Using yeast to identify methods to restore p53 function
Abstract
The transcription factor p53 is a tumor suppressor protein that guards against cancer. Amazingly, over 50% of all cancers are associated with inactivation ofp53. Thus, restoring p53 transcription factor activity would be an effective strategy to fight many forms of the disease. So far, this has not been possible. Although one or both copies ofp53 are mutant in most cancer cells, p53 activity can also be impaired without any p53 mutations. Furthermore, certain mutations in one copy ofp53 not only inhibit the activity of wild-type (WT) p53 molecules in the cell, but also inhibit the activities of the paralogs p63 and p73. The long-term goal of this proposal is to restore p53/p63/p73 transcription factor activity to such cancer cells. To explain the above it has been hypothesized that p53 can be inactivated by forming a self-seeding (i.e. prion) aggregate that can attract WT p53, p63, and p73 molecules to join the aggregate, thereby inactivating them as well. Thus, p53 mutations that cause it to misfold into a prion would cause cancer even in the presence of WT p53, p63, or p73. This hypothesis is supported by recent reports of p53 aggregates in cancer tissues. Also, WT p53, p63, and p73 were each shown to co-localize with mutant p53 aggregates in a SaOS-2 human cell line, in a mouse kidney p53R l 75H/Rl 75H lymphoma, and in a p53R282W human colon adenocarcinoma. Our preliminary data shows that high expression of the human p53 protein with the cancer mutation RI 75H in yeast causes the p53-R 175H to form prion aggregates. Furthermore, is was recently shown that even wild-type p53 can form aggregates that self-seed (i.e. are prions) in yeast. This makes it likely that the stochastic formation of just a small amount of p53 prion seed in humans would create a chain reaction leading to more seed spreading to daughter cells and amplifying the dominant-negative effect caused by the ability of the aggregates to attract and inactivate WT p53 and related p63 and p73. It is proposed to use the yeast system to investigate the relative frequency with which p53 with different disease mutations can form prions as well as the effect of stress on the formation p53 prions. It is further proposed to screen for genes that inhibit p53 prion formation and to select for p53 mutations that prevent p53 from joining the prion while retaining transcriptional activation activity. Results uncovered in this proposal that promote retention ofp53 activity, should be of therapeutic value for cancer.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810151
Entities
People
- Susan W. Liebman
Organizations
- Army Contracting Command
- United States Army
- University of Nevada, Reno