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      Effect of Astaxanthin on Activation of Autophagy and Inhibition of Apoptosis in Helicobacter pylori-Infected Gastric Epithelial Cell Line AGS

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      , , *
      Nutrients
      MDPI
      Helicobacter pylori, astaxanthin, autophagy, apoptosis, AMP-activated protein kinase

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          Abstract

          Helicobacter pylori ( H. pylori) infection leads to the massive apoptosis of the gastric epithelial cells, causing gastric ulcers, gastritis, and gastric adenocarcinoma. Autophagy is a cellular recycling process that plays important roles in cell death decisions and can protect cells by preventing apoptosis. Upon the induction of autophagy, the level of the autophagy substrate p62 is reduced and the autophagy-related ratio of microtubule-associated proteins 1A/1B light chain 3B (LC3B)-II/LC3B-I is heightened. AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) are involved in the regulation of autophagy. Astaxanthin (AST) is a potent anti-oxidant that plays anti-inflammatory and anti-cancer roles in various cells. In the present study, we examined whether AST inhibits H. pylori-induced apoptosis through AMPK-mediated autophagy in the human gastric epithelial cell line AGS (adenocarcinoma gastric) in vitro. In this study, H. pylori induced apoptosis. Compound C, an AMPK inhibitor, enhanced the H. pylori-induced apoptosis of AGS cells. In contrast, metformin, an AMPK activator, suppressed H. pylori-induced apoptosis, showing that AMPK activation inhibits H. pylori-induced apoptosis. AST inhibited H. pylori-induced apoptosis by increasing the phosphorylation of AMPK and decreasing the phosphorylation of RAC-alpha serine/threonine-protein kinase (Akt) and mTOR in H. pylori-stimulated cells. The number of LC3B puncta in H. pylori-stimulated cells increased with AST. These results suggest that AST suppresses the H. pylori-induced apoptosis of AGS cells by inducing autophagy through the activation of AMPK and the downregulation of its downstream target, mTOR. In conclusion, AST may inhibit gastric diseases associated with H. pylori infection by increasing autophagy through the activation of the AMPK pathway.

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          Most cited references64

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          Statement by an American Association of Clinical Endocrinologists/American College of Endocrinology Consensus Panel on Type 2 Diabetes Mellitus: An Algorithm for Glycemic Control

          This report presents an algorithm to assist primary care physicians, endocrinologists, and others in the management of adult, nonpregnant patients with type 2 diabetes mellitus. In order to minimize the risk of diabetes-related complications, the goal of therapy is to achieve a hemoglobin A1c (A1C) of 6.5% or less, with recognition of the need for individualization to minimize the risks of hypoglycemia. We provide therapeutic pathways stratified on the basis of current levels of A1C, whether the patient is receiving treatment or is drug naïve. We consider monotherapy, dual therapy, and triple therapy, including 8 major classes of medications (biguanides, dipeptidyl-peptidase-4 inhibitors, incretin mimetics, thiazolidinediones, alpha-glucosidase inhibitors, sulfonylureas, meglitinides, and bile acid sequestrants) and insulin therapy (basal, premixed, and multiple daily injections), with or without orally administered medications. We prioritize choices of medications according to safety, risk of hypoglycemia, efficacy, simplicity, anticipated degree of patient adherence, and cost of medications. We recommend only combinations of medications approved by the US Food and Drug Administration that provide complementary mechanisms of action. It is essential to monitor therapy with A1C and self-monitoring of blood glucose and to adjust or advance therapy frequently (every 2 to 3 months) if the appropriate goal for each patient has not been achieved. We provide a flow-chart and table summarizing the major considerations. This algorithm represents a consensus of 14 highly experienced clinicians, clinical researchers, practitioners, and academicians and is based on the American Association of Clinical Endocrinologists/American College of Endocrinology Diabetes Guidelines and the recent medical literature.
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            Therapeutic metformin/AMPK activation blocked lymphoma cell growth via inhibition of mTOR pathway and induction of autophagy

            Adenosine monophosphate-activated protein kinase (AMPK) acts as a major sensor of cellular energy status in cancers and is critically involved in cell sensitivity to anticancer agents. Here, we showed that AMPK was inactivated in lymphoma and related to the upregulation of the mammalian target of rapamycin (mTOR) pathway. AMPK activator metformin potentially inhibited the growth of B- and T-lymphoma cells. Strong antitumor effect was also observed on primary lymphoma cells while sparing normal hematopoiesis ex vivo. Metformin-induced AMPK activation was associated with the inhibition of the mTOR signaling without involving AKT. Moreover, lymphoma cell response to the chemotherapeutic agent doxorubicin and mTOR inhibitor temsirolimus was significantly enhanced when co-treated with metformin. Pharmacologic and molecular knock-down of AMPK attenuated metformin-mediated lymphoma cell growth inhibition and drug sensitization. In vivo, metformin induced AMPK activation, mTOR inhibition and remarkably blocked tumor growth in murine lymphoma xenografts. Of note, metformin was equally effective when given orally. Combined treatment of oral metformin with doxorubicin or temsirolimus triggered lymphoma cell autophagy and functioned more efficiently than either agent alone. Taken together, these data provided first evidence for the growth-inhibitory and drug-sensitizing effect of metformin on lymphoma. Selectively targeting mTOR pathway through AMPK activation may thus represent a promising new strategy to improve treatment of lymphoma patients.
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              Regulation and function of autophagy during cell survival and cell death.

              Autophagy is an important catabolic process that delivers cytoplasmic material to the lysosome for degradation. Autophagy promotes cell survival by elimination of damaged organelles and proteins aggregates, as well as by facilitating bioenergetic homeostasis. Although autophagy has been considered a cell survival mechanism, recent studies have shown that autophagy can promote cell death. The core mechanisms that control autophagy are conserved between yeast and humans, but animals also possess genes that regulate autophagy that are not present in yeast. These regulatory differences may be explained by the need to control autophagy in a cell context-specific manner in multicellular animals, such as during cell survival and cell death. Autophagy was thought to be a bulk cytoplasmic degradation mechanism, but recent studies have shown that specific cargo is recruited for degradation. This suggests the possibility that either cell survival or death may be regulated by selective autophagic clearance of cytoplasmic material. Here we summarize the mechanisms that regulate autophagy and how they may contribute to cell survival and death.
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                Author and article information

                Journal
                Nutrients
                Nutrients
                nutrients
                Nutrients
                MDPI
                2072-6643
                11 June 2020
                June 2020
                : 12
                : 6
                : 1750
                Affiliations
                Brain Korea 21 PLUS Project, Department of Food and Nutrition, College of Human Ecology, Yonsei University, Seoul 03722, Korea; beachmn@ 123456naver.com (H.L.); jwlim11@ 123456yonsei.ac.kr (J.W.L.)
                Author notes
                [* ]Correspondence: kim626@ 123456yonsei.ac.kr ; Tel.: +82-2-2123-3125; Fax: +82-2-364-5781
                Author information
                https://orcid.org/0000-0002-7019-917X
                Article
                nutrients-12-01750
                10.3390/nu12061750
                7353244
                32545395
                98e2b3d5-708d-49ca-9029-5dc16a9a1a9a
                © 2020 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

                History
                : 27 March 2020
                : 08 June 2020
                Categories
                Article

                Nutrition & Dietetics
                helicobacter pylori,astaxanthin,autophagy,apoptosis,amp-activated protein kinase

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