Chronic myeloid leukemia (CML) therapy has markedly improved patient prognosis after introduction of imatinib mesylate for clinical use. However, a subset of patients develops resistance to imatinib and other tyrosine kinase inhibitors (TKIs), mainly due to point mutations in the region encoding the kinase domain of the fused BCR-ABL oncogene. To identify potential therapeutic targets in imatinib‑resistant CML cells, we derived imatinib-resistant CML-T1 human cell line clone (CML-T1/IR) by prolonged exposure to imatinib in growth media. Mutational analysis revealed that the Y235H mutation in BCR-ABL is probably the main cause of CML-T1/IR resistance to imatinib. To identify alternative therapeutic targets for selective elimination of imatinib-resistant cells, we compared the proteome profiles of CML-T1 and CML-T1/IR cells using 2-DE-MS. We identified eight differentially expressed proteins, with strongly upregulated Na+/H+ exchanger regulatory factor 1 (NHERF1) in the resistant cells, suggesting that this protein may influence cytosolic pH, Ca2+ concentration or signaling pathways such as Wnt in CML-T1/IR cells. We tested several compounds including drugs in clinical use that interfere with the aforementioned processes and tested their relative toxicity to CML-T1 and CML-T1/IR cells. Calcium channel blockers, calcium signaling antagonists and modulators of calcium homeostasis, namely thapsigargin, ionomycin, verapamil, carboxyamidotriazole and immunosuppressive drugs cyclosporine A and tacrolimus (FK-506) were selectively toxic to CML-T1/IR cells. The putative cellular targets of these compounds in CML-T1/IR cells are postulated in this study. We propose that Ca2+ homeostasis can be a potential therapeutic target in CML cells resistant to TKIs. We demonstrate that a proteomic approach may be used to characterize a TKI-resistant population of CML cells enabling future individualized treatment options for patients.

• MeSH
• bcr-abl fúzní proteiny metabolismus   MeSH
• chemorezistence účinky léků   MeSH
• chronická myeloidní leukemie farmakoterapie   metabolismus   MeSH
• homeostáza účinky léků   MeSH
• imatinib mesylát farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• mutace účinky léků   MeSH
• nádorové buněčné linie MeSH
• proteom metabolismus   MeSH
• proteomika metody   MeSH
• signální transdukce účinky léků   MeSH
• vápník metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bcr-abl fúzní proteiny MeSH
• imatinib mesylát MeSH
• inhibitory proteinkinas MeSH
• proteom MeSH
• vápník MeSH

BACKGROUND AND OBJECTIVE: The availability of different tyrosine kinase inhibitors (TKIs) with distinct anti-leukemic potency enables optimization of current therapeutic regimens; however, some patients lose their therapy response and acquire TKI resistance. In this study, we describe a single-center experience of monitoring BCR-ABL1 kinase domain (KD) mutations and discuss the impact of treatment on mutation selection. METHODS: Chronic myelogenous leukemia (CML) patients treated with TKIs at the Department of Internal Medicine-Hematology and Oncology, Masaryk University and University Hospital Brno during 2003-2011 were included in this study. A total number of 100 patients who did not achieve an optimal therapy response or who lost their therapy response were screened for the presence of BCR-ABL1 KD mutations, using direct sequencing. RESULTS: Our data show that pretreatment with non-specific non-TKI drugs prior to TKI therapy does not preferentially select for initial BCR-ABL1 KD mutations, in contrast to first-line imatinib therapy, which shows a clear predominance of T315I or P-loop mutations compared with mutations located in other KD regions. In addition, the median time to detection of P-loop mutations was substantially shorter in patients treated with first-line imatinib than in those pretreated with non-TKI drugs. Furthermore, analysis of CML patients who had recurrent resistance to TKI therapy revealed possible therapy-driven selection of BCR-ABL1 KD mutations. Finally, we confirm the previously described poor prognosis of CML patients with mutations in the BCR-ABL1 KD, since 40.0% of our CML patients who harbored a BCR-ABL1 KD mutation died from CML while receiving TKI treatment. Moreover, among the patients who are still on treatment, 27.8% have already progressed. Our data also confirm the unique position of the T315I mutation with respect to its strong resistance to currently approved TKIs. CONCLUSION: On the basis of the 'real-life' data described in this study, it is possible that the therapy itself results in its failure and selects the most resistant mutations under the selective pressure of the applied therapy regimen in some CML patients who harbor BCR-ABL1 KD mutations.

• MeSH
• bcr-abl fúzní proteiny genetika   MeSH
• chronická myeloidní leukemie farmakoterapie   genetika   MeSH
• dospělí MeSH
• inhibitory proteinkinas terapeutické užití   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mutace MeSH
• protinádorové látky terapeutické užití   MeSH
• senioři MeSH
• tyrosinkinasy genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bcr-abl fúzní proteiny MeSH
• inhibitory proteinkinas MeSH
• protinádorové látky MeSH
• tyrosinkinasy MeSH

BACKGROUND AND OBJECTIVE: It has been shown that the occurrence of the BCR-ABL1 T315I mutation leads to a very poor therapeutic outcome in chronic myelogenous leukemia (CML) patients treated with tyrosine kinase inhibitors. Therefore, early detection of this mutation could potentially lead to early therapeutic intervention and a better prognosis with the ongoing treatment regimen. METHODS: The detection of BCR-ABL1 kinase domain (KD) mutations was performed by direct sequencing of peripheral blood (PB), total bone marrow (BM), and BM CD34+ cells from a reported CML patient. RESULTS: In this patient, the T315I mutation was detected in BM CD34+ cells 6 months prior to its emergence in PB, suggesting evolution and expansion of the T315I mutation clone, which most likely originated from more primitive CML cells. CONCLUSION: Our finding reflects the natural development of a T315I mutation within the hematopoietic system of the reported patient and indicates the importance of BCR-ABL1 mutation monitoring in more primitive cell populations. Considering the natural history of T315I development in this reported CML case, we hypothesize that BCR-ABL1 KD mutations may be pre-concentrated in more primitive CML cells, which subsequently expand into the PB. These findings may have future implications for the strategy used for detecting BCR-ABL1 mutations.

• MeSH
• antigeny CD34 analýza   MeSH
• bcr-abl fúzní proteiny genetika   MeSH
• benzamidy MeSH
• buňky kostní dřeně cytologie   enzymologie   MeSH
• chronická myeloidní leukemie krev   farmakoterapie   genetika   MeSH
• hydroxymočovina terapeutické užití   MeSH
• imatinib mesylát MeSH
• lidé MeSH
• mutace MeSH
• piperaziny terapeutické užití   MeSH
• progrese nemoci MeSH
• protinádorové látky terapeutické užití   MeSH
• pyrimidiny terapeutické užití   MeSH
• senioři MeSH
• tyrosinkinasy genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny CD34 MeSH
• bcr-abl fúzní proteiny MeSH
• benzamidy MeSH
• hydroxymočovina MeSH
• imatinib mesylát MeSH
• nilotinib MeSH Prohlížeč
• piperaziny MeSH
• protinádorové látky MeSH
• pyrimidiny MeSH
• tyrosinkinasy MeSH