evidence that the absence of GSTP in null animals resulted in enhanced expression of other GST isoforms in the null mice (GST alpha, 1.48%, GST mu, 1.68% of resolved proteins) compared with the wild-type animals (GST alpha, 1.50%, GST mu, 1.40%). In contrast, some members of the thiol specific antioxidant family of proteins, notably antioxidant protein 2 and thioredoxin peroxidases, were expressed at a higher level in the GSTP null mouse livers. These changes presumably reflect the recently described role of GSTP in cell signalling and may underlie the protection against paracetamol toxicity seen in these animals. [source] Glutathione S -transferase pi is upregulated in the stromal compartment of hormone independent prostate cancerTHE PROSTATE, Issue 2 2003Ming Li Abstract Background Glutathione S -transferase (GST) pi is a detoxifying enzyme abundant in normal prostate basal cells but only rarely expressed in prostate cancer cells. The current studies are the first to focus on GST pi in the stromal compartment of prostate tumors. Methods We employed immunohistochemical, immunofluorescence, and Western blot analysis to measure GST pi expression and subcellular localization in 21 primary and metastatic tumors from patients with hormone independent prostate cancer, as well as seven lymph node metastases and six prostatectomy specimens. Results GST pi was detectable in stromal cells in 17 of the 21 hormone independent prostate tumors. GST pi tissue distribution in hormone independent tumors coincided with vimentin staining, suggesting that GST pi is expressed by reactive fibroblasts and/or myofibroblasts. Conclusions The current results suggest that prostate cancer cells induce an injury response in the stroma during progression to hormone independence, which results in GST pi expression. Stromal GST pi may contribute to chemoresistence of advanced prostate cancer. Prostate 56: 98,105, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||