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Articles by J Ju
Total Records ( 2 ) for J Ju
  J Ju , S. C Picinich , Z Yang , Y Zhao , N Suh , A. N Kong and C. S. Yang
 

The cancer-preventive activity of vitamin E has been studied. Whereas some epidemiological studies have suggested a protective effect of vitamin E against cancer formation, many large-scale intervention studies with -tocopherol (usually large doses) have not demonstrated a cancer-preventive effect. Studies on -tocopherol in animal models also have not demonstrated robust cancer prevention effects. One possible explanation for the lack of demonstrable cancer-preventive effects is that high doses of -tocopherol decrease the blood and tissue levels of -tocopherols. It has been suggested that -tocopherol, due to its strong anti-inflammatory and other activities, may be the more effective form of vitamin E in cancer prevention. Our recent results have demonstrated that a -tocopherol-rich mixture of tocopherols inhibits colon, prostate, mammary and lung tumorigenesis in animal models, suggesting that this mixture may have a high potential for applications in the prevention of human cancer. In this review, we discuss biochemical properties of tocopherols, results of possible cancer-preventive effects in humans and animal models and possible mechanisms involved in the inhibition of carcinogenesis. Based on this information, we propose that a -tocopherol-rich mixture of tocopherols is a very promising cancer-preventive agent and warrants extensive future research.

  H. J Lee , J Ju , S Paul , J. Y So , A DeCastro , A Smolarek , M. J Lee , C. S Yang , H. L Newmark and N. Suh
 

Purpose: Tocopherols are lipophilic antioxidants present in vegetable oils. Although the antioxidant and anticancer activities of -tocopherol (vitamin E) have been studied for decades, recent intervention studies with -tocopherol have been negative for protection from cancer in humans. The tocopherols consist of four isoforms, which are the , β, , and variants, and recent attention is being given to other isoforms. In the present study, we investigated the inhibitory effect of a tocopherol mixture rich in - and -tocopherols against mammary tumorigenesis.

Experimental Design: Female Sprague Dawley rats were treated with N-methyl-N-nitrosourea (NMU), and then fed diets containing 0.1%, 0.3%, or 0.5% mixed tocopherols rich in - and -tocopherols for 9 weeks. Tumor burden and multiplicity were determined, and the levels of markers of inflammation, proliferation, and apoptosis were evaluated in the serum and in mammary tumors. The regulation of nuclear receptor signaling by tocopherols was studied in mammary tumors and in breast cancer cells.

Results: Dietary administration of 0.1%, 0.3%, or 0.5% mixed tocopherols suppressed mammary tumor growth by 38%, 50%, or 80%, respectively. Tumor multiplicity was also significantly reduced in all three mixed tocopherol groups. Mixed tocopherols increased the expression of p21, p27, caspase-3, and peroxisome proliferator activated receptor-, and inhibited AKT and estrogen signaling in mammary tumors. Our mechanistic study found that - and -tocopherols, but not -tocopherol, activated peroxisome proliferator activated receptor- and antagonized estrogen action in breast cancer.

Conclusion: The results suggest that - and -tocopherols may be effective agents for the prevention of breast cancer.

 
 
 
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