Follicular lymphoma-like B cells in healthy individuals: a novel intermediate step in early lymphomagenesis

Follicular lymphoma is one of the most common adult lymphoma, and remains virtually incurable despite its relatively indolent nature. t(14;18)(q32;q21) translocation, the genetic hallmark and early initiating event of follicular lymphoma (FL) pathogenesis, is also present at low frequency in the peripheral blood of healthy individuals. It has long been assumed that in healthy individuals t(14;18) is carried by circulating quiescent naive B cells, where its oncogenic potential would be restrained. Here, we question this current view and demonstrate that in healthy individuals, t(14;18) is actually carried by an expanding population of atypical B cells issued from germinal centers, displaying genotypic and phenotypic features of FL, and prone to constitute potent premalignant FL niches. These findings strongly impact both on the current understanding of disease progression and on the proper handling of t(14;18) frequency in blood as a potential early biomarker for lymphoma

In Vivo Reinsertion of Excised Episomes by the V(D)J Recombinase: A Potential Threat to Genomic Stability

It has long been thought that signal joints, the byproducts of V(D)J recombination, are not involved in the dynamics of the rearrangement process. Evidence has now started to accumulate that this is not the case, and that signal joints play unsuspected roles in events that might compromise genomic integrity. Here we show both ex vivo and in vivo that the episomal circles excised during the normal process of receptor gene rearrangement may be reintegrated into the genome through trans-V(D)J recombination occurring between the episomal signal joint and an immunoglobulin/T-cell receptor target. We further demonstrate that cryptic recombination sites involved in T-cell acute lymphoblastic leukemia–associated chromosomal translocations constitute hotspots of insertion. Eventually, the identification of two in vivo cases associating episomal reintegration and chromosomal translocation suggests that reintegration events are linked to genomic instability. Altogether, our data suggest that V(D)J-mediated reintegration of episomal circles, an event likely eluding classical cytogenetic screenings, might represent an additional potent source of genomic instability and lymphoid cancer

Zebrafish screen identifies novel compound with selective toxicity against leukemia

To detect targeted antileukemia agents we have designed a novel, high-content in vivo screen using genetically engineered, T-cell reporting zebrafish. We exploited the developmental similarities between normal and malignant T lymphoblasts to screen a small molecule library for activity against immature T cells with a simple visual readout in zebrafish larvae. After screening 26 400 molecules, we identified Lenaldekar (LDK), a compound that eliminates immature T cells in developing zebrafish without affecting the cell cycle in other cell types. LDK is well tolerated in vertebrates and induces long-term remission in adult zebrafish with cMYC-induced T-cell acute lymphoblastic leukemia (T-ALL). LDK causes dephosphorylation of members of the PI3 kinase/AKT/mTOR pathway and delays sensitive cells in late mitosis. Among human cancers, LDK selectively affects survival of hematopoietic malignancy lines and primary leukemias, including therapy-refractory B-ALL and chronic myelogenous leukemia samples, and inhibits growth of human T-ALL xenografts. This work demonstrates the utility of our method using zebrafish for antineoplastic candidate drug identification and suggests a new approach for targeted leukemia therapy. Although our efforts focused on leukemia therapy, this screening approach has broad implications as it can be translated to other cancer types involving malignant degeneration of developmentally arrested cells

Quality of life of patients with hip fracture was better during the COVID-19 period than before, an ancillary study from the HiFIT multicenter study

BackgroundThe COVID-19 pandemic had a global impact on people life, notably because of lockdown periods. This could particularly affected patients suffering from hip fracture, who could have been more isolated during these periods. We aim at evaluating the impact of the COVID-19 period (including lockdown periods) on quality of life (QOL) in older adult patients 90 days after a surgery for a hip fracture.Subject and methodsAncillary study of the prospective randomized controlled HiFIT study. We compared the QOL measured at 90 days after a hip fracture surgery using the EuroQOL-5 dimensions 3 levels (EQ-5D), the Perceived Quality of life (PQOL) and the Instrumental Activities of Daily Living (IADL) in patients included in the Hifit study before and during the COVID-19 pandemic.ResultsThe characteristics of the 161 patients included before and of the 213 included during the COVID period (including 122 (57%) during COVID with containment periods and 91 (43%) during COVID without containment periods) were similar (mean age 84 ± 10 years; 282 (75%) women). The majority (81%) of the patients alive at 90 days had returned to their previous place of residence in both periods. During the COVID period, EQ-5D showed better patient pain/discomfort and anxiety/depression levels. The PQOL happiness was not different, with around 81% of the patient being “happy” or “very happy” during the two periods and the IADL was also similar during the two periods. In the multivariate analysis odd ratios of having poorer outcomes were increased before COVID for pain/discomfort (OR 2.38, 95%CI [1.41–4.15], p = 0.001), anxiety (OR 1.89 [1.12–3.21], p = 0.017) and mobility (1.69 [1.02–2.86], p = 0.044).ConclusionPatient’s quality of life measured using different scales was not altered during the COVID period compared to before COVID, 90 days after a hip fracture. Surprisingly, the Pain/Discomfort and Anxiety dimensions of the EQ-5D questionnaires were even better during the COVID period.Clinical trial registration:https://clinicaltrials.gov/ (NCT02972294)

Hacia un modelo de reflexión de la práctica profesional del profesor de matemáticas

Resumen basado en el de la publicaciónSe comunica el desarrollo de una investigación cualitativa cuyo objetivo es ayudar al profesor de matemáticas a reflexionar sobre la actividad matemática de sus estudiantes durante la clase. Para esto se propone un modelo de reflexión que le facilite analizar aspectos puntuales de su práctica docente. En la comunicación se presenta la estructura del modelo que es aplicado en tres casos de estudio, y se reportan algunos resultados del proceso reflexivo en uno de ellos.CantabriaES

Recombinase, chromosomal translocations and lymphoid neoplasia: targeting mistakes and repair failures.

A large number of lymphoid malignancies is characterized by specific chromosomal translocations, which are closely linked to the initial steps of pathogenesis. The hallmark of these translocations is the ectopic activation of a silent proto-oncogene through its relocation at the vicinity of an active regulatory element. Due to the unique feature of lymphoid cells to somatically rearrange and mutate receptor genes, and to the corresponding strong activity of the immune enhancers/promoters at that stage of cell development, B- and T-cell differentiation pathways represent propitious targets for chromosomal translocations and oncogene activation. Recent progress in the understanding of the V(D)J recombination process has allowed a more accurate definition of the translocation mechanisms involved, and has revealed that V(D)J-mediated translocations result both from targeting mistakes of the recombinase, and from illegitimate repair of the V(D)J recombination intermediates. Surprisingly, V(D)J-mediated translocations turn out to be restricted to two specific sub-types of lymphoid malignancies, T-cell acute lymphoblastic leukemias, and a restricted set of mature B-cell Non-Hodgkin's lymphomas

MYC fails to efficiently shape malignant transformation in T-cell acute lymphoblastic leukemia.

International audienceMYC is a potent oncogene involved in ∼70% of human cancers, inducing tumorigenesis with high penetrance and short latency in experimental transgenic models. Accordingly, MYC is recognized as a major driver of T-cell acute lymphoblastic leukemia (T-ALL) in human and zebrafish/mouse models, and uncovering the context by which MYC-mediated malignant transformation initiates and develops remains a considerable challenge. Because MYC is a very complex oncogene, highly dependent on the microenvironment and cell-intrinsic context, we generated transgenic mice (tgMyc(spo)) in which ectopic Myc activation occurs sporadically (<10(-6) thymocytes) within otherwise normal thymic environment, thereby mimicking the unicellular context in which oncogenic alterations initiate human tumors. We show that while Myc(+) clones in tgMyc(spo) mice develop and initially proliferate in thymus and the periphery, no tumor or clonal expansion progress in aging mice (n = 130), suggesting an unexpectedly low ability of Myc to initiate efficient tumorigenesis. Furthermore, to determine the relevance of this observation in human pathogenesis we analyzed a human T-ALL case at diagnosis and relapse using the molecular stigmata of V(D)J recombination as markers of malignant progression; we similarly demonstrate that despite the occurrence of TAL1 and MYC translocations in early thymocyte ontogeny, subsequent oncogenic alterations were required to drive oncogenesis. Altogether, our data suggest that although central to T-ALL, MYC overexpression per se is inefficient in triggering the cascade of events leading to malignant transformation