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TERT promoter mutations lead to high transcriptional activity under hypoxia and temozolomide treatment and predict poor prognosis in gliomas.

Chen C, Han S, Meng L, Li Z, Zhang X, Wu A - PLoS ONE (2014)

Bottom Line: Mutations in the TERT promoter enhanced gene transcription even under hypoxic and TMZ treatment conditions, inducing upregulation of TERT mRNA expression.Patients with TERT promoter mutations had lower survival rates, even after adjusting for other known or potential risk factors, and the incidence of mutation was correlated with patient age.TERT promoter mutations maintained its ability of inducing high transcriptional activity even under hypoxic and TMZ treatment conditions, and the presence of mutations was associated with poor prognosis in glioma patients.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Medical Genomics, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, China.

ABSTRACT

Objective: This study explored the effects of telomerase reverse transcriptase (TERT) promoter mutations on transcriptional activity of the TERT gene under hypoxic and temozolomide (TMZ) treatment conditions, and investigated the status and prognostic value of these mutations in gliomas.

Methods: The effect of TERT promoter mutations on the transcriptional activity of the TERT gene under hypoxic and TMZ treatment conditions was investigated in glioma cells using the luciferase assay. TERT promoter mutations were detected in 101 glioma samples (grades I-IV) and 49 other brain tumors by sequencing. TERT mRNA expression in gliomas was examined by real-time PCR. Hazard ratios from survival analysis of glioma patients were determined relative to the presence of TERT promoter mutations.

Results: Mutations in the TERT promoter enhanced gene transcription even under hypoxic and TMZ treatment conditions, inducing upregulation of TERT mRNA expression. Mutations were detected in gliomas, but not in meningiomas, pituitary adenomas, cavernomas, intracranial metastases, normal brain tissues, or peripheral blood of glioma patients. Patients with TERT promoter mutations had lower survival rates, even after adjusting for other known or potential risk factors, and the incidence of mutation was correlated with patient age.

Conclusion: TERT promoter mutations were specific to gliomas. TERT promoter mutations maintained its ability of inducing high transcriptional activity even under hypoxic and TMZ treatment conditions, and the presence of mutations was associated with poor prognosis in glioma patients. These findings demonstrate that TERT promoter mutations are novel prognostic markers for gliomas that can inform prospective therapeutic strategies.

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Luciferase reporter assays for transcriptional activity from the TERT core promoter with −124 C>T or −146 C>T mutations compared to wild-type promoter in U87 cell lines.Cells were treated with TMZ, or cultured under hypoxic conditions through CoCl2 treatment or exposure to 1% O2. WT, wild-type; 124T, −124 C>T mutation; 146T, −146 C>T mutation. (A) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity in the presence of TMZ. No significant difference was observed between the DMSO (control) and TMZ (50 µM) treatment groups. (B) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity under hypoxic conditions. No significant difference was observed between control and CoCl2 treatment groups (B); similar results were observed when hypoxia was induced by exposure to 1% O2 (C). The means of four measurements per experimental group are shown; error bars indicate standard deviation. *P<0.05; **P<0.01.
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pone-0100297-g003: Luciferase reporter assays for transcriptional activity from the TERT core promoter with −124 C>T or −146 C>T mutations compared to wild-type promoter in U87 cell lines.Cells were treated with TMZ, or cultured under hypoxic conditions through CoCl2 treatment or exposure to 1% O2. WT, wild-type; 124T, −124 C>T mutation; 146T, −146 C>T mutation. (A) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity in the presence of TMZ. No significant difference was observed between the DMSO (control) and TMZ (50 µM) treatment groups. (B) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity under hypoxic conditions. No significant difference was observed between control and CoCl2 treatment groups (B); similar results were observed when hypoxia was induced by exposure to 1% O2 (C). The means of four measurements per experimental group are shown; error bars indicate standard deviation. *P<0.05; **P<0.01.

Mentions: A luciferase reporter assay was used to test whether transcriptional activity from the mutated TERT promoter changed as a result of hypoxia and TMZ treatment in the U87 glioma cell line. Compared to the wild-type TERT promoter, −124 C>T and −146 C>T mutations induced increases of approximately 3- and 1.5-fold, respectively, in transcriptional activity (Fig. 3). Cells treated with 50 µM TMZ or the equivalent volume of DMSO had nearly identical luciferase activity, suggesting that TERT transcription in glioma cells was not blocked by TMZ (Fig. 3A). Cells treated with CoCl2 had luciferase activity levels comparable to control cells, indicating that chemically induced hypoxia had no effect on TERT transcription (Fig. 3B). Similarly, no difference in luciferase activity was observed between cells exposed to normoxic and hypoxic conditions (Fig. 3C). Taken together, these results indicate that mutations in the TERT promoter lead to persistently high transcriptional activity even under hypoxic or TMZ treatment conditions.


TERT promoter mutations lead to high transcriptional activity under hypoxia and temozolomide treatment and predict poor prognosis in gliomas.

Chen C, Han S, Meng L, Li Z, Zhang X, Wu A - PLoS ONE (2014)

Luciferase reporter assays for transcriptional activity from the TERT core promoter with −124 C>T or −146 C>T mutations compared to wild-type promoter in U87 cell lines.Cells were treated with TMZ, or cultured under hypoxic conditions through CoCl2 treatment or exposure to 1% O2. WT, wild-type; 124T, −124 C>T mutation; 146T, −146 C>T mutation. (A) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity in the presence of TMZ. No significant difference was observed between the DMSO (control) and TMZ (50 µM) treatment groups. (B) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity under hypoxic conditions. No significant difference was observed between control and CoCl2 treatment groups (B); similar results were observed when hypoxia was induced by exposure to 1% O2 (C). The means of four measurements per experimental group are shown; error bars indicate standard deviation. *P<0.05; **P<0.01.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4061075&req=5

pone-0100297-g003: Luciferase reporter assays for transcriptional activity from the TERT core promoter with −124 C>T or −146 C>T mutations compared to wild-type promoter in U87 cell lines.Cells were treated with TMZ, or cultured under hypoxic conditions through CoCl2 treatment or exposure to 1% O2. WT, wild-type; 124T, −124 C>T mutation; 146T, −146 C>T mutation. (A) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity in the presence of TMZ. No significant difference was observed between the DMSO (control) and TMZ (50 µM) treatment groups. (B) Compared to wild-type, 124T and 146T displayed significantly higher TERT promoter activity under hypoxic conditions. No significant difference was observed between control and CoCl2 treatment groups (B); similar results were observed when hypoxia was induced by exposure to 1% O2 (C). The means of four measurements per experimental group are shown; error bars indicate standard deviation. *P<0.05; **P<0.01.
Mentions: A luciferase reporter assay was used to test whether transcriptional activity from the mutated TERT promoter changed as a result of hypoxia and TMZ treatment in the U87 glioma cell line. Compared to the wild-type TERT promoter, −124 C>T and −146 C>T mutations induced increases of approximately 3- and 1.5-fold, respectively, in transcriptional activity (Fig. 3). Cells treated with 50 µM TMZ or the equivalent volume of DMSO had nearly identical luciferase activity, suggesting that TERT transcription in glioma cells was not blocked by TMZ (Fig. 3A). Cells treated with CoCl2 had luciferase activity levels comparable to control cells, indicating that chemically induced hypoxia had no effect on TERT transcription (Fig. 3B). Similarly, no difference in luciferase activity was observed between cells exposed to normoxic and hypoxic conditions (Fig. 3C). Taken together, these results indicate that mutations in the TERT promoter lead to persistently high transcriptional activity even under hypoxic or TMZ treatment conditions.

Bottom Line: Mutations in the TERT promoter enhanced gene transcription even under hypoxic and TMZ treatment conditions, inducing upregulation of TERT mRNA expression.Patients with TERT promoter mutations had lower survival rates, even after adjusting for other known or potential risk factors, and the incidence of mutation was correlated with patient age.TERT promoter mutations maintained its ability of inducing high transcriptional activity even under hypoxic and TMZ treatment conditions, and the presence of mutations was associated with poor prognosis in glioma patients.

View Article: PubMed Central - PubMed

Affiliation: Research Center for Medical Genomics, Key Laboratory of Medical Cell Biology, Ministry of Education, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, China.

ABSTRACT

Objective: This study explored the effects of telomerase reverse transcriptase (TERT) promoter mutations on transcriptional activity of the TERT gene under hypoxic and temozolomide (TMZ) treatment conditions, and investigated the status and prognostic value of these mutations in gliomas.

Methods: The effect of TERT promoter mutations on the transcriptional activity of the TERT gene under hypoxic and TMZ treatment conditions was investigated in glioma cells using the luciferase assay. TERT promoter mutations were detected in 101 glioma samples (grades I-IV) and 49 other brain tumors by sequencing. TERT mRNA expression in gliomas was examined by real-time PCR. Hazard ratios from survival analysis of glioma patients were determined relative to the presence of TERT promoter mutations.

Results: Mutations in the TERT promoter enhanced gene transcription even under hypoxic and TMZ treatment conditions, inducing upregulation of TERT mRNA expression. Mutations were detected in gliomas, but not in meningiomas, pituitary adenomas, cavernomas, intracranial metastases, normal brain tissues, or peripheral blood of glioma patients. Patients with TERT promoter mutations had lower survival rates, even after adjusting for other known or potential risk factors, and the incidence of mutation was correlated with patient age.

Conclusion: TERT promoter mutations were specific to gliomas. TERT promoter mutations maintained its ability of inducing high transcriptional activity even under hypoxic and TMZ treatment conditions, and the presence of mutations was associated with poor prognosis in glioma patients. These findings demonstrate that TERT promoter mutations are novel prognostic markers for gliomas that can inform prospective therapeutic strategies.

Show MeSH
Related in: MedlinePlus