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Advanced preclinical CRISPR mouse models to explore context-dependent effects of TP53 mutations in cancer
The tumor suppressor p53 is the most frequently mutated protein in cancer patients and exhibits a unique mutational spectrum that is dominated by missense mutations. In contrast to the most prevalent hotspot mutations, 70% of all missense mutations are non-hotspot mutations with yet poorly character...
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| Format: | Dissertation |
| Sprache: | Englisch |
| Veröffentlicht: |
Philipps-Universität Marburg
2023
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| Online Zugang: | PDF-Volltext |
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| Zusammenfassung: | The tumor suppressor p53 is the most frequently mutated protein in cancer patients and exhibits a unique mutational spectrum that is dominated by missense mutations. In contrast to the most prevalent hotspot mutations, 70% of all missense mutations are non-hotspot mutations with yet poorly characterized functions in tumorigenesis. Non- hotspot mutants often retain some wildtype activity, which corresponds to a partial loss- of-function (pLOF). Mutations that affect the DNA binding cooperativity of p53 fall into this class of mutants.
This work demonstrates that the prototypical DNA binding cooperativity mutant E177R can either promote tumorigenesis or induce tumor regression dependent on the cellular and genetic context. Expression of E177R in normal tissues resulted in increased susceptibility to spontaneous and oncogene-driven tumor development, emphasizing the pathogenic role of pLOF mutants. In striking contrast, expression of E177R in p53- deficient tumor cells revealed that the residual transcriptional activity of the mutant is able to promote the regression of already manifested tumors. That the same p53 mutant can have opposite effects on tumor growth highlights how genetic context determines the consequences of a cancer mutation.
To investigate the impact of specific mutations in different genetic contexts, we have developed a new method for generating genetically defined mouse tumors for preclinical studies. We have applied the CRISPR technology to induce cancer mutations rapidly and precisely in somatic cells and present a flexible toolkit based on adenoviral vectors for in vivo delivery of CRISPR effectors. In addition, we have generated a conditional reporter mouse that expresses a Gaussia princeps luciferase (GLuc). When GLuc is secreted by tumor cells, it accumulates in the blood and serves as a tumor marker to monitor cancer development and therapy responses. By combining the use of CRISPR adenoviruses and GLuc reporter mice, we have established a preclinical mouse tumor model that allows the rapid and flexible induction of autochthonous tumors that are easily monitored using blood samples to study the impact of a cancer mutation on tumorigenesis and cancer therapy in a genetically defined context. |
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| Umfang: | 104 Seiten |
| DOI: | 10.17192/z2023.0178 |