Chronic lymphocytic leukemia of Eμ-TCL1 transgenic mice undergoes rapid cell turnover that can be offset by extrinsic CD257 to accelerate disease progression
ABSTRACT Results of heavy-water labeling studies have challenged the notion that chronic lymphocytic leukemia (CLL) represents an accumulation of noncycling B cells. We examined leukemia cell turnover in Emu-TCL1 transgenic (TCL1-Tg) mice, which develop a CLL-like disease at 8 to 12 months of age. We found that leukemia cells in these mice not only had higher proportions of proliferating cells but also apoptotic cells than did nonleukemic lymphocytes. We crossed TCL1-Tg with BAFF-Tg mice, which express high levels of CD257. TCL1 x BAFF-Tg mice developed CLL-like disease at a significantly younger age and had more rapid disease progression and shorter survival than TCL1-Tg mice. Leukemia cells of TCL1 x BAFF-Tg mice had similar proportions of proliferating cells, but fewer proportions of dying cells, than did the CLL cells of TCL1-Tg mice. Moreover, leukemia cells from either TCL1 x BAFF-Tg or TCL1-Tg mice produced more aggressive disease when transferred into BAFF-Tg mice than into wild-type (WT) mice. Neutralization of CD257 resulted in rapid reduction in circulating leukemia cells. These results indicate that the leukemia cells of TCL1-Tg mice undergo high levels of spontaneous apoptosis that is offset by relatively high rates of leukemia cell proliferation, which might allow for acquisition of mutations that contribute to disease evolution.
- SourceAvailable from: James Q Wang
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- "It is apparent that antigenic stimulation, autoimmunity, and inflammation contribute to the development of CLL (90). One mechanism through which these stimuli promote CLL development is induction of B cell activating factor (BAFF), a member of the TNF family, recently shown to accelerate development of CLL-like disease in mice (91). In addition, cytokines such as IL6 and interactions with bone marrow stromal cells support CLL expansion and suppress apoptosis through the expression of Bcl-2, Survivin, and Mcl-1 (92, 93). "
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- "It has been proposed that repeated antigenic stimulation, autoimmunity, and inflammation are risk factors for chronic lymphocytic leukemia (CLL), the most common hematopoietic malignancy that accounts for 30% of all leukemias (Chiorazzi et al., 2005). One mechanism through which such stimuli promote CLL development is induction of B cell activating factor (BAFF), a member of the TNF family, recently shown to accelerate development of CLL-like disease in mice (Enzler et al., 2009). Cytokines (such as IL-4 and VEGF), chemokines (such as SDF-1), and interactions with bone marrow stromal cells support CLL expansion and suppress apoptosis through upregulation of Bcl-2, survivin, and MCL-1 (Granziero et al., 2001; Pedersen et al., 2002). "
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