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ObjectivesNon-alcoholic fatty liver disease (NAFLD) can persist in the stage of simple hepatic steatosis or progress to steatohepatitis (NASH) with an increased risk for cirrhosis and cancer. We examined the mechanisms controlling the progression to severe NASH in order to develop future treatment strategies for this disease.DesignNFATc1 activation and regulation was examined in livers from patients with NAFLD, cultured and primary hepatocytes and in transgenic mice with differential hepatocyte-specific expression of the transcription factor (Alb-cre, NFATc1c.a . and NFATc1Δ/Δ ). Animals were fed with high-fat western diet (WD) alone or in combination with tauroursodeoxycholic acid (TUDCA), a candidate drug for NAFLD treatment. NFATc1-dependent ER stress-responses, NLRP3 inflammasome activation and disease progression were assessed both in vitro and in vivo.ResultsNFATc1 expression was weak in healthy livers but strongly induced in advanced NAFLD stages, where it correlates with liver enzyme values as well as hepatic inflammation and fibrosis. Moreover, high-fat WD increased NFATc1 expression, nuclear localisation and activation to promote NAFLD progression, whereas hepatocyte-specific depletion of the transcription factor can prevent mice from disease acceleration. Mechanistically, NFATc1 drives liver cell damage and inflammation through ER stress sensing and activation of the PERK-CHOP unfolded protein response (UPR). Finally, NFATc1-induced disease progression towards NASH can be blocked by TUDCA administration.ConclusionNFATc1 stimulates NAFLD progression through chronic ER stress sensing and subsequent activation of terminal UPR signalling in hepatocytes. Interfering with ER stress-responses, for example, by TUDCA, protects fatty livers from progression towards manifest NASH.

The bromodomain and extraterminal (BET) inhibitor JQ1 synergizes with the histone deacetylase inhibitor SAHA to suppress tumor growth in mouse models of pancreatic cancer. Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers and shows resistance to any therapeutic strategy used. Here we tested small-molecule inhibitors targeting chromatin regulators as possible therapeutic agents in PDAC. We show that JQ1, an inhibitor of the bromodomain and extraterminal (BET) family of proteins, suppresses PDAC development in mice by inhibiting both MYC activity and inflammatory signals. The histone deacetylase (HDAC) inhibitor SAHA synergizes with JQ1 to augment cell death and more potently suppress advanced PDAC. Finally, using a CRISPR-Cas9–based method for gene editing directly in the mouse adult pancreas, we show that de-repression of p57 (also known as KIP2 or CDKN1C) upon combined BET and HDAC inhibition is required for the induction of combination therapy–induced cell death in PDAC. SAHA is approved for human use, and molecules similar to JQ1 are being tested in clinical trials. Thus, these studies identify a promising epigenetic-based therapeutic strategy that may be rapidly implemented in fatal human tumors.

Pancreatic ductal adenocarcinoma (PDAC) is among the most aggressive and metastatic malignancies worldwide. Migrating cancer stem cells (miCSCs), marked by CD133⁺CXCR4⁺ expression is a key driver of PDAC progression, which currently lack effective therapeutic targets. Activated pancreatic stellate cells (PSCs) within the tumor microenvironment secrete CXCL12, the ligand for CXCR4, thereby promoting stemness, epithelial-to-mesenchymal transition (EMT), and chemoresistance in miCSCs. Despite advances in understanding PDAC biology, clinically effective strategies that target CXCR4⁺ CSC populations remain limited. In order to investigate the molecular mechanisms sustaining miCSCs, we performed protein–protein interaction network analysis, which identified the transcription factor BMI1 as a key downstream effector of the CXCL12/CXCR4 axis. Functional studies using shRNA-mediated knockdown of CXCR4 and BMI1 were conducted to assess their roles in miCSC migration, EMT, and self-renewal. We further evaluated the therapeutic potential of the endogenous CXCR4 antagonist EPI-X4 and its optimized derivative JM#21 in PDAC cell lines. We addressed the peptide stability by encapsulating JM#21 into mesoporous silica nanoparticles (MSNs) designed for improved half-life and sustained release under physiological conditions. BMI1 was confirmed as a critical mediator of CXCL12/CXCR4-driven stemness and EMT. Knockdown of CXCR4 or BMI1 significantly impaired miCSC maintenance and migration towards CXCL12. Both EPI-X4 and JM#21 potently inhibited CXCL12-mediated signaling, reduced EMT and stemness markers, and suppressed miCSC migratory potential. JM#21 displayed superior efficacy and re-sensitized previously resistant PDAC cell lines to gemcitabine and paclitaxel. Functional assays demonstrated that nanoparticle-loaded JM#21 more effectively suppressed EMT markers and self-renewal than the free peptide, highlighting the advantage of nanoparticle delivery in therapeutic applications. Given their biocompatibility and modularity, silica nanoparticles offer a promising platform for stabilizing peptide drugs. Our findings reveal that tumor–stroma crosstalk via the CXCL12/CXCR4/BMI1 axis plays a central role in sustaining miCSC-driven metastasis and therapy resistance in PDAC. Targeting this signaling pathway with nanoparticle-stabilized JM#21 represents a novel and clinically promising therapeutic strategy to disrupt PDAC progression and improve the efficacy of existing combination treatments.

Pancreatic ductal adenocarcinoma (PDAC) displays a high degree of spatial subtype heterogeneity and co-existence, linked to a diverse microenvironment and worse clinical outcome. However, the underlying mechanisms remain unclear. Here, by combining preclinical models, multi-center clinical, transcriptomic, proteomic, and patient bioimaging data, we identify an interplay between neoplastic intrinsic AP1 transcription factor dichotomy and extrinsic macrophages driving subtype co-existence and an immunosuppressive microenvironment. ATAC-, ChIP-, and RNA-seq analyses reveal that JUNB/AP1- and HDAC-mediated epigenetic programs repress pro-inflammatory signatures in tumor cells, antagonizing cJUN/AP1 signaling, favoring a therapy-responsive classical neoplastic state. This dichotomous regulation is amplified via regional TNF-α + macrophages, which associates with a reactive phenotype and reduced CD8 + T cell infiltration in patients. Consequently, combined preclinical anti-TNF-α immunotherapy and chemotherapy reduces macrophages and promotes CD3 + /CD8 + T cell infiltration in basal-like PDAC, improving survival. Hence, tumor cell-intrinsic epigenetic programs, together with extrinsic microenvironmental cues, facilitate intratumoral subtype heterogeneity and disease progression. The mechanisms of intratumoral subtype heterogeneity in pancreatic ductal adenocarcinoma (PDAC) remain unclear. Here, the authors analyse PDAC tumours and preclinical models using multi-omics and imaging; they demonstrate that AP1 dichotomy influences tumor plasticity, heterogeneity, and immune response, with potential therapeutic implications.

Chromatin remodeling processes can drive acinar cell fate decisions.

ObjectiveATM serine/threonine kinase (ATM) is the most frequently mutated DNA damage response gene, involved in homologous recombination (HR), in pancreatic ductal adenocarcinoma (PDAC).DesignCombinational synergy screening was performed to endeavour a genotype-tailored targeted therapy.ResultsSynergy was found on inhibition of PARP, ATR and DNA-PKcs (PAD) leading to synthetic lethality in ATM-deficient murine and human PDAC. Mechanistically, PAD-induced PARP trapping, replication fork stalling and mitosis defects leading to P53-mediated apoptosis. Most importantly, chemical inhibition of ATM sensitises human PDAC cells toward PAD with long-term tumour control in vivo. Finally, we anticipated and elucidated PARP inhibitor resistance within the ATM-null background via whole exome sequencing. Arising cells were aneuploid, underwent epithelial-mesenchymal-transition and acquired multidrug resistance (MDR) due to upregulation of drug transporters and a bypass within the DNA repair machinery. These functional observations were mirrored in copy number variations affecting a region on chromosome 5 comprising several of the upregulated MDR genes. Using these findings, we ultimately propose alternative strategies to overcome the resistance.ConclusionAnalysis of the molecular susceptibilities triggered by ATM deficiency in PDAC allow elaboration of an efficient mutation-specific combinational therapeutic approach that can be also implemented in a genotype-independent manner by ATM inhibition.

BackgroundPancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer with a 5-year survival rate of 12%. It has two major molecular subtypes: classical and basal, regulated by the master transcription factors (MTFs) GATA6 and ΔNp63, respectively.ObjectiveThis study sought to uncover the transcriptional regulatory mechanisms controlling PDAC subtype identity.DesignWe integrated primary tumour single-cell RNA-seq, patient-derived xenograft RNA-seq and multispectral imaging to identify MTF-dependent, subtype-specific markers. We created subtype-specific fluorescent reporter systems and conducted drug screenings to find actionable targets. We analysed chromatin accessibility (ATAC-seq), genome-wide occupancy (ChIP-seq) for epigenetic status (H3K27ac), MTFs (GATA6, ΔNp63), RNA polymerase II (Pol II), H3K4me3-anchored chromatin topology (HiChIP) and nascent RNA capture sequencing (PRO-seq). Additionally, we used nuclease-dead Cas9 (dCas9) to manipulate transcriptional regulatory mechanisms.ResultsOur approach identified glucocorticoid receptor (GR) agonists as agents that suppress the classical transcriptional programme by interacting with GATA6. GATA6 regulates classical-specific transcription through promoter-proximal pause release. Depletion of GATA6 increased Pol II occupancy at GATA6-bound enhancers and transcriptional start sites, stabilising enhancer–promoter interactions. Artificially inducing pausing at GATA6-bound enhancers with dCas9 abrogated target gene expression and induced pausing at both the enhancer and target gene promoter. Conversely, in basal PDAC ΔNp63 promotes Pol II recruitment and stabilises enhancer–promoter interactions.ConclusionThis study provides new insights into the transcriptional control and role of GR agonists in controlling PDAC molecular subtype identity.

Targeting KRAS downstream signaling remains an important therapeutic approach in pancreatic cancer. We used primary pancreatic ductal epithelial cells and mouse models allowing the conditional expression of oncogenic Kras G12D , to investigate KRAS signaling integrators. We observed that the AP1 family member FRA1 is tightly linked to the KRAS signal and expressed in pre-malignant lesions and the basal-like subtype of pancreatic cancer. However, genetic-loss-of-function experiments revealed that FRA1 is dispensable for Kras G12D -induced pancreatic cancer development in mice. Using FRA1 gain- and loss-of-function models in an unbiased drug screen, we observed that FRA1 is a modulator of the responsiveness of pancreatic cancer to inhibitors of the RAF–MEK–ERK cascade. Mechanistically, context-dependent FRA1-associated adaptive rewiring of oncogenic ERK signaling was observed and correlated with sensitivity to inhibitors of canonical KRAS signaling. Furthermore, pharmacological-induced degradation of FRA1 synergizes with MEK inhibitors. Our studies establish FRA1 as a part of the molecular machinery controlling sensitivity to MAPK cascade inhibition allowing the development of mechanism-based therapies.

Pancreatic ductal adenocarcinoma (PDAC) is associated with accumulation of particular oncogenic mutations and recent genetic sequencing studies have identified ataxia telangiectasia-mutated (ATM) mutations in PDAC cohorts. Here we report that conditional deletion of ATM in a mouse model of PDAC induces a greater number of proliferative precursor lesions coupled with a pronounced fibrotic reaction. ATM-targeted mice display altered TGFβ-superfamily signalling and enhanced epithelial-to-mesenchymal transition (EMT) coupled with shortened survival. Notably, our mouse model recapitulates many features of more aggressive human PDAC subtypes. Particularly, we report that low expression of ATM predicts EMT, a gene signature specific for Bmp4 signalling and poor prognosis in human PDAC. Our data suggest an intimate link between ATM expression and pancreatic cancer progression in mice and men. Mutations in the serine/threonine kinase ataxia teleangiectasia mutated (ATM) have been linked to pancreatic ductal adenocarcinoma (PDAC) cohorts. Here Russell et al . show that loss of ATM induces a greater number of proliferative precursor lesions in a mouse model, recapitulating many features of human PDAC subtypes.

BackgroundThe efficacy of pharmacological glycogen synthase kinase-3β (GSK3β) inhibition is currently being investigated in unselected cohorts of metastatic pancreatic ductal adenocarcinoma (PDAC). Here, we sought to determine the clinical significance of nuclear GSK3β accumulation in patients with resectable PDAC.ObjectiveThis study aimed to explore the therapeutic potential and underlying mechanisms of GSK3β pathway disruption in PDAC with enriched nuclear GSK3β levels.DesignWe investigated the activation and function of GSK3β and its downstream transcription factor NFATc1 in tumour recurrence, growth and resistance using human PDAC tissues, patient-derived organoids and tumour cells, PDAC explants, cell lines and murine models. GSK3β signalling was disrupted using genetic and pharmacological approaches. Live-cell imaging, proliferation, homologous recombination (HR) repair and comet assays, messenger RNA sequencing and chromatin immunoprecipitation were used to explore GSK3β-NFATc1 signalling-mediated target gene regulation in DNA repair, growth and resistance.ResultsNuclear GSK3β accumulates in a subset of resected PDAC and promotes proliferation and DNA repair through NFATc1. The GSK3βhigh/NFATc1high subtype accounts for 14% of resected PDAC and is associated with rapid tumour recurrence and poor survival. The GSK3β-NFATc1 signalling pathway contributes to cisplatin resistance by inducing BRCA genes transcription, which facilitates HR-mediated DNA double-strand breaks (DSBs) repair. Disruption of the GSK3β-NFATc1 axis impairs HR-driven DSB repair, increasing cisplatin sensitivity in vitro and in preclinical PDAC models.ConclusionWe have identified a highly aggressive GSK3βhigh/NFATc1high subtype that predicts early recurrence, poor survival and cisplatin resistance in PDAC. This subtype reveals new treatment vulnerabilities suggesting that patients with PDAC may benefit from stratification-based tailored treatment strategies.