Dietary tocopherols inhibit cell proliferation, regulate expression of ERα, PPARγ, and Nrf2, and decrease serum...

Area of Science:

• Oncology
• Nutritional Science
• Molecular Biology

Background:

• Vitamin E research for cancer prevention has focused on α-tocopherol.
• γ-tocopherol exhibits superior anti-inflammatory and anti-tumor properties in preclinical models.
• Estrogen (E2) plays a role in mammary carcinogenesis, making it a target for chemoprevention.

Purpose of the Study:

• To evaluate the chemopreventive potential of a γ-tocopherol-rich mixture (γ-TmT) in a rat model of mammary cancer.
• To investigate the effects of γ-TmT on estrogen levels, inflammation, and cell proliferation markers.
• To explore the impact of γ-TmT on key molecular pathways involved in mammary carcinogenesis.

Main Methods:

• Female ACI rats were treated with sustained-release 17β-estradiol (E2) and dietary γ-TmT (0.3% or 0.5%) for 2 or 10 weeks.
• Serum E2 and inflammatory markers (prostaglandin E2, 8-isoprostane) were measured.
• Mammary gland tissues were analyzed for hyperplasia, cell proliferation (PCNA), inflammation (COX-2), estrogen receptor (ERα, ERβ), apoptosis (caspase 3), and key transcription factors (PPARγ, Nrf2) via immunohistochemistry and mRNA expression.

Main Results:

• Dietary γ-TmT (0.5%) significantly reduced serum E2 levels and suppressed inflammatory markers.
• γ-TmT treatment decreased epithelial hyperplasia, PCNA, COX-2, and ERα expression in mammary glands.
• γ-TmT increased cleaved-caspase 3, PPARγ, and Nrf2 expression, and upregulated ERβ and PPARγ mRNA levels.

Conclusions:

• γ-tocopherol mixture (γ-TmT) effectively suppresses inflammation and E2-induced cell proliferation in a mammary carcinogenesis model.
• γ-TmT upregulates protective pathways involving PPARγ and Nrf2.
• γ-TmT demonstrates potential as a chemopreventive agent for human breast cancer.