Furine and Pyrimidine Enzymic Programs and Nucleotide Pattern in Sarcoma1

Home , Uridine kinase, Uridine phosphorylase

[CANCER RESEARCH 43. 1019-1023, March 1983] 0008-5472/83/0043-0000$02.00 Furine and Pyrimidine Enzymic Programs and Nucleotide Pattern in Sarcoma1

George Weber,2 Michael E. Burt, Robert C. Jackson, Noemi Prajda, May S. Lui, and Eiji Takeda

Laboratory for Experimental Oncology, Indiana University School of Medicine, Indianapolis, Indiana 46223 [G. W., R. C. J., N. P., M. S. L., E. T.], and the Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland 20205 [M. E. B.]

ABSTRACT 4.5- to 12-fold. The cytidine triphosphate concentration in creased 17-fold. In the muscle, the concentrations of cytidine The purpose of this study was to elucidate the enzymic diphosphate, inosine monophosphate, and xanthosine mono- program and nucleotide pattern of a chemically induced, trans- phosphate were too low for the sensitivity of our method to plantable sarcoma and to compare the biochemical makeup detect, but these pools were well measurable in the sarcoma. with that of normal and differentiating skeletal muscle in the The enzymic program of sarcoma was distinguished from rat. that of the muscle of 6-day-old rats by the quantitatively more The activities of 28 key enzymes of pyrimidine, purine, and pronounced alterations in the sarcoma. The activities of uridine carbohydrate metabolism were determined in the 100,000 x phosphorylase, hexokinase, 6-phosphogluconate dehydroge- g supernatant fluid or in purified extracts. The concentrations nase, and adenosine deaminase were higher in sarcoma but of the adenosine, guanosine, uridine, and cytidine mono-, di-, were lower or not significantly altered in 6-day-old muscle as and triphosphates were measured by high-pressure liquid chro- compared to activities of adult muscle. The activities of aden matography of samples prepared by the freeze-clamp method. osine monophosphate deaminase and xanthine oxidase de The results of enzymic and metabolite assays were given in creased in sarcoma, whereas they were unchanged or in nmol/hr/mg protein and nmol/g, respectively, and for com creased, respectively, in 6-day-old muscle. parability were also expressed as percentages of the muscle In the sarcoma, important segments of alterations in enzy- of adult rat as the reference normal tissue in this study. These mology of carbohydrate, purine, and pyrimidine metabolism percentages denote that the activities in sarcoma or in differ were identified that proved to be a program shared with that entiating muscle were higher or lower than those in the muscle observed in chemically induced and virus-derived transplanta- of adult rats. ble rat and avian hepatocellular carcinomas and in primary In pyrimidine metabolism, the specific activities of cytidine human liver, kidney, and colon neoplasms. There were also diphosphate reducÃase, cytidine triphosphate synthetase, and sarcoma-specific markers in the enzymic programs and nu thymidine kinase increased in the sarcoma 60-, 78-, and 80- cleotide patterns that readily distinguish this tumor from other fold over those of the muscle. The activities of the key glycolytic examined neoplasms. enzymes, hexokinase and phosphofructokinase, increased 7- The present investigation revealed a formidable biochemical and 3-fold, whereas that of pyruvate kinase decreased to 35%. capacity for replication in the sarcoma cells. These biochemical The activities of glucose-6-phosphatase and fructose-1,6-di- studies also point out possible targets in the strategy of anti- phosphatase declined to 42 and 48%, respectively. The activ cancer drug treatment of sarcoma. ities of enzymes involved in pentose phosphate production and utilization increased, with that of the glucose-6-phosphate de- INTRODUCTION hydrogenase being elevated 288-fold. The activity of galactokinase was unchanged, whereas that of uridine diphosphoglu- Previous work in this laboratory demonstrated, in a spectrum cose pyrophosphorylase decreased to 22%. In purine metab of chemically induced, transplantable hepatocellular carcino olism, the activities of the first three enzymes of guanosine mas of the liver, a transformation- and progression-linked im triphosphate biosynthesis, inosine monophosphate dehydro- balance in the activities of key enzymes of carbohydrate, purine, and pyrimidine metabolism and in the pattern of ribo- genase, guanosine monophosphate synthetase, and guanosine monophosphate kinase, increased 22-, 2-, and 5-fold, respec nucleotides and deoxyribonucleoside triphosphates (3, 9, 10). tively. In contrast, the activities of adenylosuccinate lyase and Subsequent studies indicated the presence of the metabolic adenosine monophosphate deaminase decreased to 28 and imbalance in a series of carcinomas of kidney and colon in the 42%. The activities of adenosine deaminase and kinase in rat and mouse and, recently, in human renal and colon carci creased 1.8- and 3.5-fold. The activity of the rate-limiting nomas (1,2,12). The purpose of the present investigation was enzyme of de novo inosine monophosphate biosynthesis, ami- to answer the following questions. Is the biochemical imbalance dotransferase, increased 13-fold, whereas that of the rate- discovered in carcinomas applicable to sarcoma? Are the limiting purine-catabolic enzyme, xanthine oxidase, decreased enzymic indications of an imbalance in the cellular metabolic to 54%. programs verifiable by the pattern of nucleotides in sarcoma? In the sarcoma, the concentrations of adenosine tri-, di-, and Is the biochemical pattern of the sarcoma different from that of monophosphate decreased to 24, 49, and 76%. In contrast, differentiating muscle? Is it possible to identify a shared pattern the pools of guanosine tri-, di-, and monophosphate increased of biochemical imbalance in carcinomas and sarcoma? Are 9- to 11-fold, and those of the uridylates were also elevated there any sarcoma-specific biochemical alterations?

1This investigation was supported by USPHS Grants CA-13526, CA-05034. MATERIALS AND METHODS and CA-10792. 2 To whom requests for reprints should be addressed. For these studies, a methylcholanthrene-induced sarcoma line car Received July 22, 1982; accepted December 3, 1982. ried in male Fischer (F344) rats (Charles River Laboratories, Portage,

MARCH 1983 1019

Mich.) and skeletal muscles from control, normal rats of the same sex, In the sarcoma, the activities of all synthetic enzymes ex strain, age, and weight were used. The tumor was a rhabdomyosar- amined were very markedly increased as compared to muscle, coma; the induction, maintenance, histology, and biological behavior ranging from a rise of 78- to 80-fold for thymidine kinase and are described in detail elsewhere.3 This is a fairly rapidly growing CTP synthetase to increases of 26- and 14-fold for uridine neoplasm which resembles the macroscopic appearance and growth kinase and uracil phosphoribosyltransferase. These elevations rate of hepatoma 3924A and reaches a diameter of 1.5 cm in about 14 were much more marked (about 10-fold higher) than were days, with death occurring 30 to 34 days after inoculation. The 12- to 18-day-old tumor has no necrosis, and it is well suited for the metabolic those observed in the rapidly growing liver tumors compared to the resting liver (16). studies that were conducted. The animals were inoculated s.c. by injection of 106 viable tumor In carbohydrate metabolism in the muscle, the activities of cells, and 1 week later the tumor-bearing and control rats were shipped the key glycolytic enzymes, hexokinase, phosphofructokinase, by air from the National Cancer Institute to Indiana University. All rats and pyruvate kinase, were higher than those in rat liver (11). were housed in individual cages in air-conditioned rooms, which were This is expected in view of the well-known glycolytic capacity illuminated daily from 6 a.m. to 7 p.m. Purina laboratory chow and of skeletal muscle. In the sarcoma, the activities of phospho water were available ad libitum. Rats were always killed between 9 and fructokinase and hexokinase increased 3- to 7-fold, which is in 10 a.m. line with observations made in hepatic carcinomas of similar Biochemical Methods. Animals were stunned, decapitated, and rapid growth rates (11 ). In contrast to results in hepatomas, bled; tumors were excised, and 10% homogenates were prepared in the appropriate media as reported earlier (1, 2, 13). For the freeze- the activity of pyruvate kinase, which is orders of magnitude higher than any other enzyme that we have studied, was clamp studies, the animals received light ether anesthesia, and tumors decreased to one-third of that observed in the control muscle. and muscles were removed as described elsewhere (1 7). Preparation of the extracts and methods for measurement of en In muscle, the gluconeogenic enzymes, glucose-6-phospha- zymes were described in detail elsewhere (1, 2, 5, 13). Preliminary tase and fructose-1,6-diphosphatase, were present only in low kinetic studies were carried out to ensure that the enzyme assays were activities, which were further decreased to 42 to 48% in the conducted under linear kinetic conditions, at optimum substrate and sarcoma. These results are in line with the decline in activities activator concentrations, and that the activities measured were pro of gluconeogenic enzymes first reported in hepatomas (11 ). portionate with the amount of enzyme added and reaction time elapsed. In pentose phosphate metabolism in the muscle, the activity Preparation of the tissue material for determination of concentrations of glucose-6-phosphate dehydrogenase proved to be rate lim of ribonucleotides and deoxynucleoside triphosphates by high-pres iting, being 10 times lower than that of the subsequent enzyme, sure liquid chromatography and enzymatic methods (3) was cited 6-phosphogluconate dehydrogenase. The activity of glucose- elsewhere. Protein content was determined by a standard procedure 6-phosphate dehydrogenase was the lowest among the en (7). Expression and Evaluation of Results. Enzymic activities were zymes of carbohydrate metabolism examined in this study. calculated as nmol product formed per hr, per g (wet weight) of tissue, Therefore, it is interesting that in the sarcoma the activity of per average cell or per mg protein, as specific activity. The concentra this dehydrogenase was increased the most markedly of all the tions of nucleotides were calculated in nmol per g (wet weight) of enzymes assayed, i.e., 288-fold over the value of normal con tissue. trol muscle. The 6-phosphogluconate dehydrogenase activity The results were subjected to statistical evaluation by means of the was elevated 12-fold. Transaldolase, which channels fructose t test for small samples. Differences between means yielding a proba 6-phosphate into ribose 5-phosphate biosynthesis, in the mus bility of less than 5% were considered to be of statistical significance. cle had an activity twice as high as that of 6-phosphogluconate dehydrogenase, and the activity increased 7.7-fold in the sar RESULTS AND DISCUSSION coma. The enzyme that utilized ribose 5-phosphate for phos- phoribosylpyrophosphate biosynthesis, phosphoribosyl pyro- Enzymic Programs of Muscle and Sarcoma phosphate synthetase, also had low activity in the muscle, but it increased only 1.5-fold in the sarcoma. The activities of key enzymes of carbohydrate, purine, and In purine metabolism among the synthetic enzymes, the pyrimidine metabolism are summarized in Table 1, which pro activity of IMP dehydrogenase was the lowest, resembling that vides the means and standard errors of activities observed in in liver (5). However, the muscle activity was much lower than normal muscle and the results in the sarcoma as percentages that in the rat liver. In the sarcoma, the dehydrogenase activity of the values in muscle. In pyrimidine metabolism, the activities increased 22-fold, the highest rise among all the purine en of the synthetic enzymes were low as compared to those zymes examined. The activities of the enzymes involved in GTP observed in rat liver (16). In the muscle, the rate-limiting en biosynthesis subsequent to the action of IMP dehydrogenase, zyme of CTP biosynthesis, CTP synthetase, had an activity GMP synthetase and GMP kinase, were orders of magnitude about one-tenth that in liver. The activity of thymidine kinase higher than that of the rate-limiting enzyme, the dehydroge was also low; however, that of the other salvage enzyme, nase. These enzymic activities increased in the sarcoma to 2- uridine kinase, was the highest in this group of synthetic to 5-fold the values of the muscle. It is interesting that the enzymes. The activity of uridine kinase was 5 times higher than activities of the enzymes of the purine cycle, adenylosuccinase that of the enzymes of the de novo synthetic pathway, orotidine and AMP deaminase, were decreased in the sarcoma, indicat 5'-monophosphate decarboxylase and orotate phosphoribo- ing that this cycle which may be a characteristic liver and syltransferase. muscle function was decreased in the sarcoma. The activity of AMP deaminase was the highest among the purine enzymes in 3 M. B. Popp, M. E. Burt, and M. F. Brennan. Natural history and cell of origin the muscle. The activities of enzymes involved in adenosine of a methylcholanthrene-induced sarcoma in the Fischer 344 rat, submitted for metabolism, adenosine deaminase and kinase, were also high, publication. but these activities further increased 1.8- and 3.5-fold. This

1020 CANCER RESEARCH VOL. 43

Table 1 Enzymic programs of muscle and sarcoma in rat

muscle (% (% of adult enzymesPyrimidineCDPMetabolic areas and no.1.17.4.12.7.1.216.3.4.24.1.1.232.4.2.102.4.2.92.7.1.482.4.2.32.7.1.12.7.1.112.7.1.403.1.3.93.1.3.111.1.1.491.1.1.442.2.1.22.7.6.1Adultprotein)0.0430.280.483.753.900.8019.800.18478.03,340.0488,000.01,130.01,190.057.0598.01.180.076.0Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±0.005a0.040.060.090.450.170.830.0032.0190.012,000.090.070.01.015.0110.02.5Sarcoma(nmol/hr/mg ofmuscle)5,95368,004"7.768"5,086"3,589"3,425"2,626"1,378"686"314"35"42"48"28,825*1.154"770"158"6-day-ol'lmusclomuscle)i,noo"600"376"1,431"976"1,722"5847"18"1.215"80"175"

reducÃaseThymidine klnaseCTP synthetaseOrotidine decar-boxylaseOrotate5'-monophosphate

phosphoribosyltransferaseUracil phosphoribosyltransferaseUridine kinaseUridine phosphorylaseGlycolysisHexokinasePhosphofructokinasePyruvate

kinaseGluconeogenesisGlucose-6-phosphataseFructose-1

,6-diphosphatasePentose

phosphateGlucose-6-phosphate dehydroge-nase6-Phosphogluconate

dehydroge-naseTransaldolasePhosphoribosyl

pyrophosphate syn thetaseEC

Galactose Galactokinase 2.7.1.6 3.9 0.4 95 Uridine diphosphoglucose pyro- 2.7.7.9 17.4 1.5 22" phosphorylase

Purine IMP dehydrogenase 1.2.1.14 0.038 Â± 0.007 2,160 GMP synthetase 6.3.5.2 14.5 Â± 0.4 218" GMP kinase 2.7.4.8 840.0 37.0 524" 504" Adenylosuccinate lyase 6.3.4.4 520.0 10.0 28" AMP deaminase 3.5.4.6 18,640.0 149.0 144 Adenosine deaminase 3.5.4.4 955.0 35.0 177"< 115 351 " Adenosine kinase 2.7.1.20 104.0 0.04 Amidotransferase 2.4.2.14 7.8 4.0 1,345" 188" Xanthine oxidase 1.2.3.2 4.9 Â± 1.0 54" 200" Mean Â±S.E. of 4 or more experiments. ' Significantly different from muscle of adult rats (p < 0.05). behavior is in contrast with that in hepatic carcinoma where in activity of hexokinase was decreased to 47%, whereas in the the rapidly growing tumors the activity of adenosine deaminase sarcoma it was increased to 686%. The pyruvate kinase activity was increased 3- to 4.5-fold and that of adenosine kinase was 18%, whereas in the sarcoma it was 35%, of the normal decreased to less than 20% of that observed in the control liver muscle. Minor increases were observed in the activities of (4). glucose-6-phosphate dehydrogenase and transaldolase. How The activity of the first committed enzyme of de novo purine ever, the activity of 6-phosphogluconate dehydrogenase was biosynthesis, amidophosphoribosyltransferase (amidotransfer- decreased, whereas in the sarcoma it was elevated 12-fold. In ase), in the sarcoma was markedly increased (13-fold), purine metabolism, the GMP kinase activity was as high as in whereas that of the rate-limiting catabolic enzyme, xanthine the sarcoma. However, the activities of AMP deaminase and oxidase, was decreased to 54%. As a result, the ratio of adenosine deaminase in the developing muscle were the same amidotransferase to xanthine oxidase was markedly elevated. as in normal muscle, whereas in sarcoma the first one de creased and the latter increased. In the 6-day-old muscle, the Enzymic Program of Differentiating Muscle amidotransferase activity was 2-fold higher whereas in the sarcoma it was 13-fold higher than in the normal muscle. In the The enzymic program of differentiating muscle of the rat sarcoma, the xanthine oxidase activity was decreased, (Table 1) shows some similarities to and also sharp differences whereas it was high in the differentiating muscle. Thus, the from that of the sarcoma. The activities of the pyrimidine- enzymic program of the sarcoma can be readily separated from synthetic enzymes were increased in comparison with normal that of the differentiating muscle through the quantitatively muscle, but to a smaller extent than those of the sarcoma. more pronounced alterations in the sarcoma and by the differ However, uridine phosphorylase activity was decreased. The ent behavior of uridine phosphorylase, hexokinase, 6-phos-

MARCH 1983 1021

phogluconate dehydrogenase, AMP deaminase, adenosine de- dehydrogenase, GMP synthetase, and GMP kinase (Table 1). aminase, and xanthine oxidase. The elevated concentrations of UTP, UDP, and UMP are in good agreement with the marked increase in the activities of Ribonucleotide Pattern in Muscle and Sarcoma enzymes involved in the de novo and salvage pathways of uridylate biosynthesis. The increased concentration of CTP The overall pattern of purine and pyrimidine ribonucleotides reflects the elevation in the activity of the rate-limiting enzyme in muscle (Table 2) resembled that of liver in that the concen of biosynthesis, CTP synthetase (Table 1). trations of adenylates were 2 orders of magnitude higher than those of the other nucleotides and the concentrations of cyti- Identification of Shared Programs in Neoplasms and Tumor- dylates were the lowest (3). Particularly low CTP concentration specific Enzymic and Metabolic Pattern in Sarcoma was found in the muscle, the other nucleotides (CDP, IMP, and XMP) being too low to measure with accuracy by current Shared Programs in Different Types of Neoplastic Cells. methods. The strikingly high concentrations of ATP and ADP In elucidating the biochemical strategy of gene logic, it was were in line with expectations for these nucleotides because of reported from this laboratory that there are shared programs in their vital role in muscle function. the enzymic and metabolic imbalance that are displayed in Comparison of the purine and pyrimidine ribonucleotide con various types of neoplasms (9, 10, 14). Evidence was pre centrations shows a characteristic pattern in the sarcoma. The sented that important segments of alterations in enzymology of concentrations of ATP, ADP, and AMP and total adenylates in carbohydrate, purine, pyrimidine, and other metabolic areas the sarcoma decreased to 24, 49, 76, and 32%, respectively, occurred in chemically induced and virus-derived, transplant- of those observed in normal muscle. The decrease in concen able rat, mouse, and avian tumors and in primary human liver tration of adenylates is similar to that in renal cell carcinomas and kidney and colon neoplasms (1, 6, 8, 15). Three major (18) and hepatomas (3, 17) in the rat. By contrast, the concen aspects of gene logic were identified in the various tumors (14). trations of GTP, GDP, GMP, and total guanylates were very Reciprocal regulation plays a vital role in control of the rate markedly increased over those in muscle. The 9-fold increase and direction of opposing metabolic pathways by determining in concentration of GTP and the elevation in that of total the amounts of antagonistic key enzymes (14). This metabolic guanylates (14-fold) were in marked contrast with values in rat imbalance amplifies the metabolic capabilities of the tumor liver carcinomas which were in the normal range of the control cells. Such a pattern was observed in the present investigation liver. The concentrations of DTP, UDP, the UDP sugars, and in the sarcoma in the elevation in activity of the synthetic total uridylates were markedly increased in the sarcoma but enzyme, amidotransferase, and the decline in that of the op were not significantly altered in the rapidly growing hepatoma. posing catabolic enzyme, xanthine oxidase. This reciprocal The 17-fold increase in CTP concentration is the most marked regulation resulted in a 31-fold increase in the ratio of the among the ribonucleotides in the sarcoma; a 4- to 5-fold activities of the opposing enzymes of purine metabolism which elevation was observed in the rapidly growing hepatoma is more marked than the rise observed for this enzyme ratio in 3924A. other tumors. The decreased concentration of adenylates is in line with the A second principle that we identified in purine and pyrimidine decrease in the activities of enzymes of de novo ATP produc metabolism was the relationship of the extent of rise in activity tion in the sarcoma (Table 2). The increased concentrations of of an enzyme in a tumor compared with the absolute activity GTP, GDP, and GMP reflect the elevated activities of IMP observed in the homologous normal tissue of origin. An exam ple of this relationship is in human colon tumor where the Table 2 activities of thymidine kinase and CTP synthetase which were Purine and pyrimidine ribonucleotides in rat sarcoma and skeletal muscle the lowest in normal colon mucosa were increased the most wtSarcoma113074316520380.74188134122444282207149513115151395519Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±Â±15737201079833282434113831537%markedly in the neoplasms (1). A similar relationship holds in the sarcoma where thymidine kinase, CTP synthetase, and ofmuscle24Â°49"7632b87989"111661432"4546121 NucleotidesATPADPAMPSAAdenylate CDP reducÃase had the lowest activities in the muscle, but these activities were increased to the greatest extent among the pyrimidine-synthetic enzymes in the sarcoma. In purine metabolism in the muscle, the activity of IMP dehydrogenase chargeGTPGDPGMPEGUTPUDPUMPUDP was the lowest; in the sarcoma, it was increased the most markedly among the enzymes of purine biosynthesis. Observations in an array of 14 different rat, mouse, avian, and human tumors indicated the operation of an integrated program of enzymic and metabolic imbalance that conferred 76529b654"17006selective advantages to the cancer cells (6, 8, 9, 10, 14). In the sarcoma, we confirmed the presence of a coordinated sugarsSUCTPCDPIMPXMPnmol/g.Muscle4725151021864530.85191203162170971763000Â±Â±Â±Â±Â±Â±+Â±Â±Â±Â±311a70574374254118193wetpattern of alterations in the activities of key enzymes yielding a highly meaningful picture (Tables 1 and 2). Tumor-specific Differences. In parallel with striking similar ities in the overall biochemical strategy of different cancer cells, we also expect organ- and cell-specific alterations in

Mean Â±S.E. of 4 or more experiments. neoplasms of different cellular origin, and we reported such ' Significantly different from muscle (p < 0.05). differences for the various tumor systems (1, 14). In the sar-

1022 CANCER RESEARCH VOL. 43

Downloaded from cancerres.aacrjournals.org on September 26, 2021. © 1983 American Association for Cancer Research. Biochemistry of Rat Sarcoma coma, a striking contrast with other neoplasms was the de this enzyme, an inhibition by drugs of the final common pathway crease in activity of pyruvate kinase which was ubiquitously of CTP biosynthesis, CTP synthetase (e.g., by glutamine antag increased in all other tumors examined thus far. In sarcoma, onists or competitive inhibitors), also would be circumvented. galactokinase activity did not increase, but it was elevated 4- The marked elevation in thymidine kinase activity provides a fold in human colon carcinoma. In sarcoma, the activities of heightened capacity for production of thymidylates which are AMP deaminase and adenylosuccinase decreased, but they also crucial for DNA biosynthesis. In the design of combination increased in liver and kidney tumors. The activity of adenosine chemotherapy of sarcoma, there is a need for agents that in kinase that was low in rapidly growing hepatomas showed a addition to inhibition of the de novo pathways would block the 3.5-fold increase in the sarcoma. These alterations provide a activities of the salvage synthetic processes. The present stud pattern of sarcoma-specific markers that distinguishes the en- ies, while revealing the formidable biochemical capacities dis zymic features of this tumor from those of any others that we played by sarcoma cells, also point out possible approaches in have examined thus far. There are also differences in the the strategy of anticancer drug treatment of this neoplasm. nucleotide pattern where the marked increases in concentra tions of guanylates and uridylates contrast with the normal liver values observed in hepatocellular carcinomas. In sarcoma, the REFERENCES 17-fold increase of CTP concentration was quantitatively far beyond the rise in hepatoma 3924A (4- to 5-fold). These 1. DentÃ³n, J. E., Lui, M. S., Aoki. T., Sebolt. J., Takeda, E., Eble, J. N., Glover, J.L., and Weber, G. Enzymology of pyrimidine and carbohydrate metabolism differences assist in characterizing the metabolic individuality in human colon carcinomas. Cancer Res., 42: 1176-1183, 1982. of the sarcoma and in the biochemical differential diagnosis of 2. Jackson, R. C., Goulding, F. J., and Weber, G. Enzymes of purine metabo lism in human and rat renal cortex and renal cell carcinoma. J. Nati. Cancer this tumor. Inst., 62. 749-754. 1979. Selective Advantages Conferred to Sarcoma Cells by the 3. Jackson, R. C., Lui, M. S., Boritzki, T. J., Morris, H. P.. and Weber, G. Enzymic and Metabolic Imbalance. The biological malignancy Purine and pyrimidine nucleotide patterns of normal, differentiating and and rapid growth rate of the sarcoma are reflected in the regenerating liver and of hepatomas in rats. Cancer Res., 40: 1286-1291, 1980. pronounced elevations in the activities of key enzymes of 4. Jackson, R. C.. Morris, H. P., and Weber, G. Enzymes of the purine pyrimidine and purine biosynthesis and in the decrease in ribonucleotide cycle in rat hepatomas and kidney tumors. Cancer Res., 37: 3057-3065, 1977. catabolic capacity (9, 10). The increased activities of key 5. Jackson, R. C., Morris, H. P., and Weber, G. Partial purification, properties enzymes of glycolysis and pentose phosphate production and and regulation of inosine 5'-phosphate dehydrogenase in normal and malig utilization should provide an increased capability for the pro nant rat tissues. Biochem. J.. 166: 1-10, 1977. 6. Kovalszky, I , Jeney. A., Asbot, R., and Lapis, K. Biochemistry and enzyme duction of ribose 5-phosphate and phosphoribosyl pyrophos- induction in MC-29 virus-induced transplantable avian hepatoma. Cancer phate. Res., 36. 2140-2145, 1976. 7. Lowry, O. H., Rosebrough, N. J., Farr, A. L., and Randall, R. J. Protein The markedly enlarged pools of guanylates, uridylates, and measurement with the Folin phenol reagent. J. Biol. Chem., 193: 265-275, cytidylates should provide a stepped-up capability for nucleic 1951. acid production, in particular, the provision of substrate for 8. Prajda, N.. Eckhardt, S., Suba, Z., and Lapis. K. Biochemical behavior of ribonucleotide reducÃasefor the de novo biosynthesis of deoxy- MC-29 virus-induced transplantable chicken hepatoma. J. Toxicol. Environ. Health, 5. 503-508, 1979. nucleoside triphosphates. The markedly increased capacities 9. Weber, G. Enzymology of cancer cells, Part 1. N. Engl. J. Med.. 296: 486- of the salvage pathways, as shown by elevated activities of 493. 1977. thymidine kinase (80-fold) and uridine kinase (26-fold), would 10. Weber. G. Enzymology of cancer cells. Part 2. N. Engl. J. Med.. 296: 541- 551, 1977. contribute strongly to the increased potential for nucleic acid 11. Weber, G. Differential carbohydrate metabolism in tumor and host. In: M. S. biosynthesis. The enzymic and metabolic imbalance discov Arnott, J. van Eys, and Y.-M. Wang (eds.). Molecular Interrelations of Nutrition and Cancer (UT System Cancer Center 34th Annual Symposium ered in the sarcoma should confer selective advantages to on Fundamental Cancer Research), pp. 191 -208. New York: Raven Press, these cancer cells. The pronounced enzymic and metabolic 1982. imbalance and particularly the increase in both de novo and 12. Weber, G., Goulding, F. J., Jackson, R. C.. and Eble, J. N. Biochemistry of human renal cell carcinoma. In: W. Davis and K. R. Harrap (eds.). Charac salvage enzymic activities explain, in part at least, the difficul terization and Treatment of Human Tumours, pp. 227-234. Amsterdam: ties encountered in the chemotherapeutic control of this malig Excerpta Medica, 1978. 13. Weber, G., Hager, J. C., Lui, M. S., Prajda, N., Tzeng, O. Y., Jackson, R. C.. nant neoplasm. Takeda, E., and Eble, J. N. Biochemical programs of slowly and rapidly Relevance of Enzymology of Sarcoma to the Design of growing human colon carcinoma xenografts. Cancer Res., 41: 854-859, Anticancer Drug Treatment. The difficulties in achieving last 1981. 14. Weber. G., Lui, M. S., Takeda, E., and DentÃ³n, J. E. Enzymology of human ing remissions in experimental or human sarcomas by inhibitors colon tumors. Life Sci., 27: 793-799, 1980. of the de novo pathways of pyrimidine metabolism may be 15. Weber, G., Olah. E., Lui, M. S.. Kizaki, H., Tzeng, D. Y., and Takeda, E. Biochemical commitment to replication in cancer cells. Adv. 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George Weber, Michael E. Burt, Robert C. Jackson, et al.

Cancer Res 1983;43:1019-1023.

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