Research Interests
Dr. Yan's research interests are in the area of diet, nutrition and cancer prevention. Many studies have been conducted since last century and demonstrated the roles of diet and nutrition in primary cancer prevention (the active measure to decrease the occurrence of cancer in the first place). However, their roles in secondary cancer prevention (the active measure to reduce invasive malignancy and occurrence) remain largely unexplored. In fact, in the U.S., half of all cancer cases are diagnosed each year with invasive malignancy. Dr. Yan currently investigates the role of selenium in secondary cancer prevention, emphasizing on the malignant spread to the lungs in small animal models. He is also interested in the effects of dietary fat on cancer spread aimed at investigating the roles obesity in the development and growth of secondary tumors.
Another area of Dr. Yan's research is selenium bioavailability from foods produced in Northern Plains, a major agricultural area growing foods widely consumed by all Americans and with soils rich in selenium. Understanding the bioavailability of selenium from this natural resource will lead to future studies on the health benefits of these value-added high-selenium agricultural products (e.g. wheat, soy, beans, peas, lentils).
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Research Accomplishments
Demonstrated that dietary supplementation with selenium reduces pulmonary metastasis of melanoma cells in a mouse model. This investigation contributes to the limited studies on selenium and malignant spread and provides evidence that selenium may play a role in secondary cancer prevention.
Demonstrated that dietary supplementation with soy protein, flaxseed or their bioactive components inhibits cancer spread in animal models. These studies suggest that foods and their constituents may be used as a nutritional adjuvant in reducing the risk of secondary cancer.
Demonstrated that selenium affects tumor cell surface adhesion molecules, e.g. fibronectin receptors, by inhibiting the cell attachment to extracellular matrix, which is an important step in the cascade of cancer invasion and malignant spread.
Demonstrated using in vitro models that the generation of reactive oxygen species from the reaction of glutathione with selenium compounds (e.g. selenite or selenocystine) in cells may be a potential mechanism of selenium-induced cytotoxicity. It may also be related to the anti-carcinogenic and anti-tumorigenic effects of selenium.
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