Cell bioassays for detection of aromatase gene activators
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 incidence of breast cancer in the United States is on the rise. Most breast cancers are initially hormone-dependent and require estrogens for growth. Estrogens are produced by the enzyme aromatase which is active in various tissues including the breast. Aromatase activity is regulated differently in different tissues and in mammary tissue containing a tumor this enzyme is overexpressed, leading to localized overproduction of growth-stimulatory estrogens. Elevated aromatase gene expression in breast cancer is caused by the increased activity of the specific aromatase promoters pII, I.3, I.4 and I.7. Determining the effects of chemical exposures on the activity of these aromatase promoters in humans is not possible and specific screening tools do not yet exist. In this research application, we propose to construct breast cancer cells that contain the above 4 promoters of aromatase coupled to a luciferase gene. These cell constructs will be able to produce light upon exposure to chemicals that stimulate the activity of one or more of these promoters. Increased aromatase promoter activity results in increased expression of mammary aromatase, production of estrogens and ultimately stimulation of hormone-dependent mammary tumors.
 
 
 
 
 
 Research questions:
 
 
 
 Are chemicals capable of activating the breast cancer-relevant aromatase promoters PII, I.3, I.4 and I.7, thus increasing the risk of developing hormone-dependent mammary tumors? How can we detect this?
 
 
 
 
 
 General methodology:
 
 
 
 Aromatase promoter gene sequences for pII, I.3, I.4 and I.7 will be coupled to the gene for the enzyme luciferase which upon stimulation produces light. These constructs will be incorporated into the DNA of commercially available breast cancer cell lines. These stably transfected cells will be characterized and validated by determining their response to compounds known to stimulate the activity of each of the inserted aromatase promoters. Cell constructs that respond to these compounds as would endogenous aromatase will be selected for the screening of various chemicals known or suspected to cause endocrine disruption, including pesticides, environmentally persistent chemicals (e.g. flame retardants), and chemicals used in large quantities in industrial processes or consumer products (e.g. phthalate plasticizers, bisphenol A, etc).
 
 
 
 
 
 Innovative elements:
 
 
 
 This research project would provide a number of screening tools to identify chemicals that may increase the risk of breast cancer by interfering with the regulation of aromatase via promoters that are specifically active in the presence of breast tumors. These screening tools would be relatively cheap to use and have the capacity to evaluate large numbers of chemicals many of which that have not been assessed for potential disruption of mammary-specific expression of aromatase. So far, breast cancer-relevant screening tools for aromatase disruption do not exist.
 
 
 
 
 
 Advocacy involvement and relevance to the human issues associated with breast cancer:
 
 
 
 Better understanding of the risks posed by chemicals to which women are exposed either in daily life or under certain exceptional circumstances for the development of hormone-dependent breast cancer. The proposed screening tools will provide scientifically based information that will influence decisions on acceptable exposure levels to certain chemicals or whether or not to avoid use of certain chemicals in consumer products.