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 -578 bp 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.
Original language | English (US) |
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Pages (from-to) | 119-128 |
Number of pages | 10 |
Journal | Cancer detection and prevention |
Volume | 31 |
Issue number | 2 |
DOIs | |
State | Published - 2007 |
Externally published | Yes |
Keywords
- Telomerase inhibition
- Vitamin E acetate
- hTERT
ASJC Scopus subject areas
- Oncology
- Cancer Research