Influence of Localized DDT Exposure on Breast Cancer
Creators: name: University Of California Office Of The President
Publisher: name: University of California Office of the President
publisherIdentifier: https://ror.org/00dmfq477
publisherIdentifierScheme: ROR
Year: 2024

description: The increase in prevalence of breast cancer over the past 50 years has been speculated to be related to the production and use of many chemicals and pesticides, such as DDT, that have now been shown to have hormonal activities. That is, DDT and other chemicals can mimic or interfere with natural hormonal responses in humans and animals. Therefore, the exposure to these unnatural hormones may disrupt normal responses resulting in accelerated breast cancer development. Some studies in women have suggested that higher levels of the pesticide DDT stored in breast fat increased breast cancer risk, while other studies show no increase in risk, indicating that more evidence is needed to evaluate the role of DDT in breast cancer. DDT has been banned in the US for about 20 years; however, this pesticide is persistent and remains in the environment and stored in the fat of humans and animals. In addition, DDT remains in use in third world countries; therefore, it continues to invade our environment despite the ban in this country. Every person will carry some level of DDT within their body for their lifetime. 
 
 
 
 
 
 
 
 In the body and the environment, DDT is broken down into related compounds that have been shown to either act like estrogens or anti-androgen (inhibit the actions of the male sex hormones, androgens). The ability of the DDT compounds to mimic the female sex hormones as well an inhibit the action of the male sex hormones has had devastating consequences on sexual development of wildlife exposed to DDT by environmental contamination. It is reasonable to speculate that the hormonal actions of DDT may be linked to breast cancer, since growth of the cancer-prone cells in the breast is stimulated by estrogens and inhibited by androgens. Because DDT is not eliminated from our bodies after exposure, remains stored in the fat surrounding the breast tissue where cancer originates, and can act like hormonal agents, DDT has tremendous potential to influence breast cancer. Therefore, we will investigate how localized exposure of these chemicals influence hormonally regulated responses such as growth and tumor development in the mammary glands of mice. 
 
 
 
 
 
 
 
 We will use a line of mice that develops mammary cancer that frequently progresses to metastatic cancer in the lungs. The cancer in the mice is induced by the most common gene found to be increased in human breast cancer (the oncogene, neu, or HER2). We will locally treat the mammary gland with DDT and assess the effects of DDT on tumor outcomes, such as incidence, age of onset, and progression of the disease to invade the lungs. From these data we will be able to demonstrate that the individual DDT compounds can act like an estrogen or an anti-androgen to influence breast tissue to develop cancer. 
 
 
 
 
 
 
 
 By determining whether DDT can directly influence growth and tumor development in the breast by mimicking the natural hormones, we can help assess risk in women and devise means to counteract the actions of this chemical prior to tumor onset.