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Cancer Detect Prev. 2007;31(2):119-28. Epub 2007 Feb 28.

Vitamin E suppresses telomerase activity in ovarian cancer cells.

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  • 1Department of Pathology and Cell Biology, University of South Florida, 12901 Bruce B. Downs Boulevard, Tampa, FL 33612, USA.

Abstract

BACKGROUND:

Dietary factors influence tumor formation and progression. Vitamin E is a dietary anti-oxidant capable of eliminating free radical damage, inducing apoptosis and decreasing oncogene expression. Therefore, Vitamin E may be a strong candidate for cancer prevention and/or chemotherapeutic intervention. Since telomerase, a ribonucleoprotein uniquely expressed in over 95% of cancers, plays an important role in cellular immortalization, cell growth and tumor progression, the present study investigated the effects of Vitamin E on telomerase activity in human ovarian cancer.

METHODS:

Normal and malignant ovarian surface epithelial (OSE) cells were cultured with and without D-alpha tocopheryl acetate (Vitamin E). MTS and Western immunoblot assays were used to examine the effect of Vitamin E on cell growth, survival and cytotoxicity. PCR-ELISA, RT-PCR and luciferase reporter assays were performed to determine the effect of Vitamin E on telomerase activity.

RESULTS:

Vitamin E suppressed endogenous telomerase activity in ovarian cancer cells, but had no similar effects in telomerase-negative normal OSE cells. Vitamin E also reduced hTERT-mRNA transcript levels and reduced hTERT promoter activity maximally targeting the -976 to -578bp promoter regions. In addition, Vitamin E improved cisplatin-mediated cytotoxicity as evidenced by reduced cancer cell growth and increased cleaved caspase 3 activity. In contrast, Vitamin E protected telomerase-negative OSE cells from cisplatin-mediated cytotoxicity as evidenced by decreased cleaved caspase 3 activity.

CONCLUSION:

Our data suggest that, by suppressing telomerase activity, Vitamin E may be an important protective agent against ovarian cancer cell growth as well as a potentially effective therapeutic adjuvant.

PMID:
17335992
[PubMed - indexed for MEDLINE]
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