Chronic frontal lobe functional deficits after traumatic brain injury (TBI) may be associated with altered catecholamine systems in the frontal cortex. To test this, tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) levels were examined by immunohistochemistry and Western blot at 1, 7, 14, and 28 days after TBI or sham surgery. No alterations in DBH levels were observed by Western blot at any time point examined, but there was a significant increase in TH expression 28 days after TBI (optical density 334 +/- 68% or 3.3-fold, ipsilateral and 218 +/- 39% or 2.2-fold, contralateral) relative to the sham controls. The increase in TH may reflect a compensatory response of dopaminergic neurons to upregulate their synthesizing capacity and increase the efficiency of dopamine neurotransmission chronically after TBI.

The aim of this study was to study the expression of Syk gene and methylation in its promoter region in the lung cancer and to investigate the relationship between silencing of the Syk gene and DNA methylation of the Syk promoter region in lung cancer cell lines.Real-time PCR and immunohistochemistry were used to examine the Syk expression in specimens from 3 lung cancer cell lines and 16 lung cancer patients (tumor tissues and adjacent normal tissues). MSP was used to analyze the methylation status of the Syk promoter region. We also investigated the role of restoring Syk expression by using a DNA methyltransferase inhibitor, 5-aza-CdR, in suppressing invasion of lung cancer cell lines.No expression of the Syk gene was detected in the 3 lung cancer cell lines. In the 16 lung cancer patient samples, Syk expression was significantly lower in the tumor tissues than that in their adjacent normal tissues (P<0.05). Consistently, immunohistochemistry analysis of Syk protein expression showed that in the lung cancer tissues Syk protein expression was also significantly lower than that in their adjacent normal tissues. In the two lung cancer cell lines (NL9980, YTMLC-9) that lack the endogenous Syk expression, 4uM demethylation agent 5-aza-CdR treatment was able to reactivate the Syk gene expression, but not NCI-H446.In conclusion, hypermethylation leads to silencing of the Syk gene in human lung carcinoma cell lines. Methylation of the Syk promoter and loss of Syk expression in lung cancer cell lines are independent biomarkers. Syk may be a potential tumor suppressor in human lung cancer.