Investigation on phosphate dependent glutaminase (EC 3.5.1.2) activity in host tissues of EAC-bearing mice and response of liver EC 3.5.1.2 on Cu-ATP therapy

Randomized clinical trial of adenosine 5'-triphosphate on tumor growth and survival in advanced lung cancer patients

We recently reported that regular infusions of adenosine 5'-triphosphate (ATP) inhibited loss of body weight and quality of life in patients with non-small cell lung cancer (NSCLC). In the present paper we investigated whether ATP affects tumor growth and survival in the same group of patients. Fifty-eight NSCLC patients (stage IIIB or IV) were randomly assigned to receive either 10 i.v. 30-h ATP infusions every 2-4 weeks over a 24-week period (n = 28) or no ATP (control patients, n = 30). ATP was given for a median of 6.5 infusions. Differences in time to progression and survival between patients in both groups were tested by means of the log-rank test and Cox regression analysis. Forty-nine patients were evaluable for tumor response. None of the evaluable patients showed a complete or partial response. Median time to progression was 3.9 months [95% confidence interval (CI) = 2.3-5.5] in the ATP group compared to 3.0 months (95% CI = 2.4-3.7) in the control group (p = 0.71). Median survival was 5.6 months (95% CI = 1.1-10.1) for the ATP group and 4.7 months (95% CI = 2.6-6.8) for the control group (p = 0.68). ATP treatment was associated with a significant increase in survival in the subgroup of weight-losing patients with stage IIIB NSCLC: in this subgroup, median survival was 9.3 months (95% CI = 2.1-16.5) for ATP-treated patients versus 3.5 months (95% CI = 2.3-4.7) for control patients (between-group difference: p = 0.009). No significant effect of ATP was observed for weight-losing patients with stage IV NSCLC or for weight-stable NSCLC patients. Although ATP as a single therapy does not lead to tumor regression or increased survival in patients with advanced lung cancer, it may prolong survival in weight-losing patients with stage IIIB lung cancer. The latter finding is intriguing, but requires confirmation in larger clinical trials.

Adenosine triphosphate: established and potential clinical applications

Adenosine 5'-triphosphate (ATP) is a purine nucleotide found in every cell of the human body. In addition to its well established role in cellular metabolism, extracellular ATP and its breakdown product adenosine, exert pronounced effects in a variety of biological processes including neurotransmission, muscle contraction, cardiac function, platelet function, vasodilatation and liver glycogen metabolism. These effects are mediated by both P1 and P2 receptors. A cascade of ectonucleotidases plays a role in the effective regulation of these processes and may also have a protective function by keeping extracellular ATP and adenosine levels within physiological limits. In recent years several clinical applications of ATP and adenosine have been reported. In anaesthesia, low dose adenosine reduced neuropathic pain, hyperalgesia and ischaemic pain to a similar degree as morphine or ketamine. Postoperative opioid use was reduced. During surgery, ATP and adenosine have been used to induce hypotension. In patients with haemorrhagic shock, increased survival was observed after ATP treatment. In cardiology, ATP has been shown to be a well tolerated and effective pulmonary vasodilator in patients with pulmonary hypertension. Bolus injections of ATP and adenosine are useful in the diagnosis and treatment of paroxysmal supraventricular tachycardias. Adenosine also allowed highly accurate diagnosis of coronary artery disease. In pulmonology, nucleotides in combination with a sodium channel blocker improved mucociliary clearance from the airways to near normal in patients with cystic fibrosis. In oncology, there are indications that ATP may inhibit weight loss and tumour growth in patients with advanced lung cancer. There are also indications of potentiating effects of cytostatics and protective effects against radiation tissue damage. Further controlled clinical trials are warranted to determine the full beneficial potential of ATP, adenosine and uridine 5'-triphosphate.

Early differential expression of two glutaminase mRNAs in mouse spleen after tumor implantation

The influence of progressive tumor growth on phosphate-activated glutaminase (PAG) expression in splenocytes from mice bearing Ehrlich ascites carcinoma cells was investigated. Implantation of Ehrlich ascites tumor cells in the peritoneal cavity of mice led to a 2.3-fold stimulation of spleen PAG activity 48 h later. Four days after tumor implantation the glutaminase activity had returned to nearly basal value and remained at this level throughout the tumor development. Northern blot analysis indicated that two species of glutaminase mRNA were expressed in the spleen, which showed a differential expression pattern during the first 2 days after tumor implantation. The abundance of the transcript of higher electrophoretic mobility (approximately 3 kb) constantly increased over the first 2 days of tumor growth. The mRNA of lower electrophoretic mobility (approximately 6 kb) peaked at 12 h after tumor implantation and returned to control values at 48 h. These results demonstrate that tumor has the capability of altering glutaminase expression in the host spleen.