hypoxanthine concentrations in normal subjects and ... · antimycotics mixture (grand island...

[CANCER RESEARCH 44, 3144-3148. July 1984]

Hypoxanthine Concentrations in Normal Subjects and Patients with SolidTumors and Leukemia1

Wally E. Wung and Stephen B. Howell2

Department of Medicine, the Cancer Center, and the General Clinical Research Center, University of California, San Diego, La Jolla, California 92093

ABSTRACT

Mean plasma hypoxanthine (Hyp) concentrations determinedby high-pressure liquid chromatography were 0.56 MM (range,0.2 to 1.9 MM)in 16 normal subjects, 0.68 MM(range, 0.1 to 1.1MM)in 10 untreated acute leukemic subjects, and 0.89 MM(range,0.3 to 2.6 MM)in 14 solid tumor patients. Despite large differencesin Hyp concentration between patients, every 4-hr sampling,

indicated that diurnal variation in individual patients was small(maximum, 2.3-fold). While the mean plasma and malignanteffusion Hyp concentrations did not differ significantly, bonemarrow plasma Hyp concentration averaged 4.0-fold greater

than that of simultaneously drawn venous plasma. Allopurinol300 mg p.o. caused a mean 1.5-fold increase in plasma Hyp

within 3 hr. In 17 patients with acute leukemia, treatment withallopurinol at 300 mg daily plus initiation of chemotherapy causeda mean 7-fdd increase in plasma Hyp to 4.6 MM(range, 1 to 12MM).The ability of Hyp to modulate the toxicity of antimetabolitesaffecting purine synthesis (6-diazao-5-oxonorleucine, 6-methyl-mercaptopurine riboside, 6-mercaptopurine, and 6-thioguanine)was determined in vitro using human B-lymphoblast (WI-L2) andpromyelocytic leukemia (HL-60) cell lines. Hyp permitted growth

of both cell lines in the presence of clinically achievable concentrations of all 4 drugs, but the initial culture concentrations ofHyp required were above those found in patients. Since Hypwas consumed rapidly during the culture period, the averageHyp concentrations required for the protection of cells wereactually much lower. We conclude that, in patients with acuteleukemia receiving allopurinol during chemotherapy, plasma Hypconcentrations are significantly elevated; the potential for antagonism of antimetabolite activity is uncertain.

INTRODUCTION

Antimetabolites which interfere with de novo purine synthesisconstitute an important part of the armamentarium of drugsavailable for the treatment of leukemia and other cancers (4, 15,26, 36). However, not all patients respond equally well to thesedrugs, and some eventually become refractory to the therapy.Resistance to purine analogues has been attributed to the deficiency of enzymes necessary to convert them to their nucleotideforms (7, 31). Other mechanisms have been observed in experimental tumors, such as increased degradation of drugs andinability of resistant cells to convert the ribonucleotide analoguesto the deoxyribonucleotide analogue (10, 29).

This study was designed to examine the possibility that in-

1This work was supported by Grants CA23100 and CA23334 from the National

Cancer Institute and by the University of California, San Diego General ClinicalResearch Center, NIH, Division of Research Resource (Grant RR00827). Thisresearch was conducted in part by the Clayton Foundation for Research, CaliforniaDivision.

2Clayton Foundation Investigator. To whom requests for reprints should be

addressed.Received April 10, 1981 Â¡accepted April 2, 1984.

creased plasma Hyp3 concentrations during treatment may also

be a mechanism of resistance to antimetabolites acting in thepurine biosynthetic pathways. Extracellular Hyp is important forthe activity of purine antimetabolites in 2 aspects: it can beutilized to restore purine nucleotide pools in cells the de novosynthesis of which has been blocked, and it potentially maycompete with some of these antimetabolites for transport intothe cell or for the enzymes necessary to convert the drugs totheir active nucleotides (9).

Using a newly developed high-pressure liquid Chromatographie

method (43), we have measured plasma Hyp in groups of normalsubjects, patients with solid tumors, and patients with acuteleukemia. Frequent blood samples were obtained from somepatients to assess diurnal variation, and Hyp concentration inbone marrow and malignant effusions was compared to that ofvenous plasma to determine the distribution of Hyp in differentbody compartments. We also examined the effect on plasmaHyp of treatment with HPP alone or the combination of HPP andchemotherapy. Finally, the effect of Hyp at concentrations encompassing the range observed in vivo was tested for its abilityto modulate the toxicity of de novo purine synthesis inhibitorstoward the HL-60 promyelocytic leukemia and the WI-L2 lym-

phoblast human cell lines.

MATERIALS AND METHODS

Subjects and Patients. Blood samples were obtained from 5 groupsof subjects and patients for Hyp measurement: (a) normal laboratorypersonnel; (b) patients with acute lymphocytic leukemia or acute nonlym-

phocytic leukemia, either untreated or in relapse; (c) patients with advanced solid tumors of many types; (d) patients with malignant pleuralor peritoneal effusions due to solid tumor involvement; and (e) patientswith acute leukemia undergoing initial induction chemotherapy for eitheruntreated or relapsed disease. No restrictions were placed on diet oractivity in any group of subjects or patients, and samples were drawn atrandom times of day. For all groups except the normal subjects andacute leukemic subjects receiving induction chemotherapy, blood samples were obtained at least 3 weeks following any prior therapy and at atime when no toxicity attributable to prior therapy was evident.

High-Pressure Liquid Chromatography. A detailed procedure for

simultaneous measurement of plasma Hyp, uric acid, HPP, and oxipurinolwas developed in this laboratory and has been published elsewhere (43).Delay in separation of plasma from the formed elements of blood hasbeen shown to increase plasma Hyp. Therefore, samples were collectedin prechilled heparinized tubes, and plasma was separated immediatelyby centrifugation, precipitated with 0.1 volume of 4.4 N HCIO<, andneutralized with Alamine/Freon, as described by Khym (21). A high-

pressure liquid Chromatographie system (Waters Associates, Milford,MA) with a reverse-phase C,fi-^Bondapak column was used in this study.

Peaks were identified by their retention times and their absorbance ratiosat 254 and 280 nm. An aliquot of 20-/il sample was analyzed isocratically

'The abbreviations used are: Hyp, hypoxanthine; DON, 6-diazo-5-oxonorteu-cine; HPP, 4-hydroxy-3,4-pyrazotopyrimidine (allopurinol); HGPRT, hypoxanthine-guanine phosphoribosyltransferase; 6-MP, 6-mercaptopurine; MMPR, 6-methyl-mercaptopurine riboside; 6-TG. 6-thioguanine.

3144 CANCER RESEARCH VOL. 44

Research. on February 27, 2021. © 1984 American Association for Cancercancerres.aacrjournals.org Downloaded from

http://cancerres.aacrjournals.org/

Plasma Hyp and Antimetabolite Activity

using phosphate eluent (50 HIM KH2PO4, pH 4.60). The limit of detectionfor all compounds of interest was 0.1 MM.

Cell Culture and Growth Studies. A human B-lymphoblast (WI-L2)and a human promyelocytic leukemia (HL-60) cell line were used todetermine the growth-inhibitory effect of various concentrations of anti-

metabolites and the blockade of this effect by Hyp in vitro. These cellswere grown in RPMI 1640 medium (Cell Culture Facility, University ofCalifornia, San Diego, La Jolla, CA) supplemented with 10% fetal calfserum (Irvine Scientific, Irvine, CA), 1% glutamine, and 1% antibiotics-

antimycotics mixture (Grand Island Biological Co., Grand Island, NY).Growth assays were performed in LJnbro multiwell tissue culture plates(Flow Laboratories, Inc., McLean, VA). The tog-phase cells were washed

with RPM11640 medium to remove any Hyp in the growth medium. Hypand antimetabolites (6-MP, 6-TG, MMPR, and DON) were prepared in

the same medium, except that fetal calf serum was replaced with bovineserum albumin (5 mg/ml) or 10% charcoal-treated fetal calf serum. Cellswere cultured at 105/ml in triplicate with 1 to 100 MMHyp and 1, 4, and10 MM of each antimetabolite at 37Â° for 3 days under 4% CO2. The

number of cells was counted electronically using a Model ZB CoulterCounter, and the percentage of control growth in antimetabolite-treatedcultures was calculated by comparison with cells growing in Hyp-freeand antimetabolite-free medium.

RESULTS

Means and Ranges of Plasma Hyp. Previous reports haveindicated that, in acute leukemia, both the production and plasmaconcentration of uric acid were increased (29). Similar changesin plasma Hyp, which is the precursor of uric acid, have not beenreported. A comparison of plasma Hyp concentrations in randomly collected blood samples from 16 normal subjects, 10untreated acute leukemic subjects, and 14 untreated solid tumorpatients is summarized in Chart 1. The geometric mean plasmaHyp concentration was 0.56 MM(range, 0.2 to 1.9 MM)in normalsubjects, 0.68 MM (range, 0.1 to 1.1 MM) in acute leukemicsubjects, and 0.89 MM (range, 0.3 to 2.6 MM) in solid tumorpatients, and the differences between these groups were notsignificant. Included in Chart 1 are measurements made onmalignant ascites or pleural effusions from solid tumor patients.The geometric mean effusion Hyp concentration was 0.4 MM(range, 0.1 to 1.0 MM),about one-half of that in plasma of solid

tumor patients.Mean plasma uric acid concentration in these acute leukemic

4xlO~~

g5

IxlO,-6

o.

IxlO,-7

ft

T

NORMAL LEUKEMIC SOLID MALIGNANTSUBJECTS PATIENTS TUMOR EFFUSIONS

PATIENTS

Chart 1. Scattergram of plasma Hyp concentrations in normal subjects (n =16), acute leukemic subjects (n - 10), and solid tumor patients (n = 14). Hypconcentrations in malignant effusions (n = 9) are also included. Bars, geometric

means.

IO'6

ia,-70600 1200 1800 2400

TIME OF DAY

Chart 2. Diurnal variations of plasma Hyp concentration in 4 untreated solidtumor patients. No restrictions were placed on the patients' diets or activities.

patients was 410 MM(range, 110 to 610 MM)(data not shown),which is 1.5-fold greater than the mean of 276 MM(range, 210

to 340 MM)found in the normal subjects; plasma uric acid in thesolid tumor patients was not significantly different from that innormal subjects (mean, 255 MM;range, 150 to 440 MM).

Diurnal Variation of Plasma Hyp. Four solid tumor patientswere studied for diurnal variation of plasma Hyp. None of thesepatients was receiving chemotherapy or HPP at the time ofsampling. Blood was collected at intervals of 4 hr for a period of24 hr. No restriction was placed on food intake or physicalactivity during the sampling time. Chart 2 shows that, in each ofthese 4 patients, plasma Hyp concentration remained withinrelatively narrow limits over 24 hr compared to the wider rangefound between patients. The average variation in plasma Hypconcentration over 24 hr was 1.9-fold, and the range was 1.4-to 2.3-fold. The variation could not be related to meals, activity,

or sleep.Effects of HPP and Chemotherapy on Plasma Hyp. The

effect of a single dose of 300 mg of HPP p.o. on plasma Hypconcentration and the pharmacokinetics of HPP were examinedin the same 4 patients in whom diurnal variation was also studied.Chart 3 shows the plasma concentrations of Hyp, HPP, andoxypurinol, the major metabolite of HPP, during the 8 hr followingHPP ingestion. In 3 of 4 patients, plasma HPP peaked at 2 hrand then fell rapidly, with an elimination half-life of 55 to 65 min.

In the fourth patient, gastrointestinal absorption of HPP wasdelayed. Maximum plasma oxypurinol was reached about 2 hrafter HPP ingestion, and it averaged 35 MM(range, 21 to 60 MM).This level remained steady for each patient over the next 6 hr.Other investigators have also reported a long half-life of 14 to

20 hr for oxypurinol (3, 23). Plasma Hyp concentration increasedto a mean of 1.35 MM(range, 0.55 to 2.50 MM)during the 6-hrperiod following HPP ingestion. There was a 1.5-fold increase

over the mean Hyp concentration during the preceding 24 hrbefore the administration of HPP.

Plasma Hyp was measured before and then again 48 hr afterthe initiation of treatment with HPP, daunorubicin, and 1-ÃŸ-o-

arabinofuranosylcytosine on 6 courses in 5 patients with acuteleukemia (Chart 4). In addition, individual nonpaired measurements were made either before or 48 hr after initiation of treatment on 11 courses given to 6 other acute leukemic subjects.Whereas a single dose of HPP alone did not substantially increase plasma Hyp, the combination of HPP plus the initiation ofchemotherapy did. Considering only the 6 paired observations,the plasma Hyp concentration increased by a mean of 8.6-fold

(p < 0.01 ; f test for paired observations). When all measurements

JULY 1984 3145



IV.E. Wung and S. B. Howe//

10-4rOXIPURINOL

V* \

01 2345678

HYPOXANTHINE

HOURS

Chart 3. Plasma HPP ( ), oxypurinol ( ), and Hyp concentration timecurves obtained in the same patients as in Chart 2 following the p.o. ingestion of a300-mg dose of HPP.

were included, the plasma Hyp concentration was 7-fold higher

at 24 hr, with a mean of 4.6 pM (range 0.9 to 12.0 /UM).A linearrelationship was observed between plasma Hyp and oxypurinolconcentrations measured in the same samples (r = 0.71 ; p <

0.01).Hyp Concentration in Bone Marrow. Hyp concentration in

bone marrow was compared with venous blood plasma in 9 solidtumor patients, and the results are shown in Chart 5. In allpatients, the marrow plasma Hyp concentrations were consistently greater than those of simultaneously drawn venous plasma.The mean difference between marrow plasma and venousplasma was 5.7 pu (p < 0.01 ; f test for paired observations).The possibility that this difference was due to hemolysis inmarrow specimens was excluded by the finding that there wasno increase in Hyp concentration in marrow plasma when RBCwere added and subjected to mechanical destruction.

Effect of Hyp on Antimetabolite Activity. Both WI-L2 andHL-60 cells are normally grown in medium containing 10% fetal

calf serum, which itself contributes large amounts of Hyp to theculture. In order to avoid this problem, WI-L2 cells were grownin purine-free RPMI 1640 medium containing bovine serum al

bumin (5 mg/ml), transferrin (35 pg/m\), insulin (5 pg/m\), 2.5 nwselenium, and 20 pM ethanolamine. HL-60 cells were grown inRPM11640 medium containing charcoal-stripped fetal calf serumat a final concentration of 10%. The fetal calf serum containedless than 1 pM Hyp after treatment with charcoal (0.5 g per 10ml of serum) as determined by high-pressure liquid chromatog-

raphy. Both media were supplemented with known concentra

tions of Hyp in experimental cultures.Chart 6 shows the effect of initial Hyp concentration between

1 and 100 ^M on the proliferation of WI-L2 and HL-60 cells inthe presence of 6-MP, 6-TG, MMPR, and DON. Antimetabolite

concentrations from 1 to 10 ^M were chosen as representativeof the concentrations of these drugs that can be achievedclinically (25, 27). Increasing the Hyp concentration 10-fold from

1 to 10 pM resulted in increased growth at all 3 concentrationsof all of the drugs; however, the magnitude of this effect wasnot large. A further 10-fold increase in initial Hyp concentration

increased growth substantially, even in cultures treated with thehighest antimetabolite concentrations, to 50% or more of thegrowth occurring in non-drug-treated control cultures for both

cell lines. Thus, Hyp antagonized the antiproliferative effect of all4 drugs, but a 50% reduction in antimetabolite effect requiredHyp concentration above those observed even in patients withacute leukemia receiving HPP and induction therapy who had amarked increase in Hyp production.

It is important to emphasize that the data depicted in Chart 6

I0~5r

O

gI-zLuO

S 10-6LU OZ J

Xl-

lo_

IO',-7

PRIOR TOTREATMENT

48HR AFTERSTART OF CHEMOTHERAPY AND HPP

Chart 4. Plasma Hyp concentrations in acute leukemic patients before and 48hr after the administration of HPP and combined chemotherapy consisting ofdoxorubicin and 1-/3-D-arabinofuranosylcytosine. HPP was given in daily doses of

300 mg p.o. during chemotherapy. Measurements made on the same patients areconnected by a solid line; bars, geometric means.

1-5

is1Â°â€¢*-/ *

10,-6

PLASMA BONE MARROW

Chart 5. Comparison between venous plasma and bone marrow plasma Hypconcentrations in 9 solid tumor patients. Venous blood was collected at the momentof bone marrow aspiration; plasma was recovered from the 2-ml marrow aspirateby centrifugation. Measurements made on the same patients are connected by asolid line.




Plasma Hyp and Antimetabolite Activity

WI-L2

DON

HL-60

DONDISCUSSION

IO"6 IO"5 IO"4 IO"6 IO"5 IO"4

HYPOXANTHINE CONCENTRATIONmol/liter

Chart 6. Effects of Hyp on the degree of growth inhibition produced by purineantimetaboliteson WI-L2 and HL-60cells during a 3-day culture. The antirnetaboliteconcentrations were irr" (A), 4 x 10"Â»(â€¢),and KT5 (x) M.

Table 1Hyp concentration in cultures of WI-L2and HL-60 cells

Finalconcentration(pufConcentration0-M)1.0

10100Medium

alone1.0

10.598Medium

plusWI-L2ceUs"<0.1

<0.118Medium

plusHL-60cells'<0.1

1.169

8 After 3 days of culture.0 Finalcell density was 1.5 x KP/ml.c Final cell density was 0.9 x to'/mi.

are based on the initial concentration of Hyp in the culture. Table1 indicates that, while the concentration of Hyp remained stablein medium to which no cells were added, both WI-L2 and HL-60cells consumed much of the Hyp present during the 3-day period

of growth. Thus, the average concentration of Hyp was significantly lower than was the initial concentration, and this wasmore marked in cultures with the lower starting Hyp concentrations. The impact of considering average rather than initial Hypconcentrations on the curves depicted in Chart 6 would be toflatten their slopes somewhat but, on the other hand, it indicatesthat average Hyp concentrations even lower than 10 fiM werecapable of affecting purine antirnetabolite activity.

Little information is available on the concentration of Hyp invarious human body fluids under physiological conditions, andthe accuracy of concentrations reported previously has nowbeen called into question by the finding that special handling ofspecimens is required to avoid leakage of Hyp from RBC andplatelets (43). The release of Hyp during clotting probably accounts for the fact that the mean plasma Hyp values reportedhere are 10-fold less than are those reported for human serum

by other investigators (20, 33, 34).Although there was a wide variation in plasma Hyp concentra

tions measured at random times in individual subjects, a comparison of mean values in normal subjects, solid tumor patients,and acute leukemics revealed no significant differences amongthese groups. In addition, in individual subjects, plasma Hypconcentration varied by an average of only 1.9-fold during a 24-hr period. These observations suggest that plasma Hyp may beregulated by metabolic controls which must affect either theentrance of Hyp into the plasma or its clearance or both. Ourmeasurements provide some information on how changes in theproduction or clearance of Hyp influence plasma Hyp concentration. The finding of similar mean plasma Hyp concentrations inleukemic and normal subjects suggests that the increased production in leukemia (30) does not exceed the clearance capacityof xanthine oxidase or urinary excretion (8, 9, 14, 30). Undernormal circumstances, the clearance of Hyp via xanthine oxidaseis less significant than is that by other mechanisms, since inhibition of xanthine oxidase by HPP caused only a 1.5-fold increase

in Hyp concentration. However, when HPP was combined withincreased Hyp production resulting from initiation of chemotherapy in patients with acute leukemia, there was a 7-fold increase

in plasma Hyp concentration. Thus, under conditions of increased catabolic flux of purines, the activity of xanthine oxidasedoes have a very significant effect on plasma Hyp, and this wasreflected by the good correlation between plasma Hyp andoxyourinol, which is the active metabolite of HPP present inhighest concentration in plasma after administration of HPP (14,16).

The finding of a mean 4.0-fold higher concentration of Hyp in

bone marrow than in venous plasma is of interest for severalreasons. First, it suggests that, in contrast to liver, which clearslarge amounts of Hyp from plasma on a single pass (32), bonemarrow is a net producer of Hyp. A number of investigators haveconcluded that bone marrow cells and gastrointestinal mucosacells have a very limited capacity to carry out de novo purinesynthesis, and they depend on preformed purine in plasma forsynthesis of purine nucleotides via the salvage pathway (1, 24,28, 32, 39, 40). However, Hyp itself is an important regulator ofpurine synthesis (17-19, 36, 38), and concentrations as low as

1 /im are sufficient to decrease de novo synthesis in fibroblasts(38) and marrow (22). All of the previous studies on de novopurine synthesis in marrow cells were performed under conditions in which the concentration of Hyp in the cell environmentwas probably quite high (1,24,28,36,39,40). Thus, rather thanreflecting an inability of marrow cells to synthesize purine denovo, the limited incorporation of [14C]formate used to measure

the activity of this pathway may be due to the inhibitory actionof the high local concentration of Hyp. If the rapid cell proliferationin the gut is also accompanied by high local concentrations ofHyp, then the hypothesis that gut cells cannot produce purines

JULY 1984 3147



W.E. WungandS. B. Howell

via thÃ©de novo route may also be incorrect (28).Several investigators have reported previously that Hyp can

reverse the cytotoxicity of MMPR (2, 37). Our finding that Hypreduces the activity of 6-MP, 6-TG, MMPR, and DON indicatesthat the effect is not merely due to competition for HGPRT orfor transport into the cell, since MMPR is phosphorylated byadenosine kinase rather than HGPRT (5, 35) and since DONdoes not require HGPRT for activation. The results of this studyshow that the concentrations of plasma Hyp in patients receivingHPP and chemotherapy are elevated into a range which is justbelow that which begins to interfere with the cytotoxic activityof clinically relevant concentrations of purine antimetabolitesagainst human leukemiacells in vitro. It is important to emphasizethat the curves in Chart 6 were constructed using the concentrations of Hyp present at the beginning of culture. Hyp concentration decreased rapidly as cells grew and, at the end of the 3-dayculture period, there was practically no Hyp left in the mediumoriginally containing 10 MMHyp, and there was a 30 to 60%reduction of Hyp in the cultures originally containing a 100 J/Mconcentration. Thus, no matter what the mechanism of the Hypeffect, the degrees of modulation depicted in Chart 6 wereactually achieved with average Hyp concentrations that wereconsiderably below the initial concentrations indicated on theabscissa. Although the growth conditions of leukemia cells Invitro are quite different than those in vivo, this raises the possibility that the 7-fold increase in plasma Hyp that accompaniedinitiation of chemotherapy in acute leukemic patients receivingHPP may be sufficient to reduce the effectiveness of the anti-purine antimetabolites during induction therapy. The increase inHyp also provides a potential explanation of the observation inrabbits that, although HPP can block the catabolism of 6-MP(11-13) and increase the area under the plasma concentrationtimes time curve (41), it does not increase the toxicity of 6-MP(42). Additional studies are required to evaluate completely therole of Hyp and HPP in modulating the activity 6-MP and theother antipurine antimetabolites in humans (6) and to validatethe extrapolation that we have made between in vitro resultsand in vivo observations.

REFERENCES

1. Abrams, R., and Goldinger. J. M. Utilization of purines for nucleic acid synthesisin bone marrow slices. Biochim. Biophys. Acta, 30: 261-268, 1951.

2. Bennet, L. L, Jr, and Adamson, D. J. Reversal of the growth-inhibitory effectsof 6-methylmercaptopurine ribonucleoside. Biochem. Pharmacol.. 79: 2171-2175. 1970.

3. Brown, M., and Bye, A. The determination of allopurinol and oxipurinol inhuman plasma and urine. J. Chromatogr., 743: 195-293,1977.

4. Burchenol. J. H., Murphy, M. L., Ellison, R. R., Sykes, N. P., Tan, T. C., Leone,L. A., Kamofsky, D. A., Graver, L. F., Dargeon, H. W., and Rhoads, C. P.Clinical evaluation of antimetabolite 6-mercaptopurine in the treatment ofleukemia and allied diseases. Blood, 8: 965-999,1953.

5. Caldwell, I. C., Henderson, J. F., and Paterson, A. R. P. The enzymicformationof 6-(methylmercapto)purine ribonucleoside 5'-phosphate. Can. J. Biochem.,

44:229-245,1966.6. Coffey, J. J., White, C. A., Lesk, A. B., Rogers, W. I., and Serpick, A. A. Effect

of allopurinol on the pharmacokinetics of 6-mercaptopurine (NSC-755) incancer patients. Cancer Res., 32. 1283-1289,1972.

7. Davison, T. D.. and Winger, T. S. Purine nucleotide pyrophosphorylase in 6-mercaptopurine sensitive and resistant human leukemias. Cancer Res., 24:261-267, 1964.

8. DeConti, R. C., and Calabresi, P. Use of allopurinol for prevention and controlof hyperuricemia in patients with neoplastic disease. N. Engl. J. Med., 274:481-486, 1966.

9. Edwards, N. L., Recker, D. P., and Fox, I. H. Hypoxanthine salvage in man.Its importance in urate overproduction in the Lesch-Nyhan syndrome. Adv.Exp. Med. Biol., 722A 301-305, 1980.

10. Elton, G. B. Biochemistry and pharmacology of purine analogues. Fed. Proc.,26: 893-903,1967.

11. Elton, G. B., Callahan, S. W., Hitchings, G. H., Rundtes, R. W., Laszlo, J.Experimental, clinical and metabolic studies of thiopurines. Cancer Chemother.Rep., 76: 197-202.1962.

12. Elion, G. B., Callahan, S. W., Nathan, H., Bieber, S., Rundtes, R. W., andHitching, G. H. Potentiation by inhibition of drug degradation: 6-substitutedpurines and xanthine oxidase. Biochem. Pharrnacol., 72: 85-93,1963.

13. Elion, G. B., Callahan, S. W., Rundles, R. W., and Hitchings, G. H. Relationshipbetween metabolic fates and antitumor activities of thiopurines. Cancer Res.,1207-1217,1963.

14. Elton, G. B., Kovensky, Z., Hitchings, G. H., Metz, E., and Rundles. R. W.Metabolism studies of allopurinol, an inhibitor of xanthine oxidase. Biochem.Pharmacol., 75: 863-880,1966.

15. Gee, T. S., Yu, K. P., and Clarkson, B. D. Treatment of adult leukemia witharabinosyl cytoxine and thtoguanine. Cancer (Phila.), 23: 1019-1032,1969.

16. Hande, K., Reed, E., and Chabner, B. Allopurinol kinetics. Clin. Pharmacol.Ther., 23:598-605. 1978.

17. Henderson, F. J. Feedback inhibition of purine biosynthesis in ascites tumorcells by purine analogues. Biochem. Pharmacol., 72: 551-556,1963.

18. Hershfield, M. S., and Seegmiller, J. E. Regulation of tie novo purine biosynthesis in human lymphoWasts. J. Biol. Chem., 25?. 7384-7354, 1976.

19. Hershfield, M. S., and Seegmiler, J. E. Regulation of de novo purine synthesisin human lymphoWasts. J. Biol. Chem., 252: 6002-6010,1977.

20. Joiley. R. L., and Scott, C. D. Preliminary results from high-resolution analysisof ultraviolet-absorbing and carbohydrate constituents in several pathologicalbody fluids. Clin. Chem., 76: 687-696,1970.

21. Khym, J. X. Analytical system for rapid separation of tissue nucleotides at lowpressure on conventional anton exchanger. Clin. Chem., 27:1245-1252,1975.

22. King, M. E., Honeysett, J. M., and Howell, S. B. Regulation of de novo purinesynthesis in human bone marrow mononuclear cells by hypoxanthine. J. Clin.Invest., 72: 965-970,1983.

23. Kramer, W. G., and Feldman, S. High-performance liquid Chromatographieassay for allopurinol and oxipurinol in human plasma. J. Chromatogr., 762:92-97,1979.

24. Lajtha, L. G., and Vane, J. R. Dependence of bone marrow on the liver forpurine supply. Nature (Lond.), 182: 191-192,1958.

25. LePage, G. A., and Whitecar, J. P., Jr. Pharmacology of 6-thioguanine in man.Cancer Res., 37:1627-1631,1971.

26. Ungston, R. B., Venditi, J. M.. Cooney, D. A., and Carter, S. K. Glutamineantagonist in chemotherapy. Adv. Pharmacol. Chemother., 8: 57-120,1970.

27. Loo, T. L., Luce, J. K., Sullivan, M. P., and Frei, E., III. Clinical pharmacologicalobservation on 6-mercaptopurine and 6-methylmercaptopurine riboside. Clin.Pharmacol. Ther., 794: 180-194, 1967.

28. Mackinnon, A. M., and Deller, D. T. Purine nucleotide biosynthesis in gastrointestinal mucosa. Biochim. Biophys. Acta, 379:1-4, 1973.

29. Martin, W. E., Crichton, T. K., Yag, R. C., and Evans, A. E. The metabolism ofthioinosmic acid by 6-mercaptopurine sensitive and resistant leukemic leukocytes. Proc. Soc. Exp. Btol. Med., 740: 423-428, 1972.

30. Merrill, D., and Jackson, H. The renal complication of leukemia. N. Engl. J.Med., 228: 271 -276, 1943.

31. Moore, E. C., and LePage, G. A. The metabolism of 6-thtoguanine in normaland neoplastic tissues. Cancer Res., 78: 1075-1083,1958.

32. Pritchard, J. B., O'Connor, N., Oliver, J. M., and Berline, R. D. Uptake and

supply of purine compounds by the liver. Am. J. Phystol., 229:967-972,1975.33. Putterman, G. J., Shaikh, B., and Hallmark, M. R. Simultaneous analysis of

substrates, products, and inhibitors of xanthine oxidase by high-pressure liquidchromatography and gas chromatography. Anal. Chem., 98:18-26,1979.

34. Saugstad, O. D. Hypoxanthine as a measurement of hypoxia. Pediatr. Res.,9: 158-161,1975.

35. Sehnet*, H. P., Hill, P. L., and Bennett, L. L., Jr. Purification and properties ofadenosine kinase from human tumor cells of type H. Ep. No. 2. J. Bid. Chem.,242: 1997-2004,1967.

36. Scott, J. L. Human leukocyte metabolism in vitro. I. Incorporation of [8-C14]

adenine into the nucleic acids of leukemic leukocytes. J. Clin. Invest., 47: 67-79,1962.

37. Shantz, G. D., Fontenelle, L. J., and Henderson, J. F. Inhibition of purinebiosynthesis de novo and of Ehrlich ascites tumor cell growth by methylmer-captopurine ribonucleoside. Biochem. Pharmacol., 27:1203-1206,1971.

38. Thompson, L. F., Willis, R. C., Stoop, J. M., and Seegmiller, J. E. Purinemetabolism in cultured human fibroblasta derived from patients deficient inhypoxanthine phosphoribosyltransferase, purine nucleoside phosphorylase, oradenosine deaminase. Proc. Nati. Acad. Sci. USA, 75: 3722-3726,1978.

39. Trotter, J. Incorporation of isotopie formate into the thymine of bone marrowdeoxyribonudeic acid in vitro. J. Am. Chem. Soc., 76: 2196-2197,1954.

40. Trotter, J., and Best, A. The metabolism of [14C]formate by rabbit bone marrowin vitro. Arch. Biochem. Biophys., 54: 318-329, 1955.

41. Tteriikkis, L., Day, J. L., Brown, D. A., and Schroeder, E. C. Effect of allopurinolon the pharmacokinetics of 6-mercaptopurine in rabbits. Cancer Res., 43:1675-1679,1983.

42. Walker, R. I., Horvath, W. L., Rule, W. S., and Palmer, J. G. The failure ofallopurinol to enhance 6-mercaptopurine toxicity in rabbits. Cancer Res., 33:755-758,1973.

43. Wung, W. E., and Howell, S. B. Simultaneous liquid chromatography of 5-fluorouracil, undine, hypoxanthine, xanthine, uric acid, allopurinol. and oxypu-rinol in plasma. Clin. Chem., 26: 1704-1708, 1980.




1984;44:3144-3148. Cancer Res Wally E. Wung and Stephen B. Howell with Solid Tumors and LeukemiaHypoxanthine Concentrations in Normal Subjects and Patients

Updated version

http://cancerres.aacrjournals.org/content/44/7/3144

Access the most recent version of this article at:

E-mail alerts related to this article or journal.Sign up to receive free email-alerts

Subscriptions

Reprints and

[email protected] at

To order reprints of this article or to subscribe to the journal, contact the AACR Publications

Permissions

Rightslink site. Click on "Request Permissions" which will take you to the Copyright Clearance Center's (CCC)

.http://cancerres.aacrjournals.org/content/44/7/3144To request permission to re-use all or part of this article, use this link



http://cancerres.aacrjournals.org/cgi/alerts

mailto:[email protected]



hypoxanthine concentrations in normal subjects and ... · antimycotics mixture (grand island...

Documents