Search

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disease that arises from the oncogenic transformation of developing T cells during T-lymphopoiesis. Although T-ALL prognosis has improved markedly in recent years, relapsing and refractory patients with dismal outcomes still represent a major clinical issue. Consequently, understanding the pathological mechanisms that lead to the appearance of this malignancy and developing novel and more effective targeted therapies is an urgent need. Since the discovery in 2004 that a major proportion of T-ALL patients carry activating mutations that turn NOTCH1 into an oncogene, great efforts have been made to decipher the mechanisms underlying constitutive NOTCH1 activation, with the aim of understanding how NOTCH1 dysregulation converts the physiological NOTCH1-dependent T-cell developmental program into a pathological T-cell transformation process. Several molecular players have so far been shown to cooperate with NOTCH1 in this oncogenic process, and different therapeutic strategies have been developed to specifically target NOTCH1-dependent T-ALLs. Here, we comprehensively analyze the molecular bases of the cross-talk between NOTCH1 and cooperating partners critically involved in the generation and/or maintenance and progression of T-ALL and discuss novel opportunities and therapeutic approaches that current knowledge may open for future treatment of T-ALL patients., Ministerio de Ciencia e Innovación, Fundación Asociación Española Contra el Cáncer, Unión Europea, Fundación Unoentrecienmil, Fundación Ramón Areces, Fundación Inocente Inocente, Depto. de Inmunología, Oftalmología y ORL, Fac. de Medicina, TRUE, pub

Relapsed or refractory T acute lymphoblastic leukemia (T-ALL) still carries poor prognosis. Aiming to improve outcomes, the therapeutic potential of an anti-CCR9 monoclonal antibody (mAb 92R), targeting the human chemokine-receptor CCR9 is analyzed on orthotopic xenotransplants. 92R mAb treatment of mice carrying human CCR9+ T-ALL cell lines or primary T cell leukemias inhibits tumor growth and increases survival. The therapeutic effects of 92R are specific and synergize with chemotherapeutic agents increasing survival. Furthermore, 92R decreases size of non-hematopoietic tumors with a forced CCR9 expression and of solid tumors generated by the pancreatic adenocarcinoma cell line AsPC-1. In addition, a humanized version of 92R mAb (Srb1) is also able to inhibit growth of CCR9+ T-ALL tumor cells in vivo, increasing survival 2.66-fold. Finally, 92R mAb prevents liver accumulation of infiltrates and reduces tumor cell numbers in already formed infiltrates. Thus, the humanized version of 92R mAb (Srb1), displays therapeutic potential for CCR9+ tumor treatment and might represent one of the first therapeutic antibodies for precision medicine on T-ALL patients.

Many patients with lymphoid tumors do not respond to existing therapies or relapse quickly after initial remission. A minor fraction of tumor cells, the tumor-initiating cells (TICs), has self-renewal capacity, is particularly resistant to cancer therapies, and likely accounts for tumor relapse. Targeting critical pathways that are specific to TIC function may therefore improve cancer treatment. As TICs are the only tumor cells able to grow in soft gels, we are investigating the mechanisms underlying the growth in soft gels. The balance between reactive oxygen species (ROS) and antioxidants levels regulates numerous cellular processes, including cell signaling, proliferation and death. Here we show that culture of lymphoid cells in soft-agar hydrogels induces ROS production and kills all non-tumor lymphoid cells but allows the survival and proliferation of a minor fraction of lymphoma cells. Treatment with the antioxidant N-acetylcysteine inhibits lethality and even enables the growth of primary non-tumor lymphoid cells in soft-agar. A fraction of lymphoma cells overcomes ROS-induced lethality by increasing the production of the antioxidant glutathione (GSH), whereas non-tumor cells fail to induce this response. Pharmacological inhibition of GCL, the limiting enzyme in GSH biosynthesis, or knockdown of GCLC, the GCL catalytic subunit, dropped GSH production in lymphoma cells, sharply decreased their viability and proliferation in softagar, and inhibited their growth in immunodeficient mice. B-cells from ¿MYC mice, a mouse model of B-cell lymphoma, show increased ROS and GSH levels relative to Bcells from control mice. Importantly, pharmacological GCL inhibition impaired lymphoma growth in female ¿MYC mice, increasing their tumor-free survival. We also found higher ROS and GSH levels in tumor B-cells from B-cell lymphoma and leukemia patients than in non-tumor T-cells from the same subject or in B-cells from healthy donors, strongly suggesting that GCL inhibition cou

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disease that arises from the oncogenic transformation of developing T cells during T-lymphopoiesis. Although T-ALL prognosis has improved markedly in recent years, relapsing and refractory patients with dismal outcomes still represent a major clinical issue. Consequently, understanding the pathological mechanisms that lead to the appearance of this malignancy and developing novel and more effective targeted therapies is an urgent need. Since the discovery in 2004 that a major proportion of T-ALL patients carry activating mutations that turn NOTCH1 into an oncogene, great efforts have been made to decipher the mechanisms underlying constitutive NOTCH1 activation, with the aim of understanding how NOTCH1 dysregulation converts the physiological NOTCH1-dependent T-cell developmental program into a pathological T-cell transformation process. Several molecular players have so far been shown to cooperate with NOTCH1 in this oncogenic process, and different therapeutic strategies have been developed to specifically target NOTCH1-dependent T-ALLs. Here, we comprehensively analyze the molecular bases of the cross-talk between NOTCH1 and cooperating partners critically involved in the generation and/or maintenance and progression of T-ALL and discuss novel opportunities and therapeutic approaches that current knowledge may open for future treatment of T-ALL patients.

The present invention relates to the treatment of T-cell acute lymphoblastic leukemia (T-ALLs) by means of immunotherapy with a monoclonal antibody which recognizes the pre-TCR receptor which, due to its presence in all phases of T-ALL pre-TCR+ development, can also be used as a leukemia-initiating cell (LIC) biomarker and as a therapeutic target useful for monitoring minimal residual disease and identifying compounds inhibiting the disease.

The present invention relates to the treatment of T-cell acute lymphoblastic leukemia (T-ALLs) by means of immunotherapy with a monoclonal antibody which recognizes the pre-TCR receptor which, due to its presence in all phases of T-ALL pre-TCR+ development, can also be used as a leukemia-initiating cell (LIC) biomarker and as a therapeutic target useful for monitoring minimal residual disease and identifying compounds inhibiting the disease.

Tratamiento terapéutico de leucemias linfoblásticas agudas de células T con un anticuerpo monoclonal frente al receptor pre-TCR. La presente invención está dirigida al tratamiento de leucemias linfoblásticas agudas de células T (T-ALL) por inmunoterapia con un anticuerpo monoclonal que reconoce el receptor pre-TCR que, debido a su presencia en todas las fases de desarrollo de las T-ALL pre-TCR+, se puede usar además como un biomarcador de células iniciadoras de leucemia (LIC) y como una diana terapéutica útil para el seguimiento de enfermedad mínima residual, y la identificación de compuestos inhibidores de la enfermedad.

La presente invención está dirigida ai tratamiento de leucemias iínfobíásticas agudas de células T (T-ALL) por inmunoterapia con un anticuerpo monoclonal que reconoce el receptor pre-TCR que, debido a su presencia en todas las fases de desarrollo de las T- ALL pre-TCR+, se puede usar además como un biomarcador de células iniciadoras de leucemia (LIC) y como una diana terapéutica útil para el seguimiento de enfermedad mínima residual, y la identificación de compuestos inhibidores de la enfermedad. [ES], The present invention relates to the treatment of T-cell acute lymphoblastic leukemias (T-ALLs) by means of immunotherapy using a monoclonal antibody that recognises the pre-T cell receptor (pre-TCR) which, owing to its presence at all stages of T-ALL pre-TCR+ development, can also be used as a biomarker for leukaemia-initiating cells (LICs) and as a therapeutic target useful for monitoring minimal residual disease and identifying compounds that inhibit the disease. [EN]

The cellular receptor Notch1 is a central regulator of T-cell development, and as a consequence, Notch1 pathway appears upregulated in > 65% of the cases of T-cell acute lymphoblastic leukemia (T-ALL). However, strategies targeting Notch1 signaling render only modest results in the clinic due to treatment resistance and severe side effects. While many investigations reported the different aspects of tumor cell growth and leukemia progression controlled by Notch1, less is known regarding the modifications of cellular metabolism induced by Notch1 upregulation in T-ALL. Previously, glutaminolysis inhibition has been proposed to synergize with anti-Notch therapies in T-ALL models. In this work, we report that Notch1 upregulation in T-ALL induced a change in the metabolism of the important amino acid glutamine, preventing glutamine synthesis through the downregulation of glutamine synthetase (GS). Downregulation of GS was responsible for glutamine addiction in Notch1-driven T-ALL both in vitro and in vivo. Our results also confirmed an increase in glutaminolysis mediated by Notch1. Increased glutaminolysis resulted in the activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway, a central controller of cell growth. However, glutaminolysis did not play any role in Notch1-induced glutamine addiction. Finally, the combined treatment targeting mTORC1 and limiting glutamine availability had a synergistic effect to induce apoptosis and to prevent Notch1-driven leukemia progression. Our results placed glutamine limitation and mTORC1 inhibition as a potential therapy against Notch1-driven leukemia.

[EN] The present invention relates to the treatment of T-cell acute lymphoblastic leukemias (T-ALLs) by means of immunotherapy using a monoclonal antibody that recognises the pre-T cell receptor (pre-TCR) which, owing to its presence at all stages of T-ALL pre-TCR+ development, can also be used as a biomarker for leukaemia-initiating cells (LICs) and as a therapeutic target useful for monitoring minimal residual disease and identifying compounds that inhibit the disease., [ES] Tratamiento terapéutico de leucemias linfoblásticas agudas de células T con un anticuerpo monoclonal frente al receptor pre-TCR. La presente invención está dirigida al tratamiento de leucemias linfoblásticas agudas de células T (T-ALL) por inmunoterapia con un anticuerpo monoclonal que reconoce el receptor pre-TCR que, debido a su presencia en todas las fases de desarrollo de las T-ALL pre-TCR+, se puede usar además como un biomarcador de células iniciadoras de leucemia (LIC) y como una diana terapéutica útil para el seguimiento de enfermedad mínima residual, y la identificación de compuestos inhibidores de la enfermedad.

Targeting Notch signaling has emerged as a promising therapeutic strategy for chronic lymphocytic leukemia (CLL), particularly in NOTCH1-mutated patients. We provide first evidence that the Notch ligand DLL4 is a potent stimulator of Notch signaling in NOTCH1-mutated CLL cells while increases cell proliferation. Importantly, DLL4 is expressed in histiocytes from the lymph node, both in NOTCH1-mutated and -unmutated cases. We also show that the DLL4-induced activation of the Notch signaling pathway can be efficiently blocked with the specific anti-Notch1 antibody OMP-52M51. Accordingly, OMP-52M51 also reverses Notch-induced MYC, CCND1, and NPM1 gene expression as well as cell proliferation in NOTCH1-mutated CLL cells. In addition, DLL4 stimulation triggers the expression of protumor target genes, such as CXCR4, NRARP, and VEGFA, together with an increase in cell migration and angiogenesis. All these events can be antagonized by OMP-52M51. Collectively, our results emphasize the role of DLL4 stimulation in NOTCH1-mutated CLL and confirm the specific therapeutic targeting of Notch1 as a promising approach for this group of poor prognosis CLL patients.

Increasing evidences show that the ATPase Inhibitory Factor 1 (IF1), the physiological inhibitor of the ATP synthase, is overexpressed in a large number of carcinomas contributing to metabolic reprogramming and cancer progression. Herein, we show that in contrast to the findings in other carcinomas, the overexpression of IF1 in a cohort of colorectal carcinomas (CRC) predicts less chances of disease recurrence, IF1 being an independent predictor of survival. Bioinformatic and gene expression analyses of the transcriptome of colon cancer cells with differential expression of IF1 indicate that cells overexpressing IF1 display a less aggressive behavior than IF1 silenced (shIF1) cells. Proteomic and functional in vitro migration and invasion assays confirmed the higher tumorigenic potential of shIF1 cells. Moreover, shIF1 cells have increased in vivo metastatic potential. The higher metastatic potential of shIF1 cells relies on increased cFLIP-mediated resistance to undergo anoikis after cell detachment. Furthermore, tumor spheroids of shIF1 cells have an increased ability to escape from immune surveillance by NK cells. Altogether, the results reveal that the overexpression of IF1 acts as a tumor suppressor in CRC with an important anti-metastatic role, thus supporting IF1 as a potential therapeutic target in CRC.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological disorder that results from the progressive accumulation of genomic alterations in T-cell precursors developing in the thymus. T-ALL is characterized by the infiltration of bone marrow by immature T-cell lymphoblasts, while immature T-cell tumors characterized by a thymic mass and limited bone marrow infiltration are instead diagnosed as T-cell lymphoblastic lymphoma (T-LBL). T-ALL was described as an independent disease in the 1970s, after finding thymus-associated markers expressed on the surface of leukemic cells from pediatric patients [1]. Its incidence is higher in children than in adults (up to 25% and 15% of newly diagnosed ALL cases, respectively) [2], and it is twice as prevalent in males as in females [3]. Patients with T-ALL are frequently classified as high-risk due to the unfavorable features of the disease that include high leukocyte count, hematopoietic failure, and medullar and extramedullar infiltration with high probability of a ectation of the central nervous system (CNS), which represents a frequent site of relapse [4]. In 1995, the European Group for Immunological Characterization of Leukemias (EGIL) established a classification of different clinically relevant T-ALL subtypes based on the expression of cell surface markers corresponding to sequential intrathymic T-cell developmental stages [5]: pro-T, pre-T, cortical and mature T-ALL (Figure 1). However, in recent years, improved genomic and transcriptomic techniques have provided new insights into the characterization of the prevalent genetic lesions involved in T-ALL pathogenesis [6–8], which has proved more valuable for risk-stratification of patients at the time of diagnosis [9–11]. Detection of translocations of enhancers or promoters of T-cell receptor (TCR) genes to other chromosomal regions helped the identification of the first T-ALL oncogenes

Intense chemotherapy regimens of patients diagnosed with T cell acute lymphoblastic leukemia (T-ALL) have proved successful for improving patient’s overall survival, especially in children. But still T-ALL treatment remains challenging, since side effects of chemotherapeutic drugs often worsen patient’s quality of life, and relapse rates remain significant. Hence, the availability of experimental animal models capable of recapitulating the biology of human T-ALL is obligatory as a critical tool to explore novel promising therapies directed against specific targets that have been previously validated in in vitro assays. For this purpose, patient-derived xenografts (PDX) of primary human T-ALL are currently of great interest as preclinical models for novel therapeutic strategies toward transition into clinical trials. In this chapter, we describe the lab workflow to perform PDX assays, from the initial processing of patient T-ALL samples, genetic in vitro modifications of leukemic cells by lentiviral transduction, inoculation routes, monitoring for disease development, and mouse organ examination, to administration of several treatments.

[Background]: NOTCH1 gene mutations in mantle cell lymphoma (MCL) have been described in about 5–10% of cases and are associated with significantly shorter survival rates. The present study aimed to investigate the biological impact of this mutation in MCL and its potential as a therapeutic target., [Methods]: Activation of Notch1 signaling upon ligand-stimulation and inhibitory effects of the monoclonal anti-Notch1 antibody OMP-52M51 in NOTCH1-mutated and -unmutated MCL cells were assessed by Western Blot and gene expression profiling. Effects of OMP-52M51 treatment on tumor cell migration and tumor angiogenesis were evaluated with chemotaxis and HUVEC tube formation assays. The expression of Delta-like ligand 4 (DLL4) in MCL lymph nodes was analyzed by immunofluorescence staining and confocal microscopy. A MCL mouse model was used to assess the activity of OMP-52M51 in vivo., [Results]: Notch1 expression can be effectively stimulated in NOTCH1-mutated Mino cells by DLL4, whereas in the NOTCH1-unmutated cell line JeKo-1, less effect was observed upon any ligand-stimulation. DLL4 was expressed by histiocytes in both, NOTCH1-mutated and –unmutated MCL lymph nodes. Treatment of NOTCH1-mutated MCL cells with the monoclonal anti-Notch1 antibody OMP-52M51 effectively prevented DLL4-dependent activation of Notch1 and suppressed the induction of numerous direct Notch target genes involved in lymphoid biology, lymphomagenesis and disease progression. Importantly, in lymph nodes from primary MCL cases with NOTCH1/2 mutations, we detected an upregulation of the same gene sets as observed in DLL4-stimulated Mino cells. Furthermore, DLL4 stimulation of NOTCH1-mutated Mino cells enhanced tumor cell migration and angiogenesis, which could be abolished by treatment with OMP-52M51. Importantly, the effects observed were specific for NOTCH1-mutated cells as they did not occur in the NOTCH1-wt cell line JeKo-1. Finally, we confirmed the potential activity of OMP-52M51 to inhibit DLL4-induced Notch1-Signaling in vivo in a xenograft mouse model of MCL., [Conclusion]: DLL4 effectively stimulates Notch1 signaling in NOTCH1-mutated MCL and is expressed by the microenvironment in MCL lymph nodes. Our results indicate that specific inhibition of the Notch1-ligand-receptor interaction might provide a therapeutic alternative for a subset of MCL patients.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy resulting from the dysregulation of signaling pathways that control intrathymic T-cell development. Relapse rates are still significant, and prognosis is particularly bleak for relapsed patients. Therefore, development of novel therapies specifically targeting pathways controlling leukemia-initiating cell (LIC) activity is mandatory for fighting refractory T-ALL. The interleukin-7 receptor (IL-7R) is a crucial T-cell developmental pathway that is commonly expressed in T-ALL and has been implicated in leukemia progression; however, the significance of IL-7R/IL-7 signaling in T-ALL pathogenesis and its contribution to disease relapse remain unknown. To directly explore whether IL-7R targeting may be therapeutically efficient against T-ALL relapse, we focused on a known Notch1-induced T-ALL model, because a majority of T-ALL patients harbor activating mutations in NOTCH1, which is a transcriptional regulator of IL-7R expression. Using loss-of-function approaches, we show that Il7r-deficient, but not wild-type, mouse hematopoietic progenitors transduced with constitutively active Notch1 failed to generate leukemia upon transplantation into immunodeficient mice, thus providing formal evidence that IL-7R function is essential for Notch1-induced T-cell leukemogenesis. Moreover, we demonstrate that IL-7R expression is an early functional biomarker of T-ALL cells with LIC potential and report that impaired IL-7R signaling hampers engraftment and progression of patient-derived T-ALL xenografts. Notably, we show that IL-7R–dependent LIC activity and leukemia progression can be extended to human B-cell acute lymphoblastic leukemia (B-ALL). These results have important therapeutic implications, highlighting the relevance that targeting normal IL-7R signaling may have in future therapeutic interventions, particularly for preventing T-ALL (and B-ALL) relapse.

Relapsed/refractory T-cell acute lymphoblastic leukemia (T-ALL) has a dismal outcome, and no effective targeted immunotherapies for T-ALL exist. The extension of chimeric antigen receptor (CAR) T cells (CARTs) to T-ALL remains challenging because the shared expression of target antigens between CARTs and T-ALL blasts leads to CART fratricide. CD1a is exclusively expressed in cortical T-ALL (coT-ALL), a major subset of T-ALL, and retained at relapse. This article reports that the expression of CD1a is mainly restricted to developing cortical thymocytes, and neither CD34+ progenitors nor T cells express CD1a during ontogeny, confining the risk of on-target/off-tumor toxicity. We thus developed and preclinically validated a CD1a-specific CAR with robust and specific cytotoxicity in vitro and antileukemic activity in vivo in xenograft models of coT-ALL, using both cell lines and coT-ALL patient–derived primary blasts. CD1a-CARTs are fratricide resistant, persist long term in vivo (retaining antileukemic activity in re-challenge experiments), and respond to viral antigens. Our data support the therapeutic and safe use of fratricide-resistant CD1a-CARTs for relapsed/refractory coT-ALL.

NOTCH1 is a prevalent signaling pathway in T cell acute lymphoblastic leukemia (T-ALL), but crucial NOTCH1 downstream signals and target genes contributing to T-ALL pathogenesis cannot be retrospectively analyzed in patients and thus remain ill defined. This information is clinically relevant, as initiating lesions that lead to cell transformation and leukemia-initiating cell (LIC) activity are promising therapeutic targets against the major hurdle of T-ALL relapse. Here, we describe the generation in vivo of a human T cell leukemia that recapitulates T-ALL in patients, which arises de novo in immunodeficient mice reconstituted with human hematopoietic progenitors ectopically expressing active NOTCH1. This T-ALL model allowed us to identify CD44 as a direct NOTCH1 transcriptional target and to recognize CD44 overexpression as an early hallmark of preleukemic cells that engraft the BM and finally develop a clonal transplantable T-ALL that infiltrates lymphoid organs and brain. Notably, CD44 is shown to support crucial BM niche interactions necessary for LIC activity of human T-ALL xenografts and disease progression, highlighting the importance of the NOTCH1/CD44 axis in T-ALL pathogenesis. The observed therapeutic benefit of anti-CD44 antibody administration in xenotransplanted mice holds great promise for therapeutic purposes against T-ALL relapse.

A key unsolved question regarding the developmental origin of conventional and plasmacytoid dendritic cells (cDCs and pDCs, respectively) resident in the steady-state thymus is whether early thymic progenitors (ETPs) could escape T cell fate constraints imposed normally by a Notch-inductive microenvironment and undergo DC development. By modeling DC generation in bulk and clonal cultures, we show here that Jagged1 (JAG1)-mediated Notch signaling allows human ETPs to undertake a myeloid transcriptional program, resulting in GATA2-dependent generation of CD34 CD123 progenitors with restricted pDC, cDC, and monocyte potential, whereas Delta-like1 signaling down-regulates GATA2 and impairs myeloid development. Progressive commitment to the DC lineage also occurs intrathymically, as myeloid-primed CD123 monocyte/DC and common DC progenitors, equivalent to those previously identified in the bone marrow, are resident in the normal human thymus. The identification of a discrete JAG1 thymic medullary niche enriched for DC-lineage cells expressing Notch receptors further validates the human thymus as a DC-poietic organ, which provides selective microenvironments permissive for DC development.

Rho guanine exchange factors (GEFs), the enzymes that stimulate Rho GTPases, are deemed as potential therapeutic targets owing to their protumorigenic functions. However, the understanding of the spectrum of their pathobiological roles in tumors is still very limited. We report here that the GEF Vav1 unexpectedly possesses tumor-suppressor functions in immature T cells. This function entails the noncatalytic nucleation of complexes between the ubiquitin ligase Cbl-b and the intracellular domain of Notch1 (ICN1) that favors ICN1 ubiquitinylation and degradation. Ablation of Vav1 promotes ICN1 signaling and the development of T cell acute lymphoblastic leukemia (T-ALL). The downregulation of Vav1 is essential for the pathogenesis of human T-ALL of the TLX clinical subtype, further underscoring the suppressor role of this pathway.

Evidence links aryl hydrocarbon receptor (AHR) activation to rheumatoid arthritis (RA) pathogenesis, although results are inconsistent. AHR agonists inhibit pro-inflammatory cytokine expression in macrophages, pivotal cells in RA aetiopathogenesis, which hints at specific circuits that regulate the AHR pathway in RA macrophages. We compared microRNA (miR) expression in CD14(+) cells from patients with active RA or with osteoarthritis (OA). Seven miR were downregulated and one (miR-223) upregulated in RA compared to OA cells. miR-223 upregulation correlated with reduced Notch3 and Notch effector expression in RA patients. Overexpression of the Notch-induced repressor HEY-1 and co-culture of healthy donor monocytes with Notch ligand-expressing cells showed direct Notch-mediated downregulation of miR-223. Bioinformatics predicted the AHR regulator ARNT (AHR nuclear translocator) as a miR-223 target. Pre-miR-223 overexpression silenced ARNT 3'UTR-driven reporter expression, reduced ARNT (but not AHR) protein levels and prevented AHR/ARNT-mediated inhibition of pro-inflammatory cytokine expression. miR-223 counteracted AHR/ARNT-induced Notch3 upregulation in monocytes. Levels of ARNT and of CYP1B1, an AHR/ARNT signalling effector, were reduced in RA compared to OA synovial tissue, which correlated with miR-223 levels. Our results associate Notch signalling to miR-223 downregulation in RA macrophages, and identify miR-223 as a negative regulator of the AHR/ARNT pathway through ARNT targeting.

© 2015 Macmillan Publishers Limited. Epithelial organs develop through tightly coordinated events of cell proliferation and differentiation in which endocytosis plays a major role. Despite recent advances, how endocytosis regulates the development of vertebrate organs is still unknown. Here we describe a mechanism that facilitates the apical availability of endosomal SNARE receptors for epithelial morphogenesis through the developmental upregulation of plasmolipin (pllp) in a highly endocytic segment of the zebrafish posterior midgut. The protein PLLP (Pllp in fish) recruits the clathrin adaptor EpsinR to sort the SNARE machinery of the endolysosomal pathway into the subapical compartment, which is a switch for polarized endocytosis. Furthermore, PLLP expression induces apical Crumbs internalization and the activation of the Notch signalling pathway, both crucial steps in the acquisition of cell polarity and differentiation of epithelial cells. We thus postulate that differential apical endosomal SNARE sorting is a mechanism that regulates epithelial patterning.

La presente invención se refiere al tratamiento terapéutico de leucemias linfoblásticas agudas (LLA) humanas de células T y B (LLA-T y LLA-B) y linfomas humanos, por inhibición del receptor de interleuquina- 7 (IL-7R) humana. Un primer aspecto de la presente invención es un agente inhibidor o bloqueante, preferentemente un anticuerpo o un fragmento del mismo, capaz de bloquear la función de la cadena {al} del receptor de interleuquina 7 (IL-7RĮ) humano, para la prevención y/o el tratamiento de una LLA humana o de un linfoma humano. Asimismo, la presente invención hace referencia a una composición farmacéutica y a un modelo de identificación, expansión y mantenimiento in vivo de células iniciadoras de LLA-T y LLA-B primarias humanas con capacidad de iniciar el injerto de la leucemia en ratones inmunodeficientes, así como la caracterización de estas células iniciadoras de LLA-T y LLA-B como células que expresan altos niveles del IL-7R.

[EN] The present invention relates to the therapeutic use of CD44 inhibitor agents against human acute lymphoblastic leukaemia (ALL). Specifically, the present invention relates to an agent for inhibiting the function of CD44 for the use thereof in medicine, preferably for the prevention and/or treatment of human T-ALL, as well as to a pharmaceutical composition and to a kit. The present invention also relates to a method for preventing and/or treating human T-ALL, to a model of ICN1-induced human T-ALL pre-leukemic cells in mice, and to a xenotransplant model in mice for the study of early molecular alterations associated with the generation of cells that initiate and maintain human T-ALL, [ES] La presente invención describe la aplicación terapéutica de agentes inhibidores de CD44 frente a la leucemia linfoblástica aguda (ALL) humana. En concreto, la presente invención hace referencia a un agente inhibidor de la función de CD44 para su uso en medicina, preferentemente para la prevención y/o tratamiento de la T-ALL humana, así como a una composición farmacéutica y un kit. La presente invención también hace referencia aun método de prevención y/o tratamiento de la T-ALL humana, aun modelo de células pre- leucémicas de la T-ALL humana en ratón inducidas por ICN1, y a un modelo de xenotrasplante en ratón para el estudio de las alteraciones moleculares tempranas que se asocian a la generación de las células que inician y mantienen la T-ALL humana

La presente invención describe la aplicación terapéutica de agentes inhibidores de CD44 frente a la leucemia linfoblástica aguda (ALL) humana. En concreto, la presente invención hace referencia a un agente inhibidor de la función de CD44 para su uso en medicina, preferentemente para la prevención y/o tratamiento de la T-ALL humana, así como a una composición farmacéutica y un kit. La presente invención también hace referencia a un método de prevención y/o tratamiento de la T-ALL humana, a un modelo de células pre-leucémicas de la T-ALL humana en ratón inducidas por ICN1, y a un modelo de xenotrasplante en ratón para el estudio de las alteraciones moleculares tempranas que se asocian a la generación de las células que inician y mantienen la T-ALL humana

Increasing evidence suggests that mesenchymal stem/stromal cells (MSCs) carrying specific mutations are at the origin of some sarcomas. We have reported that the deficiency of p53 alone or in combination with Rb (Rb -/- p53 -/-) in adipose-derived MSCs (ASCs) promotes leiomyosarcoma-like tumors in vivo. Here, we hypothesized that the source of MSCs and/or the cell differentiation stage could determine the phenotype of sarcoma development. To investigate whether there is a link between the source of MSCs and sarcoma phenotype, we generated p53 -/- and Rb -/- p53 -/- MSCs from bone marrow (BM-MSCs). Both genotypes of BM-MSCs initiated leiomyosarcoma formation similar to p53 -/- and Rb -/- p53 -/- ASCs. In addition, gene expression profiling revealed transcriptome similarities between p53- or Rb-p53-deficient BM-MSCs/ASCs and muscle-associated sarcomagenesis. These data suggest that the tissue source of MSC does not seem to determine the development of a particular sarcoma phenotype. To analyze whether the differentiation stage defines the sarcoma phenotype, BM-MSCs and ASCs were induced to differentiate toward the osteogenic lineage, and both p53 and Rb were excised using Cre-expressing adenovectors at different stages along osteogenic differentiation. Regardless the level of osteogenic commitment, the inactivation of Rb and p53 in BM-MSC-derived, but not in ASC-derived, osteogenic progenitors gave rise to osteosarcoma-like tumors, which could be serially transplanted. This indicates that the osteogenic differentiation stage of BM-MSCs imposes the phenotype of in vivo sarcoma development, and that BM-MSC-derived osteogenic progenitors rather than undifferentiated BM-MSCs, undifferentiated ASCs or ASC-derived osteogenic progenitors, represent the cell of origin for osteosarcoma development. © 2013 Macmillan Publishers Limited All rights reserved.

Notch receptors are master regulators of many aspects of development and tissue renewal in metazoans. Notch1 activation is essential for T-cell specification of bone marrow-derived multipotent progenitors that seed the thymus, and for proliferation and further progression of early thymocytes along the T-cell lineage. Deregulated activation of Notch1 significantly contributes to the generation of T-cell acute lymphoblastic leukaemia (T-ALL). In addition to Notch1 signals, survival and proliferation signals provided by the IL-7 receptor (IL-7R) are also required during thymopoiesis. Our understanding of the molecular mechanisms controlling stage-specific survival and proliferation signals provided by Notch1 and IL-7R has recently been improved by the discovery that the IL-7R is a transcriptional target of Notch1. Thus, Notch1 controls T-cell development, in part by regulating the stage- and lineage-specific expression of IL-7R. The finding that induction of IL-7R expression downstream of Notch1 also occurs in T-ALL highlights the important contribution that deregulated IL-7R expression and function may have in this pathology. Confirming this notion, oncogenic IL7R gain-of-function mutations have recently been identified in childhood T-ALL. Here we discuss the fundamental role of Notch1 and IL-7R signalling pathways in physiological and pathological T-cell development in mice and men, highlighting their close molecular underpinnings. © 2012 Springer-Verlag Berlin Heidelberg.

The immune system is probably one of the most complex cellular organizations in the body. Its complexity is not superfluous, but rather it is required to fulfill the complicated purpose of the immune system, namely: the recognition of the diverse repertoire of microorganisms and pathogens; the detection of neoplastic lesions originating from a range of tissues; and, while executing these tasks, the maintenance of peripheral tolerance by suppressing detrimental responses against healthy tissues. Since they were discovered by R. Steinman et al. nearly 40 years ago, dendritic cells (DCs) have emerged to be critical players in conducting the immune response to fulfill these roles. Here, we provide a general view on some aspects of DC immunology, highlighting the crucial role that R. Steinman's research in the DC field has played during all those years. This review will also give an outline on DC research in the particular aspects that represent the focus of research groups in Spain (recently organized as the DC.esp working group within SEI). Firstly, some of the subtypes of DC will be described, particularly thymic DC and their role on tolerance; then the DC role in tolerance will be examined, followed by their implications in viral infections. Finally, antigen targeting DCs will be reviewed taking into account the crucial contributions made by R. Steinman et al. This chapter will end by reviewing some DCs based therapies in viral infections. © 2012 Sociedad Española de Inmunología. Published by Elsevier España, S.L. All rights reserved.