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Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

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Related in: MedlinePlus

Western blot analysis of effect of nilotinib on the tyrosine kinase activity of Bcr/Abl in vivo. S-5 and S-9 are lymphoma lysates prepared from two mice transplanted with 8093 cells in the nilotinib-treated group 23 hours and 2 hours after the last nilotinib treatment respectively. Lanes A-5, A-21 and 8093 contain lysates prepared from lymphoma cell lines A-5, A-21 and 8093. 8093 is the parental cell line and A-5, A-21 lymphoma cells were isolated from two mice in the nilotinib treatment group and cultured ex vivo. All leukemia cell lysates shown here are from mice, which developed lymphoma during Nilotinib treatment. Membranes were reacted with antibodies indicated below each panel. Arrows indicate the positions of P190 Bcr/Abl, P160 Bcr (endogenous mouse) and phosphorylated and non-phosphorylated Crkl.
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Figure 4: Western blot analysis of effect of nilotinib on the tyrosine kinase activity of Bcr/Abl in vivo. S-5 and S-9 are lymphoma lysates prepared from two mice transplanted with 8093 cells in the nilotinib-treated group 23 hours and 2 hours after the last nilotinib treatment respectively. Lanes A-5, A-21 and 8093 contain lysates prepared from lymphoma cell lines A-5, A-21 and 8093. 8093 is the parental cell line and A-5, A-21 lymphoma cells were isolated from two mice in the nilotinib treatment group and cultured ex vivo. All leukemia cell lysates shown here are from mice, which developed lymphoma during Nilotinib treatment. Membranes were reacted with antibodies indicated below each panel. Arrows indicate the positions of P190 Bcr/Abl, P160 Bcr (endogenous mouse) and phosphorylated and non-phosphorylated Crkl.

Mentions: Nilotinib acts by inhibiting the tyrosine kinase activity of the Bcr/Abl protein, which is essential for Bcr/Abl mediated oncogenic transformation [4-6]. As shown in Fig 4A for one representative sample S9, the tyrosine kinase activity of Bcr/Abl was significantly inhibited 2 hours after nilotinib treatment in vivo but was fully active 23 hours after the treatment, as is evident from sample S5 (Fig. 4A) based on immunoblotting of the lysates with an antibody against phosphotyrosine.


Nilotinib treatment in mouse models of P190 Bcr/Abl lymphoblastic leukemia.

Kaur P, Feldhahn N, Zhang B, Trageser D, Müschen M, Pertz V, Groffen J, Heisterkamp N - Mol. Cancer (2007)

Western blot analysis of effect of nilotinib on the tyrosine kinase activity of Bcr/Abl in vivo. S-5 and S-9 are lymphoma lysates prepared from two mice transplanted with 8093 cells in the nilotinib-treated group 23 hours and 2 hours after the last nilotinib treatment respectively. Lanes A-5, A-21 and 8093 contain lysates prepared from lymphoma cell lines A-5, A-21 and 8093. 8093 is the parental cell line and A-5, A-21 lymphoma cells were isolated from two mice in the nilotinib treatment group and cultured ex vivo. All leukemia cell lysates shown here are from mice, which developed lymphoma during Nilotinib treatment. Membranes were reacted with antibodies indicated below each panel. Arrows indicate the positions of P190 Bcr/Abl, P160 Bcr (endogenous mouse) and phosphorylated and non-phosphorylated Crkl.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2169263&req=5

Figure 4: Western blot analysis of effect of nilotinib on the tyrosine kinase activity of Bcr/Abl in vivo. S-5 and S-9 are lymphoma lysates prepared from two mice transplanted with 8093 cells in the nilotinib-treated group 23 hours and 2 hours after the last nilotinib treatment respectively. Lanes A-5, A-21 and 8093 contain lysates prepared from lymphoma cell lines A-5, A-21 and 8093. 8093 is the parental cell line and A-5, A-21 lymphoma cells were isolated from two mice in the nilotinib treatment group and cultured ex vivo. All leukemia cell lysates shown here are from mice, which developed lymphoma during Nilotinib treatment. Membranes were reacted with antibodies indicated below each panel. Arrows indicate the positions of P190 Bcr/Abl, P160 Bcr (endogenous mouse) and phosphorylated and non-phosphorylated Crkl.
Mentions: Nilotinib acts by inhibiting the tyrosine kinase activity of the Bcr/Abl protein, which is essential for Bcr/Abl mediated oncogenic transformation [4-6]. As shown in Fig 4A for one representative sample S9, the tyrosine kinase activity of Bcr/Abl was significantly inhibited 2 hours after nilotinib treatment in vivo but was fully active 23 hours after the treatment, as is evident from sample S5 (Fig. 4A) based on immunoblotting of the lysates with an antibody against phosphotyrosine.

Bottom Line: In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out.Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced.These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Molecular Carcinogenesis, Division of Hematology/Oncology, Saban Research Institute, Childrens Hospital Los Angeles and the Keck School of Medicine, University of Southern California, Los Angeles, California, USA. pavinder@gmail.com

ABSTRACT

Background: Ph-positive leukemias are caused by the aberrant fusion of the BCR and ABL genes. Nilotinib is a selective Bcr/Abl tyrosine kinase inhibitor related to imatinib, which is widely used to treat chronic myelogenous leukemia. Because Ph-positive acute lymphoblastic leukemia only responds transiently to imatinib therapy, we have used mouse models to test the efficacy of nilotinib against lymphoblastic leukemia caused by the P190 form of Bcr/Abl.

Results: After transplant of 10,000 highly malignant leukemic cells into compatible recipients, untreated mice succumbed to leukemia within 21 days, whereas mice treated with 75 mg/kg nilotinib survived significantly longer. We examined cells from mice that developed leukemia while under treatment for Bcr/Abl kinase domain point mutations but these were not detected. In addition, culture of such cells ex vivo showed that they were as sensitive as the parental cell line to nilotinib but that the presence of stromal support allowed resistant cells to grow out. Nilotinib also exhibited impressive anti-leukemia activity in P190 Bcr/Abl transgenic mice that had developed overt leukemia/lymphoma masses and that otherwise would have been expected to die within 7 days. Visible lymphoma masses disappeared within six days of treatment and leukemic cell numbers in peripheral blood were significantly reduced. Treated mice survived more than 30 days.

Conclusion: These results show that nilotinib has very impressive anti-leukemia activity but that lymphoblastic leukemia cells can become unresponsive to it both in vitro and in vivo through mechanisms that appear to be Bcr/Abl independent.

Show MeSH
Related in: MedlinePlus