INT6 May Influence Breast Cancer Formation by Regulating the 26S Proteasome
Abstract
INT6 is a target of MMTV, whose insertion generates truncated proteins that induce tumor formation. Our lab demonstrate an evolutionarily conserved function of Int6 in the model system Schizosaccharomyces pombe: regulation of proteasome transport and assembly. In this project, I propose to test the hypothesis that Int6 acts as a breast tumor suppressor, which functions to regulate the 26S proteasome, in human mammary epithelial cells. Using siRNAs to reduce Int6 expression level, I found that Int6 is important for genomic stability, as proposed. Furthermore, cells in which Int6 expression is knocked down are hypersensitive to a proteasome inhibitor. This result supports our idea that Int6 can regulate the proteasome in human mammary epithelial cells. Finally, I showed that the dosage of Int6 is important for the development of acini in 3D culture system. In parallel to these studies, I further examined how Int6 can regulate the proteasome. My data show that mutating a conserved leucine in the PCI domain of Int6 leads to its mislocalization in human mammary epithelial cells, and overexpressing this mutant protein in MCF10A cells causes malignant growth in 3D culture. Also, by measuring the protein dynamics in S. pombe using Fluorescent loss in photo bleaching (FLIP), I showed that the proteasome subunit Pad1-GFP is actively entering the nucleus, and this process is affected by int6 deletion.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2006
- Accession Number
- ADA455348
Entities
People
- Eric Chang
- Zhe Sha
Organizations
- Baylor College of Medicine