RESUMEN
Morgana is a ubiquitous HSP90 co-chaperone protein coded by the CHORDC1 gene. Morgana heterozygous mice develop with age a myeloid malignancy resembling human atypical myeloid leukemia (aCML), now renamed MDS/MPN with neutrophilia. Patients affected by this pathology exhibit low Morgana levels in the bone marrow (BM), suggesting that Morgana downregulation plays a causative role in the human malignancy. A decrease in Morgana expression levels is also evident in the BM of a subgroup of Philadelphia-positive (Ph+) chronic myeloid leukemia (CML) patients showing resistance or an incomplete response to imatinib. Despite the relevance of these data, the mechanism through which Morgana expression is downregulated in patients' bone marrow remains unclear. In this study, we investigated the possibility that Morgana expression is regulated by miRNAs and we demonstrated that Morgana is under the control of four miRNAs (miR-15a/b and miR-26a/b) and that miR-15a may account for Morgana downregulation in CML patients.
Asunto(s)
Proteínas HSP90 de Choque Térmico , Leucemia Mielógena Crónica BCR-ABL Positiva , MicroARNs , Animales , Humanos , Ratones , Médula Ósea/metabolismo , Médula Ósea/patología , Regulación hacia Abajo , Regulación Leucémica de la Expresión Génica , Proteínas HSP90 de Choque Térmico/metabolismo , Proteínas HSP90 de Choque Térmico/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , MicroARNs/genética , MicroARNs/metabolismo , Chaperonas Moleculares/metabolismo , Chaperonas Moleculares/genéticaRESUMEN
Impressive response rates and the good tolerability have allowed imatinib to become the gold standard frontline therapy for all CML patients in the early chronic phase. Optimal outcomes are attained with more than two thirds of the CML cases treated with standard dose imatinib (400 mg daily). Criteria to establish failure and suboptimal responses to imatinib have been defined. Treatment guidelines have also suggested imatinib dose escalation based on clinical assessments of disease response. However, despite all the effort to optimize therapy with imatinib, cases of real resistance exist. For imatinib resistant and intolerant cases, second generation powerful tyrosine kinase inhibitors (TKIs) have been developed and registered. Sequential kinase inhibitor therapy is used to overcome resistance however, a future strategy might be a combination therapy with different ABL kinase inhibitors in the same therapeutic scheme, used sequentially or simultaneousl.
Respostas impressionantes e boa tolerância transformaram o imatinibe no "padrão ouro" de tratamento de primeira linha na LMC em fase crônica precoce. Evolução favorável em mais de 2/3 dos pacientes com LMC é obtida com dose standard de 400 mg por dia. Critérios para estabelecer falha de tratamento e resposta "sub-ótima" têm sido definidos. Guidelines têm sugerido que o escalonamento da dose do imatinibe possa melhorar a resposta em subgrupo de pacientes. Entretanto, a despeito de todos os esforços para otimizar a resposta ao imatinibe, casos de resistência realmente existem. Para os casos de intolerância ou resistência ao imatinibe, inibidores potentes de segunda geração foram desenvolvidos e registrados (nilotinibe e dasatinibe). Além disto, terapêutica sequencial de inibidores podem ultrapassar a resistência, e a terapia combinada usada sequencialmente ou simultaneamente pode ser usada como estratégia futura.