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Signalling thresholds and negative B-cell selection in acute lymphoblastic leukaemia.

B cells are selected for an intermediate level of B-cell antigen receptor (BCR) signalling strength: attenuation below minimum (for example, non-functional BCR) or hyperactivation above maximum (for example, self-reactive BCR) thresholds of signalling strength causes negative selection. In ∼25% of cases, acute lymphoblastic leukaemia (ALL) cells carry the oncogenic BCR-ABL1 tyrosine kinase (Philadelphia chromosome positive), which mimics constitutively active pre-BCR signalling. Current therapeutic approaches are largely focused on the development of more potent tyrosine kinase inhibitors to suppress oncogenic signalling below a minimum threshold for survival. We tested the hypothesis that targeted hyperactivation--above a maximum threshold--will engage a deletional checkpoint for removal of self-reactive B cells and selectively kill ALL cells. Here we find, by testing various components of proximal pre-BCR signalling in mouse BCR-ABL1 cells, that an incremental increase of Syk tyrosine kinase activity was required and sufficient to induce cell death. Hyperactive Syk was functionally equivalent to acute activation of a self-reactive BCR on ALL cells. Despite oncogenic transformation, this basic mechanism of negative selection was still functional in ALL cells. Unlike normal pre-B cells, patient-derived ALL cells express the inhibitory receptors PECAM1, CD300A and LAIR1 at high levels. Genetic studies revealed that Pecam1, Cd300a and Lair1 are critical to calibrate oncogenic signalling strength through recruitment of the inhibitory phosphatases Ptpn6 (ref. 7) and Inpp5d (ref. 8). Using a novel small-molecule inhibitor of INPP5D (also known as SHIP1), we demonstrated that pharmacological hyperactivation of SYK and engagement of negative B-cell selection represents a promising new strategy to overcome drug resistance in human ALL.

Amino Acid Motifs

Pathway incompatibility between NF-κB and RAS signaling constrains oncogenicity in B-cell leukemia.

Oncogenic pathways do not always cooperate; in some contexts, their co-activation is antagonistic and suppresses tumorigenesis, a phenomenon we termed pathway incompatibility. However, the mechanisms underlying this antagonism and the role of receptor context in shaping these interactions remain unclear. During normal B-cell development, precursor B-cell receptor (pre-BCR) signaling supports survival and proliferation of early B-cell precursors before transition to expression of the mature B-cell receptor (BCR). B-cell acute lymphoblastic leukemia (B-ALL), the most common childhood cancer, is characterized by developmental arrest prior to BCR expression, and approximately 35% of cases harbor activating RAS-ERK mutations that mimic pre-BCR-dependent survival signaling. NF-κB plays context-dependent roles in B-cell malignancies, but whether it influences the compatibility between oncogenic RAS signaling and BCR expression remains poorly understood. Activation of canonical NF-κB induced apoptotic depletion of RAS-driven B-ALL cells. Mechanistically, NF-κB suppressed pre-BCR-dependent survival signaling while promoting expression of BCR components. Consistent with this shift, oncogenic RAS signaling was poorly tolerated in BCR-positive cells unless BCR expression was disrupted. Pharmacologic activation of NF-κB reduced ERK signaling and selectively impaired viability of RAS-driven B-ALL cells, with enhanced effects in combination with ERK inhibition. Together, these findings show that canonical NF-κB signaling promotes BCR expression, which constrains oncogenic RAS activity, and establish pathway incompatibility as a mechanism through which receptor context can limit oncogenic potential.

Cancer biology

Tonic signaling of the B-cell antigen-specific receptor is a common functional hallmark in chronic lymphocytic leukemia cell phosphoproteomes at early disease stages.

B-cell chronic lymphocytic leukemia (B-CLL) is characterized by highly heterogeneous genomic alterations and altered signaling pathways, with limited studies on its proteome. Our study presents a comprehensive analysis of the proteome and phosphoproteome in B-CLL and CLL-like monoclonal B-cell lymphocytosis (MBL) primary cells. Using high-resolution mass spectrometry, we identified 2970 proteins and 316 phosphoproteins across five tumor samples, including 55 newly identified phosphopeptides (ProteomeXchange-PXD005997). Our multifaceted approach also integrated protein microarrays and western blotting for further data validation in a new patient cohort of 14 patients. Despite sharing 73% of their proteomes, the phosphoproteomes varied significantly among samples, independent of cytogenetic alterations and immunoglobulin heavy variable cluster (IGHV) mutational status. We identified common functional hallmarks in B-CLL and MBL phosphoproteomes, notably tonic signaling (low-level, constitutive signaling) of the B-cell antigen-specific receptor (BCR) and nuclear factor NF-kappa-B (NF-kβ)/signal transducer and activator of transcription 3 (STAT3) pathways. Nine phosphoproteins involved in BCR signaling were further validated, showing a high correlation with early disease stages. Our study advances the field by providing a detailed perspective on the proteome and phosphoproteome of B-CLL cells, revealing signaling pathways crucial for disease development and progression. Integrating diverse proteomics techniques and identifying novel phosphopeptides offers new insights into CLL biology, potentially informing future therapeutic strategies and biomarker development for early diagnosis and personalized treatment.

Humans

Transcriptomic responses of gill and intestinal tissues in Nile tilapia (Oreochromis niloticus) to bacterial infection following sequential nanoimmersion and hydrogel-based multivalent vaccination.

Bacterial pathogens, including Flavobacterium oreochromis, Aeromonas veronii, Streptococcus agalactiae, and Edwardsiella tarda, represent major infectious threats to Nile tilapia (Oreochromis niloticus). A multivalent vaccination strategy integrating cationic nanoemulsion immersion with oral hydrogel boosters was developed to investigate tissue-specific immune responses at the transcriptomic level. Gill tissues were collected following immersion challenge and intestinal tissues following intraperitoneal injection challenge, reflecting the physiologically relevant infection biology of each pathogen and the mechanistic rationale of each delivery platform. RNA sequencing (RNA-seq) generated high-quality datasets (mapping rate > 81.64%) with strong concordance to quantitative real-time PCR (qRT-PCR) validation (r = 0.83). Comparative transcriptomic analysis revealed distinct yet complementary immune signatures between tissues. Gill transcriptomes were enriched in phagosome, focal adhesion, extracellular matrix-receptor interaction (ECM-receptor interaction), and cytokine-cytokine receptor interaction pathways, accompanied by increased expression of major histocompatibility complex class I/II (MHC class I/II), mannose receptor, αVβ3 integrin, and calnexin, indicating innate activation, enhanced phagocytic capacity, epithelial barrier reinforcement, and adaptive immune coordination. Intestinal transcriptomes showed predominant enrichment of adaptive immune pathways, including the intestinal immune network for immunoglobulin (Ig) production, Forkhead box O (FoxO) signaling, and mitogen-activated protein kinase (MAPK) signaling, with increased expression of T-cell receptor (TCR), inducible T-cell co-stimulator ligand (ICOS-L), C-X-C chemokine receptor type 4 (CXCR4), and polymeric immunoglobulin receptor (pIgR), reflecting T and B cell coordination, lymphocyte trafficking, and mucosal immunoglobulin transport, alongside innate engagement through phagosome pathway enrichment. Shared upregulation of MHC class II, B-cell receptor (BCR) signaling, integrin alpha M (ITGAM), and immunoglobulin-associated components across both tissues suggests coordinated mucosal immune activation through a conserved immune module, warranting direct experimental validation. Collectively, these findings provide transcriptomic evidence that this vaccination strategy elicits an integrated, tissue-specialized immune response, advancing mechanistic understanding of gill and intestinal immunity in vaccine-induced protection of teleost fish.

Animals

Late acquisition of BCR::ABL1 during clonal evolution of SAMD9-associated MDS with phenotypic shift from AML to B-ALL.

We describe a unique case of SAMD9-associated myelodysplastic syndrome (MDS) with monosomy 7 that evolved over 16 years into BCR::ABL1-positive acute myeloid leukemia (AML) and subsequently manifested as B-cell acute lymphoblastic leukemia (B-ALL). Genomic analysis at AML diagnosis revealed a germline SAMD9 mutation together with somatic RUNX1 and PPM1D mutations, supporting stepwise clonal evolution, with BCR::ABL1 emerging as a late leukemogenic event. The dominant leukemic population at AML onset showed myeloid morphology and immunophenotype, whereas a minor CD19+CD10+ population was already detectable. Following venetoclax and azacitidine therapy, the dominant leukemic phenotype shifted to B-ALL while retaining BCR::ABL1 positivity. Detection of the Philadelphia chromosome in mature neutrophils at both AML onset and ALL relapse supported multilineage involvement of a multipotent BCR::ABL1-positive clone. Ponatinib achieved disease control. This case highlights late acquisition of BCR::ABL1 during SAMD9-associated clonal evolution and therapy-driven phenotypic shift within a shared Ph-positive leukemic stem-cell hierarchy.

Humans

Systematic characterization of neurotransmitter receptor dysregulation identifies a neural-related prognostic signature associated with biochemical recurrence in prostate cancer.

BACKGROUND: The nervous system is increasingly recognized to play a critical role in tumor initiation and progression. Central to this complex relationship are the interactions between neurotransmitters secreted by neurons and their receptors (neurotransmitter receptors, NTRs) expressed on cancer cells, which activate multiple intracellular signaling pathways. However, the spectrum of NTR dysregulation and its association with biochemical recurrence (BCR) in prostate cancer (PCa) has not been explored. Therefore, the aim of this study was to fill this gap. METHODS: We systematically characterized the expression profiles of 130 NTR genes by integrating bulk and single-cell transcriptomic data. Consistently dysregulated NTR (cdNTR) genes were identified and used to construct a PCa signature (PCaSig) using elastic-net regression. The robustness of PCaSig was evaluated across three independent cohorts. In addition, the associations of PCaSig with clinicopathological characteristics, genomic alterations, tumor immune-related characteristics, and biological pathways were comprehensively investigated. RESULTS: Thirteen cdNTR genes with strong cell-type specificity, particularly in luminal epithelial cells, were identified. PCaSig robustly stratified patients into distinct BCR risk groups across multiple independent cohorts and remained an independent predictor after adjustment for clinicopathological factors. High PCaSig scores were associated with aggressive clinicopathological features, elevated tumor mutation burden (TMB), suppression of neurotransmitter-related signaling, and activation of cell-cycle and immune-related pathways. Notably, PCaSig refined prognostic stratification regardless of TMB status and was associated with distinct immune-related characteristics, including immune checkpoint expression and immune cell infiltration. Incorporation of PCaSig into a clinical nomogram significantly improved prognostic accuracy and clinical net benefit. CONCLUSIONS: These findings establish NTR dysregulation as a previously underappreciated dimension of PCa and support PCaSig as a clinically relevant tool for personalized management.

Neurotransmitter receptor (NTR)

Proteomics as a theranostic compass in BCR::ABL1-negative myeloproliferative neoplasms: Integrating biomarker discovery with therapeutic stratification.

Classic BCR::ABL1-negative myeloproliferative neoplasms (MPNs)-polycythaemia vera, essential thrombocythaemia, and primary myelofibrosis-are clonal haematopoietic stem cell disorders with marked heterogeneity in clinical phenotype, disease trajectory, and therapeutic response. Genomic stratification by driver and cooperating mutations only partially accounts for this variability, leaving gaps in predicting thrombotic risk, fibrotic progression, leukaemic transformation, and treatment benefit. Proteomics bridges this gap by providing function-proximal readouts of protein abundance, post-translational modifications, pathway activity, and intercellular signalling that genomics and transcriptomics cannot capture, positioning it as a theranostic platform in which the same molecular readouts simultaneously inform diagnostic stratification and therapeutic decision-making. We propose a five-stage translational framework spanning from discovery-scale mass spectrometry and affinity-based plasma profiling to targeted validation, multicentre standardisation, and machine learning-integrated clinical panels. Proteomic evidence is synthesised across the following four disease axes: clonal fitness in haematopoietic stem and progenitor cells; bone marrow microenvironmental remodelling and fibrosis; chronic inflammation and thrombosis; and leukaemic transformation. We further describe how phosphoproteomics reveals resistance mechanisms to JAK inhibitors, including AXL-MAPK bypass and PP2A-autophagy-mediated tolerance, and how protein-level biomarkers (BCL2-BCL-XL, RAS-ERK, CAMK2G, and ROCK1/2) can guide individualised therapeutic selection. Affinity-based platforms (Olink PEA and SomaScan) and spatially resolved technologies (CODEX and single-cell proteomics) complement discovery proteomics. At present, however, this evidence base is constrained by small and heterogeneous cohorts, limited cross-platform reproducibility, and a scarcity of independent external validation for candidate protein panels. Realising this vision will require multicentre standardisation, analytically validated panel assays, and prospective clinical studies that translate molecular findings into decision-grade tools for patients with MPNs.

Humans

Genetic Profile, Treatment Response, and Outcomes of BCR::ABL1-Positive Mixed-Phenotype Acute Leukemia: A Study From the BCR::ABL1 Pathology Group.

Mixed-phenotype acute leukemia (MPAL) with BCR::ABL1 fusion is rare, and its clinicopathological features, genetic landscape, therapeutic response, and patient outcomes remain incompletely defined, as does its relationship to blast-phase chronic myeloid leukemia. In this multicenter study of 44 patients, 86.4% had B/myeloid MPAL, 72.7% showed lymphoid predominance, 40.9% had complex karyotypes, and 68.3% harbored somatic mutations, most commonly RUNX1 mutations (46.3%). RUNX1 mutations frequently co-occurred with acute myeloid leukemia (AML)-associated alterations, whereas DNMT3A, TET2, and BCORL1 mutations were restricted to RUNX1-mutated cases. In contrast, acute lymphoblastic leukemia (ALL)-associated alterations (IKZF1 mutation/deletion and ETV6 mutations) were confined to RUNX1-wild-type patients. TP53 and signaling pathway mutations (NRAS, KRAS, PTPN11, and FLT3) were not detected. Forty-two patients received induction chemotherapy and/or immunotherapy combined with tyrosine kinase inhibitors: 74.2% of lymphoid-predominant patients and 63.6% of myeloid-predominant patients received ALL- and AML-type therapies, respectively. Ten patients relapsed, and 2 had primary refractory disease; some exhibited a dynamic shift in predominant lineage immunophenotype, chromosomal alterations, and somatic mutations at the relapse or refractory stage. The overall remission rate was 86.8%, with no significant differences across ALL-, AML-, or hybrid-type regimens. After a median follow-up of 24.2 months, the median overall survival was 52.5 months. Complex karyotype was associated with inferior overall survival compared with cases lacking additional chromosomal alterations (P = .02), whereas RUNX1 mutations were not. No significant differences in genetic profiles, treatment response, or outcomes were observed between patients with and without chronic myeloid leukemia-like features. This study provides a comprehensive genomic and clinical characterization of BCR::ABL1-positive MPAL, supporting improved risk stratification and future therapeutic strategies.

Adolescent