Yuan YF et al. - In a study to evaluate the π-class glutathione-S-transferase (GSTP1) expression level and GSTP1 DNA methylation status in a series of pituitary adenomas, it was shown that GSTP1 inactivation through CpG hypermethylation is common in pituitary adenomas and may contribute to aggressive pituitary tumor behavior Methods
Using immunohistochemistry, expression of GSTP1 was identified in all of the various normal hormone-producing adenohypophysial cell types
Results
In pituitary adenomas, loss or reduced expression of GSTP1 was detected in 27 of 53 tumors
Expression of GSTP1 was significantly lower in invasive adenomas than in noninvasive adenomas
Using methylation-specific polymerase chain reaction (MS-PCR), GSTP1 DNA promoter hypermethylation was detected in adenomas but not in normal tissues
GSTP1 methylation was more frequent in grade II, III, and IV tumors than in grade I tumors
Frequency of GSTP1 methylation was higher in invasive tumors than in noninvasive tumors
Methylation status correlated with significant downregulation of GSTP1 expression; the frequency of GSTP1 methylation was higher in tumors with reduced-GSTP1 expression than in tumors with normal or high GSTP1 expression
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