Tocopherols are naturally occurring phenolic compounds and are the major forms of vitamin E in our body. Tocopherols exist in four forms, designated as alpha (?), beta (?), gamma (?), and delta (?). Recent clinical trials with ?-tocopherol have provided disappointing results for cancer prevention. We believe these studies were designed based on insufficient knowledge of the cancer preventive activities of the different forms of the tocopherols. There is an urgent need for investigating the activities of the different forms, such as ?-tocopherol, the major form of vitamin E in the diet in the U.S, and for identifying molecular mechanisms and targets of tocopherols. Our recent studies demonstrate that tocopherol mixtures that are rich in ?-tocopherol (?-TmT) inhibit progression of mammary hyperplasia and induce apoptosis in vivo and in cell lines, and prevent mammary tumorigenesis in animal models of breast cancer. We hypothesize that ?- and ?-tocopherols suppress oxidative/nitrosative stress, modulate estrogen receptor (ER) and peroxisome proliferator-activated receptor-? (PPAR?) signaling, inhibit cell proliferation and induce apoptosis, resulting in the inhibition of breast carcinogenesis. We propose to test our hypotheses and achieve our objectives by addressing four Specific Aims: 1. Investigate the dose-dependent inhibitory effects of a naturally occurring tocopherol mixture ?-TmT on estrogen-induced hyperplasia and tumorigenesis in the ACI rat model of mammary cancer. 2. Purify individual tocopherols (T), ?-T, ?-T, and ?-T, and determine their cancer preventive activities in estrogen-mediated mammary tumorigenesis in ACI rats. 3. Elucidate the molecular mechanisms of action of tocopherols in modulating estrogen receptors (ERs) and PPAR?, resulting in suppressing cell proliferation and cell survival in cell lines. 4. Investigate the molecular mechanisms of action of tocopherols in suppressing oxidative/nitrosative stress, and the possible involvement of NF-E2 related factor-2 (Nrf2). Tocopherols are commonly occurring in vegetable oils and readily available as dietary supplements. Understanding the effects of naturally occurring tocopherol mixtures and individual tocopherols and identifying the key mechanisms of action is critical for their use in prevention of cancer. Our data will be valuable for future studies in selecting the optimal form or mixtures of tocopherols and in designing better protocols for human breast cancer prevention trials. This study will provide the first comprehensive evaluation of tocopherol mixtures and individual tocopherols for the prevention of breast cancer.

Public Health Relevance

Tocopherols have been examined for many years for their anti-oxidant activities as well as cancer preventive effects, but recent large-scale clinical trial with alpha-tocopherol provided conflicting results to general public. We propose to determine the effectiveness of naturally occurring tocopherols, in individual forms and mixtures, for the prevention of breast cancer, and to investigate their molecular mechanisms of action. Understanding the effects of naturally occurring tocopherol mixtures and individual tocopherols and identifying the key mechanisms of action are critical for their use in the prevention of cancer in humans.

Agency
National Institute of Health (NIH)
Institute
National Center for Complementary & Alternative Medicine (NCCAM)
Type
Research Project (R01)
Project #
1R01AT007036-01A1
Application #
8369477
Study Section
Special Emphasis Panel (ZAT1-SM (25))
Program Officer
Hopp, Craig
Project Start
2012-08-01
Project End
2017-07-31
Budget Start
2012-08-01
Budget End
2013-07-31
Support Year
1
Fiscal Year
2012
Total Cost
$391,003
Indirect Cost
$137,413
Name
Rutgers University
Department
Biology
Type
Schools of Pharmacy
DUNS #
001912864
City
New Brunswick
State
NJ
Country
United States
Zip Code
08901
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Das Gupta, Soumyasri; Sae-tan, Sudathip; Wahler, Joseph et al. (2015) Dietary γ-Tocopherol-Rich Mixture Inhibits Estrogen-Induced Mammary Tumorigenesis by Modulating Estrogen Metabolism, Antioxidant Response, and PPARγ. Cancer Prev Res (Phila) 8:807-16
Das Gupta, Soumyasri; So, Jae Young; Wall, Brian et al. (2015) Tocopherols inhibit oxidative and nitrosative stress in estrogen-induced early mammary hyperplasia in ACI rats. Mol Carcinog 54:916-25
Wahler, Joseph; Suh, Nanjoo (2015) Targeting HER2 Positive Breast Cancer with Chemopreventive Agents. Curr Pharmacol Rep 1:324-335