Galangin increases the cytotoxic activity of imatinib mesylate in imatinib-sensitive and imatinib-resistant Bcr-Abl expressing leukemia cells

The in vitro effect of sintamil, as a modulator alone and in combination with hydroxyurea (HU), on cytotoxicity was studied in 16 cases of human chronic myeloid leukemia (CML). We investigated the cytotoxicity of the drugs as a function of the exposure dose (HU, 10−4 M; sintamil, 10 μg/ml) and the exposure time (1 h) to the agent. Cytotoxicity was evaluated as the inhibition of incorporation of [3H-methyl]thymidine in the nucleic acids of CML cells. Cytotoxicity of HU was greatly enhanced (P < 0.001) by 1 h exposure of the CML cells to sintamil. The present data indicate that sintamil potentiates the cytotoxic activity of HU in CML cells.

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New Humulenes from Hyptis incana (Labiatae)

Natural Product Communications ◽

10.1177/1934578x1300801201 ◽

2013 ◽

Vol 8 (12) ◽

pp. 1934578X1300801

Author(s):

Mitsuru Satoh ◽

Yoshio Satoh ◽

Yasuhiro Anzai ◽

Daisuke Ajisawa ◽

Keiichi Matsuzaki ◽

...

Keyword(s):

Cytotoxic Activity ◽

Inhibitory Activity ◽

Leukemia Cells ◽

Moderate Activity ◽

Mouse Leukemia ◽

Aerial Parts ◽

Growth Inhibitory ◽

Growth Inhibitory Activity ◽

Potent Growth

Two new humulene-type sesquiterpenes, named hyptishumulene I (1) and II (2), have been isolated, together with eight known compounds, a humulene-type sesquiterpene (3), a monoterpene (4) and six abietane-type diterpenoids (5–10) from the aerial parts of Hyptis incana (Labiatae). The cytotoxic activity of the isolated compounds against mouse leukemia cells (L1210) was examined. The abietane-type diterpenoids (5–10) showed rather potent growth inhibitory activity (IC50<15 μM), while the new humulene-type compounds (1 and 2) exhibited moderate activity (IC50>50 μM).

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t(8;21)-Positive AML with Mutant Kit Is a Novel Therapeutic Target of Imatinib Mesylate.

Blood ◽

10.1182/blood.v104.11.1164.1164 ◽

2004 ◽

Vol 104 (11) ◽

pp. 1164-1164

Author(s):

Hiroya Asou ◽

Taiichi Kyo ◽

Toshiya Inaba

Keyword(s):

Mast Cell ◽

Imatinib Mesylate ◽

Therapeutic Target ◽

Kinase Domain ◽

Leukemia Cells ◽

Human Mast Cell ◽

Cell Leukemia ◽

Short Term ◽

Kit Mutation ◽

Mast Cell Leukemia

Abstract Point mutations in the kinase domain of c-Kit are frequently associated with t(8;21)-acute myeloid leukemia (AML). In our study, eleven (26 %) of 43 patients had mutations: six Asp816Val, two Asp816Tyr, one Asp816Ala, one Asp816His, and one Asn822Lys. Here, we provide evidences that proliferation of leukemia cells expressing both the AML1-ETO chimera and a c-Kit mutation heavily depends on signals originating from mutated c-Kit, and this mutation is a possible therapeutic target for imatinib mesylate. We initially investigated effects of imatinib on the growth of the Kasumi-1 cell line, which harbors both t(8;21) and a c-Kit kinase domain mutation (Asn822Lys). Imatinib inhibited autophosphorylation of c-Kit at the standard concentration (0.1 μM), and induced cell cycle arrest and apoptosis in an even faster time course than Ph1-positive cell lines treated with this drug. By contrast, growth of SKNO-1, another t(8;21)-positive leukemia cells without c-Kit mutation was not affected by imatinib. To test whether imatinib is effective for Asp816 c-Kit mutants, we isolated t(8;21)-positive fresh leukemia cells from untreated patients. Numbers of cells with an Asp816 mutant from four patients after short-term cultures in the presence of imatinib (0.1 μM, 4 days) were 20–30 % of those in the absence of imatinib, while no significant difference was observed for cells isolated from four patients without c-Kit mutation. (Viability of fresh leukemia cells without imatinib was maintained over 80% during this short-term culture.) Moreover, autophosphorylation of mutated c-Kit in leukemia cells from one patient with an Asp816 mutant was inhibited by imatinib. Our results disagree with those of previous studies, which indicated that cells with c-Kit mutations in the kinase domain are resistant to imatinib in murine IL-3-dependent cells and human mast cell leukemia cells. This discrepancy could be explained by high expression levels of c-Kit mutants in IL-3-dependent cells by powerful ectopic promoters, since overexpression of Bcr-Abl kinase is one of the major causes of resistance to imatinib in the treatment of CML patients. In addition, drug metabolism may be different between human t(8;21)-positive leukemia cells and in murine IL-3-dependent cells or mast cell leukemia cells. Although t(8;21) in AML represents a favorable prognostic indicator for achievement of cure, a substantial number of these patients relapse and eventually die of their disease. Indeed, of five patients harboring both t(8;21) and c-Kit mutations who we identified and followed up for more than five years, four relapsed. Therefore, our results suggest that imatinib would be useful for eliminating minimal residual disease in these patients after achievement of complete remission.

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CD40-Activation of Chronic Lymphocytic Leukemia Cells Induces Latent Sensitivity to Fas/TRAIL-Mediated Apoptosis Via a P53-Independent, C-Abl-Dependent Pathway.

Blood ◽

10.1182/blood.v104.11.342.342 ◽

2004 ◽

Vol 104 (11) ◽

pp. 342-342 ◽

Cited By ~ 1

Author(s):

Arnon P. Kater ◽

Frank Dicker ◽

Tetsuya Fukuda ◽

Thomas J. Kipps

Keyword(s):

Gene Therapy ◽

Imatinib Mesylate ◽

Leukemia Cell ◽

Lymphocytic Leukemia ◽

Leukemia Cells ◽

Cd40 Ligation ◽

Γ Radiation ◽

Abl Kinase ◽

Cd40 Activation ◽

Inactivating Mutations

Abstract Patients with chronic lymphocytic leukemia (CLL) experienced rapid reductions in leukemia cell count and lymph node size following an intravenous infusion of autologous CLL cells that were transduced to express a recombinant ligand for CD40 (CD154), including patients with leukemia cells that had inactivating mutations in P53 . Subsequent studies demonstrated that ligation of CD40 on CLL cells induced latent sensitivity to Fas (CD95)-dependent apoptosis and that this might account, in part, for the early reductions in leukemia cell counts observed in patients treated with CD154 gene therapy (Proc Natl Acad Sci U S A 100:3854–9, 2002). We found that ligation of CD40 induces CLL cells to express P53, as well as P53-dependent genes encoding CD95, DR5, and p21. Similar effects were observed following treatment of CLL cells with γ-radiation. In contrast to the effects of γ-radiation, however, CD40-ligation also induced CLL cells to express high-levels of Bid, a pro-apoptotic protein that mediates cross talk between extrinsic death receptors and mitochondrial-dependent apoptotic pathways. CLL cells that had inactivating mutations in P53 also were induced to express CD95, DR5, p21, and Bid following CD40-ligation, but not following γ-radiation, demonstrating that the gene expression response to CD40-ligation is dependent on a factor(s) other than p53. A good candidate for this is P73, a member of the P53 gene family that has been implicated in lymphocyte activation-induced cell death. Consistent with this notion, we found that ligation of CD40 on CLL cells induced expression of the α isoform of P73. The induction of P73 and latent sensitivity to CD95 (and TRAIL)-mediated apoptosis could be inhibited with the c-abl kinase inhibitor, imatinib mesylate, when added at the time of CD40-ligation. However, transduction of leukemia cells with a mutant gene encoding a c-abl kinase resistant to imatinib mesylate resulted in CLL cells that could be induced by CD40-ligation to express P73 and Bid even in the presence of imatinib mesylate. We conclude that sensitization to CD95-mediated apoptosis following CD40-activation is via a p53-independent, c-abl-kinase dependent process that is associated with activation of p73. Unlike p53, p73 mutations are extremely rare in human cancer. As such, CD154-based immune gene therapy may have activity even in patients who have CLL cells with dysfunctional P53 that are resistant to many of the anti-leukemia drugs currently used in the treatment of this disease.

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Constitutive Activation of SRC-Family Kinases in Chronic Myelogenous Leukemia Patients Resistant to Imatinib Mesylate in the Absence of BCR-ABL Mutations: A Rationale for Use of SRC/ABL Dual Kinase Inhibitor-Based Therapy.

Blood ◽

10.1182/blood.v106.11.1087.1087 ◽

2005 ◽

Vol 106 (11) ◽

pp. 1087-1087 ◽

Cited By ~ 1

Author(s):

Nicholas J. Donato ◽

Ji Wu ◽

Ling-Yuan Kong ◽

Feng Meng ◽

Francis Lee ◽

...

Keyword(s):

Cell Survival ◽

Imatinib Mesylate ◽

Src Family Kinases ◽

Myelogenous Leukemia ◽

Leukemic Cells ◽

Imatinib Resistance ◽

Kinase Activation ◽

Abl Kinase ◽

Lyn Kinase ◽

Imatinib Resistant

Abstract BCR-ABL is an unregulated tyrosine kinase expressed as a consequence of a reciprocal chromosomal translocation that is common in chronic myelogenous and acute lymphocytic leukemia. BCR-ABL induces transformation of hematopoetic stem cells through tyrosine phosphorylation of multiple substrates. The src-family kinases (SFKs), Lyn and Hck, are highly activated by BCR-ABL in leukemic cells and recent studies suggest that they are substrates and essential mediators of BCR-ABL signal transduction and transformation. In cells selected for resistance to the BCR-ABL inhibitor, imatinib mesylate, Lyn kinase is overexpressed and its activation is not dependent on or regulated by BCR-ABL, suggesting that autonomous regulation of SFKs may play a role in imatinib resistant. In this report, activation of Lyn and Hck was compared in CML specimens derived from imatinib responsive and resistant patients that did not express a mutant BCR-ABL protein as their primary mediator of resistance. In imatinib sensitive cell lines and specimens derived from imatinib responsive CML patients imatinib effectively reduced activation of both BCR-ABL and SFKs. However, in multiple specimens from resistant patients, imatinib reduced BCR-ABL kinase activation but failed to reduce SFK activation. The dual ABL/SRC inhibitor, BMS-354825, blocked activation of both BCR-ABL and SFKs expressed in leukemic cells and correlated with clinical responsiveness to this agent. Animal models demonstrated that loss of imatinib-mediated inhibition of Lyn kinase activation significantly impaired its anti-tumor activity which was recovered by treatment with BMS-354825. Direct silencing of Lyn or Hck reduced CML cell survival in imatinib resistant patient specimens and cell models, suggesting a direct role for these kinases in cell survival. Our results show that SFK activation is mediated by BCR-ABL in imatinib responsive cells but these kinases escape control by BCR-ABL in CML patients that develop imatinib resistance in the absence of BCR-ABL point mutations. This form of resistance can effectively be overcome by BMS-354825 through its dual SRC and ABL kinase inhibitory activities. Dual specificity kinase inhibitors may be indicated for the treatment and prevention of imatinib resistance in CML when it is associated with constitutively activated src-family kinases.

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