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Early immune dysregulation in Mtb/SIV co-infection resists cART treatment at the single-cell level.

Using single-cell transcriptomics of bronchoalveolar lavage cells from Mtb/SIV co-infected rhesus macaques on cART, we reveal profound immune dysregulation during early SIV co-infection of latent tuberculosis. SIV induces a sharp decline in CD4+ T cells, NK, and NKT cells, with incomplete recovery of Mtb-specific TH1 effector responses despite viral suppression. Instead, a persistent TH17-skewed environment emerges, alongside sustained myeloid inflammation driven by Type I interferon signaling and pro-inflammatory regulators such as KLF6 and NFKB1. Ligand-receptor network analyses demonstrate expanded CD4+ T cell-macrophage crosstalk and loss of immune homeostasis that cART fails to fully restore. These findings expose how SIV remodels the pulmonary immune landscape to impair protective immunity against Mtb, providing a transcriptomic framework to explain TB reactivation in HIV infection. Our work highlights the urgent need for adjunctive immunotherapies to complement cART, aiming to rebalance immune responses and improve TB control in co-infected individuals.

HIV

Paternal exposure to polystyrene nanoplastics induces inter- and transgenerational bronchopulmonary dysplasia-like damage in male offspring by FtMt hypermethylation-mediated ferroptosis.

Bronchopulmonary dysplasia (BPD) is a major cause of chronic lung disease in both preterm infants and adults, but its etiology remains incompletely understood. In this study, F0 generation mice were exposed to polystyrene nanoplastics (PS-NPs), and F1 to F3 generations were obtained by breeding. Multi-omics sequencing including whole genome methylation sequencing, single cell transcriptome sequencing and transcriptome sequencing was performed on the lungs of offspring. The levels of Fe2+, lipid peroxidation products and key gene expression were determined. Male mice exposed to PS-NPs at environmentally relevant doses produced offspring (F1 and F2) that exhibited a typical BPD-like phenotype. Meanwhile, the F0 males showed diminished sperm motility, demonstrating that paternal PS-NPs exposure constituted an etiological factor for BPD in descendants. Mechanistic studies showed that PS-NPs exposure upregulated the expression of DNA methyltransferase Dnmt3a, leading to global hypermethylation of the sperm genome. Importantly, the hypermethylated promoter signature of the mitochondrial ferritin (FtMt) gene partially resisted epigenetic reprogramming and was transmitted to the lungs of offspring, resulting in persistently low FtMt expression in F1 and F2 lungs. This led to increased intracellular Fe2+ levels, subsequently triggered ferroptosis in alveolar epithelial cells, and ultimately impaired alveolarization. Knockdown of FtMt confirmed that FtMt deficiency was sufficient to induce ferroptosis and BPD-like lung injury both in vitro and in vivo. Furthermore, using in vitro fertilization of F0 sperm combined with Dnmt3a siRNA microinjection, we directly demonstrated that Dnmt3a is a key driver for FtMt to escape reprogramming and maintain its hypermethylation. In summary, this study reveals for the first time that paternal PS-NPs exposure causes BPD through a Dnmt3a-FtMt hypermethylation intergenerational and transgenerational axis, providing an epigenetic basis for understanding paternal derived chronic lung disease and potential targets for early intervention.

Animals

Sustained NF-κB activation allows mutant alveolar stem cells to co-opt a regeneration program for tumor initiation.

Disruptions to regulatory signals governing stem cell fate open the pathway to tumorigenesis. To determine how these programs become destabilized, we fate-map thousands of murine wild-type and KrasG12D-mutant alveolar type II (AT2) stem cells in vivo and find evidence for two independent AT2 subpopulations marked by distinct tumorigenic capacities. By combining clonal analyses with single-cell transcriptomics, we unveil striking parallels between lung regeneration and tumorigenesis that implicate Il1r1 as a common activator of AT2 reprogramming. We show that tumor evolution proceeds through the acquisition of lineage infidelity and reversible transitions between mutant states, which, in turn, modulate wild-type AT2 dynamics. Finally, we discover how sustained nuclear factor κB (NF-κB) activation sets tumorigenesis apart from regeneration, allowing mutant cells to subvert differentiation in favor of tumor growth.

Animals

Generation and validation of a Myh11Dre-Spp1Cre intersectional mouse model for lineage tracing of disease-associated smooth muscle cell states.

BACKGROUND: Phenotypic modulation of vascular smooth muscle cells (VSMCs) is a hallmark of vascular remodeling and cardiovascular disease. Recent lineage-tracing and single-cell transcriptomic studies have identified secreted phosphoprotein 1 (SPP1) as a prominent marker associated with disease-associated VSMC states, particularly those linked to fibrotic remodeling and vascular calcification. However, the cellular origins and fate of SPP1-associated VSMC populations remain incompletely understood. METHODS AND RESULTS: We generated a novel Spp1-rSTOPr-Cre (Spp1Cre) knock-in mouse line in which Cre recombinase is expressed from the endogenous Spp1 locus following Dre-mediated excision of a rox-flanked transcriptional STOP cassette. Correct targeting of the knock-in allele was validated by internal, 5' junction, 3' junction, and long-range PCR analyses, as well as Sanger sequencing. To establish an intersectional lineage-tracing strategy, Spp1Cre mice were crossed with Myh11DreERT2 and Rosa26-RSR-LSL-tdTomato-LSL-eGFP reporter mice, enabling permanent labeling of VSMC-derived populations following activation of the endogenous Spp1 locus. Under physiological conditions, eGFP-positive cells were detected at low frequency within the vascular wall and were predominantly negative for the contractile markers ACTA2 and MYH11. As a proof-of-principle application, eGFP-positive cells markedly expanded within atherosclerotic lesions induced by AAV-PCSK9D377Y and high-fat diet feeding. These lineage-traced cells remained largely ACTA2- and MYH11-negative, consistent with a modulated phenotype. Notably, only a minority of eGFP-positive cells expressed SPP1 or fibronectin at the time of analysis, demonstrating the utility of permanent lineage tracing for tracking cells with a history of endogenous Spp1 activation during vascular remodeling. CONCLUSION: We report the generation and validation of a novel Myh11Dre-Spp1Cre intersectional mouse model for lineage tracing of VSMC-derived populations that have activated the endogenous Spp1 locus. This genetic resource provides a valuable platform for investigating the origin, fate, and phenotypic evolution of Spp1-associated VSMC populations during vascular remodeling and cardiovascular disease.

Animals

A stem-like chromatin program in small-cell lung cancer is associated with poor outcomes after chemoimmunotherapy.

Small-cell lung cancer (SCLC) is an aggressive malignancy with substantial tumor heterogeneity and limited clinically actionable biomarkers beyond established features such as liver metastases. We profile tumor-intrinsic chromatin accessibility in a patient-derived xenograft biobank and identify three recurrent chromatin programs: neuroendocrine, marked by ASCL1/NEUROD1 activity; immunogenic, marked by IRF-associated activity; and stem-like, marked by TEAD/OCT activity. These programs are reproduced at the cohort level across bulk and single-cell transcriptomic datasets comprising more than 800 tumors, including 300 extensive-stage samples. In patients treated with chemoimmunotherapy, the stem-like program is associated with inferior survival, including a median overall survival of 7.41 months versus 15.9 and 12.6 months for immunogenic and neuroendocrine groups, respectively. This association remains significant after adjustment for liver metastases, brain metastases, and elevated lactate dehydrogenase. These findings support a high-risk stem-like SCLC chromatin program for prospective biomarker refinement and therapeutic investigation.

ATAC-seq

Acbd7 is essential for preserving hair cell-mediated auditory and vestibular function.

Understanding the molecular basis of hair cell function is essential for elucidating inner ear physiology and developing therapies for auditory-vestibular disorders. Here, we identify acyl-CoA binding domain-containing 7 (Acbd7) as a hair cell-specific gene critical for sensory maintenance. Single-cell transcriptomics of mouse cochlear organoids revealed Acbd7 as a top hair cell-enriched transcript, with its spatiotemporal expression confirmed from embryonic development through adulthood in both auditory and vestibular hair cells. Acbd7‑deficient mice exhibited pronounced hair cell degeneration, characterized by synaptic defects and diminished calcium currents in inner hair cells and loss of outer hair cells. Transcriptomic and proteomic analyses linked Acbd7 to the regulation of Ca2+ signaling and fatty acid metabolism pathways. Our findings establish Acbd7 as a critical regulator of Ca2+ homeostasis and functional integrity in hair cells, thereby elucidating a key mechanism by which a fatty acid metabolism factor sustains hair cell function and providing potential therapeutic targets for inner ear disorders.

Animals

A refined MASH-HCC model identifies macrophage Gadd45b as a key orchestrator of inflammation-driven neoplastic progression.

Metabolic dysfunction-associated steatohepatitis (MASH) is emerging as a leading driver of hepatocellular carcinoma (HCC), yet the molecular mechanisms linking metabolic stress, chronic inflammation and tumorigenesis remain poorly understood. Here we established a metabolically relevant, time-efficient MASH-to-HCC model in C57BL/6N mice by combining a MASH diet with controlled CCl4 administration, enabling stepwise recapitulation of MASH-associated neoplastic progression. Using this model, we identified growth arrest and DNA damage 45b (Gadd45b) as a novel MASH-derived protumorigenic regulator selectively activated under metabolic stress. Integrated analyses of human bulk and single-cell transcriptomic datasets and mouse transcriptomic deconvolution revealed concordant macrophage remodeling and GADD45B/Gadd45b expression dynamics during MASH-to-HCC progression. Mechanistically, fatty acids and TNFα preferentially induced Gadd45b in macrophages, where it amplified TNFα-NF-κB signaling. Macrophage-derived inflammatory signals subsequently induced Gadd45b and NF-κB activation in hepatocytes, establishing a feed-forward inflammatory loop that promoted fibrogenic and partial EMT-like programs and tumor spheroid formation. Importantly, temporal profiling during spheroid formation and progression revealed transient induction of Gadd45b during early spheroid establishment, but not during later progression, indicating that Gadd45b-mediated inflammatory signaling primarily promotes tumor initiation rather than subsequent growth. Consistent with human data, Gadd45b expression increased with disease severity and positively correlated with inflammatory factors in the MASH-HCC model, whereas pharmacological inhibition attenuated the Gadd45b-inflammation signaling axis. Collectively, our findings establish macrophage Gadd45b as a key orchestrator linking metabolic stress, chronic inflammation, and neoplastic transformation during MASH-to-HCC progression. Our refined MASH-HCC model provides a robust platform for mechanistic studies and preclinical evaluation of inflammation-targeted therapies.

Journal Article

Maternal COVID-19 infection associated with offspring neurodevelopmental disorders.

Maternal COVID-19 infection increases the incidence of neurodevelopmental disorders (NDDs) in offspring, although the underlying mechanisms have not been elucidated. This study demonstrated that COVID-19 infection during pregnancy disrupted the balance of maternal and fetal immune environments, driving alterations in astrocytes, endothelial cells, and excitatory neurons. A risk score was established using 47 unique genes in the single-cell transcriptome of gestational mothers. The high risk score in CD4 proliferating T cell level served as an indicator for increased risk of offspring NDDs. Summary-based Mendelian randomization and phenome-wide association study analyses were conducted to identify the causal association of the transcriptional changes with the increased risk of offspring NDDs. Additionally, 10 drugs were identified as potential therapeutic candidates. Our findings support a model where the maternal COVID-19 infection changed the levels of CD4 proliferating T cells, leading to the alterations of astrocytes, endothelial cells, and excitatory neurons in offspring, contributing to the increased risk of NDDs in these individuals.

Humans

A step-wise, deterministic and fatal mouse model of myeloid neoplasm with spontaneous acquisition of patient-relevant RTK-RAS mutations.

Leukaemia arises through the stepwise transformation of healthy haematopoietic cells, yet the asymptomatic premalignant phase and its progression to overt disease remain poorly understood. To model this process, we engineered a patient-derived CEBPA mutation into Hoxb8-FL multipotent murine progenitors and transplanted them into syngeneic mice, capturing a clinically silent premalignant stage. All recipients developed overt disease after ~12 months with 100% penetrance and all acquired secondary RTK-RAS mutations, often with identical amino acid changes to those in patients. Single-cell transcriptomics and phenotypic profiling showed that premalignant mutant cells adopt a plasmacytoid dendritic progenitor-like state in vitro which generates both myeloid and B-lymphoid lineages during premalignancy in vivo, with individual tumours restricted to one lineage. The specificity for RTK-RAS mutations coupled with ongoing differentiation, reflects clinically relevant biological contexts thus providing a tractable model of myeloid neoplasm for mechanistic studies and drug discovery.

Journal Article

Receptor-defined targeting of a genomically unique melanoma-enriched noncanonical antigen.

Effective T cell-based immunotherapies require functional receptors that can be engineered and redeployed to recognize tumor-restricted antigens. Noncanonical peptides arising from transcription outside annotated protein-coding regions expand the antigenic landscape of cancer; however, systematic strategies to biologically prioritize and functionally validate such targets remain underdeveloped. Here, we integrated de novo transcript analysis, exon-resolved quantification, RNA in situ hybridization, and immunopeptidomics to identify melanoma-associated noncanonical transcripts and advance candidates through receptor-level validation. Among three recurrent melanoma-associated transcripts, EVA003 emerged as a lead target based on its distinct repeat-enriched genomic architecture, consistent tumor-enriched exon-level expression across independent datasets, and a genomically unique immunogenic core sequence. We demonstrate endogenous presentation of EVA003-derived peptides on HLA-A*03:01 and detect specific reactivity in patient-derived tumor-infiltrating lymphocytes. Single-cell transcriptomic profiling identified a dominant peptide-reactive clonotype, enabling isolation of a naturally occurring T cell receptor. Transfer of this receptor into healthy donor T cells conferred antigen-dependent activation and cytotoxicity against both peptide-pulsed targets and melanoma cells expressing EVA003 endogenously. Together, these findings establish a biologically informed strategy for prioritizing noncanonical tumor antigens and demonstrate that genomically unique, tumor-enriched noncanonical peptides can be presented to molecularly defined receptors capable of mediating cancer cell killing. These findings support the integration of prioritized noncanonical antigens into engineered T cell therapeutic strategies.

Humans

Targeting super elongation complex-driven RNA polymerase II elongation reduces plaque vulnerability.

Atherosclerotic plaque rupture is a major cause of myocardial infarction and stroke, yet the mechanisms governing plaque stability remain incompletely understood. Endothelial activation can trigger endothelial-to-mesenchymal transition, a program linked to endothelial dysfunction and lesion vulnerability. Here we investigated whether transcriptional pause release and RNA polymerase II elongation constitute an early regulatory layer that promotes endothelial-to-mesenchymal transition and atherosclerosis. Analysis of human plaque single-cell transcriptomics indicated increased expression of super elongation complex components in endothelial cells with a transition signature. In primary human endothelial cell models, pharmacological inhibition of the super elongation complex attenuated the induction of mesenchymal markers. AFF4, pCDK9, and pSMAD2/3 showed physical interaction during endothelial transition. Genome-wide profiling of RNA polymerase II occupancy revealed reduced promoter-proximal pausing during early transition, accompanied by a rapid increase in nascent transcriptional elongation rates. Super elongation complex inhibition restored pausing and suppressed fast-responding transition-associated target genes. In a human cardiac organoid model, inhibition of the super elongation complex prevented EndMT-induced fibrillar collagen deposition and prevented the loss of beating rate. In a hyperlipidemic Pcsk9 gain-of-function mouse model, super elongation complex inhibition administered both prophylactically and therapeutically after established atherosclerosis reduced plaque burden and reduced features of plaque vulnerability. Finally, analysis of 1048 human plaque segments from the Athero-Express biobank showed significant associations between the elongation axis and multiple vulnerability-related plaque traits. Together, these findings identify rapid transcriptional elongation as a mechanistic driver of endothelial plasticity and features of plaque vulnerability and support targeting the elongation machinery as a potential strategy to reduce features of plaque vulnerability in atherosclerotic disease.

Humans

Immune cell-specific genetic architecture of Alzheimer's disease revealed by multi-omics analysis for therapeutic target discovery and prioritization.

Alzheimer's disease (AD) is a multifactorial neurodegenerative condition in which accumulating genetic and molecular evidence implicates dysregulation of peripheral immune processes in disease pathogenesis. Nevertheless, the contribution of distinct peripheral immune cell subsets and associated gene regulatory landscapes to AD risk remains incompletely defined. To address this gap, we integrated single-cell expression quantitative trait loci (sc&#x2011;eQTL) data from the OneK1K cohort with AD GWAS summary statistics. We systematically interrogated immune cell-specific genes for their contributions to AD risk by integrating genetic causal inference with Bayesian colocalization analyses, and identified 24 eGenes that passed both the MR significance threshold (P&#x2009;<&#x2009;0.05) and the criterion for strong shared genetic signals (PP.H4&#x2009;>&#x2009;0.8). Notable candidates included GATS, HLA-DOB, HLA-DQA1, PM20D1, and others, with each gene demonstrating a cell-type-specific association restricted to its corresponding immune cell type, such as monocytes, CD8&#x2009;+&#x2009;T cells, or B cells. Independent peripheral blood single-cell transcriptomic data further supported disease-associated shifts in cell-type-specific expression patterns in AD. Phenome-wide association studies (PheWAS) indicated limited associations with off-target traits, indicating a favorable safety profile for therapeutic intervention, with the exceptions of B4GALNT3, PM20D1, and CNN2. Integration of immune gene targets with pharmacological databases yielded three candidate compound, including NSC321521 (targeting HLA-DQA1), phenoxybenzamine (targeting GSTP1), and rimexolone (targeting BIN1). Among these compounds, Predicted blood-brain barrier permeability was observed only for phenoxybenzamine and rimexolone, with docking studies indicating stable interactions, such as those between NSC321521 and HLA-DQA1, phenoxybenzamine and GSTP1, and rimexolone and BIN1. This integrative approach highlights key immune&#x2011;cell&#x2011;specific genes involved in AD and proposes repurposable drugs with central nervous system potential, paving the way for more targeted immunomodulatory strategies in AD.

Humans

LKB1 inactivation promotes epigenetic remodeling-induced lineage plasticity and antiandrogen resistance in prostate cancer.

Epigenetic regulation profoundly influences the fate of cancer cells and their capacity to switch between lineages by modulating essential gene expression, thereby shaping tumor heterogeneity and therapy response. In castration-resistant prostate cancer (CRPC), the intricacies behind androgen receptor (AR)-independent lineage plasticity remain unclear, leading to a scarcity of effective clinical treatments. Utilizing single-cell RNA sequencing on both human and mouse prostate cancer samples, combined with whole-genome bisulfite sequencing and multiple genetically engineered mouse models, we investigated the molecular mechanism of AR-independent lineage plasticity and uncovered a potential therapeutic strategy. Single-cell transcriptomic profiling of human prostate cancers, both pre- and post-androgen deprivation therapy, revealed an association between liver kinase B1 (LKB1) pathway inactivation and AR independence. LKB1 inactivation led to AR-independent lineage plasticity and global DNA hypomethylation during prostate cancer progression. Importantly, the pharmacological inhibition of TET enzymes and supplementation with S-adenosyl methionine were found to effectively suppress AR-independent prostate cancer growth. These insights shed light on the mechanism driving AR-independent lineage plasticity and propose a potential therapeutic strategy by targeting DNA hypomethylation in AR-independent CRPC.

Male

Rescue of imprinted genes by epigenome editing in human cellular models of Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is a genomic imprinting disorder caused by the loss of function of the paternal chromosome 15q11-13, resulting in a spectrum of symptoms associated with hypothalamic dysfunction. PWS patients lack the expression of paternally expressed genes (PEGs) in the 15q11-13 locus but possess an epigenetically silenced set of these genes in the maternal allele. Thus, activation of these silenced genes can serve as a therapeutic target for PWS. Here, we leverage CRISPR-based epigenome editing system to modulate the DNA methylation status of the PWS imprinting control region (PWS-ICR) in induced pluripotent stem cells (iPSCs) derived from PWS patients. Successful demethylation in the PWS-ICR restores the PEG expression from the maternal allele and reorganizes the methylation patterns in other PWS-associated imprinted regions beyond the PWS-ICR. Remarkably, these corrected epigenomic patterns and PEG expression are maintained following the differentiation of these cells into hypothalamic organoids. Finally, the single-cell transcriptomic analysis of epigenome-edited organoids demonstrates a partial restoration of the transcriptomic dysregulation observed in PWS. This study highlights the utility of epigenome editing technology as a therapeutic approach in addressing PWS and potentially other imprinting disorders.

Prader-Willi Syndrome

Hypoxia-activated scleraxis a mediates epicardial progenitor differentiation into a unique cardiac perivascular cell type.

The epicardium provides progenitor cells and paracrine signals essential for heart development and regeneration, yet the mechanisms regulating epicardial cell fate remain poorly understood. Here, we identify the transcription factor Scleraxis a (scxa) as a key regulator of epicardial progenitor differentiation in zebrafish. Single-cell transcriptomics, genetic lineage tracing, and cardiac injury models reveal transient scxa expression in activated epicardial progenitor cells (aEPCs) during developmental coronary angiogenesis and heart regeneration. scxa+ epicardial cells predominantly differentiate into a previously uncharacterized col18a1a+ perivascular population, termed epicardial-derived perivascular mesenchymal cells (Epi-PMCs), which is distinct from pericytes, vascular smooth muscle cells, and mammalian adventitial fibroblasts. Epi-PMCs closely associate with coronary vessels and may contribute to vascular stabilization and remodeling, potentially through collagen XVIII. Loss of scxa increases coronary vessel density. Hypoxia and Hif signaling induce scxa expression, identifying a hypoxia-responsive mechanism that promotes epicardial differentiation toward a vascular-supportive fate during heart development and regeneration.

Animals

CRISPRi screens in human iPSC-derived astrocytes elucidate regulators of distinct inflammatory reactive states.

Astrocytes become reactive in response to insults to the central nervous system by adopting context-specific cellular signatures and outputs, but a systematic understanding of the underlying molecular mechanisms is lacking. In this study, we developed CRISPR interference screening in human induced pluripotent stem cell-derived astrocytes coupled to single-cell transcriptomics to systematically interrogate cytokine-induced inflammatory astrocyte reactivity. We found that autocrine-paracrine IL-6 and interferon signaling downstream of canonical NF-&#x3ba;B activation drove two distinct inflammatory reactive signatures, one promoted by STAT3 and the other inhibited by STAT3. These signatures overlapped with those observed in other experimental contexts, including mouse models, and their markers were upregulated in human brains in Alzheimer's disease and hypoxic-ischemic encephalopathy. Furthermore, we validated that markers of these signatures were regulated by STAT3 in vivo using a mouse model of neuroinflammation. These results and the platform that we established have the potential to guide the development of therapeutics to selectively modulate different aspects of inflammatory astrocyte reactivity.

Humans

Gata3 dosage governs primitive endoderm versus trophectoderm specification in embryonic stem cells.

Transcription factor (TF) dosage represents an overlooked aspect of developmental regulation. While Gata3 has traditionally been viewed as a determinant of trophectoderm (TE), its potential role in primitive endoderm (PE) has remained unclear. Here, we demonstrate that Gata3 functions as a dosage-sensitive regulator directing mutually exclusive lineage programs in mouse embryonic stem (ES) cells. Low levels of Gata3 (Gata3-L) promote PE-like transcriptional states, while high levels (Gata3-H) drive TE identity by rapidly repressing pluripotency and inducing TE markers. Genome-wide binding analysis reveals a dose-dependent redistribution of Gata3 across enhancers, with chromatin engagement consistent with pioneer factor-like activity. Functional 3D blastoid assays combined with single-cell transcriptomics further establish that Gata3 dosage alone is sufficient to instruct the spatial segregation of PE- versus TE-like compartments. These findings redefine Gata3 not merely as a TE determinant but as a central dosage-sensitive switch in lineage specification. More broadly, our results position TF dosage as a fundamental regulatory parameter that integrates enhancer selection, chromatin engagement, and spatial patterning, providing new opportunities to refine stem cell-based models and engineer developmental outcomes.

GATA3 Transcription Factor

RHAMM drives formation of polyploid cancer cells and confers resistance to ER-targeted therapy in breast cancer.

Endocrine resistance in ER+ breast cancer remains a major clinical challenge. Here, we identify RHAMM as a key driver of resistance by orchestrating polyploid cancer cell (PCC) formation. Single-cell transcriptomics uncovered a G2/M-enriched, RHAMM+ subpopulation in endocrine-resistant tumors. Mechanistically, RHAMM binds Septin9/10 to promote aberrant cytoskeleton polymerization, activating YAP independent of Hippo signaling, which induces cytokinesis failure and facilitates PCC generation. Concurrently, RHAMM destabilizes p21 mRNA, enabling cell cycle progression despite genomic instability. The RHAMM-p21 axis serves as a bypass mechanism supporting polyploidization. Upon endocrine treatment, RHAMM is transcriptionally up-regulated by Slug. Clinically, RHAMMhigh signatures are enriched in metastatic and recurrent ER+ tumors and correlate with poor prognosis, highlighting its therapeutic relevance. Importantly, targeting RHAMM or YAP abrogates PCC formation and restores fulvestrant sensitivity. These findings reveal RHAMM-mediated polyploidization as an adaptive mechanism underlying endocrine resistance, suggesting the therapeutic potential of targeting the RHAMM-YAP axis.

Humans