Identification of Substances for Ubiquitin-Dependent Proteolysis During Breast Tumor Progression

摘要

Ubiquitylation is post-translational modification in which a small and highly abundant protein called ubiquitin is attached to proteins. Ubiquitylation regulates several processes that are central to breast tumorigenesis, including cell division, inflammation, and angiogenesis. However, defining how ubiquitylation contributes to breast tumorigenesis has been technically limited. We developed an innovative methodology that utilizes protein microarrays as a platform to evaluate the ubiquitylation activity of breast tumor specimens on a proteome-wide scale. In this proposal, we utilized this methodology to define changes in ubiquitylation activity during breast tumor progression. Extracts from breast tumors of either low or high grade/stage were profiled and ubiquitylation activity (fluorescence intensity) quantified for >8,000 substrates on the protein microarray. Several distinct differences in ubiquitylation activity (>2-fold) were observed, with many of the substrates being involved in processes such as cell division, angiogenesis, and metastasis. Several targets of ubiquitylation were then validated. The results of this study show that distinct changes in ubiquitylation activity accompany the progression of breast tumors to more advanced disease. These activities likely drive breast tumor progression and could potentially represent novel targets for therapeutic intervention.