Antiapoptotic proteins Bcl2 and BclX do not protect chronic myeloid leukemia cells from imatinib-mediated growth arrest

Imatinib (Glivec, Gleevec, STI571), a Bcr-Abl kinase inhibitor, is the most used drug in chronic myeloid leukemia. Imatinib induces apoptosis in a number of CML-derived cell lines, including K562. However, in order to achieve hematological remissions it is required chronic treatment with the drug, a fact inconsistent with a cytotoxic mechanism of imatinib in vivo. In this work we have analysed the effects of imatinib on the proliferation and apoptosis of K562-derived cell lines with constitutive expression of the anti-apoptotic genes Bcl2 and BclX. We found that imatinib-mediated apoptosis was completely abrogated in both Bcl2- and BclX-cell lines. However, imatinib inhibited proliferation, although growth rate was higher than in parental K562. We conclude that, besides its apoptotic effect, imatinib acts through an apoptosis-independent mechanism to arrest cell growth.The work was supported by grant PM98-0109 and SAF2002-04193 from Spanish Ministry of Science and Technology to J.L.Peer Reviewe

Las proteínas antiapoptóticas Bcl2 y BclX no protegen a las células de leucemia mieloide crónica de la parada proliferativa inducida por imatinib

Imatinib (Glivec, Gleevec, STI571), a Bcr-Abl kinase inhibitor, is the most used drug in chronic myeloid leukemia. Imatinib induces apoptosis in a number of CML-derived cell lines, including K562. However, in order to achieve hematological remissions it is required chronic treatment with the drug, a fact inconsistent with a cytotoxic mechanism of imatinib in vivo. In this work we have analysed the effects of imatinib on the proliferation and apoptosis of K562-derived cell lines with constitutive expression of the anti-apoptotic genes Bcl2 and BclX. We found that imatinib-mediated apoptosis was completely abrogated in both Bcl2- and BclXcell lines. However, imatinib inhibited proliferation, although growth rate was higher than in parental K562. We conclude that, besides its apoptotic effect, imatinib acts through an apoptosis-independent mechanism to arrest cell growth.El imatinib (Glivec, Gleevec, STI571) es un inhibidor de la quinasa Bcr-Abl, y es el fármaco de más uso en leucemia mieloide crónica (LMC). El imatinib induce apoptosis en varias líneas celulares derivadas de LMC, entre ellas K562. Sin embargo, para obtener remisión hematológica es necesario el tratamiento continuado con imatinib, un hecho no consistente con un mecanismo de acción citotóxico in vivo del fármaco in vivo. En este trabajo hemos analizado un los efectos del imatinib en la proliferación y apoptosis de líneas celulares derivadas de K562 con expresión constitutiva de las proteínas antiapoptóticas Bcl2 y BclX. Hemos encontrado que la apoptosis mediada por imatinib era completamente abolida en las líneas celulares con expresión de Bcl2 y BclX. Sin embargo, el imatinib inhibía la proliferación, aunque este efecto fue menos severo que en las células parentales K562. Concluimos que, además de su efecto apoptótico, el imatinib actúa a través de un mecanismo independiente de la apoptosis para detener la proliferación

MYC in chronic myeloid leukemia: Induction of aberrant DNA synthesis and association with poor response to imatinib

El pdf es la versión post-print.-- et al.Untreated chronic myeloid leukemia (CML) progresses from chronic phase to blastic crisis (BC). Increased genomic instability, deregulated proliferation, and loss of differentiation appear associated to BC, but the molecular alterations underlying the progression of CML are poorly characterized. MYC oncogene is frequently deregulated in human cancer, often associated with tumor progression. Genomic instability and induction of aberrant DNA replication are described as effects of MYC. In this report, we studied MYC activities in CML cell lines with conditional MYC expression with and without exposure to imatinib, the front-line drug in CML therapy. In cells with conditional MYC expression, MYC did not rescue the proliferation arrest mediated by imatinib but provoked aberrant DNA synthesis and accumulation of cells with 4C content. We studied MYC mRNA expression in 66 CML patients at different phases of the disease, and we found that MYC expression was higher in CML patients at diagnosis than control bone marrows or in patients responding to imatinib. Further, high MYC levels at diagnosis correlated with a poor response to imatinib. MYC expression did not directly correlate with BCR-ABL levels in patients treated with imatinib. Overall our study suggests that, as in other tumor models, MYC-induced aberrant DNA synthesis in CML cells is consistent with MYC overexpression in untreated CML patients and nonresponding patients and supports a role for MYC in CML progression, possibly through promotion of genomic instability. ©2011 AACR.This work was supported by a grant from the Ministerio de Ciencia e Innovacion of Spain (SAF08-01581) and by the RTICC (Red Temática de Investigación Cooperativa en Cancer, RD06/0020/0017) to J. León and a grant from Instituto de Salud Carlos III (FIS08/0829) to M.D. Delgado.Peer Reviewe

High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al.Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2.The work has been funded by grants SAF11-23796 from MINECO and RD12/0036/0033 (to JL), and RD12/0036/0004 (to DC) and RD12/0036/0060 (to MAP) from Instituto Carlos III. These funding was co-sponsored by the European Union FEDER program. JC was recipient of a Fellowship from Fundación Marqués de Valdecilla and from the University of Cantabria.Peer Reviewe

Procedimiento para determinar la eficacia del tratamiento y el grado de progresión de la leucemia mieloide crónica mediante el uso de SPI-1/PU.1.

Procedimiento para determinar la eficacia del tratamiento y el grado de progresión de la leucemia mieloide crónica mediante el uso de SPI-1/PU.1 que consiste en la determinación de mRNA o de proteína del gen SPI-1/PU.1, en muestras de células de sangre o médula ósea de pacientes de LMC y su comparación con muestras de sujetos sanos o del mismo paciente tras el tratamiento antileucémico. Niveles de mRNA o proteína de SPI-1/PU.1 altos o comparables a los de sujetos sanos son indicadores de respuesta al tratamiento. La presencia de SPI-1/PU.1 es indicador de respuesta al tratamiento y recuperación de hematopoyesis normal. Por el contrario, una expresión reducida es indicador de persistencia de la leucemia y mal pronóstico.Solicitud: 200402864 (22.11.2004)Nº Pub. de Solicitud: ES2315040A1 (16.03.2009)Nº de Patente: ES2315040B2 (16.10.2009

Treatment‐free remission after dasatinib in patients with chronic myeloid leukaemia in chronic phase with deep molecular response: Final 5‐year analysis of DASFREE

Patients with chronic myeloid leukaemia in chronic phase (CML-CP) who have a sustained deep molecular response (DMR) are eligible to discontinue treatment and attempt treatment-free remission (TFR). In the DASFREE study (ClinicalTrials.gov; NCT01850004), the 2-year TFR rate after dasatinib discontinuation was 46%; here we present the 5-year update. Patients with a stable DMR after ≥2 years of dasatinib therapy discontinued treatment and were followed for 5 years. At a minimum follow-up of 60 months, in 84 patients discontinuing dasatinib, the 5-year TFR rate was 44% (n = 37). No relapses occurred after month 39 and all evaluable patients who relapsed and restarted dasatinib (n = 46) regained a major molecular response in a median of 1.9 months. The most common adverse event during the off-treatment period was arthralgia (18%, 15/84); a total of 15 withdrawal events were reported in nine patients (11%). At the 5-year final follow-up, almost half of the patients who discontinued dasatinib after a sustained DMR maintained TFR. All evaluable patients who experienced a relapse quickly regained a DMR after restarting dasatinib, demonstrating that dasatinib discontinuation is a viable and potentially long-term option in patients with CML-CP. The safety profile is consistent with the previous report

High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle

Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2

Recensiones [Revista de Historia Económica Año I Primavera-Verano 1983 n. 1 pp. 199-231]

Bartolomé Bennassar. Valladolid en el siglo de Oro. Una ciudad de Castilla y su entorno agrario en el siglo XVI (Bartolomé Yun Casalilla).-- Miguel Artola. La economía española al final del Antiguo Régimen. IV: Instituciones (Ovidio García Regueiro).-- Charles E. Harvey. The Rio Tinto Company. An Economic History of a Leading International Mining Concern, 1873-1954 (Gabriel Tortella Casares).-- Grupo de Estudios de Historia Rural. Los precios del trigo y la cebada en España, 1891-1907; Los precios del aceite de oliva en España, 1891- 1916; El vino, 1871-1907; Dificultades para reconstruir la serie de sus cotizaciones (Teresa Carnero Arbat).-- Manuel Martín Rodríguez. Azúcar o descolonización. Origen de una crisis agraria en la Vega de Granada. El ingenio de San Juan, 1822- 1904 (José Morilla Crit).-- Manuel Tuñón de Lara (ed.). Historia de España. IX: La crisis del Estado, Dictadura, República, Guerra (1923-1939) (Pablo Martín Aceña).-- Caglar Keyder. he Definition of a Peripheral Economy: Turkey, 1923-1929 (Mourad Wahba).-- Marjorie Grice-Hutchinson. El pensamiento económico en España (1377-1740) (Carlos Barciela).-- Carl Menger. Principios de Economía Política (Juan Torras Gómez).-- Josep Fontana. (ed.) La economía española al final del Antiguo Régimen. III: Comercio y colonias (Carlos Martínez Shaw)Publicad

High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle

Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2

Impact of FLT3–ITD Mutation Status and Its Ratio in a Cohort of 2901 Patients Undergoing Upfront Intensive Chemotherapy: A PETHEMA Registry Study

FLT3–ITD results in a poor prognosis in terms of overall survival (OS) and relapse-free survival (RFS) in acute myeloid leukemia (AML). However, the prognostic usefulness of the allelic ratio (AR) to select post-remission therapy remains controversial. Our study focuses on the prognostic impact of FLT3–ITD and its ratio in a series of 2901 adult patients treated intensively in the pre-FLT3 inhibitor era and reported in the PETHEMA registry. A total of 579 of these patients (20%) harbored FLT3–ITD mutations. In multivariate analyses, patients with an FLT3–ITD allele ratio (AR) of >0.5 showed a lower complete remission (CR rate) and OS (HR 1.47, p = 0.009), while AR > 0.8 was associated with poorer RFS (HR 2.1; p 0.5). Using the maximally selected log-rank statistics, we established an optimal cutoff of FLT3–ITD AR of 0.44 for OS, and 0.8 for RFS. We analyzed the OS and RFS according to FLT3–ITD status in all patients, and we found that the group of FLT3–ITD-positive patients with AR 0.44, allo-HSCT was superior to auto-HSCT in terms of OS and RFS. This study provides more evidence for a better characterization of patients with AML harboring FLT3–ITD mutations.Depto. de MedicinaFac. de MedicinaTRUEInstituto de Salud Carlos IIIFundación CRIS Contra el CáncerInstituto de Investigación Hospital 12 de OctubreUnión Europeapu