Tag: PTEN

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Activation of PI3K/mTOR pathway occurs in most adult low-grade gliomas and predicts patient survival

J Neurooncol (2010) 97:33–40. DOI 10.1007/s11060-009-0004-4

Recent evidence suggests the Akt-mTOR pathway may play a role in development of low-grade gliomas (LGG). We sought to evaluate whether activation of this pathway correlates with survival in LGG by examining expression patterns of proteins within this pathway.

Forty-five LGG tumor specimens from newly diagnosed patients were analyzed for methylation of the putative 50-promoter region of PTEN using methylationspecific PCR as well as phosphorylation of S6 and PRAS40 and expression of PTEN protein using immunohistochemistry. Relationships between molecular markers and overall survival (OS) were assessed using Kaplan-Meier methods and exact log-rank test. Correlation between molecular markers was determined using the Mann-Whitney U and Spearman Rank Correlation tests.

Eight of the 26 patients with methylated PTEN died, as compared to 1 of 19 without methylation. There was a trend towards statistical significance, with PTEN methylated patients having decreased survival (P = 0.128). Eight of 29 patients that expressed phospho-S6 died, whereas all 9 patients lacking p-S6 expression were alive at last follow-up. There was an inverse relationship between expression of phospho-S6 and survival (P = 0.029). There was a trend towards decreased survival in patients expressing phospho-PRAS40 (P = 0.077).

Analyses of relationships between molecular markers demonstrated a statistically significant positive correlation between expression of p-S6(235) and p-PRAS40 (P = 0.04); expression of p-S6(240) correlated positively with PTEN methylation (P = 0.04) and negatively with PTEN expression (P = 0.03). Survival of LGG patients correlates with phosphorylation of S6 protein. This relationship supports the use of selective mTOR inhibitors in the treatment of low grade glioma

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Long-term survivors of glioblastoma: clinical features and molecular analysis

Acta Neurochir (2009) 151:1349–1358. DOI 10.1007/s00701-009-0387-1

Glioblastoma is a highly lethal neoplasm with a median survival of 12–14 months; only 2–5% of patients survive >3 years.

Methods At our institute, patients with glioblastoma are initially treated with maximum tumor resection followed by radiation and the intravenous injection of nimustine hydrochloride (ACNU).

Results Using this strategy, 18 of 123 (14.6%) patients treated at our hospital survived >3 years; 7 manifested no recurrence, and the other 11 had early recurrence and received additional therapies. To identify factors associated with prolonged survival, we compared these patients with 21 short-term (<1.5 years) glioblastoma survivors. In the long-term survivors, the MGMT promoter methylation was significantly more frequent. The rate of p53 mutation was lower, and the rate of PTEN mutations and the proliferation index were slightly higher in short-term survivors.

Conclusion By multivariate analysis,  we found that a younger age and MGMT promoter methylation were significant favorable factors in patients with glioblastoma.

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