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Aberrant expression of Fra-2 promotes CCR4 expression and cell proliferation in adult T-cell leukemia.

Authors :
Nakayama, T.
Hieshima, K.
Arao, T.
Jin, Z.
Nagakubo, D.
Shirakawa, A.-K.
Yamada, Y.
Fujii, M.
Oiso, N.
Kawada, A.
Nishio, K.
Yoshie, O.
Source :
Oncogene. 5/22/2008, Vol. 27 Issue 23, p3221-3232. 12p. 1 Color Photograph, 1 Black and White Photograph, 4 Graphs.
Publication Year :
2008

Abstract

Adult T-cell leukemia (ATL) is a mature CD4+ T-cell malignancy etiologically associated with human T-cell leukemia virus type 1 (HTLV-1). Primary ATL cells frequently express CCR4 at high levels. Since HTLV-1 Tax does not induce CCR4 expression, transcription factor(s) constitutively active in ATL may be responsible for its strong expression. We identified an activator protein-1 (AP-1) site in the CCR4 promoter as the major positive regulatory element in ATL cells. Among the AP-1 family members, Fra-2, JunB and JunD are highly expressed in fresh primary ATL cells. Consistently, the Fra-2/JunB and Fra-2/JunD heterodimers strongly activated the CCR4 promoter in Jurkat cells. Furthermore, Fra-2 small interfering RNA (siRNA) or JunD siRNA, but not JunB siRNA, effectively reduced CCR4 expression and cell growth in ATL cells. Conversely, Fra-2 or JunD overexpression promoted cell growth in Jurkat cells. We identified 49 genes, including c-Myb, BCL-6 and MDM2, which were downregulated by Fra-2 siRNA in ATL cells. c-Myb, BCL-6 and MDM2 were also downregulated by JunD siRNA. As Fra-2, these proto-oncogenes were highly expressed in primary ATL cells but not in normal CD4+ T cells. Collectively, aberrantly expressed Fra-2 in association with JunD may play a major role in CCR4 expression and oncogenesis in ATL.Oncogene (2008) 27, 3221–3232; doi:10.1038/sj.onc.1210984; published online 10 December 2007 [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09509232
Volume :
27
Issue :
23
Database :
Academic Search Index
Journal :
Oncogene
Publication Type :
Academic Journal
Accession number :
34523989
Full Text :
https://doi.org/10.1038/sj.onc.1210984