In vivo antiproliferative effect of NS-187, a dual Bcr-Abl/Lyn tyrosine kinase inhibitor, on leukemic cells harbouring Abl kinase domain mutations
ABSTRACT Advanced-phase chronic myeloid leukemia patients treated with imatinib often relapse due to point mutations in the Abl kinase domain. We herein examine the in vitro and in vivo effects of a Bcr-Abl/Lyn dual tyrosine kinase inhibitor, NS-187, on seven mutated Bcr-Abl proteins. NS-187 inhibited both Tyr393-phosphorylated and Tyr393-unphosphorylated Abl, resulting in significant in vitro growth inhibition of cells expressing six of seven mutated Bcr-Abl kinases, though not T315I. Furthermore, NS-187 prolonged the survival of mice injected with leukemic cells expressing all mutated Bcr-Abl tested except T315I, and its efficacy correlated well with its in vitro effects.
- SourceAvailable from: Junya Kuroda
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- "Cell lines and reagents BV173, KT-1, KCL22, MYL, K562 and MEG-01 are cell lines derived from CML patients in blast crisis phase. Generation of multidrug resistant K562/D1-9, K562 subclones artificially overexpressing FLAG-tagged Bcl-2 (K562/Bcl-2) or Bcl-X L (K562/Bcl-X L ), transformed Ba/F3-derived haematopoietic cell lines Ba/F3/wt (bearing wild-type Bcr-Abl), Ba/F3/ E255K (mutated Bcr-Abl E255K ) and Ba/F3/T315I (Bcr-Ab- l T315I ) were described elsewhere (Urasaki et al, 1996; Kimura et al, 2005; Kuroda et al, 2006; Naito et al, 2006). IMresistant K562/IMR and MYL-R, expressing higher levels of Bcr-Abl protein, were generated by continuously exposing K562 and MYL, respectively, to 1 lmol/l IM (Ito et al, 2007). "
ABSTRACT: The effect of ABT-737, a BH3-mimicking inhibitor for anti-apoptotic Bcl-2 and Bcl-X(L), but not Mcl-1, against Bcr-Abl-positive (Bcr-Abl(+)) leukaemic cells was examined. ABT-737 potently induced apoptosis in Bcr-Abl(+) chronic myeloid leukaemia (CML) cell lines and primary CML samples in vitro and prolonged the survival of mice xenografted with BV173 cells, a CML cell line. Higher expression of anti-apoptotic Bcl-2 proteins reduced cell killing by ABT-737 in each cell line, but there was no correlation between the sensitivities to ABT-737 and the specific expression patterns of Bcl-2 family proteins among cell lines. Thus, the cell killing effect of ABT-737 must be determined not only by the expression patterns of Bcl-2 family proteins but also by other mechanisms, such as high expression of Bcr-Abl, or a drug-efflux pump, in CML cells. ABT-737 augmented the cell killing effect of imatinib in Bcr-Abl(+) cells with diverse drug-resistance mechanisms unless leukaemic cells harboured imatinib-insensitive Abl kinase domain mutations, such as T315I. The combination of homoharringtonine that reduces Mcl-1 enhanced the killing by ABT-737 strongly in Bcr-Abl(+) cells even with T315I mutation. These results suggest that ABT-737 is a useful component of chemotherapies for CML with diverse drug-resistance mechanisms.British Journal of Haematology 02/2008; 140(2):181-90. DOI:10.1111/j.1365-2141.2007.06899.x · 4.96 Impact Factor
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ABSTRACT: Imatinib mesylate (Gleevec™) has improved the treatment of Bcr-Abl-positive leukemia. However, resistance is often reported in patients with advanced-stage disease. Chemical modifications of imatinib made with the guidance of molecular modeling have yielded several promising compounds that could override imatinib resistance. Among them, we selected a compound denoted NS-187. The most striking structural characteristic of NS-187 is its trifluoromethyl group at position 3 of the benzamide ring, which strengthens the hydrophobic interactions and fixes the conformation of the compound. NS-187 was 25–55 times more potent than imatinib against wild-type Bcr-Abl in vitro. At physiological concentrations, NS-187 also inhibited the phosphorylation and growth of all Bcr-Abl mutants tested except T315I. In addition to Bcr-Abl, NS-187 also inhibited Lyn, which might be involved in imatinib resistance, without affecting the phosphorylation of Src, Blk, or Yes. This indicates that NS-187 acts as a dual Bcr-Abl/Lyn inhibitor. Our proposed docking models of the NS-187/Abl complex support the notion that NS-187 is more specific for Lyn than for Src. In Balb/c-nu/nu mice, which were injected subcutaneously with Bcr-Abl-positive KU812 cells, NS-187 showed at least tenfold more potency than imatinib. We also tested the ability of NS-187 to suppress tumor growth in another murine tumor model, namely, Balb/c-nu/nu mice intravenously transplanted with BaF3 cells harboring wild-type or several mutations of Bcr-Abl (M244V, G250E, Q252H, Y253F, E255K, T315I, M351T, and H396P). NS-187 prolonged the survival of mice injected with leukemic cells expressing wild-type or all mutated Bcr-Abl except T315I, and its efficacy correlated well with its in vitro effects. NS-187 also inhibited leukemic cells harboring wild-type Bcr-Abl growth in the central nervous system, which sometimes becomes a sanctuary for leukemic cells under imatinib treatment. These results suggest that NS-187 may be a potentially valuable novel agent to combat imatinib-resistant Bcr-Abl-positive leukemia. A phase I study of NS-187 will start in 2006.Cancer Chemotherapy and Pharmacology 10/2006; 58:55-61. DOI:10.1007/s00280-006-0317-3 · 2.57 Impact Factor
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ABSTRACT: c-Src was the first protooncogene described and was among the first molecules in which tyrosine kinase activity was documented. c-Src has been defined as a common modular structure that participates in much of the crosstalk between the cytoplasmic protein tyrosine kinases and tyrosine kinase receptors. Understanding the structure and function of this important class of protein kinases and elucidating the molecular signaling events mediated by c-Src are important not only for identifying the critical pathways but also for designing new strategies to block or inhibit the action of these kinases. Despite the large amount of information available on c-Src, its precise functions in cancer remain to be elucidated. Recently, there has been renewed interest in c-Src as a molecular target for cancer therapy, and multiple c-Src inhibitors are entering clinical trials. In this review, the authors describe the function and expression of c-Src in human malignancies and the novel c-Src inhibitors and their potential applications for cancer treatment.Cancer 11/2006; 107(8):1918-29. DOI:10.1002/cncr.22215 · 4.90 Impact Factor