Abstract Fear learning involves the formation of associations between cues and aversive outcomes, a process that must be tightly regulated to prevent excessive or generalised fear. Dopamine release in the lateral amygdala (LA) drives fear acquisition, whereas endogenous opioids constrain it. However, whether opioids are dynamically released within the amygdala circuits during learning, and how they exert this control remain unclear. Here we show that met-enkephalin is locally released within the amygdala during auditory fear conditioning, with signals shifting from the aversive outcome to its predictive cue as learning progresses. The amygdalo-striatal transition zone (ASt), is the principal source of this enkephalin, released from medium spiny neurons receiving strong auditory thalamic input. This enkephalin spreads from the ASt to the LA via volume transmission. Selective knockdown in the ASt abolished opioid signals and enhanced fear learning, demonstrating that this diffuse signal constrains fear memory formation. We further show that enkephalin suppresses dopamine release in both the ASt and LA via µ-opioid receptors, identifying the ASt as a neuromodulator hub coordinating opioid and dopaminergic signalling across amygdala fear circuits. Although demonstrated here for auditory fear learning, the ASt receives multimodal sensory input, suggesting a broader mechanism through which sensory experience recruits enkephalin release to gate associative learning

Abstract 90% of pancreatic cancer (PC) patients succumb to the disease [1], necessitating development of more effective treatments. PC tumors are characterized by dense fibrotic stromal regions that contain complex, highly remodelled extracellular matrices. These fibrotic regions create protective niches promoting growth and shielding cancer cells from therapies [2]. These regions, along with other immunosuppressive elements within the tumor, prevent robust immune responses against the cancer cells, limiting immunotherapy efficacy. Accurately modeling fibrotic microenvironments in preclinical settings remains challenging. Two-dimensional models can incorporate multiple cell types and extracellular matrices, but fail to replicate nutrient and drug gradients that exist in tumors. These architectural features are particularly important when studying immune interactions, as T cells are often spatially excluded from tumor niches in patients [3]. Furthermore, in vivo models can lack sufficient immune components, make dissecting causal effects of therapies difficult and are limited by throughput costs. We present development and characterization of 3D in vitro co-culture models incorporating cancer, stroma, immune and microenvironment components using the RASTRUMTM Allegro bioprinter from Inventia Life Science. We investigate the role of CAFs in supporting immune evasion and analyze cancer-T cell dynamics in various contexts. Using single-cell RNA sequencing we show this physiologically-relevant system better mimics native PC tumors while maintaining scalability for drug screening. The modular design facilitates combinatorial drug testing and mechanistic dissection of therapy effects across distinct cell populations. This model will be utilised to identify combination therapies that are more effective in vivo, streamlining preclinical testing, particularly for immunotherapies and immunomodulators. References 1. Stoffel EM, Brand RE, Goggins M. Pancreatic Cancer: Changing Epidemiology and New Approaches to Risk Assessment, Early Detection, and Prevention. Gastroenterology. 2023 Apr;164(5):752-765. 2. Neesse A, Bauer CA, Öhlund D et al. Stromal biology and therapy in pancreatic cancer: ready for clinical translation? Gut. 2019 Jan;68(1):159-171. 3. Carstens JL, Correa de Sampaio P, Yang D et al. Spatial computation of intratumoral T cells correlates with survival of patients with pancreatic cancer. Nat Comm. 2017 Apr 27;8:15095. Citation Format: Aji Istadi, Ali McCorkindale, Silvia Lombardi, Inna Navarro, Diego Chacon Fajardo, Henry Barraclough-Franks, David Hermann, Sean Porazinski, Marco J. Herold, Paul Timpson, Greg Neely, Marina Pajic. Bioprinted multicellular microenvironments to accelerate immunotherapy discovery in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4918.

Environmental and individual experiences can result in immediate and persistent changes in behaviour. Often, such effects are also sex-dependent. Intraspecific interactions can be one of the most important environments an individual faces. Such social interactions are expected to affect a suite of behavioural traits and their correlations. Here, we used Drosophila melanogaster and high-throughput automated behavioural phenotyping to determine how social environment (group mixed sex, group single sex, and social isolation) and sex interact to affect basic behaviours (exploration, movement within a y-maze, and habituation to a startle) that likely underlie more complex behaviours such as mate searching and foraging. We show that such behaviours and some behavioural correlations are indeed context- and sex-dependent. Males tended to show greater exploration, while females were more likely to show a habituation response to startle. Males and females from the mixed sex and isolated treatments showed opposite exploratory behaviour in the Y-maze, and social treatment interacted with sex to affect the rate of habituation to a startle. Females also tended to have slightly stronger trait correlations compared to males. These results show that social environment and sex can play a significant role in shaping behaviour in Drosophila melanogaster. Our study provides insights into how the type of social stimulation and sex can interact to affect behaviours that are important in forming critical behaviours related to foraging and mate searching.

Stimulating adipose tissue thermogenesis has emerged as a promising strategy for combating obesity, with uncoupling protein 1 (UCP1) playing a central role in this process. However, the mechanisms that suppress adipose thermogenesis and energy dissipation in obesity are not fully understood. This study identifies mitochondrial carrier homolog 2 (MTCH2), an obesity susceptibility gene, as a negative regulator of energy homeostasis across flies, rodents, and humans. Notably, adipose-specific MTCH2 depletion in mice protects against high-fat-diet (HFD)-induced obesity and metabolic disorders. Mechanistically, MTCH2 deficiency promotes energy expenditure by stimulating thermogenesis in brown adipose tissue (BAT) and browning of subcutaneous white adipose tissue (scWAT), accompanied by upregulated UCP1 protein expression, enhanced mitochondrial biogenesis, and increased lipolysis in BAT and scWAT. Using integrated RNA sequencing and proteomic analyses, this study demonstrates that MTCH2 is a key suppressor of thermogenesis by negatively regulating autophagy via Bcl-2-dependent mechanism. These findings highlight MTCH2's critical role in energy homeostasis and reveal a previously unrecognized link between MTCH2, thermogenesis, and autophagy in adipose tissue biology, positioning MTCH2 as a promising therapeutic target for obesity and related metabolic disorders. This study provides new opportunities to develop treatments that enhance energy expenditure.

Directed evolution is commonly performed in prokaryotic or yeast systems, but platforms are needed to enhance functions in mammalian cells. Now, a tool known as RNA replicase-assisted continuous evolution (REPLACE) enables directed evolution in mammalian cells via mutagenesis and amplification of RNA and selection for desired phenotypes.

Non-nutritive sweeteners (NNSs) are used to reduce caloric intake by replacing sugar with compounds that are sweet but contain little or no calories. In this study, we investigate how non-nutritive sweetener sucralose to promote acute food intake in the fruit fly Drosophila melanogaster. Our results showed that acute exposure to NNSs sweetness induces a robust hyperphagic response in flies. Cellular and molecular dissection of this acute effect revealed the requirement of a reward pathway comprising of sweet taste neurons, octopaminergic neurons, and NPF neurons which drive increased food intake in response to sucralose. These data provide mechanistic insight into how NNSs can increase food intake, information that may help us better understand how artificially sweeteners may impact our physiology.

O-Fucosylation plays crucial roles in various essential biological events. Alongside the well-established O-fucosylation of epidermal growth factor-like repeats by protein O-fucosyltransferase 1 (POFUT1) and thrombospondin type 1 repeats by POFUT2, we recently identified a type of O-fucosylation on the elastin microfibril interface (EMI) domain of Multimerin-1 (MMRN1). Here, using AlphaFold2 screens, co-immunoprecipitation, enzymatic assays combined with mass spectrometric analysis and CRISPR–Cas9 knockouts, we demonstrate that FUT10 and FUT11, originally annotated in UniProt as α1,3-fucosyltransferases, are actually POFUTs responsible for modifying EMI domains; thus, we renamed them as POFUT3 and POFUT4, respectively. Like POFUT1/2, POFUT3/4 function in the endoplasmic reticulum, require folded domain structures for modification and participate in a non-canonical endoplasmic reticulum quality control pathway for EMI domain-containing protein secretion. This finding expands the O-fucosylation repertoire and provides an entry point for further exploration in this emerging field of O-fucosylation. FUT10 and FUT11, originally annotated as α1,3-fucosyltransferases, are actually protein O-fucosyltransferases participating in a non-canonical ER quality control pathway for EMI domain-containing protein secretion.

Understanding genetic dependencies in cancer is key to identifying novel actionable drug targets to advance precision medicine. Whole-genome CRISPR-knockout library screening methods have facilitated this goal. Pooled libraries of single guide RNAs (sgRNAs) targeting over 90% of the annotated protein coding genome are used to induce gene knockouts in pre-clinical cancer models. Novel genes of interest are identified by evaluating sgRNA dropout or enrichment following selection pressure application. This method is particularly beneficial for researching cancers where effective treatment strategies are limited. One example of a commonly chemoresistant cancer, particularly at relapse, is the low survival malignancy epithelial ovarian cancer (EOC), made up of multiple histotypes with distinct molecular profiles. CRISPR-knockout library screens in pre-clinical EOC models have demonstrated the ability to predict biomarkers of treatment response, identify targets synergistic with standard-of-care chemotherapy, and determine novel actionable targets which are synthetic lethal with cancer-associated mutations. Robust experimental design of CRISPR-knockout library screens, including the selection of strong pre-clinical cell line models, allows for meaningful conclusions to be made. We discuss essential design criteria for the use of CRISPR-knockout library screens to discover genetic dependencies in cancer and draw attention to discoveries with translational potential for EOC.

Platelet hyperreactivity increases the risk of cardiovascular thrombosis in diabetes and failure of antiplatelet drug therapies. Elevated basal and agonist-induced calcium flux is a fundamental cause of platelet hyperreactivity in diabetes; however, the mechanisms responsible for this remain largely unknown. Using a high-sensitivity, unbiased proteomic platform, we consistently detected over 2,400 intracellular proteins and identified proteins that were differentially released by platelets in type 2 diabetes. We identified that SEC61 translocon subunit β (SEC61B) was increased in platelets from humans and mice with hyperglycemia and in megakaryocytes from mice with hyperglycemia. SEC61 is known to act as an endoplasmic reticulum (ER) calcium leak channel in nucleated cells. Using HEK293 cells, we showed that SEC61B overexpression increased calcium flux into the cytosol and decreased protein synthesis. Concordantly, platelets in hyperglycemic mice mobilized more calcium and had decreased protein synthesis. Platelets in both humans and mice with hyperglycemia had increased ER stress. ER stress induced the expression of platelet SEC61B and increased cytosolic calcium. Inhibition of SEC61 with anisomycin decreased platelet calcium flux and inhibited platelet aggregation in vitro and in vivo. These studies demonstrate the existence of a mechanism whereby ER stress-induced upregulation of platelet SEC61B leads to increased cytosolic calcium, potentially contributing to platelet hyperreactivity in diabetes.

Pancreatic cancer (PC) is a lethal cancer, with ∼90% of patients dying within 5 years. This dire statistic underscores the limitations of current treatments and the need for improved therapeutic approaches. Immune checkpoint inhibition (ICI) has shown promise in promoting long-term progression-free survival across various cancers by reactivating a patients’ latent anti-cancer immune response. However, PC is almost completely resistant to ICI, highlighting the incomplete understanding of immune-cancer interactions in this disease. The tumor microenvironment is a key factor in immunotherapy resistance in PC, where immunosuppressive immune cells and cancer-associated fibroblasts (CAFs) act to inhibit T cell function. Additionally, the extracellular matrix (ECM) landscape of PC presents a physical barrier to T cell infiltration and motility within the tumor. Developing strategies to overcome these barriers has been challenging, partly due to the difficulty in replicating the complex PC tumor microenvironment in experimental models. The use of 3D cancer tumoroid cultures enables modeling of cancer and stromal cells spatial arrangements, mimicking native tumor microenvironments and facilitating high resolution examination of cell-to-cell and cell-to-environment interactions. However, most tumoroid cultures often use commercial matrix products like basement membrane extracts (BME), which poorly recapitulate the distinct biochemical and mechanical properties inherent to PC tumors. Here, we utilize the Inventia RASTRUMTM platform to create 3D cancer/CAF/T cell co-cultures based on synthetic PEG-based hydrogel matrices, which were tuned to mimic the stiffness and ECM composition of PC tumors. Using real-time longitudinal imaging and 3D image analysis pipelines, we visualize cancer-stromal cell interactions, which are obscured in conventional BME-based models. We also investigate the role of CAFs in supporting immune evasion and highlight the effect of multiple immunomodulators on cancer/T cell behavioral dynamics. Overall, our approach provides a scalable in vitro framework to dissect cell-to-cell interactions and offers a platform to the profile immunomodulatory properties of drugs. Future work using this platform will focus on molecular profiling of cancer-CAF-T cell interactions to provide predictive data aiding the rational design and evaluation of ICI combination therapies prior to pre-clinical in vivo work and clinical translation. Aji Istadi, Inna Navarro, Silvia Lombardi, Dannielle Upton, Mezzalina Vankan, Cesar Moreno, Michael Trpceski, Cecilia Chambers, David Hermann, Marco Herold, Paul Timpson, Sean Porazinski, Greg Neely, Marina Pajic. Modeling T cell and cancer cell interactions to examine immune checkpoint inhibition resistance in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3819.

AIMS/HYPOTHESIS:Glucose homeostasis, essential for metabolic health, requires coordinated insulin and glucagon activity to maintain blood glucose balance. Dysregulation of glucose homeostasis causes hyperglycaemia and glucose intolerance, hallmark features of type 2 diabetes. While SEC16 homologue B (SEC16B), an endoplasmic reticulum export factor, has been linked to obesity, type 2 diabetes and lipid metabolism, its role in glucose regulation remains poorly defined. This study aims to investigate SEC16B's contribution to glucose homeostasis by systematically dissecting its conserved physiological mechanisms across species. METHODS:To interrogate SEC16B's role, we combined Drosophila genetics (RNA interference-mediated dSec16 knockdown) with murine models (Sec16b deletion) under standard or high-fat diet conditions. Glucose and insulin tolerance tests assessed glucose homeostasis. Mechanistic insights into beta cell dysfunction were derived from immunostaining, glucose-stimulated insulin secretion assays and RNA-seq profiling of murine pancreatic islets. RESULTS:Both disruption of dSec16 in Drosophila and Sec16b deletion in mice triggered glucose intolerance under standard diet conditions, recapitulating conserved metabolic dysfunction. In addition, Sec16b loss impaired glycaemic control in mice fed a high-fat diet. Mechanistically, Sec16b deficiency impairs insulin secretion by downregulating cholinergic signalling and compromising intracellular Ca2+ influx in pancreatic beta cells. CONCLUSIONS/INTERPRETATION:Our study reveals SEC16B, a genome-wide association study-identified obesity risk gene, as an evolutionarily conserved regulator of glucose homeostasis. By linking SEC16B to cholinergic-driven insulin secretion and calcium dynamics, we resolve a mechanistic gap in beta cell dysfunction and metabolic disease. This finding provides novel insights into the mechanisms underlying glucose homeostasis and may enhance our understanding of potential treatments for metabolic diseases.

Directed evolution is a process of mutation and artificial selection to breed biomolecules with new or improved activity. Directed evolution platforms are primarily prokaryotic or yeast-based, and stable mammalian systems have been challenging to establish and apply. To this end, we develop PROTein Evolution Using Selection (PROTEUS), a platform that uses chimeric virus-like vesicles to enable extended mammalian directed evolution campaigns without loss of system integrity. This platform is stable and can generate sufficient diversity for directed evolution in mammalian systems. Using PROTEUS, we alter the doxycycline responsiveness of tetracycline-controlled transactivators, generating a more sensitive TetON-4G tool for gene regulation with mammalian-specific adaptations. PROTEUS is also compatible with intracellular nanobody evolution, and we use it to evolve a DNA damage-responsive anti-p53 nanobody. Overall, PROTEUS is an efficient and stable platform to direct evolution of biomolecules within mammalian cells.

Chronic pain has an enormous impact on the quality of life of billions of patients, families, and caregivers worldwide. Current therapies do not adequately address pain for most patients. A basic understanding of the conserved genetic framework controlling pain may help us develop better, non-addictive pain therapies. Here, we identify new conserved and druggable analgesic targets using the tissue-specific functional genomic screening of candidate "pain" genes in fly. From these efforts, we describe 23 new pain genes for further consideration. This included Acsl, a fatty acid-metabolizing enzyme, and mammalian orthologs involved in arachidonic acid metabolism. The Acsl knockdown and mutant larvae showed delayed nocifensive responses to localized and global noxious heat. Mechanistically, the Acsl knockdown reduced dendritic branching of nociceptive neurons. Surprisingly, the pain phenotype in these animals could be rescued through dietary intervention with vitamin B5, highlighting the interplay between genetics, metabolism, and nutrient environment to establish sensory perception thresholds. Together, our functional genomic screening within the sensory nociceptor has identified new nociception genes that provide a better understanding of pain biology and can help guide the development of new painkillers.

Background: Per- and polyfluoroalkyl substances (PFAS) are a large group of manufactured chemicals. Since the beginning of their commercial manufacturing in the 1950s, PFAS haven’t only found their way into numerous industrial and commercial applications, but also into the bloodstream of the majority of the human population, the natural environment and its wildlife. Exposure to high levels of PFAS can create health risks for humans and animals which may exacerbate the effects of other anthropogenic impacts faced by wildlife species. To gain a comprehensive overview of the abundance and distribution of PFAS in wildlife species, and to better understand the risk of PFAS exposure on threatened species and PFAS transfer into human food chains, we will collate the available literature into a systematic evidence map and bibliometric analysis.Methods: We will conduct a comprehensive systematic literature search on Scopus, Web of Science and the ‘grey literature’. For screening purposes, we will use decision trees, scanning title, abstract and keywords first. The next step includes full-text screening performed by two reviewers. We will only consider publications in English, peer-reviewed articles, pre-prints and theses. We will limit our search to 31 PFAS types (based on a previous study). A pilot search on Scopus resulted in ~250 potentially relevant publications. We will scan all publications included in the systematic map for predetermined indicators of quality and potential study-level biases. In addition, we will extract bibliometric records from Scopus and perform network analysis. We will present the results using a narrative summary, tables (database), bar plots and colour-coded maps. Results will be available on a dedicated freely accessible website. Discussion: This study will provide critical insight into the gaps and clusters of the literature with regards to the PFAS concentration in wildlife. Therefore, our study will inform and direct future research efforts to fill the gaps revealed.Systematic review registration: osf.io osf.io/gnt2y

Mitochondria facilitate thousands of biochemical reactions, covering a broad spectrum of anabolic and catabolic processes. Here we demonstrate that the adipocyte mitochondrial proteome is markedly altered across multiple models of insulin resistance and reveal a consistent decrease in the level of the mitochondrial processing peptidase miPEP. OBJECTIVE:To determine the role of miPEP in insulin resistance. METHODS:To experimentally test this observation, we generated adipocyte-specific miPEP knockout mice to interrogate its role in the aetiology of insulin resistance. RESULTS:We observed a strong phenotype characterised by enhanced insulin sensitivity and reduced adiposity, despite normal food intake and physical activity. Strikingly, these phenotypes vanished when mice were housed at thermoneutrality, suggesting that metabolic protection conferred by miPEP deletion hinges upon a thermoregulatory process. Tissue specific analysis of miPEP deficient mice revealed an increment in muscle metabolism, and upregulation of the protein FBP2 that is involved in ATP hydrolysis in the gluconeogenic pathway. CONCLUSION:These findings suggest that miPEP deletion initiates a compensatory increase in skeletal muscle metabolism acting as a protective mechanism against diet-induced obesity and insulin resistance.

Background: Per- and polyfluoroalkyl substances (PFAS) are a class of widely used anthropogenic chemicals. Concerns regarding their persistence and potential adverse effects have led to multiple secondary research publications. Here, we aim to assess the resulting evidence base in the systematic secondary literature by examining research gaps, evaluating the quality of reviews, and exploring interdisciplinary connections. Methods: This study employed a systematic evidence-mapping approach to assess the secondary literature on the biological, environmental, and medical aspects of exposure to 35 fluorinated compounds. The inclusion criteria encompassed systematic reviews published in peer-reviewed journals, pre-prints, and theses. Comprehensive searches across electronic databases and grey literature identified relevant reviews. Data extraction and synthesis involved mapping literature content and narrative descriptions. We employed a modified version of the AMSTAR2 checklist to evaluate the methodological rigour of the reviews. A bibliometric data analysis uncovered patterns and trends in the academic literature. A research protocol for this study was previously pre-registered (osf.io/2tpn8) and published (Vendl et al., Environment International 158 (2022) 106973). The database is freely accessible through the interactive and user-friendly web application of this systematic evidence map at https://hi-this-is-lorenzo.shinyapps.io/PFAS_SEM_Shiny_App/. Results: Our map includes a total of 175 systematic reviews. Over the years, there has been a steady increase in the annual number of publications, with a notable surge in 2021. Most reviews focused on human exposure, whereas environmental and animal-related reviews were fewer and often lacked a rigorous systematic approach to literature search and screening. Review outcomes were predominantly associated with human health, particularly with reproductive and children’s developmental health. Animal reviews primarily focused on studies conducted in controlled laboratory settings, and wildlife reviews were characterised by an over-representation of birds and fish species. Recent reviews increasingly incorporated quantitative synthesis methodologies. The methodological strengths of the reviews included detailed descriptions of study selection processes and disclosure of potential conflicts of interest. However, weaknesses were observed in the critical lack of detail in reporting methods. A bibliometric analysis revealed that the most productive authors collaborate within their own country, leading to limited and clustered international collaborations. Conclusions: In this overview of the available systematic secondary literature, we map literature content, assess reviews’ methodological quality, highlight data gaps, and draw research network clusters. We aim to facilitate literature reviews, guide future research initiatives, and enhance opportunities for cross-country collaboration. Furthermore, we discuss how this systematic evidence map and its publicly available database benefit scientists, regulatory agencies, and other stakeholders by providing access to current systematic secondary literature on PFAS exposure.

Snakebites affect about 1.8 million people annually. The current standard of care involves antibody-based antivenoms, which can be difficult to access and are generally not effective against local tissue injury, the primary cause of morbidity. Here, we used a pooled whole-genome CRISPR knockout screen to define human genes that, when targeted, modify cell responses to spitting cobra venoms. A large portion of modifying genes that conferred resistance to venom cytotoxicity was found to control proteoglycan biosynthesis, including EXT1, B4GALT7, EXT2, EXTL3, XYLT2, NDST1, and SLC35B2, which we validated independently. This finding suggested heparinoids as possible inhibitors. Heparinoids prevented venom cytotoxicity through binding to three-finger cytotoxins, and the US Food and Drug Administration-approved heparinoid tinzaparin was found to reduce tissue damage in mice when given via a medically relevant route and dose. Overall, our systematic molecular dissection of cobra venom cytotoxicity provides insight into how we can better treat cobra snakebite envenoming.

Aicardi-Goutières syndrome (AGS) is an autoinflammatory disease characterized by aberrant interferon (IFN)-α production. The major cause of morbidity in AGS is brain disease, yet the primary source and target of neurotoxic IFN-α remain unclear. Here, we demonstrated that the brain was the primary source of neurotoxic IFN-α in AGS and confirmed the neurotoxicity of intracerebral IFN-α using astrocyte-driven Ifna1 misexpression in mice. Using single-cell RNA sequencing, we demonstrated that intracerebral IFN-α-activated receptor (IFNAR) signaling within cerebral endothelial cells caused a distinctive cerebral small vessel disease similar to that observed in individuals with AGS. Magnetic resonance imaging (MRI) and single-molecule ELISA revealed that central and not peripheral IFN-α was the primary determinant of microvascular disease in humans. Ablation of endothelial Ifnar1 in mice rescued microvascular disease, stopped the development of diffuse brain disease, and prolonged lifespan. These results identify the cerebral microvasculature as a primary mediator of IFN-α neurotoxicity in AGS, representing an accessible target for therapeutic intervention.

Functionally characterizing the genetic alterations that drive pancreatic cancer is a prerequisite for precision medicine. Here, we perform somatic CRISPR/Cas9 mutagenesis screens to assess the transforming potential of 125 recurrently mutated pancreatic cancer genes, which revealed USP15 and SCAF1 as pancreatic tumor suppressors. Mechanistically, we find that USP15 functions in a haploinsufficient manner and that loss of USP15 or SCAF1 leads to reduced inflammatory TNFα, TGF-β and IL6 responses and increased sensitivity to PARP inhibition and Gemcitabine. Furthermore, we find that loss of SCAF1 leads to the formation of a truncated, inactive USP15 isoform at the expense of full-length USP15, functionally coupling SCAF1 and USP15. Notably, USP15 and SCAF1 alterations are observed in 31% of pancreatic cancer patients. Our results highlight the utility of in vivo CRISPR screens to integrate human cancer genomics and mouse modeling for the discovery of cancer driver genes with potential prognostic and therapeutic implications.