Investigation of PTEN promoter methylation in ameloblastoma.

BACKGROUND: Phosphatase and tensin homolog (PTEN) acts as a tumor suppressor gene. Inactivation of PTEN has been reported in various types of cancers. PTEN promoter methylation possibly underlies PTEN inactivation, which results in tumorigenesis. The aim of this study was to investigate whether PTEN promoter methylation contributes to PTEN inactivation in ameloblastoma and its associated protein expression. MATERIAL AND METHODS: In total, 20 fresh-frozen ameloblastoma samples were evaluated for PTEN promoter methylation using methylation-specific polymerase chain reaction (MS-PCR). A subset of 10 paraffin-embedded ameloblastoma samples was examined for PTEN expression through immunohistochemistry. Four primary cultured ameloblastoma cells were investigated for PTEN promoter methylation and PTEN transcriptional expression via reverse transcription PCR. RESULTS: PTEN promoter methylation was detected in 65% (13/20) of the ameloblastoma samples. Of 10 ameloblastoma samples, 4 exhibited reduced PTEN expression. Of 5 samples with methylated PTEN, 3 (60%) were associated with loss of PTEN expression. However, PTEN expression was detected in 4 (80%) of 5 samples with unmethylated PTEN. In addition, 3 (75%) of 4 primary ameloblastoma cell cultures exhibited an inverse correlation between PTEN promoter methylation and PTEN transcription level. CONCLUSIONS: PTEN promoter methylation is found in a number of ameloblastomas but not significantly correlated with loss of PTEN expression. Genetic or epigenetic mechanisms other than PTEN promoter methylation may contribute to PTEN inactivation in ameloblastoma tumor cells.

Comparative study of the effect of dexamethasone injection and consumption in lower third molar surgery.

The aim of this study was to compare the effect of intramuscular (IM) injection and consumption of 8 mg dexamethasone in patients after lower third molar (LTM) surgery. 20 healthy Thai patients, average age 20 years, with bilateral LTM removal were recruited for this study, a double blinded, paired sample clinical trial. The washout period was 1 month after the first operation. Clinical assessment of facial swelling, pain and maximum mouth opening were measured before and after operation for 7 days. No significant difference was found in facial swelling between IM injection and consumption of 8 mg dexamethasone after LTM surgery (paired t test P>0.05). The visual analogue scale scores for pain assessment showed no significant difference between IM injection and consumption of dexamethasone (paired t test P>0.05). The results conclude that IM injection or consumption of dexamethasone after LTM surgery can be used to control facial swelling, pain and trismus.