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

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

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

Machine Learning Improves Risk Stratification in Myelofibrosis: An Analysis of the Spanish Registry of Myelofibrosis

Myelofibrosis (MF) is a myeloproliferative neoplasm (MPN) with heterogeneous clinical course. Allogeneic hematopoietic cell transplantation remains the only curative therapy, but its morbidity and mortality require careful candidate selection. Therefore, accurate disease risk prognostication is critical for treatment decision-making. We obtained registry data from patients diagnosed with MF in 60 Spanish institutions (N = 1386). These were randomly divided into a training set (80%) and a test set (20%). A machine learning (ML) technique (random forest) was used to model overall survival (OS) and leukemia-free survival (LFS) in the training set, and the results were validated in the test set. We derived the AIPSS-MF (Artificial Intelligence Prognostic Scoring System for Myelofibrosis) model, which was based on 8 clinical variables at diagnosis and achieved high accuracy in predicting OS (training set c-index, 0.750; test set c-index, 0.744) and LFS (training set c-index, 0.697; test set c-index, 0.703). No improvement was obtained with the inclusion of MPN driver mutations in the model. We were unable to adequately assess the potential benefit of including adverse cytogenetics or high-risk mutations due to the lack of these data in many patients. AIPSS-MF was superior to the IPSS regardless of MF subtype and age range and outperformed the MYSEC-PM in patients with secondary MF. In conclusion, we have developed a prediction model based exclusively on clinical variables that provides individualized prognostic estimates in patients with primary and secondary MF. The use of AIPSS-MF in combination with predictive models that incorporate genetic information may improve disease risk stratification

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Molecular Studies for the Early Detection of Philadelphia-Negative Myeloproliferative Neoplasms

JAK2 V617F is the predominant driver mutation in patients with Philadelphia-negative myeloproliferative neoplasms (MPN). JAK2 mutations are also frequent in clonal hematopoiesis of indeterminate potential (CHIP) in otherwise “healthy” individuals. However, the period between mutation acquisition and MPN diagnosis (known as latency) varies widely between individuals, with JAK2 mutations detectable several decades before diagnosis and even from birth in some individuals. Here, we will review the current evidence on the biological factors, such as additional mutations and chronic inflammation, which influence clonal expansion and may determine why some JAK2-mutated individuals will progress to an overt neoplasm during their lifetime while others will not. We will also introduce several germline variants that predispose individuals to CHIP (as well as MPN) identified from genome-wide association studies. Finally, we will explore possible mutation screening or interventions that could help to minimize MPN-associated cardiovascular complications or even delay malignant progression