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Blood, 15 May 2008, Vol. 111, No. 10, pp. 5163-5172.
Prepublished online as a Blood First Edition Paper on March 13, 2008; DOI 10.1182/blood-2007-09-113654.
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NEOPLASIA
Induction of the IL-9 gene by HTLV-I Tax stimulates the spontaneous proliferation of primary adult T-cell leukemia cells by a paracrine mechanism
Jing Chen1,
Mike Petrus1,
Bonita R. Bryant1,
Vinh Phuc Nguyen1,
Mindy Stamer1,
Carolyn K. Goldman1,
Richard Bamford2,
John C. Morris1,
John E. Janik1, and
Thomas A. Waldmann1
1 Metabolism Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD; and
2 Transponics, Jacobus, PA
The etiologic agent of adult T-cell leukemia (ATL) is human T cell lymphotropic virus type I (HTLV-I). The HTLV-I protein Tax alters gene expression, including those of cytokines and their receptors, which plays an important role in early stages of ATL. Here we demonstrate that expression of interleukin-9 (IL-9) is activated by Tax via an NF- B motif in its proximal promoter, whereas IL-9 receptor- (IL-9R ) expression is not induced by Tax. However, supporting a role for IL-9/IL-9R in ATL, a neutralizing monoclonal antibody directed toward IL-9R inhibited ex vivo spontaneous proliferation of primary ATL cells from several patients. Fluorescence-activated cell sorter analysis of freshly isolated peripheral blood mononuclear cells from these patients revealed high level expression of IL-9R on their CD14-expressing monocytes. Furthermore, purified T cells or monocytes alone from these patients did not proliferate ex vivo, whereas mixtures of these cell types manifested significant proliferation through a contact-dependent manner. Taken together, our data suggest that primary ATL cells, via IL-9, support the action of IL-9R /CD14-expressing monocytes, which subsequently support the ex vivo spontaneous proliferation of malignant T cells. In summary, these data support a role for IL-9 and its receptor in ATL by a paracrine mechanism.

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