Molecular studies of cylindromas, which arise from the eccrine or apocrine cells 
of the skin, have demonstrated frequent alterations at chromosome 16q12-13, 
recently found to house the cylindromatosis (CYLD) gene. CYLD, a tumor 
suppressor gene, has deubiquitinating enzyme activity and inhibits the 
activation of transcription factor NF-kappaB. Loss of the deubiquitinating 
activity of CYLD is correlated with tumorigenesis. It has been reported that the 
expression of CYLD is observed in various organs. We demonstrated previously 
that human salivary gland tumor (SGT) cell line, HSG spontaneously expresses 
CYLD and also found that adenoid cystic carcinoma (ACC) arising from the hard 
palate was distinctly positive for CYLD, immunohistochemically. However, it is 
unclear whether loss of CYLD is associated with development of SGTs. This study 
examined CYLD function in SGT cells and attempted to clarify whether CYLD is 
associated with development of SGTs. The expression of CYLD and NF-kappaB mRNAs 
in HSG cells was increased by TNF-alpha. Translocation of NF-kappaB protein from 
the cytoplasm to the nucleus in HSG cells peaked at 30 min after TNF-alpha 
stimulation, then decreased at 60 min, whereas that of CYLD protein increased 
gradually in a time-dependent manner. Luciferase reporter assay indicated that 
TNF-alpha induced a 5-fold increase of NF-kappaB-dependent transcription at 4 h, 
which was further enhanced by knockdown of CYLD using RNA interference. Taken 
together, these data demonstrated that the levels of both CYLD and NF-kappaB 
mRNAs accumulated in HSG cells during 24 h after TNF-alpha stimulation, although 
the NF-kappaB activity in the cells was at least negatively regulated by CYLD. 
Immunohistochemical examinations revealed that there are several correlations 
between the expression of CYLD and NF-kappaB-related factors in 17 cases of ACC 
tissues. These findings suggest that loss of CYLD is associated with development 
of SGTs.