Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sarcoma cells exhibit higher rates of glycolysis than normal tissues and may be dependent on glucose utilization for growth. Accordingly, we tested the ability of the glucose antimetabolite 2-deoxy-D-glucose (2-DG) to inhibit the growth of an established methylcholanthrene-induced rat fibrosarcoma in three groups of F344 rats with increasing subcutaneous inoculations of tumor (2 X 10(6) cells, 1 X 10(7) cells, and 1 mm tumor fragments). Rats were randomized to receive 2-DG or saline solution at doses of 0.75 gm/kg, 1.5 gm/kg, or 1.75 gm/kg, beginning 3 days after tumor implantation and continuing for 10 days. Tumors were removed and weighed on day 14. We measured tissue [14C]-2-DG levels in tumor, brain, liver, and muscle after intraperitoneal injection of radiolabeled 2-DG. In these same tissues we determined the activity of glucose-6-phosphatase (G-6-Pase), an enzyme which dephosphorylates the intracellular glycolytic inhibitor 2-DG-6-phosphate, thus reversing the antitumor effect of 2-DG. All groups treated with 2-DG had a significant reduction in tumor weight of 50% to 70% when compared with saline solution-treated controls. Toxicity was substantial at the highest dose of 2-DG, but minimal toxicity was noted at intermediate and low doses. Tumor had the greatest uptake of [14C]-2-DG, with low levels of G-6-Pase leading to prolonged retention and highest tissue levels of radiolabeled 2-DG. Use of 2-DG inhibits established sarcoma growth because it is rapidly transported into tumors, cannot be metabolized after phosphorylation, and is dephosphorylated and released slowly from tumor cells. Rat sarcoma growth is dependent on glucose utilization and can be effectively inhibited by glucose antagonism.
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PMID:Inhibition of established rat fibrosarcoma growth by the glucose antagonist 2-deoxy-D-glucose. 303 79

Incubation of rat liver microsomes with ATP and Mg2+ in the absence or presence of an exogenous protein kinase showed no changes in the activity of glucose-6-phosphatase (D-glucose-6-phosphate phosphohydrolase, EC 3.1.3.9). These observations confirm the recent findings of the Burchells and colleagues and refute on methodological grounds the earlier conclusions of Begley and Craft implicating regulation of this enzyme by protein phosphorylation-dephosphorylation. In other studies, the time-dependent inactivation of microsomal glucose-6-phosphatase by incubation with deoxycholate was used to obtain the inactive enzyme which in the presence of a protein kinase, ATP, and Mg2+ could not be restored to its original level. A number of substrates and competitive inhibitors of glucose-6-phosphatase, most notably vanadate which is the most potent inhibitor of the enzyme identified, stabilized this enzyme against its time-dependent inactivation in the presence of detergent as effectively as did fluoride and molybdate which are also effective competitive inhibitors of glucose-6-phosphatase. An alternative explanation to the involvement of a phosphoprotein phosphatase, as discussed by the Burchells, in the time-dependent inactivation of glucose-6-phosphatase is thus suggested.
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PMID:Glucose-6-phosphatase: is activity regulated by phosphorylation-dephosphorylation? 631 50