Being pregnant while young is known to protect women against breast cancer. But why? Research published online on April 29, 2013 in BioMed Central's open access journal Breast Cancer Research finds that Wnt/Notch signaling ratio is decreased in the breast tissue of mice that have given birth, compared to virgin mice of the same age. Early pregnancy is protective against breast cancer in humans and in rodents. In humans having a child before the age of 20 decreases risk of breast cancer by half. Using microarray analysis researchers from Basel discovered that genes involved in the immune system and differentiation were up-regulated after pregnancy, while the activity of genes coding for growth factors was reduced. The activity of one particular gene, Wnt4, was also down-regulated after pregnancy. The protein from this gene (Wnt4) is a feminizing protein - absence of this protein propels a fetus towards developing as a boy. Wnt and Notch are opposing components of a system which controls cellular fate within an organism and when the team looked at Notch they found that genes regulated by Notch were up-regulated, Notch-stimulating proteins were up-regulated, and Notch-inhibiting proteins were down-regulated. Wnt/Notch signaling ratio was permanently altered in the basal stem/progenitor cells of mammary tissue of mice by pregnancy. Dr. Mohamed Bentires-Alj from the Friedrich Miescher Institute for Biomedical Research, who led this study explained, "The down-regulation of Wnt is the opposite of that seen in many cancers, and this tightened control of Wnt/Notch after pregnancy may be preventing the runaway growth present in cancer." [Press release] [Breast Cancer Research article]
Login Or Register To Read Full Story