Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0684249 (lung carcinoma)
 23,830 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

N-(Phosphonacetyl)-L-aspartate (PALA) is an analog of the transition state for the aspartate transcarbamylase reaction and has been reported previously to be a potent and specific inhibitor of de novo pyrimidine nucleotide biosynthesis. It is now shown that PALA has considerable antitumor activity against certain transplantable tumors in mice. PALA, unlike other antimetabolites, was less effective against ascitic leukemias than against two solid tumors, B16 melanoma and Lewis lung carcinoma. Another solid tumor, Ridgway osteogenic sarcoma, which is sensitivie to many established chemotherapeutic agents, did not respond to PALA. Daily or intermittent treatment with PALA did not significantly increase the life-span of mice bearing i.p. leukemia L1210. The survival time of mice bearing i.p. P388 leukemia was prolonged by PALA treatment by up to 64%. In a number of experiments mice bearing i.p. B16 melanoma survived 77 to 86% longer than did controls when treated with PALA (490 mg/kg) on Days 1, 5, and 9. Lewis lung carcinoma, a tumor refractory to most established antineoplastic agents, was highly sensitive to PALA. Treatment on Days 1, 5, and 9 following s.c. implantation of Lewis lung carcinoma was curative to 50% of the mice. If treatment was delayed until s.c. Lewis lung tumors had reached about 500 mg, PALA neither cured the mice nor produced significant tumor regression. However, extensive delay of tumor growth and prolongation of survival were still observed.
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PMID:Antitumor activity of N-(phosphonacetyl)-L-aspartic acid, a transition-state inhibitor of aspartate transcarbamylase. 106 66

5-Chlorodeoxycytidine (CldC), coadministered with modulators of pyrimidine metabolism, is an effective radiosensitizer of murine tumors. Past studies that utilized RIF-1 tumors in C3H mice and Lewis lung carcinoma (LLC) in BDF1 mice have been extended with an emphasis on using multiple cycles of drug administration followed by irradiation of LLC and the use of two additional tumor models. Four of seven cures of BDF1 mice bearing LLC were obtained with three doses of 20 Gy irradiation, in which the first and third dose were preceded by a "Standard Protocol" that includes N-(phosphonacetyl)-L-aspartic acid (PALA), 5-fluorodeoxycytidine (FdC), tetrahydrouridine, and the radiosensitizer, 5-chlorodeoxycytidine. No cures were obtained in groups of mice receiving radiation alone or drugs alone, and there were no "no takes" in untreated control groups (six mice/group). Extensive tumor inhibition, exceeding that obtained with drugs or radiation alone, was obtained with two cycles of drugs and radiation combined when a dimethybenzanthracene-induced mammary adenocarcinoma was used in BALB/c mice. With the EMT-6 tumor in BALB/c mice, doses of 10 and 20 Gy were administered 9 and 16 days after tumor implantation, each preceded with the Standard Protocol; this resulted in a tumor growth delay of 24 days. No tumor growth delay occurred with drugs or radiation alone. The omission of PALA, FdC or CldC from the Standard Protocol resulted in loss of tumor control, which was obtained with the complete protocol. The fact that 5-chlorodeoxycytidine is an effective radiosensitizer in four rodent tumor systems is compelling evidence that it has potential as a radiosensitizer of human tumors, especially in view of its tumor selectivity and its resistance to catabolism when used with modulators of its metabolism, and in view of the high levels of the key enzymes in human tumors, which can convert 5-chlorodeoxycytidine to 5-chlorodeoxyuridine triphosphate, the proximate radiosensitizer.
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PMID:5-chlorodeoxycytidine, a radiosensitizer effective against RIF-1 and Lewis lung carcinoma, is also effective against a DMBA-induced mammary adenocarcinoma and the EMT-6 tumor in BALB/c mice. 173 88

Since the introduction of the systematic development of cytostatic drugs at the beginning of the fifties ca. 1 million substances (natural products and synthetic ones) have undergone a screening and testing on continuously further developing biological systems. As a result nowadays more than ca. 20 cytostatic drugs of unequivocally proven value are at our disposal. According to their mechanism of action these preparations are subdivided into alkylantions, antimetabolites, antibiotics and substances of different efficacy. At present hormones as alternatives of the antineoplastic chemotherapy in carcinoma of the breast and the prostatic gland very dynamically develop. While cytostatic drugs in leukaemias, lymphomas, the chorionepithelioma as well as in the metastasizing carcinoma of the breast, the ovarial carcinoma and the small cell carcinoma of the lung nowadays render possible the prolongation of life, their final value is still to be clarified in other neoplastic diseases. At present the tumour chemotherapy experiences an extremely dynamic development. Hereby apart from after- and side-developments (analogues, derivatives) above all substances with principally new principle of action gain interest and importance (PALA, mitocentron, aminogluthetimide, interferon). The short-term and middle-term risks of antineoplastic drugs are relatively well known. Long-term investigations of side-effects of cytostatic drugs are still infrequent.
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PMID:[Clinically important antineoplastic agents and risks and limits of their use]. 357 67

Eighty-two patients with small cell lung carcinoma refractory to standard chemotherapy were entered in this phase II randomized study of PALA, amsacrine, teniposide, and zinostatin. Of the 66 evaluable patients, one partial response occurred among 17 patients treated with teniposide and no responses occurred with the other drugs. Two patients each treated with amsacrine and teniposide experienced life-threatening hematologic toxic effects and one patient treated with zinostatin died of thrombocytopenic pulmonary hemorrhage. The overall median patient survival was 9.6 weeks. Weight loss greater than or equal to 5% prior to therapy, extensive disease, and a nonambulatory status were associated with poor survival.
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PMID:Phase II study of PALA, amsacrine, teniposide, and zinostatin in small cell lung carcinoma (EST 2579). 609 17

PALA is an inhibitor of de novo pyrimidine biosynthesis. Studies combining PALA with 5-FU in experimental models have demonstrated synergistic antitumor activity with only additive toxicity. The phase I study of PALA in combination with 5-FU is described. Sixteen patients received a total of 29 courses of PALA given as a 24-hour infusion daily for 5 days and 5-FU given by iv bolus at the end of each 24-hour PALA infusion. Cycles were repeated at 28-day intervals. Mucositis was dose-limiting when 940 mg/m3/day of PALA was given with 345 mg/m2/day of 5-FU. Diarrhea, skin rash, and myelosuppression (in decreasing order of frequency) occurred but were not dose-limiting. Alopecia occurred in all patients. Objective responses were seen in single patients with large cell carcinoma of the lung, fibrous histiocytoma, and adenocarcinoma of the colon refractory to prior 5-FU therapy. These studies support further phase II evaluation of the PALA and 5-FU combination.
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PMID:Phase I trial of combination therapy with PALA and 5-FU. 626 72

The physiological disposition of N-(phosphonacetyl)-L-aspartate (NSC 224131; PALA), a potent inhibitor of aspartate transcarbamylase, has been studied in mouse, rat, dog, and monkey after administration of [14C]PALA at 120 mg/sq m i.v. or p.o. Concentrations of PALA equivalents in plasma, urine, and feces were determined radiochemically, and urine was analyzed chromatographically for PALA. The disposition of PALA equivalents in mouse tissues was determined radioautographically. After i.v. administration, PALA was rapidly (half-time, approximately 1 hr) and extensively (up to 80% of the dose) excreted in the urine of all species. Less than 5% was excreted in the feces. Only PALA was found in the urine of all four species, indicating that the metabolism of PALA, if it occurs at all, is insignificant. PALA equivalents were poorly taken up by mouse tumors and tissues, except kidney, bone, and to a lesser extent, skin and lung, and were rapidly and extensively cleared from all except bone. No differences were apparent in the uptake of PALA equivalents by Lewis lung carcinoma (sensitive to PALA treatment) and L1210 lymphocytic leukemia (insensitive). The pharmacokinetics of PALA in the plasma of rat, dog, and monkey, as well as mouse, were inconsistent with deposition of PALA in tissues and more consistent with the probable distribution of PALA into extracellular water. PALA equivalents were eliminate from all species at a rate (half-time, 1 to 1.5 hr) reflecting the rate of urinary excretion of the drug and at a secondary slower rate probably reflecting the rate of release of bound PALA from sites such as aspartate transcarbamylase. PALA was poorly absorbed into the systemic circulation when administered p.o., in that mouse, rat, and monkey excreted less than 5% of the dose in the urine after p.o. administration. These data on the physiological disposition of PALA explain why high doses of the drug have to be administered to achieve therapeutic and toxic effects, despite the inhibitory potency of the drug on aspartate transcarbamylase. They indicate that PALA will be ineffective administered p.o. and might be contraindicated in patients with impaired renal function and that the kinetics of aspartate transcarbamylase-bound drug is probably more important in determining dose scheduling than the kinetics of free PALA.
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PMID:Comparative physiological disposition of N-(phosphonacetyl)-L-aspartate in several animal species after intravenous and oral administration. 705 6

Pools of uridine triphosphate and cytidine triphosphate are greatly (90%) reduced in cultured L1210 cells exposed to N-(phosphonacetyl)-L-aspartate (PALA) or pyrazofurin; the concentration of the deoxynucleotides deoxycytidine triphosphate, deoxythymidine triphosphate, and deoxyguanosine triphosphate also decreases, but deoxyadenosine triphosphate pools are enlarged. Associated with these pool depletions is a pronounced inhibition of DNA synthesis even when pools are only moderately reduced; RNA synthesis is only slightly inhibited under these same conditions. DNA synthesis in permeabilized preparations of L1210 cells was also more sensitive than was RNA synthesis when the concentrations of ribonucleotide and deoxyribonucleotide triphosphates presented were equivalent to those found in PALA- or pyrazofurin-treated cells. The specific sensitivity to depletion of DNA precursors was also seen in protection of both DNA synthesis and growth of L1210 cells by deoxycytidine and thymidine. This supplement restored deoxycytidine triphosphate, deoxythymidine triphosphate, and deoxyguanosine triphosphate pools to normal but of course did not affect the marked depletions of uridine triphosphate and cytidine triphosphate or the less marked effect of PALA on RNA synthesis. The relative ability of PALA to reduce uridine triphosphate and cytidine triphosphate pool size in L1210 ascites and Lewis lung carcinoma in vivo correlates with the intrinsic sensitivity to this agent.
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PMID:Kinetics of N-(phosphonacetyl)-L-aspartate and pyrazofurin depletion of pyrimidine ribonucleotide and deoxyribonucleotide pools and their relationship to nucleic acid synthesis in intact and permeabilized cells. 712 93

Variants of the Lewis lung carcinoma were selected for resistance to N-(phosphonacetyl)-L-aspartic acid (PALA) by treatment of tumor-bearing mice with repetitive subcurative doses of PALA. The specific activity of the target enzyme, L-aspartic acid transcarbamylase (ATCase), was measured in the four variants developed. Three had markedly elevated ATCase activities; however, the fourth line, LL/PALA-C, had an ATCase activity identical to that of the parent, PALA-sensitive line (LL/O). One high-ATCase variant, LL/PALA-J, and LL/PALA-C were compared with LL/O in subsequent biochemical studies on the mechanism of resistance to PALA. Enzyme activities in the salvage pathways which phosphorylate pyrimidine nucleosides and deoxynucleosides were found to be similar in all three lines. ATCase in these lines exhibits closely comparable kinetics with its natural substrates as well as with PALA. The time courses of restitution of ATCase after a single therapeutic dose of PALA show that both resistant variants recover full activity more rapidly than the parent. Additionally, inhibition of ATCase 24 hr following graded doses of PALA is lower in the resistant lines. The uptake of [14C]PALA in vitro into cell lines derived from the three Lewis lung carcinomas apparently occurs by passive diffusion and at comparable rates in both sensitive and resistant cells. Analysis of the nucleotide content of tumors reveals comparable spectrums of purine and pyrimidine nucleotide levels in the LL/O and LL/PALA-C lines, whereas the LL/PALA-J line has augmented nucleotide pools. In all three lines, 24 hr after treatment with PALA (400 mg/kg), uridine and cytidine nucleotide levels were substantially diminished (70 to 80%) while adenosine 5'-triphosphate and guanosine 5'-triphosphate levels were elevated (50 to 100%). Estimations of precursor flux through the de novo pyrimidine pathway by measuring orotate and orotidine levels in tumors of mice treated with pyrazofurin (an inhibitor of orotidine-5'-monophosphate decarboxylase) and either 0.9% NaCl solution or PALA shows that PALA treatment eliminates orotate and orotidine accumulation in LL/O but reduces it by only 75 and 50% in LL/PALA-C and LL/PALA-J, respectively. Similarly, PALA treatment (20 microM) of tumor lines in culture provokes a dramatic decrease in the incorporation of NaH14CO3 into pyrimidine intermediates and nucleotides in the LL/O cell line only. Determinations of specific activities of the other enzymes in this pathway reveal that the activity of carbamyl phosphate synthetase II, the rate-limiting step, is elevated 2- to 3-fold in both resistant lines. Since carbamyl phosphate synthetase II exists as a complex with ATCase, the suggestion is made that levels of carbamyl phosphate synthetase II are collaterally important determinants of PALA activity. An augmented pool of carbamyl phosphate in the resistant variants may serve to competitively displace PALA from ATCase, diminish enzyme inhibition, and allow pyrimidine biosynthesis to proceed despite therapy.
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PMID:Mechanism of resistance of variants of the Lewis lung carcinoma to N-(phosphonacetyl)-L-aspartic acid. 745 75

The synthesis of new prodrugs of PALA characterised by the presence of S-acyl-3-thiopropyl, as enzyme-labile groups on the phosphonate moiety of PALA, is reported. The cytotoxic activities of PALA prodrugs were determined against human cell line (SW1573 lung carcinoma cells). A number of prodrugs bearing S-pivaloyl as acyl groups displayed cytotoxic activity in the same order of magnitude of PALA.
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PMID:Synthesis and biological evaluation of S-acyl-3-thiopropyl prodrugs of N-phosphonoacetyl-L-aspartate (PALA). 1457 35