Oxidative Stress and Estrogen Receptor Structural Changes
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: Oxidative stress induces aging and age-related diseases like breast cancer. There are &gt;30 years of accumulated scientific evidence demonstrating the critical importance of an "activated" estrogen receptor (ER, alpha isoform) mechanism driving both the initiation and promotion of most human breast cancers, in addition to serving as the molecular target for lifesaving endocrine therapy. Despite unequivocal biological and clinical evidence for profound oxidant stress-induced changes in breast cancer ER structure and function, lack of sufficiently powerful analytical tools have impeded research directed at an understanding of how various oxidants actually deform ER structure and enhance ER breast tumorigenic mechanisms, and how these effects might be reversed or prevented. Quinone oxidants, common in the human diet and endogenously produced by estrogen catabolism, generate both reactive oxygen species and "arylated" proteins. The model quinone, menadione/vitamin K3, induces differential phosphorylation, irreversible arylation, and loss of DNA-binding in full-length and variant forms of the endogenous ER expressed in human breast cancer cells . Using this quinone as a model and a powerful "mass spectrometry" approach, we plan to detect arylated and phosphorylated amino acids at the molecular level in full-length and variant forms of ER extracted from human breast cancer cells. 
 
 
 
 
 
 
 
 For this CBCRP collaborative grant, we assembled a cross-disciplinary team of translational breast cancer researchers and protein chemists who previously proved the feasibility of applying novel mass spectrometry approaches to monitor oxidant-induced structural changes in ER. Our aims are to use chemical and proteomic strategies detect quinone-induced arylation of all cysteines (Cys) and phosphorylation of all serines (Ser), threonines (Thr), and tyrosines (Tyr) within all ER forms that can be purified from control/treated ER-overexpressing breast cancer cells. This includes optimization of each step required for the MS analysis of these modified ER amino acids, and the final goal is to measure oxidant-altered ER from treated breast cancer cells. For this research we plan to use recombinant and purified ER from MCF-7 breast cancer cells. 
 
 
 
 
 
 
 
 Newer and more powerful protein chemistry procedures are needed to achieve a detailed understanding of the dysfunctional ER found in breast epithelial cells exposed to various oxidants. If we are successful in optimization and validation of the mass spectrometry approach in this project, then the ER from primary human breast biopsy specimens can then be analyzed for the type and location of modified Cys, Ser, Thr, and Tyr residues. The final goal is to relate the pattern of ER structural changes correlated with known oxidant stresses. This will be a first step to relate environmental, dietary, and lifestyle effects for new model of breast cancer based on structural modifications of the ER.