The Role of the ECM in Breast Cancer DNA Damage Repair
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: Genetic instability is recognized as a leading cause of breast tumor formation and progression. Since the genome encounters endogenous and exogenous factors that damage DNA, cells have evolved complex repair systems to prevent genomic alterations. Similarly, the extracellular matrix (ECM) provides chemical cues that attenuate tumor progression in cells that sustain tumor-initiating alterations. Thus, the extracellular matrix and DNA repair mechanisms act to maintain cellular homeostasis. Recently, much research has focused on how cells respond to damage in S phase (period of DNA synthesis). Due to the inherent vulnerability of cells during this point in the cell cycle, repair needs to be rapid and extremely efficient. Delayed or faulty repair directly promotes genomic instability, which may act as the earliest event in the genesis of breast cancer.
 
 
 
 
 
 
 
 Due to genomic vulnerability during S-phase, multiple repair pathways act to repair DNA lesions. Individuals that lack critical repair proteins, like BRCA1, NBS1, BLM or p53 exhibit an increased cancer risk, which includes breast cancer. Paradoxically, cells derived from these individuals display increased sensitivity to many chemotherapeutic drugs. Our proposal tests the hypothesis that in addition to protecting epithelial cells from genotoxic-induced cell death, the extracellular matrix confers signals that dictate the repair mechanism used to resolve lesions which occur during S-phase damage. Our aims are as follows:
 
 1. Examine the role played by the cell’s microenvironment in activating repair mechanisms that resolve damage encountered during S-phase. 
 
 2. Does the loss of a critical “caretaker protein” promote an alternative and less faithful form of repair, which may cooperate with mutant p53 to prime human mammary epithelial cells to undergo transformation following replication stress. 
 
 
 
 
 
 
 
 We will grow mammary epithelial cells in 3-D using a technique optimized by Dr. Mina Bissell at LBNL. The role ECM signaling plays in cells lacking critical repair proteins will be examined using RNA interference (RNAi) technology. Using repair protein and phospho-specific antibodies, confocal microscopy, chromosomal analysis and measurement of repair mechanisms, we will assess how the ECM interfaces with critical repair proteins to ensure efficient repair of a damaged genome. For “proof-of-principle” experiments, we will expose mammary epithelial cells to DNA damage and examine their ability to form tumors in mice. 
 
 
 
 
 
 
 
 We plan to establish a model that potentially examines the earliest stages of breast cancer. This research merges two separate fields of study. The role that the extracellular matrix plays in maintaining normal breast structure will be linked to the signals that activate the appropriate repair pathway. Breast cancer requires dysregulation of multiple tumor suppressive pathways. Even with early detection, breast tumors have undergone multiple genomic alterations, which manifest in uncontrolled growth. Understanding the most proximal event that may initiate the cascade of aberrations which result in deregulated growth would establish a useful platform for generating diagnostic strategies or interventions that may halt breast tumor progression.