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Modeling tumor-host interactions of chronic lymphocytic leukemia in xenografted mice to study tumor biology and evaluate targeted therapy.

Herman SE, Sun X, McAuley EM, Hsieh MM, Pittaluga S, Raffeld M, Liu D, Keyvanfar K, Chapman CM, Chen J, Buggy JJ, Aue G, Tisdale JF, Pérez-Galán P, Wiestner A - Leukemia (2013)

Bottom Line: We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-κB signaling in the xenografted cells.Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development.Ibrutinib inhibited BCR and NF-κB signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo.

View Article: PubMed Central - PubMed

Affiliation: Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.

ABSTRACT
Chronic lymphocytic leukemia (CLL) cells depend on microenvironmental factors for proliferation and survival. In particular, the B-cell receptor (BCR) and nuclear factor- κB (NF-κB) pathways are activated in the lymph node (LN) microenvironment. Thus, model systems mimicking tumor-host interactions are important tools to study CLL biology and pathogenesis. We investigated whether the recently established NOD/scid/γc() (NSG) mouse xenograft model can recapitulate the effects of the human microenvironment. We assessed, therefore, tumor characteristics previously defined in LN-resident CLL cells, including proliferation, and activation of the BCR and NF-κB pathways. We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-κB signaling in the xenografted cells. Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development. Ibrutinib inhibited BCR and NF-κB signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo. Thus, our data demonstrate that the SP of xenografted NSG mice can, in part, recapitulate the role of the human LN for CLL cells. In addition, we show that ibrutinib effectively disrupts tumor-host interactions essential for CLL cell proliferation and survival in vivo.

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Ibrutinib inhibits BCR and NF-κB signaling in xenografted CLL cells. Mice treated with vehicle (control) or ibrutinib were sacrificed 3-4 weeks post xenografting. (a) CLL cells of ibrutinib treated mice as compared to untreated control mice (n=6 per treatment group) show decreased expression of representative BCR (left panel) and NF-κB (right panel) target genes (described in 3). Shown is the mean (± SEM) ratio between mRNA levels for each of the indicated genes in CLL cells purified from the spleen of treated as compared to untreated mice. (b) The signature scores for the BCR and NF-κB pathways were computed as the averaged expression of the respective target genes (as in Figure 3a). Shown is the relative expression in CLL cells from the spleen normalized to PB. (c) A representative histogram shows a decrease of BTK phosphorylation (pBTK) in CLL cells of treated mice. Note: pBTK in treated mice is reduced to the level of isotype control. (d) Shown is the mean (± SEM) MFI ratio of pBTK to isotype control in CLL cells from control and ibrutinib treated mice. The multivariable analysis used to test for significance in all panels is described in Materials and Methods.
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Figure 5: Ibrutinib inhibits BCR and NF-κB signaling in xenografted CLL cells. Mice treated with vehicle (control) or ibrutinib were sacrificed 3-4 weeks post xenografting. (a) CLL cells of ibrutinib treated mice as compared to untreated control mice (n=6 per treatment group) show decreased expression of representative BCR (left panel) and NF-κB (right panel) target genes (described in 3). Shown is the mean (± SEM) ratio between mRNA levels for each of the indicated genes in CLL cells purified from the spleen of treated as compared to untreated mice. (b) The signature scores for the BCR and NF-κB pathways were computed as the averaged expression of the respective target genes (as in Figure 3a). Shown is the relative expression in CLL cells from the spleen normalized to PB. (c) A representative histogram shows a decrease of BTK phosphorylation (pBTK) in CLL cells of treated mice. Note: pBTK in treated mice is reduced to the level of isotype control. (d) Shown is the mean (± SEM) MFI ratio of pBTK to isotype control in CLL cells from control and ibrutinib treated mice. The multivariable analysis used to test for significance in all panels is described in Materials and Methods.

Mentions: Next, we sought to determine whether ibrutinib prevents activation of the BCR and NF-κB pathways in CLL cells in vivo. We analyzed tumor cells isolated from murine spleens 3-4 weeks after xenografting and measured expression of representative BCR and NF-κB target genes. Expression of all BCR and of four out of five NF-κB target genes were reduced in CLL cells of the ibrutinib treated mice as compared to control mice (Figure 5a), resulting in a decrease of the BCR and NF-κB gene scores by 61% and 47%, respectively (Figure 5b; P<.05).


Modeling tumor-host interactions of chronic lymphocytic leukemia in xenografted mice to study tumor biology and evaluate targeted therapy.

Herman SE, Sun X, McAuley EM, Hsieh MM, Pittaluga S, Raffeld M, Liu D, Keyvanfar K, Chapman CM, Chen J, Buggy JJ, Aue G, Tisdale JF, Pérez-Galán P, Wiestner A - Leukemia (2013)

Ibrutinib inhibits BCR and NF-κB signaling in xenografted CLL cells. Mice treated with vehicle (control) or ibrutinib were sacrificed 3-4 weeks post xenografting. (a) CLL cells of ibrutinib treated mice as compared to untreated control mice (n=6 per treatment group) show decreased expression of representative BCR (left panel) and NF-κB (right panel) target genes (described in 3). Shown is the mean (± SEM) ratio between mRNA levels for each of the indicated genes in CLL cells purified from the spleen of treated as compared to untreated mice. (b) The signature scores for the BCR and NF-κB pathways were computed as the averaged expression of the respective target genes (as in Figure 3a). Shown is the relative expression in CLL cells from the spleen normalized to PB. (c) A representative histogram shows a decrease of BTK phosphorylation (pBTK) in CLL cells of treated mice. Note: pBTK in treated mice is reduced to the level of isotype control. (d) Shown is the mean (± SEM) MFI ratio of pBTK to isotype control in CLL cells from control and ibrutinib treated mice. The multivariable analysis used to test for significance in all panels is described in Materials and Methods.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126654&req=5

Figure 5: Ibrutinib inhibits BCR and NF-κB signaling in xenografted CLL cells. Mice treated with vehicle (control) or ibrutinib were sacrificed 3-4 weeks post xenografting. (a) CLL cells of ibrutinib treated mice as compared to untreated control mice (n=6 per treatment group) show decreased expression of representative BCR (left panel) and NF-κB (right panel) target genes (described in 3). Shown is the mean (± SEM) ratio between mRNA levels for each of the indicated genes in CLL cells purified from the spleen of treated as compared to untreated mice. (b) The signature scores for the BCR and NF-κB pathways were computed as the averaged expression of the respective target genes (as in Figure 3a). Shown is the relative expression in CLL cells from the spleen normalized to PB. (c) A representative histogram shows a decrease of BTK phosphorylation (pBTK) in CLL cells of treated mice. Note: pBTK in treated mice is reduced to the level of isotype control. (d) Shown is the mean (± SEM) MFI ratio of pBTK to isotype control in CLL cells from control and ibrutinib treated mice. The multivariable analysis used to test for significance in all panels is described in Materials and Methods.
Mentions: Next, we sought to determine whether ibrutinib prevents activation of the BCR and NF-κB pathways in CLL cells in vivo. We analyzed tumor cells isolated from murine spleens 3-4 weeks after xenografting and measured expression of representative BCR and NF-κB target genes. Expression of all BCR and of four out of five NF-κB target genes were reduced in CLL cells of the ibrutinib treated mice as compared to control mice (Figure 5a), resulting in a decrease of the BCR and NF-κB gene scores by 61% and 47%, respectively (Figure 5b; P<.05).

Bottom Line: We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-κB signaling in the xenografted cells.Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development.Ibrutinib inhibited BCR and NF-κB signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo.

View Article: PubMed Central - PubMed

Affiliation: Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.

ABSTRACT
Chronic lymphocytic leukemia (CLL) cells depend on microenvironmental factors for proliferation and survival. In particular, the B-cell receptor (BCR) and nuclear factor- κB (NF-κB) pathways are activated in the lymph node (LN) microenvironment. Thus, model systems mimicking tumor-host interactions are important tools to study CLL biology and pathogenesis. We investigated whether the recently established NOD/scid/γc() (NSG) mouse xenograft model can recapitulate the effects of the human microenvironment. We assessed, therefore, tumor characteristics previously defined in LN-resident CLL cells, including proliferation, and activation of the BCR and NF-κB pathways. We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-κB signaling in the xenografted cells. Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development. Ibrutinib inhibited BCR and NF-κB signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo. Thus, our data demonstrate that the SP of xenografted NSG mice can, in part, recapitulate the role of the human LN for CLL cells. In addition, we show that ibrutinib effectively disrupts tumor-host interactions essential for CLL cell proliferation and survival in vivo.

Show MeSH
Related in: MedlinePlus