Twist Maintains Stemness in Latent Breast Cancer Metastases Through a Novel Non DNA-Binding Function Targetable with Small Molecules
Abstract
The Twist induced EMT program in a primary tumor is required for proliferation, migration, invasion and colonization of distant organs. Once cells are disseminated, a genetically and biochemically separate domain of Twist: the WR domain functions to maintain the metastatic tumor cells in a quiescent (possibly pluripotent) state by rendering the cells resistant to differentiation inducing signals, similar to what happens during development. The hypothesis and indeed preliminary data provided to support the original proposal were that the COOH-terminal Twist WR domain is required for binding directly to lineage specific transcription factors like Runx2 and inhibiting their DNA binding function. Thus, the goals of this grant were to define how Twist and the WR domain functions to interact with other cellular factors and maintain the undifferentiated state in these latent disseminated cells. Progress in this second year of support includes: 1. Further definition of the spectrum of proteins bound by to endogenous, cell derived Twist in a breast cancer cell line undergoing EMT. 2. Reconstitution of this complex with purified recombinant Twist-E47-Snail-Sox9 proteins. 3. The surprise discovery that this complex of proteins does NOT function to inhibit Runx1 DNA binding as originally proposed. Rather, the protein complex transiently binds to Runx2 and leads to its proteasome mediated degradation. The multiprotein complex does not require any intrinsic DNA binding capability to target and degrade Runx2, so it is the first NON DNA binding dependent function described for these transcription factors. To investigate the mechanism of proteasome mediated degradation of Runx2 by Twist-WR (and its binding proteins). Preliminary data suggest that the Snail component of the Twist complex functions as an E3 ligase for Runx2 and recruits it to the proteasome. This E3 ligase activity resides solely in 2-4 zinc fingers of Snail and is highly specific for Snail family members.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2019
- Accession Number
- AD1097049
Entities
People
- Frank Iii J. Rauscher
Organizations
- Wistar Institute