Global Analysis of Protein Ubiquitination in 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: Ubiquitin is a small protein found in all eukaryotic cells. Its main function is to “mark” other proteins for destruction, a process known as proteolysis. Normally the ubiquitinated protein is recognized by a protein complex called the proteasome, a barrel-shaped structure where the proteolysis occurs. In terms of cell physiology, ubiquitination plays an important role in the regulation of many functions including division, differentiation, protein trafficking, the response to DNA damage, and gene transcription, among others.
 
 
 
 
 
 
 
 A wealth of experimental evidence supports the notion that changes in ubiquitin-mediated proteolysis contribute to various human malignancies, including breast cancer. However, there are currently no adequate experimental tools to identify the substrates of enzymes involved in protein ubiquitination on a proteome-wide (i.e. global) scale.
 
 
 
 
 
 
 
 This project undertakes a completely new systematic approach to identify proteins that are subject to ubiquitin-mediated proteolysis and to unravel the relevant protein ubiquitination involved in breast tumor progression and metastasis. To achieve this, we have developed an innovative assay that combines protein microarrays (where &gt;8,300 human recombinant proteins are spotted onto glass microscope slides) with an ubiquitination reaction to determine novel ubiquitinated substrates. If successful, this method will enable us to define key molecular changes in a breast tumor cell’s intrinsic enzymatic activity that drives the metastatic process. We plan to place particular emphasis on the ubiquitination processes leading to the epithelial-mesenchymal transition (EMT), a precursor step of metastasis, and the change of cell-cell and cell-matrix adhesion. In our planned studies we will first obtain mouse breast tumor specimens from mammary cancer cell lines with distinctive metastasizing potential and define changes in ubiquitin ligase activity associated with breast tumor progression. Next, we will use biochemical and cell-based assays to validate the connection between ubiquitin ligase activity and its substrates. We hope to establish a mechanistic model for changes in the ubiquitination pattern occurring during breast cancer metastasis.
 
 
 
 
 
 
 
 The successful employment of our innovative protein microarray ubiquitination assay in these endeavors could lead to an understanding of how protein-ubiquitination drives breast cancer progression. This would undoubtedly contribute to a better understanding of basic cellular function and the molecular events that ensue as breast epithelial cells become metastatic. The ubiquitin proteasome system has been recognized as a valid target for the treatment of some malignancies (e.g. Bortezomib), so it is our hope that this research will lead to the discovery of a novel set of diagnostic and prognostic markers based on the tumor cell’s intrinsic enzymatic activity, which could greatly impact the diagnosis and effective treatment of breast cancer.