1: Leukemia. 2003 Sep;17(9):1845-50. 

Concurrent methylation of multiple genes in childhood ALL: Correlation with
phenotype and molecular subgroup.

Gutierrez MI, Siraj AK, Bhargava M, Ozbek U, Banavali S, Chaudhary MA, El Solh
H, Bhatia K.

King Fahad National Centre for Children's Cancer and Research, Riyadh, Saudi
Arabia.

Multiple genes have been shown to be independently hypermethylated in lymphoid
malignancies. We report here on the extent of concurrent methylation of
E-cadherin, Dap-kinase, O(6)MGMT, p73, p16, p15 and p14 in 129 pediatric ALL
cases. While most of these genes demonstrated methylation in a proportion of
cases, O(6)MGMT, p16 and p14 were infrequently methylated (11, 7 and 3%,
respectively). Methylation of at least one gene was found in the vast majority
(83%) of cases. To determine the extent and concordance of methylation we
calculated a methylation index (MI=number of methylated genes/number of studied
genes) for each sample. The average MI was 0.28, corresponding to 2/7 methylated
genes. MI was correlated with standard prognostic factors, including
immunophenotype, age, sex, WBC and presence of specific translocations
(TEL-AML1, BCR-ABL, E2A-PBX1 or MLL-AF4). We determined that children >/=10
years old and children presenting with high WBC (>/=50 x 10(9)/l) both
associated with a higher MI (P<0.01 and <0.05, respectively). T-ALLs
demonstrated a lower MI (median=0.17) than precursor B ALLs (median=0.28). Among
the different molecular subgroups, MLL-ALLs had the highest MI (mean=0.35),
while ALLs carrying the t(1;19) had the lowest MI (mean=0.07). The most common
epigenetic lesion in childhood ALL was methylation of E-cadherin (72%)
independent of the molecular subtype or other clinicopathological factors.

PMID: 12970785 [PubMed - indexed for MEDLINE]


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2: Leukemia. 2001 Mar;15(3):362-70. 

The leukemogenic transcription factor E2a-Pbx1 induces expression of the
putative N-myc and p53 target gene NDRG1 in Ba/F3 cells.

Rutherford MN, Bayly GR, Matthews BP, Okuda T, Dinjens WM, Kondoh H, LeBrun DP.

Department of Pathology, Queen's University, Kingston, Ontario, Canada.

The chimeric transcription factor E2a-Pbx1 is expressed as a result of the 1;19
chromosomal translocation in some 5% of cases of pediatric acute lymphoblastic
leukemia. We investigated the biological and transcriptional consequences of
forced expression of E2a-Pbx1 in the interleukin-3 (IL-3) dependent, bone
marrow-derived cell line Ba/F3. We show that forced expression of E2a-Pbx1
induces apoptosis in Ba/F3 cells without apparent effects on cell cycle
progression. This pro-apoptotic effect is enhanced on cytokine deprivation.
Furthermore, using cDNA representational difference analysis (RDA), we show that
these cellular effects are associated with marked induction of the gene NDRG1,
which was previously identified as a target of transcriptional repression by
N-myc and induction by the tumor suppressor protein p53. We identify a portion
of the NDRG1 promoter capable of mediating transcriptional induction by E2a-Pbx1
and show that NDRG1 is also induced on simple IL-3 deprivation of BaF3 cells.
Although we show that E2a-Pbx1 induction of NDRG1 is not impaired as a result of
targeting p53 using HPV E6, and therefore does not appear to be p53-dependent,
our results overall are consistent with the notion that induction of NDRG1 by
E2a-Pbx1 may represent part of an apoptotic or cytostatic cellular response to
oncogene activation.

PMID: 11237058 [PubMed - indexed for MEDLINE]


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3: Proteins. 1999 Dec 1;37(4):565-75. 

Hydrophobicity at the surface of proteins.

Scarsi M, Majeux N, Caflisch A.

Department of Biochemistry, University of Zurich, Switzerland.

A new method is presented to quantitatively estimate and graphically display the
propensity of nonpolar groups to bind at the surface of proteins. It is based on
the calculation of the binding energy, i.e., van der Waals interaction plus
protein electrostatic desolvation, of a nonpolar probe sphere rolled over the
protein surface, and on the color coding of this quantity on a smooth molecular
surface (hydrophobicity map). The method is validated on ten protein-ligand
complexes and is shown to distinguish precisely where polar and nonpolar groups
preferentially bind. Comparisons with existing approaches, like the display of
the electrostatic potential or the curvature, illustrate the advantages and the
better predictive power of the present method. Hydrophobicity maps will play an
important role in the characterization of binding sites for the large number of
proteins emerging from the genome projects and structure modeling approaches.

PMID: 10651272 [PubMed - indexed for MEDLINE]


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4: Oncogene. 1997 Jun 19;14(24):2917-26. 

Chimeric oncoprotein E2a-Pbx1 induces apoptosis of hematopoietic cells by a
p53-independent mechanism that is suppressed by Bcl-2.

Smith KS, Jacobs Y, Chang CP, Cleary ML.

Department of Pathology, Stanford University Medical Center, California 94305,
USA.

The chimeric oncoprotein E2a-Pbx1 results from fusion of the E2A and PBX1 genes
following t(1;19) chromosomal translocations in B cell precursor acute
leukemias. Experimentally B cell progenitors do not tolerate constitutive
expression of E2a-Pbx1 which contrasts with transformation of several other cell
types following its stable expression both in vitro and in vivo. To further
investigate the effects of E2a-Pbx1 on the B cell progenitors, we conditionally
expressed E2a-Pbx1 under control of a metal response element in hematopoietic
precursor cell lines in vitro. Inducible expression of E2a-Pbx1 resulted in cell
death with the morphologic and molecular features of apoptosis. A
structure-function analysis demonstrated that induction of apoptosis was not a
dominant-negative effect of the E2a moiety but, rather, required the DNA-binding
homeodomain of Pbx1. E2a-Pbx1-induced apoptosis proceeded through a
BCL2-responsive checkpoint eventuating in PARP inactivation but did require p53.
Constitutive expression of E2a-Pbx1 did not induce apoptosis or continued
cycling of Rat-1 fibroblasts in low serum conditions. These studies demonstrate
that E2a-Pbx1 initiates programmed cell death of hematopoietic precursers by a
mechanism that requires its chimeric transcriptional properties, but, unlike
other nuclear oncoproteins, is independent of p53.

PMID: 9205098 [PubMed - indexed for MEDLINE]


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5: Proc Natl Acad Sci U S A. 1996 Jan 9;93(1):470-4. 

Selective repression of transcriptional activators by Pbx1 does not require the
homeodomain.

Lu Q, Kamps MP.

Department of Pathology, University of California, San Diego, School of
Medicine, La Jolla 92093, USA.

PBX1 is a homeobox-containing gene identified as the chromosome 1 participant of
the t(1;19) chromosomal translocation of childhood pre-B-cell acute
lymphoblastic leukemia. This translocation produces a fusion gene encoding the
chimeric oncoprotein E2A-Pbx1, which can induce both acute myeloid and
T-lymphoid leukemia in mice. The binding of Pbx1 to DNA is weak; however, both
Pbx1 and E2A-Pbx1 exhibit tight binding to specific DNA motifs in conjunction
with certain other homeodomain proteins, and E2A-Pbx1 activates transcription
through these motifs, whereas Pbx1 does not. In this report, we investigate
potential transcriptional functions of Pbx1, using transient expression assays.
While no segments of Pbx1 activated transcription, an internal domain of Pbx1
repressed transcription induced by the activation domain of Sp1, but not by the
activation domains of VP16 or p53. This Pbx1 domain, which lies upstream of the
homeodomain and is highly conserved among Pbx proteins, is thus predicted to
bind a specific transcription factor. Surprisingly, the repression activity of
Pbx1 did not require homeodomain-dependent DNA binding. Thus, Pbx1 may be able
to alter gene transcription by both DNA-binding-dependent and
DNA-binding-independent mechanisms.

PMID: 8552663 [PubMed - indexed for MEDLINE]


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6: Leukemia. 1995 Jun;9(6):955-9. 

p53 gene inactivation in acute lymphoblastic leukemia of B cell lineage
associates with chromosomal breakpoints at 11q23 and 8q24.

Lanza C, Gaidano G, Cimino G, Lo Coco F, Basso G, Sainati L, Pastore C, Nomdedeu
J, Volpe G, Parvis G, et al.

Dipartimento di Scienze Biomediche e Oncologia Umana, Ospedale San Luigi
Gonzaga, Torino, Italy.

The clinical heterogeneity of acute lymphoblastic leukemia (ALL) of B cell
lineage reflects the presence of distinct molecular pathways leading to
well-defined ALL molecular subtypes. These molecular pathways include the
formation of the fusion transcripts BCR/ABL and E2A/PBX1, due to t(9;22) and
t(1;19), respectively, as well as rearrangements of the MLL gene at 11q23 and of
c-MYC at 8q24. Hyperdiploid ALL in the absence of chromosomal structural
abnormalities is an additional ALL molecular subtype. Mutations of the RAS
family genes and of the p53 tumor suppressor gene represent additional genetic
lesions detected in a fraction (10-20%) of ALL cases. RAS activation in ALL may
be detected in all molecular subtypes of ALL and denotes poor prognosis.
Conversely, little is known regarding the clinical and biological features of
ALL cases carrying p53 mutations. In order to help clarify the role of p53
inactivation in ALL development, we have determined the frequency of p53
mutations throughout the molecular spectrum of B cell lineage ALL. We report
that p53 inactivation in ALL of B cell lineage is restricted to cases carrying a
rearrangement of MLL or c-MYC, whereas it is consistently negative in other
molecular subgroups. These data underline the molecular heterogeneity of ALL of
B cell lineage and indicate that at least some of the molecular pathways
involved in ALL pathogenesis require more than one genetic lesion.

PMID: 7596184 [PubMed - indexed for MEDLINE]


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7: Leukemia. 1993 Oct;7(10):1615-20. 

Establishment of a new human pre-B acute lymphoblastic leukemia cell line
(KMO-90) with 1;19 translocation carrying p53 gene alterations.

Sotomatsu M, Hayashi Y, Kawamura M, Yugami S, Shitara T.

Department of Pediatrics, Gunma University School of Medicine, Maebashi, Japan.

A new human pre-B acute lymphoblastic leukemia cell line (KMO-90) was
established from the bone marrow sample of a 12-year-old girl with acute
lymphoblastic leukemia (ALL) carrying 1;19 chromosome translocation. KMO-90
cells expressed HLA-DR, CD10, CD19, and CD22 antigens. These cells had also
cytoplasmic immunoglobulin lacking surface immunoglobulin, indicating that these
had a pre-B phenotype. Chromosome analysis of this cell line showed 48, XX, +8,
+19, t(1;19)(q23;p13). Southern blot analysis showed the same sized
rearrangements of the E2A gene in KMO-90 cells as those in the original leukemic
cells. By means of reverse transcriptase-polymerase chain reaction analysis, we
detected E2A/PBX1 fusion transcripts in KMO-90 cells. KMO-90 is useful when
studying the role of the 1;19 translocation in the etiology of pre-B ALL.
Furthermore, we studied alterations of the p53 gene in this cell line by
polymerase chain reaction, single-strand conformation polymorphism analysis.
KMO-90 cells were identified to have a point mutation at codon 177 (CCC-->TCC)
of the p53 gene, suggesting that alterations of the p53 gene may have an
important role in the establishment of this cell line.

Publication Types:
    Case Reports

PMID: 8412323 [PubMed - indexed for MEDLINE]


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