Overexpression of novel short isoforms of Helios in a patient with T-cell acute lymphoblastic leukemia.
OBJECTIVE
In previous studies, we demonstrated overexpression of the dominant-negative isoform of the transcription factor Ikaros, Ik-6, in patients with blast crisis of chronic myelogenous leukemia and B-cell acute lymphoblastic leukemia. In the present study, we analyzed expression of the Ikaros family genes Ikaros, Aiolos, and Helios in a panel of human T-cell leukemia/lymphoma cell lines and bone marrow samples of patients with T-cell acute lymphoblastic leukemia.


METHODS
We performed reverse transcriptase polymerase chain reaction, sequencing analysis, immunoblotting, and Southern blotting.


RESULTS
We found overexpression of novel short isoforms of Helios (Hel-5 and Hel-6) in the HD-Mar cell line. Southern blot analysis suggested that there might be a small deletion in the Helios locus of HD-Mar. In addition, we observed decreased expression of more than one Ikaros family gene in 3 of 9 patients with T-cell acute lymphoblastic leukemia. Moreover, one of the patients overexpressed novel short isoforms of Helios (Hel-7 and Hel-8).


CONCLUSIONS
This study provides the first evidence of an Ikaros family member (other than Ikaros) of which novel short isoforms become overexpressed in human leukemia.
Nakase
Koichi
K
Department of Medicine, University of Okayama, 2-5-1 Shikatacho, Okayama 700-8558, Japan.
Ishimaru
Fumihiko
F
Fujii
Keiko
K
Tabayashi
Takayuki
T
Kozuka
Teruhiko
T
Sezaki
Nobuo
N
Matsuo
Yoshinobu
Y
Harada
Mine
M
D001853:Bone Marrow / Q000473:pathology; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051740:Ikaros Transcription Factor; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; C497239:IKZF1 protein, human; C111431:IKZF2 protein, human; C106285:IKZF3 protein, human; D020033:Protein Isoforms; D015534:Trans-Activators; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D051740:Ikaros Transcription Factor