Methylation and intratumoural heterogeneity of 14-3-3 σ in oral cancer
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- Published online on: October 1, 2007 https://doi.org/10.3892/or.18.4.817
- Pages: 817-824
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Abstract
14-3-3 σ has been a major G2/M checkpoint control gene and has demonstrated that its inactivation in various cancers occurs mostly by epigenetic hypermethylation, not by genetic change. This study investigated the methylation status and expression of the 14-3-3 σ gene in 46 oral squamous cell carcinomas by methylation-specific polymerase chain reaction, reverse transcriptase-polymerase chain reaction, Western blotting and immunohistochemistry. Exons of the p53 gene were examined for mutations by sequencing analysis and CyclinD1 by immunohistochemistry. Methylation of the 14-3-3 σ gene was detected in 13% (6/46) of the oral tumours, but not in corresponding adjacent non-malignant and normal gingival tissues. Intratumoural heterogeneity was found in the tumour tissues including three 14-3-3 σ-methylated samples. Methylation of 14-3-3 σ was detected in 3 SCC with p53 mutations and 3 with wild-type p53. Our major findings are: (a) methylation of 14-3-3 gene promoter is a rare event in oral cancer; (b) it is not always associated with 14-3-3 protein levels and there is no clear relationship between its methylation and p53 mutation; (c) loss of 14-3-3 σ expression is associated with reduced CyclinD1 gene expression.