Grant: Operating Grant

Since breast cancer develops primarily in women over the age of 40 it is often thought that the genetic changes leading to breast cancer also occur later in life. However a number of studies have shown that alterations in hormone or growth factor levels and exposure to chemicals or radiation early in life influences the risk of developing breast cancer as an adult. One area of research that has not been explored is whether breast cancer oncogenes are more potent at particular developmental stages. Using a mouse model where the expression of a breast cancer oncogene known as the type I insulin-like growth factor receptor can be controlled by an inducing agent, we will increase the expression of this gene during embryonic development, puberty and in adults and determine the effects on mammary tumorigenesis. We will also examine whether pregnancy protects the mammary gland from oncogene-induced tumor development as observed in humans. In addition, mice will be fed soy-based diets to promote mammary gland differentiation and the ability of a breast cancer oncogene to induce mammary tumors in soy-fed and control mice will be examined. These studies will determine whether a more differentiated mammary gland is less susceptible to tumor formation and whether changes in diet can promote mammary differentiation and protect against breast cancer.