LYMPHOID NEOPLASIA
t(X;14)(p11;q32) in MALT lymphoma involving GPR34 reveals a role for GPR34
in tumor cell growth
*Stephen M. Ansell,
1
Takashi Akasaka,
2
Ellen McPhail,
3
Michelle Manske,
1
Esteban Braggio,
5
Tammy Price-Troska,
1
Steven Ziesmer,
1
Frank Secreto,
1
Rafael Fonseca,
5
Mamta Gupta,
1
Mark Law,
3
Thomas E. Witzig,
1
Martin J. S. Dyer,
2
Ahmet Dogan,
4
James R. Cerhan,
6
and *Anne J. Novak
1
1
Division of Hematology, Mayo Clinic, Rochester, MN;
2
MRCToxicology Unit, University of Leicester, Leicester, United Kingdom; Divisions of
3
Hematopathology,
and
4
Anatomic Pathology, Mayo Clinic, Rochester, MN;
5
Division of Hematology, Mayo Clinic, Scottsdale, AZ; and
6
Division of Epidemiology, Mayo Clinic,
Rochester, MN
Genetic aberrations, including trisomies
3 and 18, and well-defined IGH transloca-
tions, have been described in marginal
zone lymphomas (MZLs); however, these
known genetic events are present in only
a subset of cases. Here, we report the
cloning of an IGH translocation partner
on chromosome X, t(X;14)(p11.4;q32) that
deregulates expression of an poorly char-
acterized orphan G-protein–coupled re-
ceptor, GPR34. Elevated GPR34 gene ex-
pression was detected independent of
the translocation in multiple subtypes of
non-Hodgkin lymphoma and distin-
guished a unique molecular subtype of
MZL. Increased expression of GPR34 was
also detected in tissue from brain tumors
and surface expression of GPR34 was
detected on human MZL tumor cells and
normal immune cells. Overexpression of
GPR34 in lymphoma and HeLa cells re-
sulted in phosphorylation of ERK, PKC,
and CREB; induced CRE, AP1, and NF-B–
mediated gene transcription; and increased
cell proliferation. In summary, these results
are the first to identify a role for a GPR34 in
lymphoma cell growth, provide insight into
GPR34-mediated signaling, identify a genet-
ically unique subset of MZLs that express
high levels of GPR34, and suggest that MEK
inhibitors may be useful for treatment of
GPR34-expressing tumors. (Blood. 2012;
120(19):3949-3957)
Introduction
B-cell non-Hodgkin lymphoma encompasses a heterogeneous
group of B lymphocyte–derived malignancies that are character-
ized by chromosomal translocations involving the immunoglobulin
(IG) gene loci and specific histologic subtypes of disease are
associated with a different spectrum of IG translocations.
1
Marginal
zone-derived B-cell lymphomas encompass 3 distinct entities:
extranodal marginal zone B-cell lymphoma (MZL) of mucosa
associated lymphoid tissue (MALT), nodal MZL (NMZBCL), and
splenic MZL (SMZBCL). Together they compromise nearly 12%
of all B-cell non-Hodgkin lymphomas. MALT lymphoma is
genetically unique and 5 mutually exclusive chromosomal translo-
cations have been identified in this disease thus far: t(11;18)/
BIRC3(aka API2)-MALT1,
2-4
t(1;14)/IGH-BCL10,
5
t(14;18)/IGH-
MALT1
6
t(3;14)/IGH-FOXP1,
7
and t(X;14)/IGH-GPR34.
8
Despite
this genetic heterogeneity, all but one of the translocations affect
the NF-B signaling pathway.
9
However, the known translocations
are only present in a subset of cases suggesting that additional
uncharacterized translocations or other genetic events may exist
that contribute to disease development. Identification of novel
translocations and subsequent characterization of the proteins
involved not only has relevance in the pathogenesis and diagnosis
of cancer, it also provides insight into the normal cellular functions
of a given protein and may allow for new targeted therapeutic
approaches. In the case of the IGH-BCL10 t(1;14) translocation,
cloning and characterization of Bcl10 revealed its normal cellular
function as a key molecule in antigen receptor signaling
10,11
and
NF-B activation.
12
In this study, we identify and characterize the
biologic significance of t(X;14)/IGH-GPR34. We provide evidence
that GPR34 is highly expressed in MZL independent of the
translocation, identify a role for a GPR34 in lymphoma cell growth,
provide insight into GPR34-mediated signaling, and identify a geneti-
cally unique subset of MZLs that express high levels of GPR34.
Methods
Patient material and cell lines
The Institutional Review Board at the Mayo Clinic reviewed and approved
this study. DNA and tumor tissue from NHL patients and normal controls
was acquired at the Mayo Clinic on providing written informed consent, per
the Declaration of Helsinki. HeLa cells were obtained from the ATCC,
JeKo-1 lymphoma B cells were obtained from the DSMZ, and OCI-Ly19
lymphoma B cells were provided by Dr Margaret Shipp (Dana-Farber
Cancer Institute).
Cloning of the t(X;14) breakpoint by long-distance inverse
polymerase chain reaction.
LDI-PCR to detect IGH translocation breakpoint was carried out as
previously described.
13,14
PCR primers are listed in supplemental Figure 1A
(available on the Blood Web site; see the Supplemental Materials link at the
top of the online article). Sequences of the regions of interest were analyzed
via the University of California Santa Cruz Genome Bioinformatics
database using BLAT (http://genome.ucsc.edu/cgi-bin/hgBlat/).
Submitted November 7, 2011; accepted August 27, 2012. Prepublished online
as Blood First Edition paper, September 10, 2012; DOI 10.1182/blood-2011-11-
389908.
The online version of this article contains a data supplement.
*S.M.A. and A.J.N. contributed equally as senior authors.
The publication costs of this article were defrayed in part by page charge
payment. Therefore, and solely to indicate this fact, this article is hereby
marked ‘‘advertisement’’ in accordance with 18 USC section 1734.
© 2012 by The American Society of Hematology
3949 BLOOD, 8 NOVEMBER 2012
VOLUME 120, NUMBER 19
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