RESUMO
The FOXO1 transcription factor plays an essential role in the regulation of proliferation and survival programs at early stages of B-cell differentiation. Here, we show that tightly regulated FOXO1 activity is essential for maintenance of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). Genetic and pharmacological inactivation of FOXO1 in BCP-ALL cell lines produced a strong antileukemic effect associated with CCND3 downregulation. Moreover, we demonstrated that CCND3 expression is critical for BCP-ALL survival and that overexpression of CCND3 protected BCP-ALL cell lines from growth arrest and apoptosis induced by FOXO1 inactivation. Most importantly, pharmacological inhibition of FOXO1 showed antileukemia activity on several primary, patient-derived, pediatric ALL xenografts with effective leukemia reduction in the hematopoietic, lymphoid, and central nervous system organ compartments, ultimately leading to prolonged survival without leukemia reoccurrence in a preclinical in vivo model of BCP-ALL. These results suggest that repression of FOXO1 might be a feasible approach for the treatment of BCP-ALL.
Assuntos
Proteína Forkhead Box O1/genética , Regulação Leucêmica da Expressão Gênica , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Animais , Antineoplásicos/uso terapêutico , Linfócitos B/efeitos dos fármacos , Linfócitos B/metabolismo , Linfócitos B/patologia , Linhagem Celular Tumoral , Ciclina D3/genética , Proteína Forkhead Box O1/antagonistas & inibidores , Proteína Forkhead Box O1/metabolismo , Regulação Leucêmica da Expressão Gênica/efeitos dos fármacos , Humanos , Camundongos Endogâmicos NOD , Camundongos SCID , Leucemia-Linfoma Linfoblástico de Células Precursoras B/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras B/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Quinolonas/uso terapêutico , Transdução de Sinais/efeitos dos fármacosRESUMO
Recently we reported that intact apoptosis signaling is indicative of favorable outcome in childhood acute lymphoblastic leukemia. Here we addressed this issue in 45 pediatric acute myeloid leukemia patients analyzing 2 core apoptogenic events: cytochrome c release and caspase-3 activation. In patients with good prognosis cytochrome c release was clearly found to be caspasedependent and correlated with activated caspase-3, indicating that activation of initiator or amplifier caspases such as caspase-8 together with an intact apoptosome function are elementary for favorable outcome. The functional integrity of this apoptogenic checkpoint is reflected by the parameter caspase-dependent cytochrome c-related activation of caspase-3 (CRAC(dep)). Patients with positive CRAC(dep) values (intact signaling) exhibited superior survival compared with CRAC(dep) negative patients (deficient signaling). Thus, the propensity to undergo apoptosis of leukemia cells is an important feature for favorable treatment outcome and may serve as an additional stratification tool for pediatric AML patients. This trial was registered at www.ClinicalTrials.gov as #NCT00111345.