RESUMEN
BACKGROUND: The tumor suppressor protein phosphatase and tensin homolog (PTEN) is a key regulator of the PI3K/AKT pathway which is frequently altered in a variety of tumors including a subset of acute B-lymphoblastic leukemias (B-ALL). While PTEN mutations and deletions are rare in B-ALL, promoter hypermethylation and posttranslational modifications are the main pathways of PTEN inactivation. Casein Kinase II (CK2) is often upregulated in B-ALL and phosphorylates both PTEN and DNA methyltransferase 3A, resulting in increased PI3K/AKT signaling and offering a potential mechanism for further regulation of tumor-related pathways. METHODS: Here, we evaluated the effects of CK2 inhibitor CX-4945 alone and in combination with hypomethylating agent decitabine on B-ALL proliferation and PI3K/AKT pathway activation. We further investigated if CX-4945 intensified decitabine-induced hypomethylation and identified aberrantly methylated biological processes after CK2 inhibition. In vivo tumor cell proliferation in cell line and patient derived xenografts was assessed by longitudinal full body bioluminescence imaging and peripheral blood flow cytometry of NSG mice. RESULTS: CX-4945 incubation resulted in CK2 inhibition and PI3K pathway downregulation thereby inducing apoptosis and anti-proliferative effects. CX-4945 further affected methylation patterns of tumor-related transcription factors and regulators of cellular metabolism. No overlap with decitabine-affected genes or processes was detected. Decitabine alone revealed only modest anti-proliferative effects on B-ALL cell lines, however, if combined with CX-4945 a synergistic inhibition was observed. In vivo assessment of CX-4945 in B-ALL cell line xenografts resulted in delayed proliferation of B-ALL cells. Combination with DEC further decelerated B-ALL expansion significantly and decreased infiltration in bone marrow and spleen. Effects in patient-derived xenografts all harboring a t(4;11) translocation were heterogeneous. CONCLUSIONS: We herein demonstrate the anti-leukemic potential of CX-4945 in synergy with decitabine in vitro as well as in vivo identifying CK2 as a potentially targetable kinase in B-ALL.
Asunto(s)
Antineoplásicos/farmacología , Quinasa de la Caseína II/antagonistas & inhibidores , Epigénesis Genética/efectos de los fármacos , Regulación Leucémica de la Expresión Génica/efectos de los fármacos , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Animales , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Biología Computacional , ADN (Citosina-5-)-Metiltransferasas/antagonistas & inhibidores , Metilación de ADN , ADN Metiltransferasa 3A , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Humanos , Ratones , Naftiridinas/farmacología , Fenazinas , Fosfatidilinositol 3-Quinasas/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/patología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Progress of age-related hematopoietic diseases such as myelodysplastic syndrome has previously been linked to enhanced levels of reactive oxygen species (ROS). Uncoupling protein 2 (UCP2) was found to reduce mitochondrial ROS production through uncoupling of the respiratory chain. The impact of UCP2 loss and elevated ROS on hematopoiesis during aging has not yet been investigated. In this study, UCP2 knockout mice were analyzed at aging stages of 3, 12, and 24 months with respect to oxidative and energy status of bone marrow cells. Further, the cellular bone marrow subpopulation composition was characterized, as were the differential blood counts at all time points. UCP2 knockout mice revealed enhanced levels of mitochondrial superoxide in elderly animals. Following oxidative stress, adenosine triphosphate (ATP) levels decreased more in the knockout mice than in the wild type. Investigation of bone marrow and blood counts of the knockout mice revealed an enhanced amount of monocytes and neutrophils, as well as a decreased amount of B cells and impaired erythropoiesis throughout aging. In summary, UCP2 induces protective effects on ROS and ATP levels during aging. Additionally, the results suggest an imbalance in hematopoiesis because of the lack of UCP2.
Asunto(s)
Envejecimiento/sangre , Envejecimiento/genética , Linfocitos B , Recuento de Leucocitos , Neutrófilos , Proteína Desacopladora 2/deficiencia , Adenosina Trifosfato/metabolismo , Envejecimiento/metabolismo , Animales , Linfocitos B/metabolismo , Biomarcadores , Células de la Médula Ósea/metabolismo , Eritropoyesis/genética , Inmunofenotipificación , Ratones , Ratones Noqueados , Mitocondrias/genética , Mitocondrias/metabolismo , Neutrófilos/metabolismo , Estrés Oxidativo , FenotipoRESUMEN
During aging, mitochondrial DNA (mtDNA) can accumulate mutations leading to increasing levels of reactive oxygen species (ROS). Increased ROS were described to activate formerly quiescent hematopoietic stem cells (HSC). Mutations in mtDNA were shown to enhance the risk for myelodysplastic syndrome and leukemia. However, the complex relationship between mtDNA variations, ROS and aging of the hematopoietic system is not fully understood.Herein, three mouse strains with mtDNA polymorphisms in genes of respiratory chain complexes I (ND4), III (CYTB) and IV (COX3) were compared to a reference strain during aging. Analysis focused on ROS and ATP levels, bone marrow composition and blood counts. Additionally, hematopoietic restoration capacity following cytotoxic stress was tested.Mice with polymorphisms in ND4 and CYTB gene had significantly decreasing ROS levels in bone marrow cells during aging, without effecting ATP levels. In addition, the frequency of stem and progenitor cells increased during aging but the amount of lymphocytes in the peripheral blood decreased during aging.In summary, the presence of mtDNA polymorphisms affecting the respiratory chain complexes I, III and IV was associated with altered ROS levels as well as changes in BM and peripheral blood composition during aging.
Asunto(s)
Envejecimiento/genética , Complejo III de Transporte de Electrones/genética , Genes Mitocondriales , Hematopoyesis/genética , NADH Deshidrogenasa/genética , Polimorfismo Genético , Prostaglandina-Endoperóxido Sintasas/genética , Adenosina Trifosfato/metabolismo , Factores de Edad , Envejecimiento/metabolismo , Animales , Recuento de Células Sanguíneas , Células de la Médula Ósea/metabolismo , Femenino , Técnicas de Inactivación de Genes , Ratones , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismoRESUMEN
BACKGROUND: Mitochondrial DNA (mtDNA) encodes for the respiratory chain proteins. Genetic alterations in mtDNA have been described during aging and linked to impaired hematopoiesis. MATERIALS AND METHODS: We investigated two novel conplastic mouse strains harboring a mitochondrial nt7778 G/T polymorphism leading to an amino acid exchange in respiratory chain complex V. Effects on reactive oxygen species (ROS) and adenosine triphosphate (ATP) levels, as well as bone marrow composition and peripheral blood counts, were investigated during aging (up to 24 month). RESULTS: The polymorphism correlated with significantly decreased ROS levels in aged mice. Effects on hematopoiesis were marginal and not statistically significant: numbers of erythroid cells in bone marrow, as well as mean corpuscular hemoglobin, tended to decrease over time. CONCLUSION: The investigated polymorphism is associated with decreased ROS levels in aged hematopoietic cells but does not significantly influence hematopoiesis itself.