Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.30 (PARP)
 13,611 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nucleated cells are more resistant to complement-mediated cell death than anucleated cells such as erythrocytes. There are few reports concerning the metabolic response of nucleated cells subjected to sub-lethal complement attack. It is possible that the rate of utilization of specific metabolic fuels by the cell is increased to enhance cell defence. We have measured the maximum activity of hexokinase, citrate synthase, glucose 6-phosphate dehydrogenase and glutaminase in rat mesenteric lymphocytes exposed to sub-lethal concentrations of activated complement (present in zymosan-activated serum, ZAS). These enzymes were carefully selected as they indicate changes of flux in glycolysis, TCA cycle, pentose phosphate pathway and glutaminolysis, respectively. The only enzyme activity to change on exposure of lymphocytes to ZAS was glutaminase, which was enhanced approximately by two-fold. Although rates of both glutamine and glucose utilization were enhanced by exposure to ZAS, only the rate of oxidation of glutamine was increased. Complement kills anucleated cells by simple osmotic lysis. However, it is likely that some nucleated cells will display characteristics of an ordered death mechanism and we have demonstrated that the concentration of lymphocyte ATP is dramatically decreased by activated complement. Nevertheless, the extent of cell death could be significantly reduced by the addition of inhibitors of the nuclear enzyme poly (ADP-ribose) polymerase (PARP). We conclude that glutamine metabolism is not only important for lymphocyte proliferative responses but is also important for cell defence from sub-lethal concentrations of activated complement. The rapid rate of complement-induced lymphocyte death reported here is suggested to be a consequence of over-activation of the nuclear enzyme PARP and ATP depletion.
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PMID:Sub-lethal concentrations of activated complement increase rat lymphocyte glutamine utilization and oxidation while lethal concentrations cause death by a mechanism involving ATP depletion. 1212 93

Glutamine provides cancer cells with the energy required to synthesize macromolecules. Methods which block glutamine metabolism in treatment of breast cancer inhibit oncogenic transformation and tumor growth. We investigated whether inhibiting glutamine metabolism produces effects that are synergistic with those produced by drugs which damage DNA in triple-negative breast cancer cells. HCC1937 and BT-549 breast cancer cells were co-treated with either cisplatin or etoposide in combination with BPTES (a specific inhibitor of glutaminase 1) or exposure to a glutamine-free medium, and the cell proliferation and cell apoptosis were measured by flow cytometry, immunoblotting studies, and CCK-8 assays. The results showed that both glutamine deprivation and BPTES pretreatments increased the toxic effects of cisplatin and etoposide on HCC1937 cells, as demonstrated by their reduced proliferation, increased expression of apoptosis-related proteins (cleaved-PARP, cleaved-caspase 9, and cleaved-caspase 3) and decreased Bcl-2/BAX ratio. However, in BT-549 cells, glutamine deprivation and BPTES treatment increased etoposide-induced apoptosis only when used with higher concentrations of etoposide, and the effect on cisplatin-induced apoptosis was minimal. These results suggest that the anti-cancer effects produced by a combined approach of inhibiting glutamine metabolism and administering common chemotherapeutic agents correlate with the tumor cell type and specific drugs being administered.
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PMID:Glutamine deprivation plus BPTES alters etoposide- and cisplatin-induced apoptosis in triple negative breast cancer cells. 2741 28

Amplification and overexpression of the MYC oncogene in tumor cells, including ovarian cancer cells, correlates with poor responses to chemotherapy. As MYC is not directly targetable, we have analyzed molecular pathways downstream of MYC to identify potential therapeutic targets. Here we report that ovarian cancer cells overexpressing glutaminase (GLS), a target of MYC and a key enzyme in glutaminolysis, are intrinsically resistant to platinum-based chemotherapy and are enriched with intracellular antioxidant glutathione. Deprivation of glutamine by glutamine-withdrawal, GLS knockdown, or exposure to the GLS inhibitor CB-839 resulted in robust induction of reactive oxygen species in high GLS-expressing but not in low GLS-expressing ovarian cancer cells. Treatment with CB-839 rendered GLShigh cells vulnerable to the poly(ADP-ribose) polymerase (PARP) inhibitor, olaparib, and prolonged survival in tumor-bearing mice. These findings suggest consideration of applying a combined therapy of GLS inhibitor and PARP inhibitor to treat chemoresistant ovarian cancers, especially those with high GLS expression. SIGNIFICANCE: Targeting glutaminase disturbs redox homeostasis and nucleotide synthesis and causes replication stress in cancer cells, representing an exploitable vulnerability for the development of effective therapeutics. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/20/4514/F1.large.jpg.
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PMID:Inhibition of the MYC-Regulated Glutaminase Metabolic Axis Is an Effective Synthetic Lethal Approach for Treating Chemoresistant Ovarian Cancers. 3285 5