Epidermal growth factor inhibits Fas-mediated apoptosis in salivary epithelial cells of patients with primary Sjögren's syndrome.
OBJECTIVE
Cell death is detected in the ducts of labial salivary glands (LSG) of patients with primary Sjögren's syndrome (pSS). However, the counter-mechanism to inhibit the apoptotic process remains unclear. In this study, we studied the ability of epidermal growth factor (EGF) to activate the PI3K-Akt pathway and NF-kB in primary cultured salivary gland epithelial cells (SGEC) of pSS patients.


METHODS
SGEC, obtained from 2 female pSS patients, were cultured and used for Hoechst staining and deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL) assay. The frequency of apoptosis, detected by Hoechst staining, was quantified, and statistical significance was determined through unpaired student's t-test.


RESULTS
Following twelve hours of stimulation, both PI3K inhibitors and anti-Fas antibody failed to induce apoptosis in primary cultured SGEC. However, the combination of anti-Fas antibody, along with LY294002 or Bay 11-7082, induced apoptosis which was statistically more significant than apoptosis found in the control cells (p < 0.01). Interestingly, the apoptosis induced by anti-Fas antibody along with LY294002 was clearly inhibited by the addition of 10 ng/ml EGF. Furthermore, the results of the TUNEL assay clearly indicated apoptosis through stimulation with anti-Fas antibody and LY294002 or Bay 11-7082. Furthermore, the apoptosis was completely blocked by the addition of EGF.


CONCLUSIONS
Our results suggest that salivary epithelial cells are protected from Fas mediated apoptosis, through cell survival factors including either the PI3K-Akt pathway or NF-kB.
Nakamura
H
H
First Department of Internal Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan. nhideki@nagasaki-u.ac.jp
Kawakami
A
A
Ida
H
H
Koji
T
T
Eguchi
K
K
D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D005260:Female; D006801:Humans; D020287:In Situ Nick-End Labeling; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D012469:Salivary Glands / Q000166:cytology* / Q000187:drug effects; D012859:Sjogren's Syndrome / Q000473:pathology*; D013450:Sulfones / Q000494:pharmacology; D019014:fas Receptor / Q000276:immunology / Q000502:physiology*
C434003:3-(4-methylphenylsulfonyl)-2-propenenitrile; D000906:Antibodies; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D009570:Nitriles; D013450:Sulfones; D019014:fas Receptor; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004815:Epidermal Growth Factor