Molecular and cytological features of the mouse B-cell lymphoma line iMycEmu-1.
BACKGROUND
Myc-induced lymphoblastic B-cell lymphoma (LBL) in iMycEmu mice may provide a model system for the study of the mechanism by which human MYC facilitates the initiation and progression of B cell and plasma cell neoplasms in human beings. We have recently shown that gene-targeted iMycEmu mice that carry a His6-tagged mouse Myc cDNA, MycHis, just 5' of the immunoglobulin heavy-chain enhancer, Emu, are prone to B cell and plasma cell tumors. The predominant tumor (approximately 50%) that arose in the iMycEmu mice on the mixed genetic background of segregating C57BL/6 and 129/SvJ alleles was LBL. The purpose of this study was to establish and characterize a cell line, designated iMycEmu-1, for the in-depth evaluation of LBL in vitro.


METHODS
The morphological features and the surface marker expression profile of the iMycEmu-1 cells were evaluated using cytological methods and FACS, respectively. The cytogenetic make-up of the iMycEmu-1 cells was assessed by spectral karyotyping (SKY). The expression of the inserted MycHis gene was determined using RT-PCR and qPCR. Clonotypic immunoglobulin gene arrangements were detected by Southern blotting. The global gene expression program of the iMycEmu-1 cells and the expression of 768 "pathway" genes were determined with the help of the Mouse Lymphochip(c) and Superarray(c) cDNA micro- and macroarrays, respectively. Array results were verified, in part, by RT-PCR and qPCR.


RESULTS
Consistent with their derivation from LBL, the iMycEmu-1 cells were found to be neoplastic IgMhighIgDlow lymphoblasts that expressed typical B-cell surface markers including CD40, CD54 (ICAM-1), CD80 (B7-1) and CD86 (B7-2). The iMycEmu-1 cells harbored a reciprocal T(9;11) and three non-reciprocal chromosomal translocations, over-expressed MycHis at the expense of normal Myc, and exhibited gene expression changes on Mouse Lymphochip microarrays that were consistent with MycHis-driven B-cell neoplasia. Upon comparison to normal B cells using eight different Superarray cDNA macroarrays, the iMycEmu-1 cells showed the highest number of changes on the NFkappaB array.


CONCLUSIONS
The iMycEmu-1 cells may provide a uniquely useful model system to study the growth and survival requirements of Myc-driven mouse LBL in vitro.
Han
Seong Su
SS
Laboratory of Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, USA. hanse@mail.nih.gov
Shaffer
Arthur L
AL
Peng
Liangping
L
Chung
Seung Tae
ST
Lim
Jae Hwan
JH
Maeng
Sungho
S
Kim
Joong Su
JS
McNeil
Nicole
N
Ried
Thomas
T
Staudt
Louis M
LM
Janz
Siegfried
S
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D007621:Karyotyping; D016393:Lymphoma, B-Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D008822:Mice, Transgenic; D020411:Oligonucleotide Array Sequence Analysis; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism*
C489428:Myc protein, mouse; D016271:Proto-Oncogene Proteins c-myc