Immunohistochemical expression of Notch signaling in the lining epithelium of periapical cysts.
BACKGROUND
In this study we evaluated the immunohistochemical expression of the receptors Notch 1 and Notch 2, the ligand Delta 1, and the transcription factors HES 1 and HES 5 in the epithelium of well-defined periapical cysts.


METHODS
Immunohistochemistry was carried out on 55 formalin-fixed and paraffin-embedded, well-defined periapical cysts with minimum inflammation, obtained from the archival tissue database of the Department of Oral Pathology and Surgery. Western blotting was performed to evaluate the specificity of the anti-Notch antibody and the expression of Notch signaling in 5 fresh-frozen periapical cysts. The levels of staining intensity were estimated by the performance of a semiautomated image analysis system. Descriptive statistic of mean values obtained by computerized image analysis method was performed.


RESULTS
Immunostaining reaction of all Notch signaling components was observed in the cytoplasm and/or the cytoplasmic membrane in the majority of epithelial cells of periapical cysts. Nuclear staining was observed occasionally in all cases. Notch 2 showed strong staining in 52.83% of the cases, followed by Notch 1 (35.85%), HES 1 and HES 5 moderate staining in 72.73% and 57.69% of the cases, respectively, and Delta 1 weak staining in 58.33% of the cases. No statistical correlation was found between the antibodies and the sex or the age of the study group.


CONCLUSIONS
Notch is an evolutionarily conserved signaling mechanism that regulates cell fate decisions during development and postnatal life in organisms as diverse as worms, flies, and humans. The present observations indicate that Notch pathway is active downstream in the lining epithelium of periapical cysts, suggesting an involvement of this pathway in periapical cyst growth and expansion.
Department of Endodontology, Dental School, University of Athens, Athens, Greece. emeliou@dent.uoa.gr
Eleni
E
Meliou
Nikolaos
N
Kerezoudis
Konstantinos
K
Tosios
Daniel
D
Lafkas
Hippokratis
H
Kiaris
D000293:Adolescent; D000328:Adult; D000368:Aged; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism; D005260:Female; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D010483:Periapical Diseases / Q000378:metabolism* / Q000473:pathology; D011842:Radicular Cyst / Q000378:metabolism* / Q000473:pathology; D051881:Receptor, Notch1 / Q000378:metabolism*; D051883:Receptor, Notch2 / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D015290:Second Messenger Systems / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D000072056:Transcription Factor HES-1; D055815:Young Adult
D051792:Basic Helix-Loop-Helix Proteins; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051881:Receptor, Notch1; D051883:Receptor, Notch2; D012097:Repressor Proteins; D000072056:Transcription Factor HES-1; C497761:NOTCH1 protein, human; C497764:NOTCH2 protein, human; C064045:delta protein; C077478:HES5 protein, human; C078493:HES1 protein, human