Browsing by Author "Schmitt, Rebecca E."

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    A TGF-β/KLF10 signaling axis regulates atrophy-associated genes to induce muscle wasting in pancreatic cancer
    (National Academy of Science, 2023) Dasgupta, Aneesha; Gibbard, Daniel F.; Schmitt, Rebecca E.; Arneson-Wissink, Paige C.; Ducharme, Alexandra M.; Bruinsma, Elizabeth S.; Hawse, John R.; Jatoi, Aminah; Doles, Jason D.; Anatomy, Cell Biology and Physiology, School of Medicine
    Cancer cachexia, and its associated complications, represent a large and currently untreatable roadblock to effective cancer management. Many potential therapies have been proposed and tested-including appetite stimulants, targeted cytokine blockers, and nutritional supplementation-yet highly effective therapies are lacking. Innovative approaches to treating cancer cachexia are needed. Members of the Kruppel-like factor (KLF) family play wide-ranging and important roles in the development, maintenance, and metabolism of skeletal muscle. Within the KLF family, we identified KLF10 upregulation in a multitude of wasting contexts-including in pancreatic, lung, and colon cancer mouse models as well as in human patients. We subsequently interrogated loss-of-function of KLF10 as a potential strategy to mitigate cancer associated muscle wasting. In vivo studies leveraging orthotopic implantation of pancreas cancer cells into wild-type and KLF10 KO mice revealed significant preservation of lean mass and robust suppression of pro-atrophy muscle-specific ubiquitin ligases Trim63 and Fbxo32, as well as other factors implicated in atrophy, calcium signaling, and autophagy. Bioinformatics analyses identified Transforming growth factor beta (TGF-β), a known inducer of KLF10 and cachexia promoting factor, as a key upstream regulator of KLF10. We provide direct in vivo evidence that KLF10 KO mice are resistant to the atrophic effects of TGF-β. ChIP-based binding studies demonstrated direct binding to Trim63, a known wasting-associated atrogene. Taken together, we report a critical role for the TGF-β/KLF10 axis in the etiology of pancreatic cancer-associated muscle wasting and highlight the utility of targeting KLF10 as a strategy to prevent muscle wasting and limit cancer-associated cachexia.
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    Anticachectic regulator analysis reveals Perp-dependent antitumorigenic properties of 3-methyladenine in pancreatic cancer
    (American Society for Clinical Investigation, 2022-01-25) Dasgupta, Aneesha; Arneson-Wissink, Paige C.; Schmitt, Rebecca E.; Cho, Dong Seong; Ducharme, Alexandra M.; Hogenson, Tara L.; Krueger, Eugene W.; Bamlet, William R.; Zhang, Lizhi; Razidlo, Gina L.; Fernandez-Zapico, Martin E.; Doles, Jason D.; Anatomy, Cell Biology and Physiology, School of Medicine
    Approximately 80% of pancreatic cancer patients suffer from cachexia, and one-third die due to cachexia-related complications such as respiratory failure and cardiac arrest. Although there has been considerable research into cachexia mechanisms and interventions, there are, to date, no FDA-approved therapies. A major contributing factor for the lack of therapy options could be the failure of animal models to accurately recapitulate the human condition. In this study, we generated an aged model of pancreatic cancer cachexia to compare cachexia progression in young versus aged tumor-bearing mice. Comparative skeletal muscle transcriptome analyses identified 3-methyladenine (3-MA) as a candidate antiwasting compound. In vitro analyses confirmed antiwasting capacity, while in vivo analysis revealed potent antitumor effects. Transcriptome analyses of 3-MA-treated tumor cells implicated Perp as a 3-MA target gene. We subsequently (a) observed significantly higher expression of Perp in cancer cell lines compared with control cells, (b) noted a survival disadvantage associated with elevated Perp, and (c) found that 3-MA-associated Perp reduction inhibited tumor cell growth. Finally, we have provided in vivo evidence that survival benefits conferred by 3-MA administration are independent of its effect on tumor progression. Taken together, we report a mechanism linking 3-MA to Perp inhibition, and we further implicate Perp as a tumor-promoting factor in pancreatic cancer.
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    Blocking muscle wasting via deletion of the muscle-specific E3 ligase MuRF1 impedes pancreatic tumor growth
    (Springer Nature, 2023-05-13) Neyroud, Daria; Laitano, Orlando; Dasgupta, Aneesha; Lopez, Christopher; Schmitt, Rebecca E.; Schneider, Jessica Z.; Hammers, David W.; Sweeney, H. Lee; Walter, Glenn A.; Doles, Jason; Judge, Sarah M.; Judge, Andrew R.; Anatomy, Cell Biology and Physiology, School of Medicine
    Cancer-induced muscle wasting reduces quality of life, complicates or precludes cancer treatments, and predicts early mortality. Herein, we investigate the requirement of the muscle-specific E3 ubiquitin ligase, MuRF1, for muscle wasting induced by pancreatic cancer. Murine pancreatic cancer (KPC) cells, or saline, were injected into the pancreas of WT and MuRF1-/- mice, and tissues analyzed throughout tumor progression. KPC tumors induces progressive wasting of skeletal muscle and systemic metabolic reprogramming in WT mice, but not MuRF1-/- mice. KPC tumors from MuRF1-/- mice also grow slower, and show an accumulation of metabolites normally depleted by rapidly growing tumors. Mechanistically, MuRF1 is necessary for the KPC-induced increases in cytoskeletal and muscle contractile protein ubiquitination, and the depression of proteins that support protein synthesis. Together, these data demonstrate that MuRF1 is required for KPC-induced skeletal muscle wasting, whose deletion reprograms the systemic and tumor metabolome and delays tumor growth.
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    Muscle stem cells contribute to long-term tissue repletion following surgical sepsis
    (Wiley, 2023) Schmitt, Rebecca E.; Dasgupta, Aneesha; Arneson-Wissink, Paige C.; Datta, Srijani; Ducharme, Alexandra M.; Doles, Jason D.; Anatomy, Cell Biology and Physiology, School of Medicine
    Background: Over the past decade, advances in sepsis identification and management have resulted in decreased sepsis mortality. This increase in survivorship has highlighted a new clinical obstacle: chronic critical illness (CCI), for which there are no effective treatment options. Up to half of sepsis survivors suffer from CCI, which can include multi-organ dysfunction, chronic inflammation, muscle wasting, physical and mental disabilities, and enhanced frailty. These symptoms prevent survivors from returning to regular day-to-day activities and are directly associated with poor quality of life. Methods: Mice were subjected to cecal ligation and puncture (CLP) with daily chronic stress (DCS) as an in vivo model to study sepsis late-effects/sequelae on skeletal muscle components. Longitudinal monitoring was performed via magnetic resonance imaging, skeletal muscle and/or muscle stem cell (MuSCs) assays (e.g., post-necropsy wet muscle weights, minimum Feret diameter measurements, in vitro MuSC proliferation and differentiation, number of regenerating myofibres and numbers of Pax7-positive nuclei per myofibre), post-sepsis whole muscle metabolomics and MuSC isolation and high-content transcriptional profiling. Results: We report several findings supporting the hypothesis that MuSCs/muscle regeneration are critically involved in post-sepsis muscle recovery. First, we show that genetic ablation of muscle stem cells (MuSCs) impairs post-sepsis muscle recovery (maintenance of 5-8% average lean mass loss compared with controls). Second, we observe impaired MuSCs expansion capacity and morphological defects at 26 days post-sepsis compared with control MuSCs (P < 0.001). Third, when subjected to an experimental muscle injury, sepsis-recovered mice exhibited evidence of impaired muscle regeneration compared with non-septic mice receiving the same muscle injury (CLP/DCS injured mean minimum Feret is 92.1% of control injured, P < 0.01). Fourth, we performed a longitudinal RNA sequencing study on MuSCs isolated from post-sepsis mice and found clear transcriptional differences in all post-sepsis samples compared with controls. At Day 28, CLP/DCS mice satellite cells have multiple altered metabolic pathways, such as oxidative phosphorylation, mitochondrial dysfunction, sirtuin signalling and oestrogen receptor signalling, compared with controls (P < 0.001). Conclusions: Our data show that MuSCs and muscle regeneration are required for effective post-sepsis muscle recovery and that sepsis triggers morphological, functional, and transcriptional changes in MuSCs. Moving forward, we strive to leverage a more complete understanding of post-sepsis MuSC/regenerative defects to identify and test novel therapies that promote muscle recovery and improve quality of life in sepsis survivors.
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    Myogenesis defects in a patient-derived iPSC model of hereditary GNE myopathy
    (Springer Nature, 2022-09-09) Schmitt, Rebecca E.; Smith, Douglas Y., IV.; Cho, Dong Seong; Kirkeby, Lindsey A.; Resch, Zachary T.; Liewluck, Teerin; Niu, Zhiyv; Milone, Margherita; Doles, Jason D.; Anatomy, Cell Biology and Physiology, School of Medicine
    Hereditary muscle diseases are disabling disorders lacking effective treatments. UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE) myopathy (GNEM) is an autosomal recessive distal myopathy with rimmed vacuoles typically manifesting in late adolescence/early adulthood. GNE encodes the rate-limiting enzyme in sialic acid biosynthesis, which is necessary for the proper function of numerous biological processes. Outside of the causative gene, very little is known about the mechanisms contributing to the development of GNE myopathy. In the present study, we aimed to address this knowledge gap by querying the underlying mechanisms of GNE myopathy using a patient-derived induced pluripotent stem-cell (iPSC) model. Control and patient-specific iPSCs were differentiated down a skeletal muscle lineage, whereby patient-derived GNEM iPSC clones were able to recapitulate key characteristics of the human pathology and further demonstrated defects in myogenic progression. Single-cell RNA sequencing time course studies revealed clear differences between control and GNEM iPSC-derived muscle precursor cells (iMPCs), while pathway studies implicated altered stress and autophagy signaling in GNEM iMPCs. Treatment of GNEM patient-derived iMPCs with an autophagy activator improved myogenic differentiation. In summary, we report an in vitro, iPSC-based model of GNE myopathy and implicate defective myogenesis as a contributing mechanism to the etiology of GNE myopathy.
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    Serum proteomic analysis in esophagectomy patients with postoperative delirium: A Case-Control Study
    (Elsevier, 2024) Khan, Sikandar H.; Perkins, Anthony J.; Jawaid, Samreen; Wang, Sophia; Lindroth, Heidi; Schmitt, Rebecca E.; Doles, Jason; True, Jason D.; Gao, Sujuan; Caplan, Gideon A.; Twigg, Homer L., III; Kesler, Kenneth; Khan, Babar A.; Medicine, School of Medicine
    Background: Postoperative delirium occurs in up to 80% of patients undergoing esophagectomy. We performed an exploratory proteomic analysis to identify protein pathways that may be associated with delirium post-esophagectomy. Objectives: Identify proteins associated with delirium and delirium severity in a younger and higher-risk surgical population. Methods: We performed a case-control study using blood samples collected from patients enrolled in a negative, randomized, double-blind clinical trial. English speaking adults aged 18 years or older, undergoing esophagectomy, who had blood samples obtained were included. Cases were defined by a positive delirium screen after surgery while controls were patients with negative delirium assessments. Delirium was assessed using Richmond Agitation Sedation Scale and Confusion Assessment Method for the Intensive Care Unit, and delirium severity was assessed by Delirium Rating Scale-Revised-98. Blood samples were collected pre-operatively and on post-operative day 1, and discovery proteomic analysis was performed. Between-group differences in median abundance ratios were reported using Wilcoxon-Mann-Whitney Odds (WMWodds1) test. Results: 52 (26 cases, 26 controls) patients were included in the study with a mean age of 64 (SD 9.6) years, 1.9% were females and 25% were African American. The median duration of delirium was 1 day (IQR: 1-2), and the median delirium/coma duration was 2.5 days (IQR: 2-4). Two proteins with greater relative abundance ratio in patients with delirium were: Coagulation factor IX (WMWodds: 1.89 95%CI: 1.0-4.2) and mannosyl-oligosaccharide 1,2-alpha-mannosidase (WMWodds: 2.4 95%CI: 1.03-9.9). Protein abundance ratios associated with mean delirium severity at postoperative day 1 were Complement C2 (Spearman rs = -0.31, 95%CI [-0.55, -0.02]) and Mannosyl-oligosaccharide 1,2-alpha-mannosidase (rs = 0.61, 95%CI = [0.29, 0.81]). Conclusions: We identified changes in proteins associated with coagulation, inflammation, and protein handling; larger, follow-up studies are needed to confirm our hypothesis-generating findings.