Abstract
Introduction
Autophagy is a process for recycling intracellular organelles as a survival mechanism.
Apoptosis has important biological roles in the pathogenesis of many diseases. This
study elucidated the effect of simvastatin on autophagy/apoptosis in MC3T3E1 murine
osteoblastic cells and also the significance of this action on the progression of
induced rat apical periodontitis.
Methods
We examined the H2O2-stimulated expression of LC3-II (an autophagy marker) and poly
(adenosine phosphate ribose) polymerase (PARP) fragmentation (an apoptosis marker)
in MC3T3E1 by Western analysis. In a rat model of induced apical periodontitis, the
relation between disease progression and osteoblastic expression of Beclin-1 (an autophagy
marker) and terminal deoxyuridine triphosphate nick end-labeling (an apoptosis marker)
was studied by radiographic and immunohistochemistry analyses.
Results
Western blot showed elevated levels of LC3-II and PARP cleavage after H2O2 treatment.
An autophagy inhibitor 3-methyladenine promoted whereas rapamycin (an autophagy enhancer)
diminished H2O2-induced PARP cleavage. Simvastatin enhanced H2O2-induced LC3-II formation
and simultaneously decreased PARP fragmentation. Radiography and immunohistopathology
demonstrated that simvastatin reduced the number of apoptotic osteoblasts and the
extension of periapical lesions in rats. The number of Beclin-1–synthesizing osteoblasts
also increased markedly after simvastatin treatment.
Conclusions
We found a negative relation between autophagy and apoptosis in osteoblastic cells.
In addition, simvastatin suppressed apoptosis and enhanced autophagy both in vitro and in vivo. Our data implied that simvastain might alleviate the progression of apical periodontitis
by promoting autophagy to protect osteoblasts from turning apoptotic.
Key Words
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Journal of EndodonticsAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Nitric oxide promotes the progression of periapical lesion via inducing macrophage and osteoblast apoptosis.Oral Microbiol Immunol. 2007; 22: 24-29
- The role of iNOS and PHOX in periapical bone resorption.J Dent Res. 2011; 90: 495-500
- Life and death partners: apoptosis, autophagy and the cross-talk between them.Cell Death Differ. 2009; 16: 966-975
- Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes.Reprod Biol Endocrinol. 2009; 7: 143
- Induction of programmed cell death in Kaposi’s sarcoma cells by preparations of human chorionic gonadotropin.J Natl Cancer Inst. 1999; 91: 135-143
- Identification of programmed cell death in situ via specific labeling of nuclear DNA fragmentation.J Cell Biol. 1992; 119: 493-501
- LC3, a mammalian homologue of yeast Apg8p, is localized in autophagosome membranes after processing.EMBO J. 2000; 19: 5720-5728
- Induction of autophagy and inhibition of tumorigenesis by Beclin 1.Nature. 1999; 402: 672-676
- Prevention of coronary heart disease with pravastatin in men with hypercholesterolemia: West of Scotland Coronary Prevention Study Group.N Engl J Med. 1995; 333: 1301-1307
- Human RAS superfamily proteins and related GTPases.Sci STKE. 2004; 250: 13-65
- Simvastatin as a novel strategy to alleviate periapical lesions.J Endod. 2009; 35: 657-662
- Inhibition of autophagy enhances anticancer effects of atorvastatin in digestive malignancies.Cancer Res. 2010; 70: 7699-7709
- Mevalonate cascade regulation of airway mesenchymal cell autophagy and apoptosis: a dual role for p53.PLoS One. 2011; 6: e16523
- Depletion of iNOS-derived nitric oxide by prostaglandin H synthase-2 in inflammation-activated J774.2 macrophages through lipohydroperoxidase turnover.Biochem J. 2005; 385: 815-821
- Distinct classes of phosphatidylinositol 3’-kinases are involved in signaling pathways that control macroautophagy in HT-29 cells.J Biol Chem. 2000; 275: 992-998
- Rapamycin pre-treatment protects against apoptosis.Hum Mol Genet. 2006; 15: 1209-1216
- Simvastatin inhibits cytokine-stimulated Cyr61 expression in osteoblastic cells: a therapeutic benefit for arthritis.Arthritis Rheum. 2011; 63: 1010-1020
- Guidance for industry: estimating the maximum safe starting dose in initial clinical trials for therapeutics in adult healthy volunteers.U.S. Department of Health and Human Services, Center for Drug Evaluation and Research, Rockville, MD2005 (Available at:) (Accessed May 2, 2012)
- The safety of statins in clinical practice.Lancet. 2007; 370: 1781-1790
- An extract of green tea, epigallocatechin-3-gallate, reduces periapical lesions by inhibiting cysteine-rich 61 expression in osteoblasts.J Endod. 2009; 35: 206-211
- Nonsurgical root canal therapy of large cyst-like inflammatory periapical lesions and inflammatory apical cysts.J Endod. 2009; 35: 607-615
- Immunohistochemical detection of factors related to cellular proliferation and apoptosis in radicular and dentigerous cysts.J Endod. 2011; 37: 36-39
- Autophagy is a protective mechanism in normal cartilage, and its aging-related loss is linked with cell death and osteoarthritis.Arthritis Rheum. 2010; 62: 791-801
- The autophagy-related protein Beclin 1 shows reduced expression in early Alzheimer disease and regulates amyloid beta accumulation in mice.J Clin Invest. 2008; 118: 2190-2199
- Cardiac raptor ablation impairs adaptive hypertrophy, alters metabolic gene expression, and causes heart failure in mice.Circulation. 2011; 123: 1073-1082
- Stressing the role of FoxO proteins in lifespan and disease.Nat Rev Mol Cell Biol. 2007; 8: 440-450
- Induction of endothelial nitric oxide synthase, SIRT1, and catalase by statins inhibits endothelial senescence through the Akt pathway.Arterioscler Thromb Vasc Biol. 2010; 30: 2205-2211
- Simvastatin promotes odontoblastic differentiation and expression of angiogenic factors via heme oxygenase-1 in primary cultured human dental pulp cells.J Endod. 2010; 36: 447-452
- Hydroxymethylglutaryl-coenzyme A reductase inhibitors and osteoporosis: a meta-analysis.Osteoporos Int. 2005; 16: 990-998
- Effect of pravastatin on frequency of fracture in the LIPID study: secondary analysis of a randomised controlled trial—long-term intervention with pravastatin in ischaemic disease.Lancet. 2001; 357: 509-512
- Stimulation of bone formation in vitro and in rodents by statins.Science. 1999; 286: 1946-1949
- Simvastatin treatment partially prevents ovariectomy-induced bone loss while increasing cortical bone formation.Bone. 2004; 34: 609-618
Article info
Publication history
Published online: April 09, 2012
Identification
Copyright
© 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
