[Show abstract][Hide abstract]ABSTRACT: The myelodysplastic syndromes (MDS) are a group of stem cell disorders characterized by dysplasia of one or more hematopoietic cell lineages and a risk of progression to acute myeloid leukemia. The cytidine analog azacitidine (Vidaza), a hypomethylating agent, improves survival in patients with MDS, but its mechanism of action is not well understood.
The effects of azacitidine on the MDS-derived cell line SKM-1 were investigated by DNA methylation assay, cell proliferation assay, and a subcutaneous xenograft mouse model.
Azacitidine and decitabine induced hypomethylation of the tumor suppressor gene cyclin-dependent kinase 4 inhibitor B (CDKN2B) in SKM-1 cells, whereas the deoxycytidine analog cytarabine did not. Azacitidine and decitabine also inhibited SKM-1 cell growth in vitro. In the mouse xenograft model, azacitidine significantly suppressed tumor growth.
Inhibition of DNA methyltransferase by azacitidine contributes to its antiproliferative and antitumor effects against SKM-1 cells and may explain its clinical efficacy in MDS.
Preview · Article · Mar 2012 · Anticancer research
[Show abstract][Hide abstract]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.
No preview · Article · Dec 2006 · Leukemia Research
[Show abstract][Hide abstract]ABSTRACT: Although the Abelson (Abl) tyrosine kinase inhibitor imatinib mesylate has improved the treatment of breakpoint cluster region-Abl (Bcr-Abl)-positive leukemia, resistance is often reported in patients with advanced-stage disease. Although several Src inhibitors are more effective than imatinib and simultaneously inhibit Lyn, whose overexpression is associated with imatinib resistance, these inhibitors are less specific than imatinib. We have identified a specific dual Abl-Lyn inhibitor, NS-187 (elsewhere described as CNS-9), which is 25 to 55 times more potent than imatinib in vitro. NS-187 is also at least 10 times as effective as imatinib in suppressing the growth of Bcr-Abl-bearing tumors and markedly extends the survival of mice bearing such tumors. The inhibitory effect of NS-187 extends to 12 of 13 Bcr-Abl proteins with mutations in their kinase domain but not to T315I. NS-187 also inhibits Lyn without affecting the phosphorylation of Src, Blk, or Yes. These results suggest that NS-187 may be a potentially valuable novel agent to combat imatinib-resistant Philadelphia-positive (Ph+) leukemia.