RESUMO
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 imatinibresistant 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.
Assuntos
Cálcio/metabolismo , Homeostase/efeitos dos fármacos , Mesilato de Imatinib/farmacologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Proteoma/metabolismo , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteínas de Fusão bcr-abl/metabolismo , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Mutação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Proteômica/métodos , Transdução de Sinais/efeitos dos fármacosAssuntos
Análise Mutacional de DNA/métodos , Resistencia a Medicamentos Antineoplásicos/genética , Proteínas de Fusão bcr-abl/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Adulto , Idoso , Antineoplásicos/uso terapêutico , Feminino , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia/diagnóstico , Recidiva Local de Neoplasia/genética , Neoplasia Residual/diagnóstico , Neoplasia Residual/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/diagnóstico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Inibidores de Proteínas Quinases/uso terapêuticoRESUMO
Barley alpha-amylase variability influences the quality of barley grain in the brewing, feed and food industries. alpha-Amylase proteins are encoded by multigene families in cereals, and this study focused on the barley Amy32b gene. We identified coding region single nucleotide polymorphism (cSNP) and insertion/deletion variation in DNA sequences, which resulted in amino acid substitution and stop codon formation, respectively. The substitution affected the beta1 strand in domain C, whereas the stop codon removed the beta5 strand. Possible effects of these changes on the protein are discussed. A cSNP in the coding region of the Amy32b gene was used as a specific marker to map Amy32b loci on chromosome 7H.