Functional lysosomes mediate autophagy and macropinocytosis for nutrient acquisition. Pancreatic ductal adenocarcinoma (PDAC) tumors exhibit high basal lysosomal activity, and inhibition of lysosome function suppresses PDAC cell proliferation and tumor growth. However, the codependencies induced by lysosomal inhibition in PDAC have not been systematically explored. We performed a comprehensive pharmacological inhibition screen of the protein kinome and found that replication stress response (RSR) inhibitors were synthetically lethal with chloroquine (CQ) in PDAC cells. CQ treatment reduced de novo nucleotide biosynthesis and induced replication stress. We found that CQ treatment caused mitochondrial dysfunction and depletion of aspartate, an essential precursor for de novo nucleotide synthesis, as an underlying mechanism. Supplementation with aspartate partially rescued the phenotypes induced by CQ. The synergy of CQ and the RSR inhibitor VE-822 was comprehensively validated in both 2D and 3D cultures of PDAC cell lines, a heterotypic spheroid culture with cancerassociated fibroblasts, and in vivo xenograft and syngeneic PDAC mouse models. These results indicate a codependency on functional lysosomes and RSR in PDAC and support the translational potential of the combination of CQ and RSR inhibitors. lysosome | autophagy | replication stress | pancreatic cancer | nucleotide metabolism P ancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death in the United States, and its incidence is increasing (1). PDAC carries a 5-y survival of less than 10%, as it is often diagnosed at a late stage and is widely refractory to available therapies. This lack of effective treatment options suggests an incomplete understanding of the biologic complexity of PDAC and mechanisms of therapeutic resistance.PDAC tumors are hypoperfused, resulting in poor nutrient delivery (2). To exist in this hostile microenvironment, PDAC cells rely on intracellular and extracellular scavenging pathways to acquire metabolic substrates for growth. Autophagy, a selfdegradative mechanism employed to recycle damaged cytosolic proteins and organelles, and macropinocytosis, the process of uptaking bulk extracellular material, are up-regulated in PDAC (3-6). As the final step of both autophagy and macropinocytosis, autophagic and endocytic cargo fuse with the lysosome, where macromolecules are degraded and substrates for metabolism are released (3, 4, 7). Inhibition of these pathways suppresses PDAC tumor growth and prolongs survival in animal models (4, 6, 8). Additionally, engaging autophagic programs confers resistance to chemoradiation in PDAC cells (9-11), and high levels of autophagy markers are correlated with worse survival in resected PDAC patients (12).The study of lysosomal function often focuses on proteolysis, which degrades misfolded proteins and damaged organelles (13,14). However, lysosomal degradation pathways also play a critical role in lipid (15-17) and nucleic acid metabolism. The recycling of nucleic ac...

Although histone deacetylase inhibitors (HDACi) are a promising class of anti-cancer drugs, thus far, they have been unsuccessful in early phase clinical trials for pancreatic ductal adenocarcinoma (PDAC). One potential reason for their poor efficacy is the tumor stroma, where cancer-associated fibroblasts (CAFs) are a prominent cell type and a source of resistance to cancer therapies. Here, we demonstrate that stromal fibroblasts contribute to the poor efficacy of HDACi's in PDAC. HDACi-treated fibroblasts show increased biological aggressiveness and are characterized by increased secretion of pro-inflammatory tumor-supportive cytokines and chemokines. We find that HDAC2 binds to the enhancer and promoter regions of pro-inflammatory genes specifically in CAFs and in silico analysis identified AP-1 to be the most frequently associated transcription factor bound in these regions. Pharmacologic inhibition of pathways upstream of AP-1 suppresses the HDACi-induced inflammatory gene expression and tumor-supportive responses in fibroblasts. Our findings demonstrate that the combination of HDACi's with chemical inhibitors of the AP-1 signaling pathway attenuate the inflammatory phenotype of fibroblasts and may improve the efficacy of HDACi in PDAC and, potentially, in other solid tumors rich in stroma.

Background Anosmia and ageusia are symptoms commonly associated with COVID-19, but the relationship with disease severity, onset and recovery are unclear. Objective To examine factors associated with anosmia and ageusia and the recovery from these symptoms in an ethnically diverse cohort. Methods Individuals tested for SARS-CoV-2 between March and April 2020 were eligible for the study. Randomly selected participants answered a telephone questionnaire on COVID-19 symptoms with a focus on anosmia and ageusia. Additionally, relevant past medical history and data on the COVID-19 clinical course were obtained from electronic medical records. 486 patients were in the COVID-19 group and 103 were COVID-19-negative. Results Patients who were younger were more likely to report anosmia and/or ageusia (odds ratio (OR) for anosmia per 1-year increase in age: 0·98, 95%CI:0–97-0·99, p = 0·003; for ageusia: 0·98, 95%CI:0·97-0·99, p = 0·005) as were patients with lower eosinophil counts (OR for anosmia per 0.1-K/μL increase in eosinophils: 0·02, 95%CI:0·001-0·46, p = 0·01, for ageusia 0·10, 95%CI:0·01-0·97, p = 0·047). Male gender was independently associated with a lower probability of ageusia (OR:0·56, 95%CI:0·38-0·82, p = 0·003) and earlier sense of taste recovery (HR:1·44, 95%CI:1·05-1·98, p = 0·02). Latinos showed earlier sense of taste recovery than white patients (HR:1·82, 95%CI:1·05-3·18, p = 0·03). Conclusion Anosmia and ageusia were more common among younger patients and those with lower blood eosinophil counts. Ageusia was less commonly reported among men, and time to taste recovery was earlier among both men and Latinos.

The popularity of electronic cigarettes (e-cigs) that utilize nicotine salts has rapidly increased since the introduction of JUUL pods in 2015. The immunotoxicology of nicotine salts in the respiratory tract is understudied. We hypothesized that nicotine salt counteranions induce airway inflammation and alter immune responses to inhaled allergens independent of nicotine. METHODS: The nicotine salt counteranions lactate, levulinate, salicylate or benzoate (5% solution) were administered to C57BL/6J mice by oropharyngeal aspiration daily for three days (acute exposure model) or three times weekly for three weeks (persistent exposure model). In some studies, mice were also exposed to house dust mite (HDM) allergen alone or in combination with benzoate three times weekly for three weeks. Airway inflammation was assessed by enumeration of inflammatory cells in bronchoalveolar lavage fluid and lung histology. RESULTS: Acute exposure to nicotine salt counteranions induced an influx of neutrophils into the airways. Persistent exposure to nicotine salt counteranions resulted in a mixed neutrophilic and lymphocytic airway inflammatory response. Neither acute nor persistent exposure to nicotine salt counteranions caused airway eosinophilia. In a HDM-mediated allergic airway inflammation model, co-exposure to benzoate and HDM increased the percentage of airway neutrophils but decreased the percentage of eosinophils compared to HDM alone. CONCLUSIONS: Both acute and persistent exposure to nicotine salt counteranions induces airway inflammation in mice independent of nicotine. Benzoate also induced neutrophilic inflammation in a HDMmediated allergic airway inflammation model, suggesting that exposure to e-cigs containing nicotine salts may promote a neutrophilic asthma phenotype.