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题名:HTLV-I infection of WE17/10 CD4+ cell line leads to progressive alteration of Ca2+ influx that eventually results in loss of CD7 expression and activation of an antiapoptotic pathway involving AKT and BAD which paves the way for malignant transformation
作者:H Akl, B M Badran, N E Zein, F Bex, C Sotiriou, K E Willard-Gallo, A Burny, P Martiat
来源:Leukemia [IF=6.612]21, 788 - 796 (01 Apr 2007) Original Article
URL :http://dx.doi.org/10.1038/sj.leu.2404585
日期:070415
摘要: H Akl1, B M Badran1, N E Zein2, F Bex3, C Sotiriou4, K E Willard-Gallo1, A Burny1 and P Martiat1

1Laboratory of Experimental Hematology, Bordet Institute, Faculty of Medicine, Universit Libre de Bruxelles, Brussels, Belgium
2Department of Oncology, Laboratory of Pediatric Oncology, Hopital des Enfants, Brussels, Belgium
3Department of Microbiology, Institute for Microbiological Research J-M Wiame and Laboratory of Microbiology, Universit Libre de Bruxelles, Brussels, Belgium
4Department of Medical Oncology, Micro-arrays Unit, Bordet Institute, Faculty of Medicine, Universit Libre de Bruxelles, Brussels, Belgium

Correspondence: Professor P Martiat, Department of Hematology (Laboratory of Experimental Hematology), Institut Bordet, Free University of Brussels (ULB), 121, Boulevard de Waterloo, Brussels 1000, Belgium. E-mail: pmartiat@ulb.ac.be

Received 20 October 2006; Revised 6 December 2006; Accepted 15 December 2006; Published online 8 February 2007.

Abstract

Adult T-cell leukemia/lymphoma (ATLL) is a malignancy slowly emerging from human T-cell leukemia virus type 1 (HTLV-I)-infected mature CD4+ T-cells. To characterize the molecular modifications induced by HTLV-I infection, we compared HTLV-I-infected WE17/10 cells with control cells, using micro-arrays. Many calcium-related genes were progressively downmodulated over a period of 2 years. Infected cells acquired a profound decrease of intracellular calcium levels in response to ionomycin, timely correlated with decreased CD7 expression. Focusing on apoptosis-related genes and their relationship with CD7, we observed an underexpression of most antiapoptotic genes. Western blotting revealed increasing Akt and Bad phosphorylation, timely correlated with CD7 loss. This was shown to be phosphatidylinositol 3-kinase (PI3K)-dependent. Activation of PI3K/Akt induced resistance to the apoptotic effect of interleukin-2 deprivation. We thus propose the following model: HTLV-I infection induces a progressive decrease in CD3 genes expression, which eventually abrogates CD3 expression; loss of CD3 is known to perturb calcium transport. This perturbation correlates with loss of CD7 expression and induction of Akt and Bad phosphorylation via activation of PI3K. The activation of the Akt/Bad pathway generates a progressive resistance to apoptosis, at a time HTLV-I genes expression is silenced, thus avoiding immune surveillance. This could be a major event in the process of the malignant transformation into ATLL.

Keywords: HTLV-I, Ca2+, CD7, PI3K, Akt, Bad 8.

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