Emergence of resistance to Tyrosine-Kinase Inhibitors (TKIs), such as imatinib, dasatinib and nilotinib, in Chronic Myelogenous Leukemia (CML) demands new therapeutic strategies. We and others have previously established bortezomib, a selective proteasome inhibitor, as an important potential treatment in CML. Here we show that the combined regimens of bortezomib with mitotic inhibitors, such as...

The BCR/ABL detection in uences diagnosis, prognosis and treatment decisions in patients with chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL). We studied the feasibility and the sensitivity of LSI BCR/ABL dual-colour, dual-fusion probe as a usual assay for detection BCR-ABL gene fusion in acute leukemia. A total of 3229 successfully hybridized interphase nuclei from 34 new...

The bcr-abl chimeric oncoprotein exhibits deregulated protein tyrosine kinase activity and is implicated in the pathogenesis of Philadelphia chromosome (Ph)-positive human leukemias, such as chronic myelogenous leukemia (CML). Recently we have shown that the levels of the protein tyrosine phosphatase PTP1B are enhanced in p210 bcr-abl-expressing cell lines. Furthermore, PTP1B recognizes p210 bc...

The persistence of Bcr-Abl-positive cells in patients on imatinib therapy indicates that inhibition of the Bcr-Abl kinase activity alone might not be sufficient to eradicate the leukemia cells. Many downstream effectors of Bcr-Abl have been described, including activation of both the Grb2-SoS-Ras-MAPK and Grb2-Gab2-PI3K-Akt pathways. The Bcr-Abl-Grb2 interaction, which is mediated by the direct...

The present study was undertaken to estimate the therapeutic benefit to down-regulate the Na(+)/H(+) exchanger 1 (NHE1) for reversing chemoresistance of BCR-ABL-positive leukemia patient cells and cell lines. As a result, after treatment with specific NHE1 inhibitor Cariporide or high K(+) buffer to decrease intracellular pH (pH(i)), cells from relapsed patients exhibited decreased Pgp level, e...

We report a case of a successful mobilization and harvest of the peripheral blood stem cells (PBSCs) in imatinib-pretreated and nilotinib treated 52-year-old woman diagnosed with Philadelphia chromosome-positive and BCR-ABL (b2a2) positive chronic phase CML in 2/2002. She failed interferon-alfa and imatinib treatment. She achieved her first complete molecular remission after 16 months of niloti...

In the article by Lee et al. (1), an alternative splicing of BCR-ABL is proposed as a mechanism for imatinib resistance in chronic myeloid leukemia (CML) patients. This splicing (2), which inserts 35 bp between exons 8 and 9 of ABL (35INS), results in a truncated BCRABL protein that the authors compare dynamically with the native protein. We found their work very relevant, especially the findin...

Interactions between the Bcr-Abl kinase inhibitor STI-571 (imatinib mesylate) and a novel microtubule-targeting agent (MTA), pyrrolo-1,5-benzoxazepine (PBOX)-6, were investigated in STI-571-sensitive and -resistant human chronic myeloid leukemia (CML) cells. Cotreatment of PBOX-6 with STI-571 induced significantly more apoptosis in Bcr-Abl-positive CML cell lines (K562 and LAMA-84) than either ...

The first exon of the BCR gene encodes a new serine/threonine protein kinase. Abnormal fusion of the BCR and ABL genes, resulting from the formation of the Philadelphia chromosome (Ph), is the hallmark of Ph-positive leukemia. We have previously demonstrated that the Bcr protein is tyrosine phosphorylated within first-exon sequences by the Bcr-Abl oncoprotein. Here we report that in addition to...

The potency of Abelson (ABL) tyrosine kinase inhibitors (TKIs) against chronic myeloid leukemia (CML) has been demonstrated. However, ABL TKI resistance can develop. In this study, we investigated the efficacy of a combination therapy including rigosertib (ON 01910.Na), a polo-like kinase (PLK) and phosphoinositide 3-kinase (PI3K) inhibitor, and ABL TKIs. A 72-h rigosertib treatment was found t...