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Hu Y, Wang R, Liu J, Wang Y, Dong J. Lipid droplet deposition in the regenerating liver: A promoter, inhibitor, or bystander? Hepatol Commun 2023; 7:e0267. [PMID: 37708445 PMCID: PMC10503682 DOI: 10.1097/hc9.0000000000000267] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/29/2023] [Indexed: 09/16/2023] Open
Abstract
Liver regeneration (LR) is a complex process involving intricate networks of cellular connections, cytokines, and growth factors. During the early stages of LR, hepatocytes accumulate lipids, primarily triacylglycerol, and cholesterol esters, in the lipid droplets. Although it is widely accepted that this phenomenon contributes to LR, the impact of lipid droplet deposition on LR remains a matter of debate. Some studies have suggested that lipid droplet deposition has no effect or may even be detrimental to LR. This review article focuses on transient regeneration-associated steatosis and its relationship with the liver regenerative response.
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Affiliation(s)
- Yuelei Hu
- Department of Hepatobiliary and Pancreatic Surgery, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Ruilin Wang
- Department of Cadre’s Wards Ultrasound Diagnostics. Ultrasound Diagnostic Center, The First Hospital of Jilin University, Jilin University, Changchun, China
| | - Juan Liu
- Research Unit of Precision Hepatobiliary Surgery Paradigm, Chinese Academy of Medical Sciences, Beijing, China
- Hepatopancreatobiliary Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
- Institute for Organ Transplant and Bionic Medicine, Tsinghua University, Beijing, China
- Clinical Translational Science Center, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Yunfang Wang
- Research Unit of Precision Hepatobiliary Surgery Paradigm, Chinese Academy of Medical Sciences, Beijing, China
- Hepatopancreatobiliary Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
- Institute for Organ Transplant and Bionic Medicine, Tsinghua University, Beijing, China
- Clinical Translational Science Center, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Jiahong Dong
- Department of Hepatobiliary and Pancreatic Surgery, The First Hospital of Jilin University, Jilin University, Changchun, China
- Research Unit of Precision Hepatobiliary Surgery Paradigm, Chinese Academy of Medical Sciences, Beijing, China
- Hepatopancreatobiliary Center, Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua University, Beijing, China
- Institute for Organ Transplant and Bionic Medicine, Tsinghua University, Beijing, China
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2
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Øvrebø JI, Ma Y, Edgar BA. Cell growth and the cell cycle: New insights about persistent questions. Bioessays 2022; 44:e2200150. [PMID: 36222263 DOI: 10.1002/bies.202200150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 11/08/2022]
Abstract
Before a cell divides into two daughter cells, it typically doubles not only its DNA, but also its mass. Numerous studies in cells ranging from yeast to mammals have shown that cellular growth, stimulated by nutrients and/or growth factor signaling, is a prerequisite for cell cycle progression in most types of cells. The textbook view of growth-regulated cell cycles is that growth signaling activates the transcription of G1 Cyclin genes to induce cell proliferation, and also stimulates anabolic metabolism and cell growth in parallel. However, genetic knockout tests in model organisms indicate that this is not the whole story, and new studies show that additional, "smarter" mechanisms help to coordinate the cell cycle with growth itself. Here we summarize recent advances in this field, and discuss current models in which growth signaling regulates cell proliferation by targeting core cell cycle regulators via non-transcriptional mechanisms.
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Affiliation(s)
- Jan Inge Øvrebø
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Yiqin Ma
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
| | - Bruce A Edgar
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, USA
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3
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Translational control of E2f1 regulates the Drosophila cell cycle. Proc Natl Acad Sci U S A 2022; 119:2113704119. [PMID: 35074910 PMCID: PMC8795540 DOI: 10.1073/pnas.2113704119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2021] [Indexed: 12/21/2022] Open
Abstract
E2F transcription factors are master regulators of the eukaryotic cell cycle. In Drosophila, the sole activating E2F, E2F1, is both required for and sufficient to promote G1→S progression. E2F1 activity is regulated both by binding to RB Family repressors and by posttranscriptional control of E2F1 protein levels by the EGFR and TOR signaling pathways. Here, we investigate cis-regulatory elements in the E2f1 messenger RNA (mRNA) that enable E2f1 translation to respond to these signals and promote mitotic proliferation of wing imaginal disc and intestinal stem cells. We show that small upstream open reading frames (uORFs) in the 5' untranslated region (UTR) of the E2f1 mRNA limit its translation, impacting rates of cell proliferation. E2f1 transgenes lacking these 5'UTR uORFs caused TOR-independent expression and excess cell proliferation, suggesting that TOR activity can bypass uORF-mediated translational repression. EGFR signaling also enhanced translation but through a mechanism less dependent on 5'UTR uORFs. Further, we mapped a region in the E2f1 mRNA that contains a translational enhancer, which may also be targeted by TOR signaling. This study reveals translational control mechanisms through which growth signaling regulates cell cycle progression.
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4
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He F, Antonucci L, Yamachika S, Zhang Z, Taniguchi K, Umemura A, Hatzivassiliou G, Roose-Girma M, Reina-Campos M, Duran A, Diaz-Meco MT, Moscat J, Sun B, Karin M. NRF2 activates growth factor genes and downstream AKT signaling to induce mouse and human hepatomegaly. J Hepatol 2020; 72:1182-1195. [PMID: 32105670 PMCID: PMC8054878 DOI: 10.1016/j.jhep.2020.01.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 01/02/2020] [Accepted: 01/16/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Hepatomegaly can be triggered by insulin and insulin-unrelated etiologies. Insulin acts via AKT, but how other challenges cause hepatomegaly is unknown. METHODS Since many hepatomegaly-inducing toxicants and stressors activate NRF2, we examined the effect of NRF2 activation on liver size and metabolism using a conditional allele encoding a constitutively active NRF2 variant to generate Nrf2Act-hep mice in which NRF2 is selectively activated in hepatocytes. We also used adenoviruses encoding variants of the autophagy adaptor p62/SQSTM1, which activates liver NRF2, as well as liver-specific ATG7-deficient mice (Atg7Δhep) and liver specimens from patients with hepatic sinusoidal obstruction syndrome (HSOS) and autoimmune hepatitis (AIH). RNA sequencing and cell signaling analyses were used to determine cellular consequences of NRF2 activation and diverse histological analyses were used to study effects of the different manipulations on liver and systemic pathophysiology. RESULTS Hepatocyte-specific NRF2 activation, due to p62 accumulation or inhibition of KEAP1 binding, led to hepatomegaly associated with enhanced glycogenosis, steatosis and G2/M cell cycle arrest, fostering hyperplasia without cell division. Surprisingly, all manipulations that led to NRF2 activation also activated AKT, whose inhibition blocked NRF2-induced hepatomegaly and glycogenosis, but not NRF2-dependent antioxidant gene induction. AKT activation was linked to NRF2-mediated transcriptional induction of PDGF and EGF receptor ligands that signaled through their cognate receptors in an autocrine manner. Insulin and insulin-like growth factors were not involved. The NRF2-AKT signaling axis was also activated in human HSOS- and AIH-related hepatomegaly. CONCLUSIONS NRF2, a transcription factor readily activated by xenobiotics, oxidative stress and autophagy disruptors, may be a common mediator of hepatomegaly; its effects on hepatic metabolism can be reversed by AKT/tyrosine kinase inhibitors. LAY SUMMARY Hepatomegaly can be triggered by numerous etiological factors, including infections, liver cancer, metabolic disturbances, toxicant exposure, as well as alcohol abuse or drug-induced hepatitis. This study identified the oxidative stress response transcription factor NRF2 as a common mediator of hepatomegaly. NRF2 activation results in elevated expression of several growth factors. These growth factors are made by hepatocytes and activate their receptors in an autocrine fashion to stimulate the accumulation of glycogen and lipids that lead to hepatocyte and liver enlargement. The protein kinase AKT plays a key role in this process and its inhibition leads to reversal of hepatomegaly.
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Affiliation(s)
- Feng He
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Laura Antonucci
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Shinichiro Yamachika
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Zechuan Zhang
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing 210008, Jiangsu Province, China
| | - Koji Taniguchi
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Atsushi Umemura
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | | | | | - Miguel Reina-Campos
- Cancer Metabolism and Signaling Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Angeles Duran
- Cancer Metabolism and Signaling Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Maria T Diaz-Meco
- Cancer Metabolism and Signaling Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jorge Moscat
- Cancer Metabolism and Signaling Networks Program, Sanford-Burnham-Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Beicheng Sun
- Department of Hepatobiliary Surgery, The Affiliated Drum Tower Hospital of Nanjing University Medical School, 321 Zhongshan Road, Nanjing 210008, Jiangsu Province, China.
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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5
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Ozaki M. Cellular and molecular mechanisms of liver regeneration: Proliferation, growth, death and protection of hepatocytes. Semin Cell Dev Biol 2019; 100:62-73. [PMID: 31669133 DOI: 10.1016/j.semcdb.2019.10.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 10/09/2019] [Accepted: 10/14/2019] [Indexed: 01/08/2023]
Abstract
Liver regeneration is an important and necessary process that the liver depends on for recovery from injury. The regeneration process consists of a complex network of cells and organs, including liver cells (parenchymal and non-parenchymal cells) and extrahepatic organs (thyroid, adrenal glands, pancreas, duodenum, spleen, and autonomic nervous system). The regeneration process of a normal, healthy liver depends mainly on hepatocyte proliferation, growth, and programmed cell death. Cell proliferation and growth are regulated in a cooperative manner by interleukin (IL)-6/janus kinase (Jak)/signal transducers and activators of transcription-3 (STAT3), and phosphoinositide 3-kinase (PI3-K)/phosphoinositide-dependent protein kinase 1 (PDK1)/Akt pathways. The IL-6/Jak/STAT3 pathway regulates hepatocyte proliferation and protects against cell death and oxidative stress. The PI3-K/PDK1/Akt pathway is primarily responsible for the regulation of cell size, sending mitotic signals in addition to pro-survival, antiapoptotic and antioxidative signals. Though programmed cell death may interfere with liver regeneration in a pathological situation, it seems to play an important role during the termination phase, even in a normal, healthy liver regeneration. However, further study is needed to fully elucidate the mechanisms regulating the processes of liver regeneration with regard to cell-to-cell and organ-to-organ networks at the molecular and cellular levels.
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Affiliation(s)
- Michitaka Ozaki
- Department of Biological Response and Regulation, Faculty of Health Sciences, Hokkaido University, N12, W5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan.
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6
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Wang M, Yang Y, Han L, Xu F, Li F. Cell mechanical microenvironment for cell volume regulation. J Cell Physiol 2019; 235:4070-4081. [PMID: 31637722 DOI: 10.1002/jcp.29341] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/30/2019] [Indexed: 01/05/2023]
Abstract
Cell volume regulation, as one of the fundamental homeostasis of the cell, is associated with many cellular behaviors and functions. With the increased studies on the effect of environmental mechanical cues on cell volume regulation, the relationship between cell volume regulation and mechanotransduction becomes more and more clear. In this paper, we review the mechanisms and hypotheses by which cell maintains its volume homeostasis both in vivo and in constructed cell mechanical microenvironment (CMM) in vitro. We discuss how the growth-division regulation maintains the volume homeostasis of cells in the cell cycle and how the cell cortex/membrane tension mediates the effect of CMM (i.e., osmotic pressure, matrix stiffness, and mechanical force) on cell volume regulation. We also highlight the roles of cell volume as a perfect integrator of the downstream signals of mechanotransduction from different aspects of CMM and an effective indicator for the mechanical condition that cell confronts. This interdisciplinary perspective can provide new insight into biomechanics and may shed light on bioengineering and pathological research work. We hope this review can facilitate future studies on the investigation of the role of cell volume in mechanotransduction.
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Affiliation(s)
- Meng Wang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Yaowei Yang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Lichun Han
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China.,Department of Anesthesia, Xi'an Daxing Hospital, Xi'an, China
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
| | - Fei Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China.,Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an, China
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7
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Costa C, Wang Y, Ly A, Hosono Y, Murchie E, Walmsley CS, Huynh T, Healy C, Peterson R, Yanase S, Jakubik CT, Henderson LE, Damon LJ, Timonina D, Sanidas I, Pinto CJ, Mino-Kenudson M, Stone JR, Dyson NJ, Ellisen LW, Bardia A, Ebi H, Benes CH, Engelman JA, Juric D. PTEN Loss Mediates Clinical Cross-Resistance to CDK4/6 and PI3Kα Inhibitors in Breast Cancer. Cancer Discov 2019; 10:72-85. [PMID: 31594766 DOI: 10.1158/2159-8290.cd-18-0830] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 07/12/2019] [Accepted: 10/03/2019] [Indexed: 11/16/2022]
Abstract
The combination of CDK4/6 inhibitors with antiestrogen therapies significantly improves clinical outcomes in ER-positive advanced breast cancer. To identify mechanisms of acquired resistance, we analyzed serial biopsies and rapid autopsies from patients treated with the combination of the CDK4/6 inhibitor ribociclib with letrozole. This study revealed that some resistant tumors acquired RB loss, whereas other tumors lost PTEN expression at the time of progression. In breast cancer cells, ablation of PTEN, through increased AKT activation, was sufficient to promote resistance to CDK4/6 inhibition in vitro and in vivo. Mechanistically, PTEN loss resulted in exclusion of p27 from the nucleus, leading to increased activation of both CDK4 and CDK2. Because PTEN loss also causes resistance to PI3Kα inhibitors, currently approved in the post-CDK4/6 setting, these findings provide critical insight into how this single genetic event may cause clinical cross-resistance to multiple targeted therapies in the same patient, with implications for optimal treatment-sequencing strategies. SIGNIFICANCE: Our analysis of serial biopsies uncovered RB and PTEN loss as mechanisms of acquired resistance to CDK4/6 inhibitors, utilized as first-line treatment for ER-positive advanced breast cancer. Importantly, these findings have near-term clinical relevance because PTEN loss also limits the efficacy of PI3Kα inhibitors currently approved in the post-CDK4/6 setting.This article is highlighted in the In This Issue feature, p. 1.
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Affiliation(s)
- Carlotta Costa
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts.
| | - Ye Wang
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Amy Ly
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Yasuyuki Hosono
- Division of Molecular Therapeutics, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Ellen Murchie
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Charlotte S Walmsley
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Tiffany Huynh
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Christopher Healy
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Rachel Peterson
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Shogo Yanase
- Division of Molecular Therapeutics, Aichi Cancer Center Research Institute, Nagoya, Japan
| | - Charles T Jakubik
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Laura E Henderson
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Leah J Damon
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Daria Timonina
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Ioannis Sanidas
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Christopher J Pinto
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Mari Mino-Kenudson
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - James R Stone
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Nicholas J Dyson
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Leif W Ellisen
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Aditya Bardia
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Hiromichi Ebi
- Division of Molecular Therapeutics, Aichi Cancer Center Research Institute, Nagoya, Japan.,Precision Medicine Center, Aichi Cancer Center, Nagoya, Japan.,Division of Advanced Cancer Therapeutics, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Cyril H Benes
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts
| | - Jeffrey A Engelman
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts.
| | - Dejan Juric
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Boston, Massachusetts.
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8
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Potikha T, Ella E, Cerliani JP, Mizrahi L, Pappo O, Rabinovich GA, Galun E, Goldenberg DS. Galectin-1 is essential for efficient liver regeneration following hepatectomy. Oncotarget 2017; 7:31738-54. [PMID: 27166189 PMCID: PMC5077973 DOI: 10.18632/oncotarget.9194] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/19/2016] [Indexed: 01/23/2023] Open
Abstract
Galectin-1 (Gal1) is a known immune/inflammatory regulator which acts both extracellularly and intracellularly, modulating innate and adaptive immune responses. Here, we explored the role of Gal1 in liver regeneration using 70% partial hepatectomy (PHx) of C57BL/6 wild type and Gal1-knockout (Gal1-KO, Lgals1−/−) mice. Gene or protein expression, in liver samples collected at time intervals from 2 to 168 hours post-operation, was tested by either RT-PCR or by immunoblotting and immunohistochemistry, respectively. We demonstrated that Gal1 transcript and protein expression was induced in the liver tissue of wild type mice upon PHx. Liver regeneration following PHx was significantly delayed in the Gal1-KO compared to the control liver. This delay was accompanied by a decreased Akt phosphorylation, and accumulation of the hepatocyte nuclear p21 protein in the Gal1-KO versus control livers at 24 and 48 hours following PHx. Transcripts of several known regulators of inflammation, cell cycle and cell signaling, including some known PHx-induced genes, were aberrantly expressed (mainly down-regulated) in Gal1-KO compared to control livers at 2, 6 and 24 hours post-PHx. Transient steatosis, which is imperative for liver regeneration following PHx, was significantly delayed and decreased in the Gal1-KO compared to the control liver and was accompanied by a significantly decreased expression in the mutant liver of several genes encoding lipid metabolism regulators. Our results demonstrate that Gal1 protein is essential for efficient liver regeneration following PHx through the regulation of liver inflammation, hepatic cell proliferation, and the control of lipid storage in the regenerating liver.
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Affiliation(s)
- Tamara Potikha
- The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Ezra Ella
- The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Juan P Cerliani
- Laboratory of Immunopathology, Institute of Biology and Experimental Medicine, CONICET, Buenos Aires, Argentina
| | - Lina Mizrahi
- The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Orit Pappo
- Department of Pathology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Gabriel A Rabinovich
- Laboratory of Immunopathology, Institute of Biology and Experimental Medicine, CONICET, Buenos Aires, Argentina.,Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires, Argentina
| | - Eithan Galun
- The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Daniel S Goldenberg
- The Goldyne Savad Institute of Gene Therapy, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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9
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Lanton T, Shriki A, Nechemia-Arbely Y, Abramovitch R, Levkovitch O, Adar R, Rosenberg N, Paldor M, Goldenberg D, Sonnenblick A, Peled A, Rose-John S, Galun E, Axelrod JH. Interleukin 6-dependent genomic instability heralds accelerated carcinogenesis following liver regeneration on a background of chronic hepatitis. Hepatology 2017; 65:1600-1611. [PMID: 28027584 DOI: 10.1002/hep.29004] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/23/2016] [Accepted: 12/11/2016] [Indexed: 01/05/2023]
Abstract
UNLABELLED Liver cancer, which typically develops on a background of chronic liver inflammation, is now the second leading cause of cancer mortality worldwide. For patients with liver cancer, surgical resection is a principal treatment modality that offers a chance of prolonged survival. However, tumor recurrence after resection, the mechanisms of which remain obscure, markedly limits the long-term survival of these patients. We have shown that partial hepatectomy in multidrug resistance 2 knockout (Mdr2-/- ) mice, a model of chronic inflammation-associated liver cancer, significantly accelerates hepatocarcinogenesis. Here, we explore the postsurgical mechanisms that drive accelerated hepatocarcinogenesis in Mdr2-/- mice by perioperative pharmacological inhibition of interleukin-6 (IL6), which is a crucial liver regeneration priming cytokine. We demonstrate that inhibition of IL6 signaling dramatically impedes tumorigenesis following partial hepatectomy without compromising survival or liver mass recovery. IL6 blockade significantly inhibited hepatocyte cell cycle progression while promoting a hypertrophic regenerative response, without increasing apoptosis. Mdr2-/- mice contain hepatocytes with a notable persistent DNA damage response (γH2AX, 53BP1) due to chronic inflammation. We show that liver regeneration in this microenvironment leads to a striking increase in hepatocytes bearing micronuclei, a marker of genomic instability, which is suppressed by IL6 blockade. CONCLUSION Our findings indicate that genomic instability derived during the IL6-mediated liver regenerative response within a milieu of chronic inflammation links partial hepatectomy to accelerated hepatocarcinogenesis; this suggests a new therapeutic approach through the usage of an anti-IL6 treatment to extend the tumor-free survival of patients undergoing surgical resection. (Hepatology 2017;65:1600-1611).
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Affiliation(s)
| | | | | | - Rinat Abramovitch
- Goldyne Savad Institute of Gene Therapy.,Magnetic Resonance Imaging/Magnetic Resonance Spectroscopy Laboratory, Human Biology Research Center
| | | | | | | | | | | | - Amir Sonnenblick
- Sharett Institute of Oncology, Hadassah Medical Center, Jerusalem, Israel
| | | | - Stefan Rose-John
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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10
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Pauta M, Rotllan N, Fernández-Hernando A, Langhi C, Ribera J, Lu M, Boix L, Bruix J, Jimenez W, Suárez Y, Ford DA, Baldán A, Birnbaum MJ, Morales-Ruiz M, Fernández-Hernando C. Akt-mediated foxo1 inhibition is required for liver regeneration. Hepatology 2016; 63:1660-74. [PMID: 26473496 PMCID: PMC5177729 DOI: 10.1002/hep.28286] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/18/2015] [Accepted: 10/13/2015] [Indexed: 12/24/2022]
Abstract
UNLABELLED Understanding the hepatic regenerative process has clinical interest as the effectiveness of many treatments for chronic liver diseases is conditioned by efficient liver regeneration. Experimental evidence points to the need for a temporal coordination between cytokines, growth factors, and metabolic signaling pathways to enable successful liver regeneration. One intracellular mediator that acts as a signal integration node for these processes is the serine-threonine kinase Akt/protein kinase B (Akt). To investigate the contribution of Akt during hepatic regeneration, we performed partial hepatectomy in mice lacking Akt1, Akt2, or both isoforms. We found that absence of Akt1 or Akt2 does not influence liver regeneration after partial hepatectomy. However, hepatic-specific Akt1 and Akt2 null mice show impaired liver regeneration and increased mortality. The major abnormal cellular events observed in total Akt-deficient livers were a marked reduction in cell proliferation, cell hypertrophy, glycogenesis, and lipid droplet formation. Most importantly, liver-specific deletion of FoxO1, a transcription factor regulated by Akt, rescued the hepatic regenerative capability in Akt1-deficient and Akt2-deficient mice and normalized the cellular events associated with liver regeneration. CONCLUSION The Akt-FoxO1 signaling pathway plays an essential role during liver regeneration.
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Affiliation(s)
- Montse Pauta
- Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigaciones Biomédicas en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain,Departments of Medicine and Cell Biology, Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA
| | - Noemi Rotllan
- Departments of Medicine and Cell Biology, Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA,Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut, USA,Integrative Cell Signaling and Neurobiology of Metabolism Program, Section of Comparative Medicine and Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Ana Fernández-Hernando
- Departments of Medicine and Cell Biology, Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA
| | - Cedric Langhi
- Edward A. Doisy Department of Biochemistry & Molecular Biology, and Center for Cardiovascular Research, Saint Louis University, Saint Louis, Missuri, USA
| | - Jordi Ribera
- Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigaciones Biomédicas en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
| | - Mingjian Lu
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Loreto Boix
- Barcelona Clinic Liver Cancer (BCLC) Group, Liver Unit, Hospital Clínic of Barcelona, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CIBERehd, Barcelona, Spain
| | - Jordi Bruix
- Barcelona Clinic Liver Cancer (BCLC) Group, Liver Unit, Hospital Clínic of Barcelona, University of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CIBERehd, Barcelona, Spain
| | - Wladimiro Jimenez
- Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigaciones Biomédicas en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain,Department of Physiological Sciences I, University of Barcelona, Barcelona, Spain
| | - Yajaira Suárez
- Departments of Medicine and Cell Biology, Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA,Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut, USA,Integrative Cell Signaling and Neurobiology of Metabolism Program, Section of Comparative Medicine and Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - David A. Ford
- Edward A. Doisy Department of Biochemistry & Molecular Biology, and Center for Cardiovascular Research, Saint Louis University, Saint Louis, Missuri, USA
| | - Angel Baldán
- Edward A. Doisy Department of Biochemistry & Molecular Biology, and Center for Cardiovascular Research, Saint Louis University, Saint Louis, Missuri, USA
| | - Morris J. Birnbaum
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Manuel Morales-Ruiz
- Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Centro de Investigaciones Biomédicas en Red en Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain,Department of Physiological Sciences I, University of Barcelona, Barcelona, Spain,Corresponding authors: Manuel Morales-Ruiz, Ph.D., Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, 170 Villarroel St, Barcelona, 08036, Spain, Tel: 011-34-932275466; Fax: 011-34-932275697; ., Carlos Fernandez-Hernando, Ph.D., Vascular Biology and Therapeutics Program, Yale University School of Medicine, 10 Amistad Street, New Haven, CT06520, Tel: 2037374615; Fax: 2037372290;
| | - Carlos Fernández-Hernando
- Departments of Medicine and Cell Biology, Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA,Vascular Biology and Therapeutics Program, Yale University School of Medicine, New Haven, Connecticut, USA,Integrative Cell Signaling and Neurobiology of Metabolism Program, Section of Comparative Medicine and Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, USA,Corresponding authors: Manuel Morales-Ruiz, Ph.D., Department of Biochemistry and Molecular Genetics, Hospital Clinic of Barcelona, 170 Villarroel St, Barcelona, 08036, Spain, Tel: 011-34-932275466; Fax: 011-34-932275697; ., Carlos Fernandez-Hernando, Ph.D., Vascular Biology and Therapeutics Program, Yale University School of Medicine, 10 Amistad Street, New Haven, CT06520, Tel: 2037374615; Fax: 2037372290;
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11
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Abstract
Different animal cell types have distinctive and characteristic sizes. How a particular cell size is specified by differentiation programs and physiology remains one of the fundamental unknowns in cell biology. In this Review, we explore the evidence that individual cells autonomously sense and specify their own size. We discuss possible mechanisms by which size-sensing and size-specification may take place. Last, we explore the physiological implications of size control: Why is it important that particular cell types maintain a particular size? We develop these questions through examination of the current literature and pose the questions that we anticipate will guide this field in the upcoming years.
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Affiliation(s)
- Miriam B Ginzberg
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
| | - Ran Kafri
- The Hospital for Sick Children, Toronto, Canada
| | - Marc Kirschner
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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12
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Jiao Y, Ye DZ, Li Z, Teta-Bissett M, Peng Y, Taub R, Greenbaum LE, Kaestner KH. Protein tyrosine phosphatase of liver regeneration-1 is required for normal timing of cell cycle progression during liver regeneration. Am J Physiol Gastrointest Liver Physiol 2015; 308:G85-91. [PMID: 25377314 PMCID: PMC4380483 DOI: 10.1152/ajpgi.00084.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Protein tyrosine phosphatase of liver regeneration-1 (Prl-1) is an immediate-early gene that is significantly induced during liver regeneration. Several in vitro studies have suggested that Prl-1 is important for the regulation of cell cycle progression. To evaluate its function in liver regeneration, we ablated the Prl-1 gene specifically in mouse hepatocytes using the Cre-loxP system. Prl-1 mutant mice (Prl-1(loxP/loxP);AlfpCre) appeared normal and fertile. Liver size and metabolic function in Prl-1 mutants were comparable to controls, indicating that Prl-1 is dispensable for liver development, postnatal growth, and hepatocyte differentiation. Mutant mice demonstrated a delay in DNA synthesis after 70% partial hepatectomy, although ultimate liver mass restoration was not affected. At 40 h posthepatectomy, reduced protein levels of the cell cycle regulators cyclin E, cyclin A2, cyclin B1, and cyclin-dependent kinase 1 were observed in Prl-1 mutant liver. Investigation of the major signaling pathways involved in liver regeneration demonstrated that phosphorylation of protein kinase B (AKT) and signal transducer and activator of transcription (STAT) 3 were significantly reduced at 40 h posthepatectomy in Prl-1 mutants. Taken together, this study provides evidence that Prl-1 is required for proper timing of liver regeneration after partial hepatectomy. Prl-1 promotes G1/S progression via modulating expression of several cell cycle regulators through activation of the AKT and STAT3 signaling pathway.
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Affiliation(s)
- Yang Jiao
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
| | - Diana Z. Ye
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
| | - Zhaoyu Li
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
| | - Monica Teta-Bissett
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
| | - Yong Peng
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
| | - Rebecca Taub
- 3VIA Pharmaceuticals, Fort Washington, Pennsylvania
| | - Linda E. Greenbaum
- 2Department of Cancer Biology, School of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania; and
| | - Klaus H. Kaestner
- 1Department of Genetics and Institute for Diabetes, Obesity & Metabolism, University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania;
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13
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Panwar H, Raghuram GV, Jain D, Ahirwar AK, Khan S, Jain SK, Pathak N, Banerjee S, Maudar KK, Mishra PK. Cell cycle deregulation by methyl isocyanate: Implications in liver carcinogenesis. ENVIRONMENTAL TOXICOLOGY 2014; 29:284-297. [PMID: 22223508 DOI: 10.1002/tox.21757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 11/30/2011] [Accepted: 12/03/2011] [Indexed: 05/31/2023]
Abstract
Liver is often exposed to plethora of chemical toxins. Owing to its profound physiological role and central function in metabolism and homeostasis, pertinent succession of cell cycle in liver epithelial cells is of prime importance to maintain cellular proliferation. Although recent evidence has displayed a strong association between exposures to methyl isocyanate (MIC), one of the most toxic isocyanates, and neoplastic transformation, molecular characterization of the longitudinal effects of MIC on cell cycle regulation has never been performed. Here, we sequentially delineated the status of different proteins arbitrating the deregulation of cell cycle in liver epithelial cells treated with MIC. Our data reaffirms the oncogenic capability of MIC with elevated DNA damage response proteins pATM and γ-H2AX, deregulation of DNA damage check point genes CHK1 and CHK2, altered expression of p53 and p21 proteins involved in cell cycle arrest with perturbation in GADD-45 expression in the treated cells. Further, alterations in cyclin A, cyclin E, CDK2 levels along with overexpression of mitotic spindle checkpoints proteins Aurora A/B, centrosomal pericentrin protein, chromosomal aberrations, and loss of Pot1a was observed. Thus, MIC impacts key proteins involved in cell cycle regulation to trigger genomic instability as a possible mechanism of developmental basis of liver carcinogenesis.
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Affiliation(s)
- Hariom Panwar
- Research Wing, Bhopal Memorial Hospital and Research Centre, Bhopal, India; Department of Biotechnology, Dr. Hari Singh Gour Central University, Sagar, India
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14
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Tao J, Zhi X, Tian Y, Li Z, Zhu Y, Wang W, Xie K, Tang J, Zhang X, Wang L, Xu Z. CEP55 contributes to human gastric carcinoma by regulating cell proliferation. Tumour Biol 2014; 35:4389-99. [PMID: 24390615 DOI: 10.1007/s13277-013-1578-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 12/17/2013] [Indexed: 12/13/2022] Open
Abstract
Centrosomal protein 55 (CEP55) is the latest found member in the centrosomal relative protein family, which participates in cell-cycle regulation. CEP55 exists in many kinds of normal tissues and tumour cells such as hepatocellular carcinoma, and is important in carcinogenesis. However, the role of CEP55 in the pathogenesis of gastric cancer (GC) remains unclear. The mRNA levels of CEP55 in GC tissues and GC cell lines were examined by quantitative real-time PCR, and the protein expression of CEP55 in GC tissues was detected by Western blot and immunohistochemistry. The role of CEP55 in regulating the proliferation of GC cell lines was investigated both in vitro and in vivo. CEP55 was strongly upregulated in human GC, indicating that CEP55 contributed to carcinogenesis and progression of GC. Ectopic overexpression of CEP55 enhanced the cell proliferation, colony formation, and tumourigenicity of GC cells, whereas CEP55 knockdown inhibited these effects. We discovered that cell transformation induced by CEP55 was mediated by the AKT signalling pathway. Overexpression of CEP55 enhanced the phosphorylation of AKT and inhibited the activity of p21 WAF1/Cip1. In addition, cellular proliferation was suppressed as a result of cell cycle arrest at the G2/M phase in CEP55-knockdown cells. CEP55 expression was elevated in GC compared with normal control tissues. Credible evidence showed that CEP55 can be a potential therapeutic target in GC.
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Affiliation(s)
- Jinqiu Tao
- Division of Gastric Surgery, Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, 210029, China
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15
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MicroRNA-21 accelerates hepatocyte proliferation in vitro via PI3K/Akt signaling by targeting PTEN. Biochem Biophys Res Commun 2013; 443:802-7. [PMID: 24342610 DOI: 10.1016/j.bbrc.2013.12.047] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 12/08/2013] [Indexed: 02/05/2023]
Abstract
MicroRNAs (miRNAs) are involved in controlling hepatocyte proliferation during liver regeneration. In this study, we established the miRNAs-expression patterns of primary hepatocytes in vitro under stimulation of epidermal growth factor (EGF), and found that microRNA-21 (miR-21) was appreciably up-regulated and peaked at 12h. In addition, we further presented evidences indicating that miR-21 promotes primary hepatocyte proliferation through in vitro transfecting with miR-21 mimics or inhibitor. We further demonstrated that phosphatidylinositol 3'-OH kinase (PI3K)/Akt signaling was altered accordingly, it is, by targeting phosphatase and tensin homologue deleted on chromosome 10, PI3K/Akt signaling is activated by miR-21 to accelerate hepatocyte rapid S-phase entry and proliferation in vitro.
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16
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Elucidating the metabolic regulation of liver regeneration. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 184:309-21. [PMID: 24139945 DOI: 10.1016/j.ajpath.2013.04.034] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/26/2013] [Accepted: 04/01/2013] [Indexed: 02/08/2023]
Abstract
The regenerative capability of liver is well known, and the mechanisms that regulate liver regeneration are extensively studied. Such analyses have defined general principles that govern the hepatic regenerative response and implicated specific extracellular and intracellular signals as regulated during and essential for normal liver regeneration. Nevertheless, the most proximal events that stimulate liver regeneration and the distal signals that terminate this process remain incompletely understood. Recent data suggest that the metabolic response to hepatic insufficiency might be the proximal signal that initiates regenerative hepatocellular proliferation. This review provides an overview of the data in support of a metabolic model of liver regeneration and reflects on the clinical implications and areas for further study suggested by these findings.
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17
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Chew TW, Liu XJ, Liu L, Spitsbergen JM, Gong Z, Low BC. Crosstalk of Ras and Rho: activation of RhoA abates Kras-induced liver tumorigenesis in transgenic zebrafish models. Oncogene 2013; 33:2717-27. [PMID: 23812423 DOI: 10.1038/onc.2013.240] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 04/22/2013] [Accepted: 05/03/2013] [Indexed: 12/15/2022]
Abstract
RAS and Rho small GTPases are key molecular switches that control cell dynamics, cell growth and tissue development through their distinct signaling pathways. Although much has been learnt about their individual functions in both cell and animal models, the physiological and pathophysiological consequences of their signaling crosstalk in multi-cellular context in vivo remain largely unknown, especially in liver development and liver tumorigenesis. Furthermore, the roles of RhoA in RAS-mediated transformation and their crosstalk in vitro remain highly controversial. When challenged with carcinogens, zebrafish developed liver cancer that resembles the human liver cancer both molecularly and histopathologically. Capitalizing on the growing importance and relevance of zebrafish (Danio rerio) as an alternate cancer model, we have generated liver-specific, Tet-on-inducible transgenic lines expressing oncogenic Kras(G12V), RhoA, constitutively active RhoA(G14V) or dominant-negative RhoA(T19N). Double-transgenic lines expressing Kras(G12V) with one of the three RhoA genes were also generated. Based on quantitative bioimaging and molecular markers for genetic and signaling aberrations, we showed that the induced expression of oncogenic Kras during early development led to liver enlargement and hepatocyte proliferation, associated with elevated Erk phosphorylation, activation of Akt2 and modulation of its two downstream targets, p21Cip and S6 kinase. Such an increase in liver size and Akt2 expression was augmented by dominant-negative RhoA(T19N), but was abrogated by the constitutive-active RhoA(G14V). Consequently, induced expression of the oncogenic Kras in adult transgenic fish led to the development of hepatocellular carcinomas. Survival studies further revealed that the co-expression of dominant-negative RhoA(T19N) with oncogenic Kras increased the mortality rate compared with the other single or double-transgenic lines. This study provides evidence of the previously unappreciated signaling crosstalk between Kras and RhoA in regulating liver overgrowth and liver tumorigenesis. Our results also implicate that activating Rho could be beneficial to suppress the Kras-induced liver malignancies.
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Affiliation(s)
- T W Chew
- 1] Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore [2] Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - X J Liu
- Molecular Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - L Liu
- Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - J M Spitsbergen
- Department of Microbiology and Marine and Freshwater Biomedical Sciences Center, Oregon State University, Corvallis, OR, USA
| | - Z Gong
- Molecular Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - B C Low
- 1] Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, Singapore, Singapore [2] Mechanobiology Institute, National University of Singapore, Singapore, Singapore
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18
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Up-regulation of cyclin-E(1) via proline-mTOR pathway is responsible for HGF-mediated G(1)/S progression in the primary culture of rat hepatocytes. Biochem Biophys Res Commun 2013; 435:120-5. [PMID: 23618858 DOI: 10.1016/j.bbrc.2013.04.052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 04/10/2013] [Indexed: 12/27/2022]
Abstract
Hepatocyte growth factor (HGF) is a key ligand that elicits G1/S progression of epithelial cells, including hepatocytes. Proline is also required for DNA synthesis that is induced by growth factors in primary culture of hepatocytes. However, it remains unknown how proline contributes to the G1/S progression of hepatocytes. The primary culture of rat hepatocytes using HGF plus proline can be a conceptual model for elucidating the molecular linkage of amino acids and growth factors during G1/S progression. Using this in vitro model, we provide evidence that not only induction of cyclin-D1 by HGF but also up-regulation of cyclin-E1 by proline is required for hepatocytes to enter the S-phase. Proline-enhanced cyclin-E1 induction, without changing its mRNA level, is associated with the activation of mammalian target of rapamycin (mTOR)-dependent pathways. Indeed, proline enhanced the ribosomal protein S6 phosphorylations (i.e., mTOR target), concomitantly with an increase in cyclin-E1. Inversely, mTOR-inhibitor, rapamycin suppressed the proline-mediated induction of cyclin-E1. As a result, DNA synthesis of hepatocytes, which was induced by HGF in the presence of proline, was largely abolished by mTOR-inhibitor treatment. Such a co-mitogenic effect of proline was also dependent on collagen synthesis: collagen synthesis inhibitors, such as cis-OH-proline, diminished the proline-induced cyclin-E1, and then the G1/S progression of hepatocytes was also suppressed. Overall, proline-mediated mTOR activation and collagen synthesis were found critical for HGF-induced DNA synthesis, partly via the sufficient accumulation of cyclin-E1. This is the first report to demonstrate the molecular bridge between amino acids and growth factors that drive mitogenic outcomes.
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19
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Miquet JG, Freund T, Martinez CS, González L, Díaz ME, Micucci GP, Zotta E, Boparai RK, Bartke A, Turyn D, Sotelo AI. Hepatocellular alterations and dysregulation of oncogenic pathways in the liver of transgenic mice overexpressing growth hormone. Cell Cycle 2013; 12:1042-57. [PMID: 23428905 DOI: 10.4161/cc.24026] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Growth hormone (GH) overexpression throughout life in transgenic mice is associated with the development of liver tumors at old ages. The preneoplastic pathology observed in the liver of young adult GH-overexpressing mice is similar to that present in humans at high risk of hepatic cancer. To elucidate the molecular pathogenesis underlying the pro-oncogenic liver pathology induced by prolonged exposure to elevated GH levels, the activation and expression of several components of signal transduction pathways that have been implicated in hepatocellular carcinogenesis were evaluated in the liver of young adult GH-transgenic mice. In addition, males and females were analyzed in parallel in order to evaluate sexual dimorphism. Transgenic mice from both sexes exhibited hepatocyte hypertrophy with enlarged nuclear size and exacerbated hepatocellular proliferation, which were higher in males. Dysregulation of several oncogenic pathways was observed in the liver of GH-overexpressing transgenic mice. Many signaling mediators and effectors were upregulated in transgenic mice compared with normal controls, including Akt2, NFκB, GSK3β, β-catenin, cyclin D1, cyclin E, c-myc, c-jun and c-fos. The molecular alterations described did not exhibit sexual dimorphism in transgenic mice except for higher gene expression and nuclear localization of cyclin D1 in males. We conclude that prolonged exposure to GH induces in the liver alterations in signaling pathways involved in cell growth, proliferation and survival that resemble those found in many human tumors.
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Affiliation(s)
- Johanna G Miquet
- Department of Biological Chemistry-IQUIFIB (CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Ciudad Autónoma de Buenos Aires, Argentina.
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20
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Mishra R. Cell cycle-regulatory cyclins and their deregulation in oral cancer. Oral Oncol 2013; 49:475-81. [PMID: 23434055 DOI: 10.1016/j.oraloncology.2013.01.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 01/24/2013] [Accepted: 01/25/2013] [Indexed: 11/26/2022]
Abstract
Oral cancer is a growth-related disorder, and cyclins are the prime regulators of cell division. Cyclins are associated with the pathogenesis of oral cancer and are considered valuable biomarkers for diagnosis and prognosis. These important molecules are regulated in many ways to achieve a gain in function and are involved in promoting neoplastic growth. While the causes of most cyclin overexpression are varied, these cyclins may be induced by buccal mucosal insult mainly with carcinogens that alter various pathways propelling oral cancer. Substantial experimental evidences support a link between oncogenic signaling pathways and the deregulation of cyclins in oral cancer. This review focuses on the mechanisms by which cyclins are regulated and promote oral oncogenesis.
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Affiliation(s)
- Rajakishore Mishra
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835 205, Jharkhand, India.
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21
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Zou Y, Hu M, Bao Q, Chan JY, Dai G. Nrf2 participates in regulating maternal hepatic adaptations to pregnancy. J Cell Sci 2013; 126:1618-25. [PMID: 23418358 DOI: 10.1242/jcs.118109] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Pregnancy induces widespread adaptive responses in maternal organ systems including the liver. The maternal liver exhibits significant growth by increasing the number and size of hepatocytes, by largely unknown mechanisms. Nrf2 mediates cellular defense against oxidative stress and inflammation and also regulates liver regeneration. To determine whether Nrf2 is involved in the regulation of maternal hepatic adaptations to pregnancy, we assessed the proliferation and size of maternal hepatocytes and the associated molecular events in wild-type and Nrf2-null mice at various stages of gestation. We found that wild-type maternal hepatocytes underwent proliferation and size reduction during the first half, and size increase without overt replication during the second half, of pregnancy. Although pregnancy decreased Nrf2 activity in the maternal liver, Nrf2 deficiency caused a delay in maternal hepatocyte proliferation, concomitant with dysregulation of the activation of Cyclin D1, E1, and, more significantly, A2. Remarkably, as a result of Nrf2 absence, the maternal hepatocytes were largely prevented from reducing their sizes during the first half of pregnancy, which was associated with an increase in mTOR activation. During the second half of pregnancy, maternal hepatocytes of both genotypes showed continuous volume increase accompanied by persistent activation of mTOR. However, the lack of Nrf2 resulted in dysregulation of the activation of the mTOR upstream regulator AKT1 and the mTOR target p70SK6 and thus disruption of the AKT1/mTOR/p70S6K pathway, which is known to control cell size. This suggests an mTOR-dependent and AKT1- and p70S6K-independent compensatory mechanism when Nrf2 is deficient. In summary, our study demonstrates that Nrf2 is required for normal maternal hepatic adjustments to pregnancy by ensuring proper regulation of the number and size of maternal hepatocytes.
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Affiliation(s)
- Yuhong Zou
- Department of Biology, School of Science, Center for Regenerative Biology and Medicine, Indiana University-Purdue University, Indianapolis, IN 46202, USA
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22
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Gabrielson M, Tina E. The mitochondrial transport protein SLC25A43 affects drug efficacy and drug-induced cell cycle arrest in breast cancer cell lines. Oncol Rep 2013; 29:1268-74. [PMID: 23354756 PMCID: PMC3621655 DOI: 10.3892/or.2013.2247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 12/10/2012] [Indexed: 01/21/2023] Open
Abstract
The mitochondria have been identified as key players of apoptosis, cell proliferation and cell cycle regulation. However, the role of mitochondria in breast cancer and treatment failure remains unclear. We have previously shown a common deletion of the gene SLC25A43 in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. This gene is coding for a mitochondrial inner membrane transporter and, to date, little is known about the function of this protein. We have also found that low protein expression of SLC25A43 significantly correlates with a lower S phase fraction in HER2-positive breast cancer. The aim of this study was to investigate whether knockdown (KD) of SLC25A43 could have an effect on the cytotoxicity of different cytostatic drugs using MCF10A, MCF7 and BT-474 cells. Following siRNA-mediated KD of SLC25A43, one non-malignant and two breast cancer cell lines were exposed to the anthracycline epirubicin or the taxane paclitaxel. The HER2-positive breast cancer cells were also exposed to the targeted therapy trastuzumab and dual exposure to trastuzumab and paclitaxel. We found that KD of SLC25A43 resulted in a decreased cytotoxic effect of paclitaxel in the two cancer cell lines (P<0.05). Further analysis of cell cycle phase distribution showed that KD increased the paclitaxel-induced G2/M block in these two cell lines (P<0.05). KD of SLC25A43 also reduced the inhibitory effect of trastuzumab on cell proliferation in the HER2-positive cancer cell line BT-474 (P<0.05), and the drug-induced G0/G1 block (P<0.05). Moreover, SLC25A43 influenced the percentage of Ki-67-positive cells. Our findings demonstrate that the mitochondrial protein SLC25A43 affects drug efficacy and cell cycle regulation following drug exposure in breast cancer cell lines.
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Affiliation(s)
- Marike Gabrielson
- School of Health and Medical Sciences, Örebro University Hospital, SE-70185 Örebro, Sweden.
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23
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Rictor regulates FBXW7-dependent c-Myc and cyclin E degradation in colorectal cancer cells. Biochem Biophys Res Commun 2012; 418:426-32. [PMID: 22285861 DOI: 10.1016/j.bbrc.2012.01.054] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 01/11/2012] [Indexed: 11/23/2022]
Abstract
Rictor (Rapamycin-insensitive companion of mTOR) forms a complex with mTOR and phosphorylates and activates Akt. Activation of Akt induces expression of c-Myc and cyclin E, which are overexpressed in colorectal cancer and play an important role in colorectal cancer cell proliferation. Here, we show that rictor associates with FBXW7 to form an E3 complex participating in the regulation of c-Myc and cyclin E degradation. The Rictor-FBXW7 complex is biochemically distinct from the previously reported mTORC2 and can be immunoprecipitated independently of mTORC2. Moreover, knocking down of rictor in serum-deprived colorectal cancer cells results in the decreased ubiquitination and increased protein levels of c-Myc and cyclin E while overexpression of rictor induces the degradation of c-Myc and cyclin E proteins. Genetic knockout of FBXW7 blunts the effects of rictor, suggesting that rictor regulation of c-Myc and cyclin E requires FBXW7. Our findings identify rictor as an important component of FBXW7 E3 ligase complex participating in the regulation of c-Myc and cyclin E protein ubiquitination and degradation. Importantly, our results suggest that elevated growth factor signaling may contribute to decrease rictor/FBXW7-mediated ubiquitination of c-Myc and cyclin E, thus leading to accumulation of cyclin E and c-Myc in colorectal cancer cells.
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Huang J, Glauber M, Qiu Z, Gazit V, Dietzen DJ, Rudnick DA. The influence of skeletal muscle on the regulation of liver:body mass and liver regeneration. THE AMERICAN JOURNAL OF PATHOLOGY 2011; 180:575-82. [PMID: 22155110 DOI: 10.1016/j.ajpath.2011.10.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 09/29/2011] [Accepted: 10/31/2011] [Indexed: 12/14/2022]
Abstract
The relationship between liver and body mass is exemplified by the precision with which the liver:body mass ratio is restored after partial hepatic resection. Nevertheless, the compartments, against which liver mass is so exquisitely regulated, currently remain undefined. In the studies reported here, we investigated the role of skeletal muscle mass in the regulation of liver:body mass ratio and liver regeneration via the analysis of myostatin-null mice, in which skeletal muscle is hypertrophied. The results showed that liver mass is comparable and liver:body mass significantly diminished in the null animals compared to age-, sex-, and strain-matched controls. In association with these findings, basal hepatic Akt signaling is decreased, and the expression of the target genes of the constitutive androstane receptor and the integrin-linked kinase are dysregulated in the myostatin-null mice. In addition, the baseline expression levels of the regulators of the G1-S phase cell cycle progression in liver are suppressed in the null mice. The initiation of liver regeneration is not impaired in the null animals, although it progresses toward the lower liver:body mass set point. The data show that skeletal muscle is not the body component against which liver mass is positively regulated, and thus they demonstrate a previously unrecognized systemic compartmental specificity for the regulation of liver:body mass ratio.
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Affiliation(s)
- Jiansheng Huang
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA
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Yohn NL, Bingaman CN, DuMont AL, Yoo LI. Phosphatidylinositol 3'-kinase, mTOR, and glycogen synthase kinase-3β mediated regulation of p21 in human urothelial carcinoma cells. BMC Urol 2011; 11:19. [PMID: 21864408 PMCID: PMC3173386 DOI: 10.1186/1471-2490-11-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Accepted: 08/24/2011] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND The PTEN/Phosphatidylinositol 3'-kinase (PI3-kinase) growth factor signaling pathway plays a critical role in epithelial tumor development in a multitude of tissue types. Deletion of the Pten tumor suppressor gene in murine urothelial cells in vivo results in upregulation of cyclin-dependent kinase inhibitor p21. We have previously shown in mice that p21 expression blocks an increase in urothelial cell proliferation due to Pten deletion. In this study, we utilized human urothelial carcinoma cells UMUC-3 and UMUC-14 to identify the signaling pathways downstream of PI3-kinase that regulate p21. METHODS Cells were treated with a combination of PI3-kinase stimulating growth factors and kinase inhibitors, or transfected with exogenous genes in order to identify the signaling events that are necessary for p21 induction. Mice with conditional deletion of Pten in bladder urothelium were also examined for evidence of PI3-kinase pathway signaling events that affect p21 expression. RESULTS When cells were treated with PI3-kinase activating growth factors EGF or PDGF, we found that p21 levels increased, in a manner similar to that observed in mice. We used the inhibitors LY294002, Akti-1/2, and rapamycin, to show that p21 induction is dependent upon PI3-kinase and AKT activity, and partially dependent on mTOR. We treated the cells with proteasome inhibitor MG-132 and found that p21 may be degraded in the proteasome to regulate protein levels. Importantly, our findings show that GSK-3β plays a role in diminishing p21 levels in cells. Treatment of cells with the GSK-3β inhibitor SB-216763 increased p21 levels, while exogenous expression of GSK-3β caused a decrease in p21, indicating that GSK-3β actively reduces p21 levels. We found that a combined treatment of LY294002 and SB-216763 improved the cytotoxic effect against UMUC-3 and UMUC-14 carcinoma cells over LY294002 alone, suggesting potential therapeutic uses for GSK-3β inhibitors. Immunohistochemical staining in bladders from wild-type and Pten-deleted mice indicated that GSK-3β inhibitory phosphorylation increases when Pten is deleted. CONCLUSION PI3-kinase and AKT cause an upregulation of p21 by suppressing GSK-3β activity and activating mTOR in both cultured human urothelial carcinoma cells and mouse urothelial cells in vivo.
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Affiliation(s)
- Nicole L Yohn
- Department of Biology, Denison University, Granville, OH 43023, USA
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Hierarchies of transcriptional regulation during liver regeneration. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2011; 97:201-27. [PMID: 21074734 DOI: 10.1016/b978-0-12-385233-5.00007-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The remarkable capacity of the liver to regenerate after severe injury or disease has excited interest for centuries. The goal of harnessing this process in treatment of liver disease, and the appreciation of the parallels between regeneration and tumor development in the liver, remain a major driver for research in this area. Studies of liver regeneration as a model system offer a view of intricate and precisely timed regulatory pathways that drive the process toward completion. Successful regeneration of the liver mass demands a hierarchal and well-controlled balance between proliferative and metabolic functions, which is orchestrated by signaling and regulation of transcription factors. Control and regulation of these cascades of transcriptional activities, necessary for induction, renewal, and cessation of liver growth, are the focus of this chapter.
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Fujiyoshi M, Ozaki M. Molecular mechanisms of liver regeneration and protection for treatment of liver dysfunction and diseases. JOURNAL OF HEPATO-BILIARY-PANCREATIC SCIENCES 2011; 18:13-22. [PMID: 20607568 DOI: 10.1007/s00534-010-0304-2] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Liver regeneration is a necessary process that most liver damage depends on for recovery. Regeneration is achieved by a complex interactive network consisting of liver cells (hepatocytes, Kupffer cells, sinusoidal endothelial cells, hepatic stellate cells, and stem cells) and extrahepatic organs (thyroid gland, adrenal gland, pancreas, duodenum, and autonomous nervous system). The restoration of liver volume depends on hepatocyte proliferation, which includes initiation, proliferation, and termination phases. Hepatocytes are "primed" mainly by Kupffer cells via cytokines (IL-6 and TNF-alpha) and then "proliferation" and "cell growth" of hepatocytes are induced by the stimulations of cytokines and growth factors (HGF and TGF-alpha). Liver regeneration is achieved by cell proliferation and cell growth, where the IL-6/STAT3 and PI3-K/PDK1/Akt pathways play pivotal roles, respectively. IL-6/STAT3 pathway regulates hepatocyte proliferation via cyclin D1/p21 and protects against cell death by upregulating FLIP, Bcl-2, Bcl-xL, Ref1, and MnSOD. PI3-K/PDK1/Akt is known to be responsible for regulation of cell size via its downstream molecules such as mTOR in addition to being known for its survival, anti-apoptotic and anti-oxidative properties. Although the molecular mechanisms of liver regeneration have been actively studied, the mechanisms of liver regeneration must be elucidated and leveraged for the sufficient treatment of liver diseases.
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Affiliation(s)
- Masato Fujiyoshi
- Department of General Surgery, Hokkaido University School of Medicine, N-15, W-7 Kita-ku, Sapporo, Hokkaido 060-8638, Japan
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Abstract
The unique ability of the liver to regenerate itself has fascinated biologists for years and has made it the prototype for mammalian organ regeneration. Harnessing this process has great potential benefit in the treatment of liver failure and has been the focus of intense research over the past 50 years. Not only will detailed understanding of cell proliferation in response to injury be applicable to other dysfunction of organs, it may also shed light on how cancer develops in a cirrhotic liver, in which there is intense pressure on cells to regenerate. Advances in molecular techniques over the past few decades have led to the identification of many regulatory intermediates, and pushed us onto the verge of an explosive era in regenerative medicine. To date, more than 10 clinical trials have been reported in which augmented regeneration using progenitor cell therapy has been attempted in human patients. This review traces the path that has been taken over the last few decades in the study of liver regeneration, highlights new concepts in the field, and discusses the challenges that still stand between us and clinical therapy.
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Affiliation(s)
| | - Yock Young Dan
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | | | - Nelson Fausto
- Department of Pathology, University of Washington, Seattle, WA
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DDX3 regulates cell growth through translational control of cyclin E1. Mol Cell Biol 2010; 30:5444-53. [PMID: 20837705 DOI: 10.1128/mcb.00560-10] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
DDX3 belongs to the DEAD box family of RNA helicases, but the details of its biological function remain largely unclear. Here we show that knockdown of DDX3 expression impedes G(1)/S-phase transition of the cell cycle. To know how DDX3 may act in cell cycle control, we screened for cellular mRNA targets of DDX3. Many of the identified DDX3 targets encoded cell cycle regulators, including G(1)/S-specific cyclin E1. DDX3 depletion specifically downregulates translation of cyclin E1 mRNA. Moreover, our data suggest that DDX3 participates in translation initiation of targeted mRNAs as well as in cell growth control via its RNA helicase activity. Consistent with these findings, we show that in the temperature-sensitive DDX3 mutant hamster cell line tsET24, cyclin E1 expression is downregulated at a nonpermissive temperature that inactivates mutant DDX3. Taken together, our results indicate that DDX3 is critical for translation of cyclin E1 mRNA, which provides an alternative mechanism for regulating cyclin E1 expression during the cell cycle.
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Park ES, Lim Y, Hong JT, Yoo HS, Lee CK, Pyo MY, Yun YP. Pterostilbene, a natural dimethylated analog of resveratrol, inhibits rat aortic vascular smooth muscle cell proliferation by blocking Akt-dependent pathway. Vascul Pharmacol 2010; 53:61-7. [PMID: 20398797 DOI: 10.1016/j.vph.2010.04.001] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 03/31/2010] [Accepted: 04/01/2010] [Indexed: 12/20/2022]
Abstract
Vascular smooth muscle cells (VSMCs) are the main cellular component in the arterial wall, and abnormal proliferation of VSMCs plays a central role in the pathogenesis of atherosclerosis and restenosis after angioplasty, and possibly in the development of hypertension. Pterostilbene, a natural dimethylated analog of resveratrol, is known to have diverse pharmacological activities including anti-cancer, anti-inflammation and anti-oxidant activities. The present study was designed to investigate the effects of pterostilbene on platelet-derived growth factor (PDGF)-BB-induced VSMCs proliferation as well as the molecular mechanisms of the antiproliferative effects. The cell growth of VSMCs was determined by cell counting and [(3)H]thymidine incorporation assays. Pterostilbene significantly inhibited the DNA synthesis and proliferation of PDGF-BB-stimulated VSMCs in a concentration-dependent manner. The inhibition percentages of pterostilbene at 1, 3 and 5microM to VSMCs proliferation were 68.5, 80.7 and 94.6%, respectively. The DNA synthesis of pterostilbene at 1, 3 and 5microM in VSMCs was inhibited by 47.4, 76.7 and 100%, respectively. Pterostilbene inhibited the PDGF-BB-stimulated phosphorylation of Akt kinase. However, pterostilbene did not change the expression of extracellular signal-related kinase (ERK) 1/2, PLCgamma1, phosphatidylinositol (PI)3 kinase and PDGF-Rbeta phosphorylation. In addition, pterostilbene down-regulated the cell cycle-related proteins including the expression of cyclin-dependent kinase (CDK) 2, cyclin E, CDK4, cyclin D1, retinoblastoma (Rb) proteins and proliferative cell nuclear antigen (PCNA). These findings suggest that the inhibition of pterostilbene to the cell proliferation and DNA synthesis of PDGF-BB-stimulated VSMCs may be mediated by the suppression of Akt kinase. Furthermore, pterostilbene may be a potential anti-proliferative agent for the treatment of atherosclerosis and angioplasty restenosis.
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Affiliation(s)
- Eun-Seok Park
- College of Pharmacy, Research Center for Bioresource and Health, CBITRC, Chungbuk National University, Cheongju 361-763, Republic of Korea
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Janbandhu VC, Singh AK, Mukherji A, Kumar V. p65 Negatively regulates transcription of the cyclin E gene. J Biol Chem 2010; 285:17453-64. [PMID: 20385564 DOI: 10.1074/jbc.m109.058974] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
NF-kappaB family members play a pivotal role in many cellular and organismal functions, including the cell cycle. As an activator of cyclin D1 and p21(Waf1) genes, NF-kappaB has been regarded as a critical modulator of cell cycle. To study the involvement of NF-kappaB in G(1)/S phase regulation, the levels of selected transcriptional regulators were monitored following overexpression of NF-kappaB or its physiological induction by tumor necrosis factor-alpha. Cyclin E gene was identified as a major transcriptional target of NF-kappaB. Recruitment of NF-kappaB to the cyclin E promoter was correlated with the transrepression of cyclin E gene. Ligation-mediated PCR and micrococcal nuclease-Southern assays suggested the nucleosomal nature of this region while chromatin immunoprecipitation analysis confirmed the exchange of cofactors following tumor necrosis factor-alpha treatment or release from serum starvation. There was a progressive reduction in cyclin E transcription along with the accumulation of catalytically inactive cyclin E-cdk2 complexes and arrest of cells in G(1)/S-phase. Thus, our study clearly establishes NF-kappaB as a negative regulator of cell cycle through transcriptional repression of cyclin E.
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Affiliation(s)
- Vaibhao C Janbandhu
- Virology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India
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Pregnancy restores the regenerative capacity of the aged liver via activation of an mTORC1-controlled hyperplasia/hypertrophy switch. Genes Dev 2010; 24:543-8. [PMID: 20231314 DOI: 10.1101/gad.563110] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Regenerative capacity is progressively lost with age. Here we show that pregnancy markedly improved liver regeneration in aged mice concomitantly with inducing a switch from proliferation-based liver regeneration to a regenerative process mediated by cell growth. We found that the key mediator of this switch was the Akt/mTORC1 pathway; its inhibition blocked hypertrophy, while increasing proliferation. Moreover, pharmacological activation of this pathway sufficed to induce the hypertrophy module, mimicking pregnancy. This treatment dramatically improved hepatic regenerative capacity and survival of old mice. Thus, cell growth-mediated mass reconstitution, which is relatively resistant to the detrimental effects of aging, is employed in a physiological situation and holds potential as a therapeutic strategy for ameliorating age-related functional deterioration.
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Osawa Y, Seki E, Adachi M, Suetsugu A, Ito H, Moriwaki H, Seishima M, Nagaki M. Role of acid sphingomyelinase of Kupffer cells in cholestatic liver injury in mice. Hepatology 2010; 51:237-45. [PMID: 19821528 DOI: 10.1002/hep.23262] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Kupffer cells, resident tissue macrophages of the liver, play a key role in the regulation of hepatic inflammation, hepatocyte death, and fibrosis that characterize liver diseases. However, it is controversial whether Kupffer cells promote or protect from liver injury. To explore this issue we examined the role of Kupffer cells in liver injury, cell death, regeneration, and fibrosis on cholestatic liver injury in C57BL/6 mice using a model of partial bile duct ligation (BDL), in which animals do not die and the effects of BDL can be compared between injured ligated lobes and nonligated lobes. In cholestatic liver injury, the remaining viable cells represented tolerance for tumor necrosis factor alpha (TNF-alpha)-induced hepatocyte apoptosis and regenerative features along with AKT activation. Inhibition of AKT by adenovirus expressing dominant-negative AKT abolished the survival and regenerative properties in hepatocytes. Moreover, Kupffer cell depletion by alendronate liposomes increased hepatocyte damage and the sensitivity of TNF-alpha-induced hepatocyte apoptosis in ligated lobes. Kupffer cell depletion decreased hepatocyte regeneration and liver fibrosis with reduced AKT activation. To investigate the impact of acid sphingomyelinase (ASMase) in Kupffer cells, we generated chimeric mice that contained ASMase-deficient Kupffer cells and -sufficient hepatocytes using a combination of Kupffer cell depletion, irradiation, and the transplantation of ASMase-deficient bone marrow cells. In these mice, AKT activation, the tolerance for TNF-alpha-induced apoptosis, and the regenerative responses were attenuated in hepatocytes after BDL. CONCLUSION Kupffer cells have a protective role for hepatocyte damage and promote cell survival, liver regeneration, and fibrosis in cholestatic liver disease. Kupffer cell-derived ASMase is crucial for AKT activation of hepatocytes that is required for the survival and regenerative responses.
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Affiliation(s)
- Yosuke Osawa
- Department of Informative Clinical Medicine, Gifu University Graduate School of Medicine, Gifu, Japan.
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Kim YY, Von Weymarn L, Larsson O, Fan D, Underwood JM, Peterson MS, Hecht SS, Polunovsky VA, Bitterman PB. Eukaryotic initiation factor 4E binding protein family of proteins: sentinels at a translational control checkpoint in lung tumor defense. Cancer Res 2009; 69:8455-62. [PMID: 19843855 DOI: 10.1158/0008-5472.can-09-1923] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The usurping of translational control by sustained activation of translation initiation factors is oncogenic. Here, we show that the primary negative regulators of these oncogenic initiation factors--the 4E-BP protein family--operate as guardians of a translational control checkpoint in lung tumor defense. When challenged with the tobacco carcinogen 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (NNK), 4ebp1(-/-)/4ebp2(-/-) mice showed increased sensitivity to tumorigenesis compared with their wild-type counterparts. The 4E-BP-deficient state per se creates pro-oncogenic, genome-wide skewing of the molecular landscape, with translational activation of genes governing angiogenesis, growth, and proliferation, and translational activation of the precise cytochrome p450 enzyme isoform (CYP2A5) that bioactivates NNK into mutagenic metabolites. Our study provides in vivo proof for a translational control checkpoint in lung tumor defense.
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Affiliation(s)
- Yong Y Kim
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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35
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Chin R, Nachbur U, Earnest-Silveira L, Bankovacki A, Koeberlein B, Zentgraf H, Bock CT, Silke J, Torresi J. Dysregulation of hepatocyte cell cycle and cell viability by hepatitis B virus. Virus Res 2009; 147:7-16. [PMID: 19786052 DOI: 10.1016/j.virusres.2009.09.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 09/18/2009] [Accepted: 09/18/2009] [Indexed: 12/22/2022]
Abstract
BACKGROUND/AIMS Dysregulation of the cell cycle is frequently associated with tumor development. Hepatitis B virus (HBV) is associated with a significant risk of developing hepatocellular carcinoma but the effects of HBV on cell cycle regulation are not completely understood. METHODS We have used a recombinant adeno-HBV model system to investigate the effect of infection with HBV and the replication defective lamivudine resistant mutant rtM204I mutant on hepatocyte cell cycle and cell viability. RESULTS Huh7 cells synchronised at the G1/S phase of the cell cycle were arrested at the G2/M following infection with rAdHBV-wt and rAdHBV-M204I. This was accompanied by increased levels of p21(cip1), p-cdc2, cyclins D, A and B. Cell viability was reduced and cleaved caspase 3 levels were increased in HBV- and rtM204I-infected cells. rAdHBV-M204I-infected Huh7 cells also demonstrated significant up-regulation of phospho-ERK, phospho-Akt, p53 and phospho-Mdm2 compared to mock-infected cells. These changes were comparable to those following infection of Huh7 cells with rAdHBV-wt. CONCLUSION Our results suggest that HBV, regardless of phenotype, produces cell cycle arrest and reduced hepatocyte viability. Perturbations in these cellular processes are likely to underlie HBV-associated liver oncogenic transformation and may help explain the ongoing risk of developing hepatocellular carcinoma in individuals in whom the lamivudine resistant rtM204I mutant emerges.
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Affiliation(s)
- Ruth Chin
- Department of Medicine, Austin Hospital, University of Melbourne, Heidelberg, Victoria 3084, Australia.
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Frémin C, Bessard A, Ezan F, Gailhouste L, Régeard M, Le Seyec J, Gilot D, Pagès G, Pouysségur J, Langouët S, Baffet G. Multiple division cycles and long-term survival of hepatocytes are distinctly regulated by extracellular signal-regulated kinases ERK1 and ERK2. Hepatology 2009; 49:930-9. [PMID: 19177593 DOI: 10.1002/hep.22730] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
UNLABELLED We investigated the specific role of the mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase 1 (ERK1)/ERK2 pathway in the regulation of multiple cell cycles and long-term survival of normal hepatocytes. An early and sustained epidermal growth factor (EGF)-dependent MAPK activation greatly improved the potential of cell proliferation. In this condition, almost 100% of the hepatocytes proliferated, and targeting ERK1 or ERK2 via RNA interference revealed the specific involvement of ERK2 in this regulation. However, once their first cell cycle was performed, hepatocytes failed to undergo a second round of replication and stayed blocked in G1 phase. We demonstrated that sustained EGF-dependent activation of the MAPK/ERK kinase (MEK)/ERK pathway was involved in this blockage as specific transient inhibition of the cascade repotentiated hepatocytes to perform a new wave of replication and multiple cell cycles. We identified this mechanism by showing that this blockage was in part supported by ERK2-dependent p21 expression. Moreover, continuous MEK inhibition was associated with a lower apoptotic engagement, leading to an improvement of survival up to 3 weeks. Using RNA interference and ERK1 knockout mice, we extended these results by showing that this improved survival was due to the specific inhibition of ERK1 expression/phosphorylation and did not involve ERK2. CONCLUSION Our results emphasize that transient MAPK inhibition allows multiple cell cycles in primary cultures of hepatocytes and that ERK2 has a key role in the regulation of S phase entry. Moreover, we revealed a major and distinct role of ERK1 in the regulation of hepatocyte survival. Taken together, our results represent an important advance in understanding long-term survival and cell cycle regulation of hepatocytes.
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Affiliation(s)
- Christophe Frémin
- INSERM U522, UPRES SeRAIC, IFR 140 Université de Rennes, Rennes, France
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Lee MY, Jo SD, Lee JH, Han HJ. L-leucine increases [3H]-thymidine incorporation in chicken hepatocytes: Involvement of the PKC, PI3K/Akt, ERK1/2, and mTOR signaling pathways. J Cell Biochem 2008; 105:1410-9. [DOI: 10.1002/jcb.21959] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Xu CX, Jin H, Lim HT, Kim JE, Shin JY, Lee ES, Chung YS, Lee YS, Beck G, Lee KH, Cho MH. High dietary inorganic phosphate enhances cap-dependent protein translation, cell-cycle progression, and angiogenesis in the livers of young mice. Am J Physiol Gastrointest Liver Physiol 2008; 295:G654-63. [PMID: 18703640 PMCID: PMC2575911 DOI: 10.1152/ajpgi.90213.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inorganic phosphate (P(i)) plays a key role in diverse physiological functions. Recent studies have indicated that P(i) affects Akt signaling through the sodium-dependent phosphate cotransporter. Akt signaling, in turn, plays an important role in liver development; however, the effects of high dietary P(i) on the liver have not been investigated. Here, we examined the effects of high dietary phosphate on the liver in developing mice. We found that high dietary P(i) increased liver mass through enhancing Akt-related cap-dependent protein translation, cell cycle progression, and angiogenesis. Thus careful regulation of P(i) consumption may be important in maintaining normal development of the liver.
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Affiliation(s)
- Cheng-Xiong Xu
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Hua Jin
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Hwang-Tae Lim
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Ji-Eun Kim
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Ji-Young Shin
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Eun-Sun Lee
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Youn-Sun Chung
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Yeon-Sook Lee
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - George Beck
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Kee Ho Lee
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
| | - Myung-Haing Cho
- Laboratory of Toxicology, College of Veterinary Medicine, Nano Systems Institute-National Core Research Center, Department of Food and Nutrition, College of Human Ecology, Seoul National University, Seoul, Korea; Division of Endocrinology, Metabolism, and Lipids, Emory University School of Medicine, Atlanta, Georgia; Laboratory of Radiation Molecular Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea; Center for Developmental Pharmacology and Toxicology, Seattle Children's Hospital Research Institute, Seattle, Washington; and National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul, Korea
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Ugland H, Boquest AC, Naderi S, Collas P, Blomhoff HK. cAMP-mediated induction of cyclin E sensitizes growth-arrested adipose stem cells to DNA damage-induced apoptosis. Mol Biol Cell 2008; 19:5082-92. [PMID: 18799628 DOI: 10.1091/mbc.e08-01-0094] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The differentiation capacity of mesenchymal stem cells has been extensively studied, but little is known on cell cycle-related events in the proliferation and differentiation phases of these cells. Here, we demonstrate that exposure to cAMP-increasing agents inhibits proliferation of adipose stem cells (ASCs). This antiproliferative effect is associated with both reduced cdk2 activity and pRB phosphorylation. Concomitantly, however, the level of cyclin E markedly increases upon cAMP induction, indicating that cyclin E may have cdk2-independent functions in these cells besides its role as a cdk2 activator. Indeed, we found indications of a cdk2-independent role of cyclin E in DNA damage-induced apoptosis. 8-CPT-cAMP sensitizes ASCs to gamma-irradiation-induced apoptosis, an effect abolished by knockdown of cyclin E. Moreover, cAMP induces early activation of ERK, leading to reduced degradation of cyclin E. The cAMP-mediated up-regulation of cyclin E was blocked by knockdown of ERK or by an inhibitor of the ERK kinase MEK. We conclude that cAMP inhibits cdk2 activity and pRB phosphorylation, leading to reduced ASC proliferation. Concomitant with this growth inhibition, however, cyclin E levels are increased in a MEK/ERK-dependent manner. Our results suggest that cyclin E plays an important, cdk2-independent role in genotoxic stress-induced apoptosis in mesenchymal stem cells.
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Affiliation(s)
- Hege Ugland
- Department of Biochemistry, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, N-0317 Oslo, Norway
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Seo JM, Kim TJ, Jin YR, Han HJ, Ryu CK, Sheen YY, Kim DW, Yun YP. YSK2821, a newly synthesized indoledione derivative, inhibits cell proliferation and cell cycle progression via the cell cycle-related proteins by regulating phosphatidylinositol-3 kinase cascade in vascular smooth muscle cells. Eur J Pharmacol 2008; 586:74-81. [DOI: 10.1016/j.ejphar.2008.02.076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 01/25/2008] [Accepted: 02/20/2008] [Indexed: 10/22/2022]
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Omenetti A, Diehl AM. The adventures of sonic hedgehog in development and repair. II. Sonic hedgehog and liver development, inflammation, and cancer. Am J Physiol Gastrointest Liver Physiol 2008; 294:G595-8. [PMID: 18218671 DOI: 10.1152/ajpgi.00543.2007] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hedgehog (Hh) signaling modulates tissue remodeling by controlling the fate of Hh-responsive cells. Healthy adult livers exhibit little Hh activity. However, cells involved in adult liver repair, including myofibroblasts and progenitors, are capable of producing and responding to Hh ligands. During adult liver injury, Hh ligand production increases and populations of Hh-responsive cells expand. This process is accompanied by fibrosis. Ligand production and Hh-responsive cells diminish as fibrosis resolves and normal hepatic architecture is restored, but Hh signaling persists in hepatocellular carcinomas. These findings suggest that the Hh pathway mediates remodeling responses that are triggered by adult liver damage.
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Affiliation(s)
- Alessia Omenetti
- Duke University Medical Center, Division of Gastroenterology, Department of Medicine, Durham, NC 27710, USA
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Chin R, Earnest-Silveira L, Koeberlein B, Franz S, Zentgraf H, Bowden S, Bock CT, Torresi J. Failure of Lamivudine to Reverse Hepatitis B Virus-Associated Changes in ERK, Akt and Cell Cycle Regulatory Proteins. Antivir Ther 2008. [DOI: 10.1177/135965350801300201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Background Chronic infection with hepatitis B virus (HBV) is a major factor associated with the development of hepatocellular carcinoma, but the mechanism by which this occurs is unknown. Treatment of chronic hepatitis B with lamivudine results in virological suppression and histological improvement; however, the role of lamivudine in preventing the development of hepatocellular carcinoma is less well defined. We recently reported that replication of HBV in a cell-culture system was associated with the upregulation of pERK, pAkt, pc-Myc, nuclear cyclin B1, p21cip1 and p53 together with G2 cell cycle arrest. Methods In order to determine whether lamivudine is able to reverse the HBV-induced changes on signal transduction and cell cycle, we infected Huh7 cells with a recombinant adeno-HBV virus in the presence of 0–50 μM of lamivudine. Signal transduction and cell cycle regulatory proteins were analysed by western immunoblot. Results Although lamivudine was able to inhibit HBV replication, it failed to reverse the changes on ERK and Akt phosphorylation. Correspondingly, levels of phospho-GSK3β and p21cip1/waf1 were increased, as were cyclin D1, cyclin B1, p53 and pc-Myc. Conclusions Lamivudine was ineffective in reversing the HBV-induced changes in signal transduction pathways and cell cycle regulatory proteins, indicating that the HBV-infected cells remained primed for oncogenic transformation despite viral suppression.
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Affiliation(s)
- Ruth Chin
- Department of Medicine, CCREID, Royal Melbourne Hospital, University of Melbourne, Australia
| | - Linda Earnest-Silveira
- Department of Medicine, CCREID, Royal Melbourne Hospital, University of Melbourne, Australia
| | - Bernd Koeberlein
- Department of Molecular Pathology, University Hospital of Tuebingen, Germany
| | - Susanne Franz
- Applied Tumor Virology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Hanswalter Zentgraf
- Applied Tumor Virology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Scott Bowden
- Victorian Infectious Diseases Reference Laboratory, Victoria, Australia
| | - C-Thomas Bock
- Department of Molecular Pathology, University Hospital of Tuebingen, Germany
| | - Joseph Torresi
- Department of Medicine, CCREID, Royal Melbourne Hospital, University of Melbourne, Australia
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