Leukemia (2001) 15, 1081–1088
 2001 Nature Publishing Group All rights reserved 0887-6924/01 $15.00
www.nature.com/leu
The association of the TEL-AML1 chromosomal translocation with the accumulation
of methotrexate polyglutamates in lymphoblasts and with ploidy in childhood
B-progenitor cell acute lymphoblastic leukemia: a Pediatric Oncology Group study
VM Whitehead1,2, C Payment1, L Cooley3, SJ Lauer4, DH Mahoney5, JJ Shuster6, M-J Vuchich1, ML Bernstein7, AT Look8,
DJ Pullen9 and B Camitta10
1
The Penny Cole Hematology Research Laboratory, McGill University – Montreal Children’s Hospital Research Institute, Montreal, Quebec;
Department of Pediatrics, McGill University, Montreal, PQ, Canada; 3Department of Medical Genetics, Baylor College of Medicine,
Houston, TX; 4Department of Pediatrics, Emory University School of Medicine, Atlanta, GA; 5Department of Pediatrics, Baylor College of
Medicine, Houston, TX; 6Department of Statistics and the Pediatric Oncology Group Statistical Office, University of Florida, Gainesville, FL,
USA; 7Department of Pediatrics, Hôpital Sainte-Justine, Montreal, QC, Canada; 8Department of Pediatric Oncology, Dana-Farber Cancer
Institute, Boston, MA; 9Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS; and 10Department of Pediatrics,
Midwest Children’s Cancer Center and Children’s Hospital of Wisconsin, Medical College of Wisconsin, Milwaukee, WI, USA
2
Lymphoblasts from children with B-progenitor cell acute lymphoblastic leukemia (BpALL) with chromosomal hyperdiploidy
and with translocations affecting chromosome 12p11–13,
accumulate high and low levels of methotrexate polyglutamates (MTXPGs), respectively. Recently a cryptic translocation,
t(12;21) (p13;q22), has been demonstrated by molecular and
fluorescence in situ hybridization techniques in this disease.
The chimeric TEL-AML1 transcript, which has been associated
with this translocation, can be detected in up to 25% of children
with BpALL. We detected the TEL-AML1 and/or the AML1-TEL
transcript in 30 (33%) of 91 patients studied. Levels of lymphoblast MTXPGs were lower in those with than in those without the
TEL-AML1 translocation (P = 0.004). Hyperdiploidy was rare in
lymphoblasts with the TEL-AML1 translocation (P = 0.047).
Both ploidy (P = 0.0015) and TEL-AML1 status (P = 0.0043) were
independently and significantly correlated with the log of the
lymphoblast MTXPG level. However, the presence of TEL-AML1
or of hyperdiploidy accounted for only 22% of the variation of
this value. Our results imply that each of 1.16 ⭓ DI and the
presence of the TEL-AML1 translocation confers a 50%
decrease in lymphoblast MTXPG level. When planning
reduction of therapy for either of the two excellent outcome
categories of hyperdiploid or TEL-AML1 BpALL, one should
consider the difference between these two subgroups in the
ability of lymphoblasts to accumulate MTXPGs. Leukemia
(2001) 15, 1081–1088.
Keywords: methotrexate; polyglutamates; translocation; TELAML1; hyperdiploid; lymphoblast
Introduction
Characterization of prognostic features has facilitated the
development of treatments tailored for specific subgroups of
children with B-progenitor cell acute lymphoblastic leukemia
(BpALL).1,2 In addition to age, sex and white cell count at diagnosis, certain cytogenetic abnormalities are of prognostic significance. The Philadelphia chromosome (t(9;22)(q34;q11))
confers an especially ominous outlook.3,4 In contrast, hyperdiploidy (DI ⬎ 1.16) carries an excellent prognosis.5,6 Among
patients with hyperdiploidy, those with trisomies of both chromosomes 4 and 10 have the highest cure rate.7 For the latter
patients, the aim of future therapeutic modifications will be to
reduce short- and long-term drug toxicities, while maintaining
treatment efficacy. Knowledge of the contribution of different
Correspondence: VM Whitehead, Hematology Service, Montreal
Children’s Hospital, 2300 Tupper St, Montreal, Quebec, H3H 1P3,
Canada; Fax: 514-934-4301
Received 1 December 2000; accepted 20 March 2001
agents to the cure of such patients can be important in
choosing how to reduce therapy.8,9
Large segment or cytogenetically evident translocations
affecting chromosome 12p occur infrequently in childhood
BpALL.10 Recently, a cryptic translocation, t(12;21)(p13;q22),
was detected by fluorescence in situ hybridization (FISH).11–14
Molecular studies revealed that this translocation joined
together the helix–loop–helix region of the TEL gene located
at chromosome 12p13 to almost the entire AML1 gene,
located at chromosome 21q22.15,16 TEL gene rearrangements
and the TEL-AML1 transcript have been demonstrated in up
to 25% of children with BpALL.17–19 Loss of the remaining
normal TEL allele occurs in many of these patients.13,20 The
presence of TEL-AML1 appears to be associated with an excellent prognosis in children treated with either multidrug or with
antimetabolite-based regimens.17,21–24
Methotrexate (MTX) is an important component of all such
treatments, both for central nervous system pre-symptomatic
therapy and for continuation therapy. Given in high doses by
infusion, followed by leucovorin rescue, it is the major
component of the intensification phase of treatment in
Pediatric Oncology Group (POG) therapeutic protocols.6–9
We and others have shown that lymphoblasts from children
with BpALL metabolize MTX to its most active forms, longchain MTXPGs, more vigorously than blast cells from other
leukemias.25–28 They form longer-chain MTXPGs, with five
rather than three total glutamates and accumulate much
higher levels of these long-chain MTXPGs. Accumulation of
high levels of MTXPGs in lymphoblasts in vitro was associated
with a higher cure rate29 and in vivo with more rapid disappearance of leukemic blasts.30 In particular, hyperdiploid lymphoblasts accumulate higher levels of long-chain MTXPGs
than do non-hyperdiploid lymphoblasts.31–33 These findings
suggest that increased accumulation of MTX might explain in
part the good prognosis of childhood BpALL in general and
the excellent prognosis of those with hyperdiploid BpALL in
particular.
Recently, analysis of a population of patients studied at
diagnosis revealed that all 13 patients with translocations
involving chromosome 12p failed to accumulate high levels
of MTXPGs.34 Despite this finding, none of these patients had
failed therapy, suggesting that they had a good prognosis. We
now report that lymphoblasts with the very specific t(12;21)
that results in the TEL-AML1 fusion gene also fail to accumulate high levels of MTXPGs.
Methotrexate polyglutamates and the Tel-AML1 translocation
VM Whitehead et al
1082
Table 1
The sex, age and white cell counts at diagnosis and other features of 91 children who did and did not have the TEL-AML1 translocation, compared to those in 6786 POG patients with BpALL (see Methods)
TEL-AML1
Present
Absent
Total
POG patients
All patients
Boys
Girls
30
10
20
61
37
24
91
52%
48%
6786
55%
45%
Age (years)
Median
Quartiles
3.9
3.4, 5.0
5.9
2.8, 10.0
4.6
3.2, 7.6
4.6
3.0, 8.0
White cell count (× 109/l)
Median
Quartiles
16.2
4.9, 49.0
10.2
5.2, 31.7
13.0
5.0, 37.0
8.0
4.0, 25.0
19%
0/61
2/61
2/61
24%
42/4089
129/4089
265/4089
DI ⬎ 1.16
T(4;11)(q21;q23)
T(9;22)(q34;q11)
T(1;19)(q23;p13)
Thirty of the TEL-AML1 study patients and 2702 of the POG patients had uninformative cytogenetics.
Methods
Between April 1989 and November 1994 the accumulation
of MTXPGs in bone marrow lymphoblasts at diagnosis was
successfully measured in vitro in a total of 138 children with
BpALL, older than 1 year of age, who were enrolled on POG
8901. An initial study reported on 48 of these patients.31 Two
subsequent studies analyzed 95 of these patients33,34 who had
had satisfactory cytogenetic analysis in addition to measurement of the lymphoblast MTXPG level. This group included
29 patients from the earlier study.31 In the present study, bone
marrow cell pellets were requested from virtually all (96%) of
these 138 patients from the POG ALL Cell Bank at St Jude’s
Children’s Research Hospital.
Frozen pellets were received from 100 (72%) of these
patients and the presence or absence of the TEL-AML1 translocation determined in 91 (66%) of them. Within this group
were 57 (60%) of the 95 patients reported previously including 23 (58%) of the 40 patients with ⬎50 chromosomes.33,34
The TEL-AML1 status was determined for 30 (63%) of the 48
patients reported earlier.31
Characteristics of these patients are tabulated in Table 1 and
compared with those seen in 6786 POG patients with BpALL,
less than 1 year old, who were used in the analysis of AlinC
14, 15 and 16 studies. Details of the techniques of incubation
of lymphoblasts from these patients with 1.0 ␮M 3H-MTX for
24 h, of cell washing and of extraction and quantitation of
MTX and MTXPGs by HPLC have been described previously.31,33 A lymphoblast MTXPG level ⬎500 pmol/109 cells
has been defined as high, based on biological advantage.29,30
BpALL was diagnosed by standard POG criteria.35 Karyotype analysis was carried out in the POG Cytogenetics Reference Laboratory at the University of Alabama at Birmingham
as well as in the Baylor Cancer Cytogenetics Laboratory, Houston, the Cytogenetics Laboratory, the University of Texas
Southwestern Medical Center at Dallas and the Cytogenetics
Laboratory, Medical College of Wisconsin, Milwaukee. The
DNA index (DI) was determined at St Jude Children’s
Research Hospital in Memphis.36 In this study, DI ⬎ 1.16 was
used to assign hyperdiploidy rather than the number of chromosomes, because it was available on virtually every patient,
Leukemia
whereas karyotyping of chromosomes was successful in only
61 (67%) of them.
Measurement of TEL-AML1 and AML1-TEL transcripts
RNA was harvested from cell pellets with a phenol–chloroform extraction using a commercial kit (trizol; Gibco, Burlington, Ontario, Canada), and was successfully obtained in
91 samples. 2.5 ␮g of the RNA was subjected to reverse transcriptase polymerase chain reaction (RT-PCR), using random
hexamers. The primers used to amplify the TEL-AML1 and the
AML1-TEL transcripts as well as regions of the TEL and AML1
genes were previously published.16,17 PCR for TEL-AML1 and
for AML1-TEL was performed for 40 cycles consisting of 94°C
for 1 min, 58°C for 30 s and 72°C for 1 min. Sequencing of
PCR products was by the dideoxy method, using a standard
kit (Amersham, Oakville, Ontario, Canada), following the
directions provided by the manufacturer.
The commonest breakpoint in the AML1 gene is in intron
1. However, the breakpoint is in intron 2 in a minority of
patients, yielding a smaller TEL-AML1 transcript lacking the
39 bp exon 2 and a correspondingly larger AML1-TEL
transcript.37 The larger and smaller fragments due to these
alternate breakpoints are shown in Figure 1.
For TEL-AML1 detection, the 509 (or 470) bp product was
digested with the restriction endonuclease Ava1 to yield
unique 356 and 153 (or 114) bp fragments. For the AML1-TEL
product, the Hha1 restriction endonuclease cut the 343 (or
382) bp product into identifying 262 and 81 (or 120) bp
fragments.
The amplified TEL-AML1 and AML1-TEL fragments are
shown in Figure 1. Initially, PCR yielded a smaller product, a
254 (215) bp fragment, rather than the expected 509 (470) bp
fragment. The missing region comprised nt 97 to nt 350
inclusive of the AML1 sequence. PCR of the same region of
the AML1 gene revealed the smaller species as well. This
region is GC rich and therefore prone to folding and incomplete amplification. Addition of 6% dimethylsulfoxide overcame this phenomenon and yielded the correct length DNA
fragment. Small amounts of this product are present in
Figure 1.
Methotrexate polyglutamates and the Tel-AML1 translocation
VM Whitehead et al
analysis39 was conducted, using the natural logarithm of
MTXPG as the dependent variable. This transformation
seemed to equalize the variation in the four defined groups.
All statistical tests were two-sided.
1083
Results
The presence of the TEL-AML1 and the AML1-TEL transcript
was determined successfully in 91 (66%) of 138 children with
BpALL studied on POG 8901. Characteristics of these patients
are summarized in Table 1 and compared with those in 6786
POG patients with BpALL (see Methods). The distribution of
these patients seems similar to BpALL patients in general. The
white cell count is somewhat higher in the test patients which
is normal for cell bank studies, since such patients typically
provide more material for study.
The distribution of total MTXPG levels in children with and
without the TEL-AML1 translocation is shown in Figure 2 and
Table 2. Twenty-two (79%) of the 28 children with the TELAML1 translocation and who were not hyperdiploid had a
‘clinically significant’ lower MTXPG level (⬍500 pmol/109
cells), while six had MTXPG levels previously associated with
improved outcome (⬎500 pmol/109 cells). By the Wilcoxon
test, MTXPG levels in TEL-AML1 lymphoblasts were significantly lower than in lymphoblasts without the TEL-AML1
translocation (P = 0.004). While there was considerable overlap between these two groups, the median MTXPG level of
those without TEL-AML1, 654 pmol/109 cells, was close to the
90th percentile of MTXPG levels of those with TEL-AML1, 686
pmol/109 cells (Table 2). Point estimate is that the median
MTXPG level is 2.1-fold higher without than with the TEL-
Figure 1
The TEL-AML1 and AML1-TEL transcripts amplified from
lymphoblast RNA from four children with BpALL by RT-PCR (1a–4a)
and their digestion products (1b–4b). Patient 1 has the larger (509 bp)
TEL-AML1 (1a) and Ava1 (356 bp, 153 bp) digestion fragments (1b)
and corresponding smaller (343 bp) AML1-TEL (1a) and Hha1 (262
bp, 81 bp) digestion fragments (1b). Patient 2 has the smaller (470
bp) TEL-AML1 (2a) and Ava1 (317 bp, 153 bp) digestion fragments
(2b) and corresponding larger (382 bp) AML1-TEL (2a) and Hha1 (301
bp, 81 bp) digestion fragments (2b). Patient 3 has only the smaller
(343 bp) AML1-TEL (3a) and Hha1 (262 bp, 81 bp) digestion fragments
(3b). Patient 4 has no TEL-AML1 and no AML1-TEL. There is a small
amount of the larger 254 bp product (1a and 1b) and the smaller 215
bp product (2a and 2b) due to incomplete transcription of the
TEL-AML1 RNA (see Methods).
Statistical considerations
The primary focus of this analysis was to compare the presence and absence of the TEL-AML1 translocation with lymphoblast MTXPG levels and with ploidy, using the Wilcoxon
test38 and exact conditional chi-square,38 respectively. To
quantitate the potential association between MTXPG levels
and the presence or absence of the TEL-AML1 translocation,
a Hodges–Lehmann38 confidence interval for scale was used.
The association of lymphoblast MTXPG levels and subclassification of the TEL-AML1 by transcript presence was
conducted by the Spearman correlation,38 using negative vs
small vs large Tel-AML1 and AML1-TEL as ordinal variables.
In order to study the joint relationship of lymphoblast MTXPG
level with both ploidy and TEL-AML1, a multiple regression
Figure 2
Levels of accumulation of MTXPGs in lymphoblasts from
children with BpALL with and without the TEL-AML1 translocation.
Closed and open circles identify patients with hyperdiploid (DI ⬎
1.16) and non-hyperdiploid (DI ⭐ 1.16) lymphoblasts, respectively.
Leukemia
Methotrexate polyglutamates and the Tel-AML1 translocation
VM Whitehead et al
1084
Table 2
Distribution of lymphoblast MTXPG levels in children
with BpALL with and without the TEL-AML1 translocation
TEL
Patient numbers
Patient
Percentile
10
25
50
75
90
MTXPG levels (pmol/10 9 cells)
Absent
Present
(n = 61)
(n = 30)
202
242
654
1220
2047
79
139
311
536
686
P value = 0.004.
AML1 translocation. We are 95% confident that it is between
1.4- and 3.3-fold higher.
There were 17 children whose lymphoblasts were hyperdiploid with a DI ⬎ 1.16 of which 15 lacked the TEL-AML1
translocation. TEL-AML1 was present in 28 of the 74 patients
with a DI ⭐ 1.16 (Figure 2). Evaluation by exact conditional
chi-square demonstrated that hyperdiploidy is rare in patients
with the TEL-AML1 translocation (P = 0.047). Lymphoblast
MTXPG levels were significantly lower in those with than
without the TEL-AML1 translocation in the 74 nonhyperdiploid patients, P = 0.008 (two-sided Wilcoxon test).
Thirteen patients had the TEL-AML1 transcript, four children
had the AML1-TEL transcript and 13 children had both. In 24
patients, the translocation was located within the first intron
giving a larger (509 bp) TEL-AML1 fragment and/or a smaller
(343 bp) AML1-TEL fragment. In six patients, the translocation
was within the second intron, yielding a smaller (470) TELAML1 fragment and a larger (382 bp) AML1-TEL fragment.
Spearman correlations for lymphoblast MTXPG levels vs the
presence or absence as well as the site of translocation of
these transcripts yielded R = −0.05, P = 0.78 for TEL-AML1
and R = 0.08, P = 0.67 for AML1-TEL. These results are inconclusive, perhaps reflecting too few patients. They do not infer
no correlation.
The relation of the log of the lymphoblast MTXPG level was
compared to the presence and absence of the TEL-AML1
translocation and to the presence (DI ⬎ 1.16) and absence
(DI ⭐ 1.16) of hyperdiploidy by multivariate analysis. The
initial fitted model
log (MTXPG) = 6.219–0.656(If TEL-AML1) + 0.794(If DI ⬎
1.16) + 0.340(If both TEL-AML1 + DI ⬎ 1.16).
gave an R2 = 22.1%. The P value for the (TEL-AML1 + DI ⬎
1.16) interaction was 0.65.
In the final fitted model,
log (MTXPG) = 6.207–0.625(If TEL-AML1) + 0.842(If DI
⬎ 1.16)
R2 = 22.0% and P = 0.0043 for TEL-AML1 and 0.0015 for the
DI ⬎ 1.16. R2 = the fraction of variation of log (MTXPG)
explained by the independent variables TEL-AML1 and DI ⬎
1.16. This value is low even though statistically significant.
The final model predicting MTXPG levels from this analysis
is shown in Table 3. The model is valid in the sense that the
full (saturated model) was fit to the data (ie 4 means were
modeled via four parameters initially). The interaction term
was dropped for lack of predictive value. For patients lacking
Leukemia
Table 3
Model fitted values of lymphoblast MTXPG levels in children with BpALL by the presence and absence of the TEL-AML1 translocation and by ploidy for the final model (no interaction). This is the
antilog of the means of the log scales with 95% confidence limits ().
The standard error of prediction in the log scale is 0.86
DI ⭐ 1.16
DI ⬎ 1.16
TEL-AML1 absent
pmol/10 9 cells
TEL-AML1 present
pmol/10 9 cells
496 (380 659)
1152 (728 1808)
266 (189 372)
616 (344 1107)
There were 46, 28, 15 and two children in the groups with mean
MTXPG levels of 496, 266, 1152 and 616 pmol/109 cells, respectively.
both the TEL-AML1 translocation and hyperdiploidy, the mean
predicted lymphoblast MTXPG level is 496 pmoles/109 cells.
Each of 1.16 ⭓ DI and the presence of the TEL-AML1 translocation appears to confer a 50% decrease in lymphoblast
MTXPG level.
Cell pellets were available for nine of the 14 patients previously reported to have a translocation involving 12p,
determined cytogenetically.34 Seven of these nine patients had
the TEL-AML1 translocation in addition to a translocation
involving 12p (present in patients 2, 4, 5, 6, 10, 11, 13; absent
in patients 8,14, Table 1, Ref 34). In addition, two of the three
patients reported to have del(12p) had the TEL-AML1 translocation (present in patients 16, 17, absent in patient 15).34
Patient 17 had del(12p) in the modal clone and a 12p translocation in the minor clone. Thus, eight of the 10 patients with
a 12p translocation studied previously had a TEL-AML1 translocation identified as well. We determined the TEL-AML1
status of 24 (62%) of the 39 non-hyperdiploid patients who
did not have a 12p11–13 translocation reported previously.34
Six (25%) had a TEL-AML1 translocation. These results suggest
a close association between the occurrence of the TEL-AML1
translocation and of other translocations involving chromosome 12p.
Discussion
The addition of intensification therapy, following induction,
has been associated with improved EFS in children with
BpALL.8,9 A major component of such enhanced therapy has
been infusion of MTX at high doses every few weeks.8,9 We
reported previously that the extent of accumulation of
MTXPGs in lymphoblasts of children with BpALL treated in
the early 1980s correlated with EFS.29 In a confirmatory study,
levels of MTXPGs accumulated in lymphoblasts in vivo were
found to correlate with the rapidity of decline of circulating
blasts following MTX treatment.30 We and others showed that
hyperdiploid BpALL lymphoblasts accumulated high levels of
MTXPGs.31–33 Such levels may account in part for the good
response these patients have to MTX-intensive treatment regimens. These results provide direct clinical evidence that the
ability of lymphoblasts to metabolize the pro-drug MTX to
its active forms, MTXPGs, is important to the outcome of
treatment.
Recently, we found that BpALL lymphoblasts, which had
translocations affecting chromosome 12p11–13, accumulated
low levels of MTXPGs.34 Such lymphoblasts rarely showed
hyperdiploidy. Toward completion of this study, we learned
of the occurrence of the t(12;21)(p13;q22), a cryptic translo-
Methotrexate polyglutamates and the Tel-AML1 translocation
VM Whitehead et al
cation seldom recognized cytogenetically, but demonstrated
by FISH and by RT-PCR. This translocation is the most common cytogenetic abnormality yet detected in BpALL and is
associated with an excellent prognosis in most studies. Since
this TEL-AML1 translocation involves chromosome 12p, we
were interested to determine whether lymphoblasts with this
specific translocation also lacked the ability to accumulate
MTXPGs effectively.
Results presented here demonstrate that the observation of
low lymphoblast MTXPG levels associated with 12p translocations extends to the commonest of these, namely the TELAML1 translocation. Indeed, we found that levels of lymphoblast MTXPGs were significantly lower in those with than in
those without TEL-AML1. This difference was evident despite
considerable overlap in MTXPG levels (Figure 2).
Analysis revealed that hyperdiploidy is rare in lymphoblasts
with the TEL-AML1 translocation as it was for other 12p translocations34 and as has been reported by others.17 Both DI ⬎
1.16 and the presence of the TEL-AML1 translocation proved
to be highly significantly correlated with the log of the
lymphoblast MTXPG level in childhood BpALL.
The results imply that each of 1.16 ⭓ DI and the presence
of the TEL-AML1 translocation confers a 50% decrease in lymphoblast MTXPG level. Thus roughly a four-fold difference
exists between these two good prognosis subgroups of BpALL
in their ability to metabolize MTX and to accumulate MTXPGs
(Table 3). It will be important to consider this difference in
MTX metabolism in planning reductions in therapy for groups
of these patients whose cure rate is highly favorable.
It is interesting to speculate whether it is patients with the
TEL-AML1 translocation who have benefited most from the
increased reliance of treatment on high-dose infusions of MTX
during intensification. Such treatments might compensate for
the reduced ability of TEL-AML1 lymphoblasts to accumulate
high levels of MTXPGs. Knowledge of the therapeutic outcome of patients with TEL-AML1 treated prior to the introduction of such therapy might provide an answer to this question.
At the same time, it is important to remember that success of
treatment reflects use of many effective agents. Perhaps TELAML1 lymphoblasts are particularly sensitive to another
component of therapy, such as L-asparaginase, and MTX cytotoxicity plays a lesser role in their cure. Another possibility is
that patients with the TEL-AML1 translocation have blasts that
are more sensitive to low levels of MTXPGs.
Some reports suggest that the presence of the AML1-TEL
transcript was sought only in those patients found to have
the TEL-AML1 transcript. 17 We analyzed each sample for
both and found four patients expressing only the AML1-TEL
message. This may account in part for the 30% incidence
of the TEL-AML1 translocation in this series of patients,
which is higher than the 25% usually reported. Neither the
presence nor the size of one or other of these chimeric messages showed a correlation with lymphoblast MTXPG levels,
but patient numbers were insufficient to draw any conclusions.
We found the TEL-AML1 translocation as a second cytogenetic abnormality in eight of 10 patients studied previously
who had a 12p translocation.34 While we linked cytogenetically identified 12p translocations to low lymphoblast
MTXPG levels in this initial study, current results raise the
possibility that it may be the TEL-AML1 translocation, rather
than that of the macroscopically identified segment of 12p,
which is implicated in this association.
LOH for the normal TEL allele has been found to be very
common in patients with the TEL-AML1 translocation.13,20 It
is tempting to speculate that disruption of both TEL alleles may
be associated with low MTXPG levels in this population.
Alternately, it may be that disruption of the AML1 rather than
the TEL gene is linked to low lymphoblast MTXPG levels. Certainly, accumulation of MTXPG in blasts from patients with
ANLL is much lower than in BpALL blasts.28
Several genes are involved in the regulation of accumulation of MTXPGs. The reduced folate carrier (RFC1) transports
folate and MTX into cells.40 Levels of RFC1 message are
increased in hyperdiploid lymphoblasts.41,42 MTXPGs are synthesized from MTX by the enzyme folate polyglutamate synthetase (FPGS)43 and are hydrolysed to MTX by gammaglutamyl hydrolase (GGH).44 Differences in expression of these
genes have been linked to extent and lineage specificity of
MTXPG synthesis in childhood ALL.45,46 Studies are in progress to link levels of expression of the RFC1, FPGS and GGH
genes in BpALL lymphoblasts with levels of accumulation of
MTXPGs and with the presence of TEL-AML1 or of hyperdiploidy.
1085
Acknowledgements
This research was supported in part by the following grants
from the National Cancer Institute: CA-33587, CA-25408,
CA-32053, CA-03161, CA-29139, CA-53490, CA-33625,
CA-29691, CA-28841, CA-31566, CA-52317, CA-15989. In
addition, it was supported by grants from the National Cancer Institute of Canada, the Cancer Research Society and the
McGill University – Montreal Children’s Hospital Research
Institute, and assisted by the Penny Cole Fund, the Fast
Foundation, the InterService Clubs Council Telethon of
Stars, the Lamplighters Children’s Cancer–Leukemia Association, the Children’s Cancer Fund, the Debbie Saunders
Fund, the friends of Ande, the Midwest Athletes against
Childhood Cancer (MACC Fund), the American Lebanese
Syrian Associated Charities (ALSAC) and the American Cancer Society.
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19
20
21
22
Leukemia
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Kobayashi H, Montgomery KT, Bohlander SK, Adra CN, Lim BL,
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Appendix: Participating Institutions and NCI Grant Support
Institution
Grant number
Alberta Pediatric Oncology Consortium
Alberta Children’s Hospital
Cross Cancer Institute
Baylor College of Medicine
Baylor College of Medicine
UT-Galveston
CA-03161
CA-03161
Bergan-Passiac CCOP
Hackensack Medical Center
43
44
45
46
ship to immunophenotype and ploidy. Clin Cancer Res 1998; 4:
2169–2177.
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cDNA encoding folylpoly(gamma-glutamate) synthetase and
determination of its primary structure. Proc Natl Acad Sci USA
1992; 89: 9151–9155.
Rhee MS, Lindau-Shepard B, Chave KJ, Galivan J, Ryan TJ. Characterization of human cellular gamma-glutamyl hydrolase. Mol
Pharmacol 1998; 53: 1040–1046.
Galpin AJ, Schuetz JD, Masson E, Yanishevski Y, Synold TW, Barredo JC, Pui CH, Relling MV, Evans WE. Differences in folypolyglutamate synthetase and dihydrofolate reductase expression in
human B-lineage versus T-lineage leukemic lymphoblasts: mechanisms for lineage differences in methotrexate polyglutamylation
and cytotoxicity. Mol Pharmacol 1997; 52: 155–163.
Longo GS, Gorlick R, Tong WP, Lin S, Steinherz P, Bertino JR.
Gamma-glutamyl hydrolase and folypolyglutamate synthetase
activities predict polyglutamylation of methotrexate in acute leukemias. Oncol Res 1997; 9: 259–263.
Emory University
Emory University
Hawaii (NP) CCOP
Cancer Center of Hawaii/University of
Hawaii – Manoa
Hospital for Sick Children
Hospital for Sick Children
CA-69177
CA-69177
CA-69177
CA-69177
McGill University
Children’s Hospital of Eastern Ontario
McGill University
Children’s Hospital Michigan
Children’s Hospital Michigan
Hurley Medical Center
St Johns Hospital
CA-29691
CA-29691
CA-29691
Miami Children’s Hospital
Miami Children’s Hospital
Dana-Farber Cancer Institute
Dana-Farber Cancer Institute
Maine Children’s Cancer Program
Duke University
Duke University
West Virginia University – Charleston
West Virginia University – Morgantown
Eastern Pediatric Oncology Consortium
Mount Sinai Medical School (NYC)
University of Maryland
Yale University
CA-28476
CA-28476
LSU CCOP
Children’s Hospital of New Orleans
Carolinas Consortium
Carolinas Medical Center
Children’s Hospital – Greenville System
East Carolina University
Medical University of South Carolina
Children’s Memorial Hospital – Chicago
Children’s Memorial Hospital – Chicago
Christ Hospital and Medical Center
Rush-Presbyterian–St Luke’s Medical
Center
CA-20549
Florida CCOP
All Children’s Hospital
Joe DiMaggio Children’s Hospital
Nemours Children’s Clinic – Orlando
Sacred Heart Hospital
Johns Hopkins University
Invoa Fairfax Hospital
Johns Hopkins University
Boston Floating Hospital
Boston Floating Hospital
Eastern Main Medical Center
1087
CA-07431
CA-07431
CA-07431
CA-41573
CA-41573
CA-15525
CA-15525
CA-15525
CA-69428
CA-69428
CA-69428
CA-33587
CA-33587
Medical College Virginia
Medical College Virginia
Midwest Children’s Cancer Center
Midwest Children’s Cancer Center
CA-32053
New England Consortium
Darmouth Hitchcock Medical Center
Massachusetts General Hospital
Rhode Island Hospital
SUNY Stony Brook
University of Vermont
CA-29293
CA-29293
CA-29293
CA-29293
CA-29293
Oklahoma University
Oklahoma University
Warren Clinics
CA-11233
CA-11233
Pediatric Oncology Group Operations
POG Operations Office
POG Statistical Office
CA-30969
CA-29139
Roswell Park Cancer Institute
Roswell Park Cancer Institute
CA-28383
Leukemia
Methotrexate polyglutamates and the Tel-AML1 translocation
VM Whitehead et al
1088
SPOG
SPOG
SPOG
SPOG
University of Mississippi Medical Center
Keesler AFB Hospital
University of Mississippi Medical Center
Consortium
Bern
Geneva
Lausanne
University of Rochester
University of Rochester
SUNY Syracuse
SUNY Syracuse
SWMSC
Cook Children’s Medical Center
Scott & White Memorial Hospital
UT – Southwestern Medical School
University of Virginia
University of Virginia
CA-33625
CA-33625
CA-33625
St Christopher’s Hospital
St Christopher’s Hospital
St Jude Children’s
East Tennessee State University
St Jude Children’s Research Hospital
CA-31566
CA-31566
Stanford University
Kaiser-Permanente, Santa Clara
Stanford University
University of Arizona
CA-33603
CA-33603
CA-33603
University of Alabama
University of Alabama – Birmingham
CA-25408
University of Arkansas
Arkansas Children’s Hospital
University of Florida
Nemours Children’s Clinic – Jacksonville
University of Florida
University of Kansas
University of Kansas
University of Miami
University of Miami
Leukemia
CA-15898
CA-15989
UC-Davis
UC-Davis
UCSD Consortium
Kaiser-Permanente San Diego
UC-San Diego
CA-28439
CA-28439
US TEX PED CCOP
UT-San Antonio
University of South Alabama CCOP
University of South Alabama
UNIF SERV ONC. CONS
Madigan Army Medical Center
Naval Medical Center – Portsmouth
Tripler Army Medical Center
Walter Reed Army Medical Center
Wake Forest University School of
Medicine
Wake Forest University School of
Medicine
Washington University
University of Missouri
Washington University
Wichita CCOP
St Francis/Via Christi Regional Medical
Center
CA-53128
CA-05587
CA-05587