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Mareninova OA, Gretler SR, Lee GE, Pimienta M, Qin Y, Elperin JM, Ni J, Razga Z, Gukovskaya AS, Gukovsky I. Ethanol inhibits pancreatic acinar cell autophagy through upregulation of ATG4B, mediating pathological responses of alcoholic pancreatitis. Am J Physiol Gastrointest Liver Physiol 2023; 325:G265-G278. [PMID: 37431575 PMCID: PMC10511161 DOI: 10.1152/ajpgi.00053.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/23/2023] [Accepted: 07/01/2023] [Indexed: 07/12/2023]
Abstract
Excessive alcohol intake is a major risk factor for pancreatitis, sensitizing the exocrine pancreas to stressors by mechanisms that remain obscure. Impaired autophagy drives nonalcoholic pancreatitis, but the effects of ethanol (EtOH) and alcoholic pancreatitis on autophagy are poorly understood. Here, we find that ethanol reduces autophagosome formation in pancreatic acinar cells, both in a mouse model of alcoholic pancreatitis induced by a combination of EtOH diet and cerulein (a CCK ortholog) and in EtOH+CCK-treated acinar cells (ex vivo model). Ethanol treatments decreased pancreatic level of LC3-II, a key mediator of autophagosome formation. This was caused by ethanol-induced upregulation of ATG4B, a cysteine protease that, cell dependently, regulates the balance between cytosolic LC3-I and membrane-bound LC3-II. We show that ATG4B negatively regulates LC3-II in acinar cells subjected to EtOH treatments. Ethanol raised ATG4B level by inhibiting its degradation, enhanced ATG4B enzymatic activity, and strengthened its interaction with LC3-II. We also found an increase in ATG4B and impaired autophagy in a dissimilar, nonsecretagogue model of alcoholic pancreatitis induced by EtOH plus palmitoleic acid. Adenoviral ATG4B overexpression in acinar cells greatly reduced LC3-II and inhibited autophagy. Furthermore, it aggravated trypsinogen activation and necrosis, mimicking key responses of ex vivo alcoholic pancreatitis. Conversely, shRNA Atg4B knockdown enhanced autophagosome formation and alleviated ethanol-induced acinar cell damage. The results reveal a novel mechanism, whereby ethanol inhibits autophagosome formation and thus sensitizes pancreatitis, and a key role of ATG4B in ethanol's effects on autophagy. Enhancing pancreatic autophagy, particularly by downregulating ATG4B, could be beneficial in mitigating the severity of alcoholic pancreatitis.NEW & NOTEWORTHY Ethanol sensitizes mice and humans to pancreatitis, but the underlying mechanisms remain obscure. Autophagy is important for maintaining pancreatic acinar cell homeostasis, and its impairment drives pancreatitis. This study reveals a novel mechanism, whereby ethanol inhibits autophagosome formation through upregulating ATG4B, a key cysteine protease. ATG4B upregulation inhibits autophagy in acinar cells and aggravates pathological responses of experimental alcoholic pancreatitis. Enhancing pancreatic autophagy, particularly by down-regulating ATG4B, could be beneficial for treatment of alcoholic pancreatitis.
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Affiliation(s)
- Olga A Mareninova
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, California, United States
| | - Sophie R Gretler
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, California, United States
| | - Grace E Lee
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
| | - Michael Pimienta
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
| | - Yueqiu Qin
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- Division of Gastroenterology and Hepatology, Youjiang Medical University for Nationalities, Baise, China
| | - Jason M Elperin
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
| | - Jinliang Ni
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- First Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Zsolt Razga
- Institute of Pathology, University of Szeged, Szeged, Hungary
| | - Anna S Gukovskaya
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, California, United States
| | - Ilya Gukovsky
- David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California, United States
- Southern California Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, California, United States
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Maertin S, Elperin JM, Lotshaw E, Sendler M, Speakman SD, Takakura K, Reicher BM, Mareninova OA, Grippo PJ, Mayerle J, Lerch MM, Gukovskaya AS. Roles of autophagy and metabolism in pancreatic cancer cell adaptation to environmental challenges. Am J Physiol Gastrointest Liver Physiol 2017; 313:G524-G536. [PMID: 28705806 PMCID: PMC5792215 DOI: 10.1152/ajpgi.00138.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 06/29/2017] [Accepted: 07/06/2017] [Indexed: 01/31/2023]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) displays extensive and poorly vascularized desmoplastic stromal reaction, and therefore, pancreatic cancer (PaCa) cells are confronted with nutrient deprivation and hypoxia. Here, we investigate the roles of autophagy and metabolism in PaCa cell adaptation to environmental stresses, amino acid (AA) depletion, and hypoxia. It is known that in healthy cells, basal autophagy is at a low level, but it is greatly activated by environmental stresses. By contrast, we find that in PaCa cells, basal autophagic activity is relatively high, but AA depletion and hypoxia activate autophagy only weakly or not at all, due to their failure to inhibit mechanistic target of rapamycin. Basal, but not stress-induced, autophagy is necessary for PaCa cell proliferation, and AA supply is even more critical to maintain PaCa cell growth. To gain insight into the underlying mechanisms, we analyzed the effects of autophagy inhibition and AA depletion on PaCa cell metabolism. PaCa cells display mixed oxidative/glycolytic metabolism, with oxidative phosphorylation (OXPHOS) predominant. Both autophagy inhibition and AA depletion dramatically decreased OXPHOS; furthermore, pharmacologic inhibitors of OXPHOS suppressed PaCa cell proliferation. The data indicate that the maintenance of OXPHOS is a key mechanism through which autophagy and AA supply support PaCa cell growth. We find that the expression of oncogenic activation mutation in GTPase Kras markedly promotes basal autophagy and stimulates OXPHOS through an autophagy-dependent mechanism. The results suggest that approaches aimed to suppress OXPHOS, particularly through limiting AA supply, could be beneficial in treating PDAC.NEW & NOTEWORTHY Cancer cells in the highly desmoplastic pancreatic ductal adenocarcinoma confront nutrient [i.e., amino acids (AA)] deprivation and hypoxia, but how pancreatic cancer (PaCa) cells adapt to these conditions is poorly understood. This study provides evidence that the maintenance of mitochondrial function, in particular, oxidative phosphorylation (OXPHOS), is a key mechanism that supports PaCa cell growth, both in normal conditions and under the environmental stresses. OXPHOS in PaCa cells critically depends on autophagy and AA supply. Furthermore, the oncogenic activation mutation in GTPase Kras upregulates OXPHOS through an autophagy-dependent mechanism.
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Affiliation(s)
- Sandrina Maertin
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California; ,3Department of Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany;
| | - Jason M. Elperin
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Ethan Lotshaw
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Matthias Sendler
- 3Department of Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany;
| | - Steven D. Speakman
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Kazuki Takakura
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Benjamin M. Reicher
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Olga A. Mareninova
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
| | - Paul J. Grippo
- 4Department of Medicine, University of Illinois-Chicago, Chicago, Illinois; and
| | - Julia Mayerle
- 3Department of Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany; ,5Department of Medicine II, University Hospital, Ludwig-Maximilian-University, Munich, Germany
| | - Markus M. Lerch
- 3Department of Medicine A, Ernst-Moritz-Arndt University, Greifswald, Germany;
| | - Anna S. Gukovskaya
- 1Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; ,2Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California;
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