| 1. |
- Ladds, Marcus J. G. W., et al.
(author)
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A DHODH inhibitor increases p53 synthesis and enhances tumor cell killing by p53 degradation blockage
- 2018
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In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Journal article (peer-reviewed)abstract
- The development of non-genotoxic therapies that activate wild-type p53 in tumors is of great interest since the discovery of p53 as a tumor suppressor. Here we report the identification of over 100 small-molecules activating p53 in cells. We elucidate the mechanism of action of a chiral tetrahydroindazole (HZ00), and through target deconvolution, we deduce that its active enantiomer (R)-HZ00, inhibits dihydroorotate dehydrogenase (DHODH). The chiral specificity of HZ05, a more potent analog, is revealed by the crystal structure of the (R)-HZ05/DHODH complex. Twelve other DHODH inhibitor chemotypes are detailed among the p53 activators, which identifies DHODH as a frequent target for structurally diverse compounds. We observe that HZ compounds accumulate cancer cells in S-phase, increase p53 synthesis, and synergize with an inhibitor of p53 degradation to reduce tumor growth in vivo. We, therefore, propose a strategy to promote cancer cell killing by p53 instead of its reversible cell cycle arresting effect.
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| 2. |
- Loljung, Lotta, et al.
(author)
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High expression of p63 is correlated to poor prognosis in squamous cell carcinoma of the tongue
- 2014
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In: Journal of Oral Pathology & Medicine. - : John Wiley & Sons. - 0904-2512 .- 1600-0714. ; 43:1, s. 14-19
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Journal article (peer-reviewed)abstract
- Backgroundp63 proteins are important in formation of the oral mucosa. Normal oral mucosa shows a balance between the six protein isoforms, whereas an imbalance between them is seen in squamous cell carcinomas (SCC). There is controversy over the clinical impact of p63 in SCC, which may relate to different expression in different areas. In addition, p63 isoforms can act as p53-like molecules (TAp63) or can inhibit p53 functions (Np63) and expression of these isoforms varies in different tumours. Here, we chose to concentrate on the most common intra-oral sub-site, SCC of the mobile tongue. MethodsTotal p63, Np63 and TAp63 were analysed separately using immunohistochemistry. The percentage of cells and intensity of expression of different isoforms of p63 was evaluated using a quick score method and correlated with clinical data in a group of 87 patients with tongue SCC. ResultsAll tumours expressed p63 in at least 60% of the cells when using two different antibodies detecting all 6 isoforms. p63 expression correlated significantly with 2-year survival (P=0.018), with fewer patients surviving 2years if their tumours expressed p63 with strong intensity in at least 80% of the cells (quick score 18). Looking at 5-year survival, this was even more emphasized. Np63 was expressed in all tumours, whereas expression of TAp63 was seen only in 59/87 patients, usually at very low levels. ConclusionsBased on the present data, we recommend using expression of p63 as an additional factor contributing prognostic information in analysis of SCC in the tongue.
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| 3. |
- Nekulova, Marta, et al.
(author)
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Delta Np63 alpha expression induces loss of cell adhesion in triple-negative breast cancer cells
- 2016
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In: BMC Cancer. - : BioMed Central. - 1471-2407. ; 16
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Journal article (peer-reviewed)abstract
- Background: p63, a member of the p53 protein family, plays key roles in epithelial development and carcinogenesis. In breast cancer, p63 expression has been found predominantly in basal-A (epithelial-type) triple-negative breast carcinomas (TNBC). To investigate the functional role of p63 in basal-A TNBC, we created MDA-MB-468 cell lines with inducible expression of the two major N-terminal p63 isoforms, TAp63 alpha and Delta Np63 alpha. Results: TAp63 alpha did not have significant effect on gene expression profile and cell phenotype, whilst the main effect of Delta Np63 alpha was reduction of cell adhesion. Gene expression profiling revealed genes involved in cell adhesion and migration whose expression relies on overexpression of Delta Np63 alpha. Reduced cell adhesion also led to decreased cell proliferation in vitro and in vivo. Similar data were obtained in another basal-A cell line, BT-20, but not in BT-549 basal-B (mesenchymal-like) TNBC cells. Conclusions: In basal-A TNBC cells, Delta Np63 alpha has much stronger effects on gene expression than TAp63 alpha. Although p63 is mentioned mostly in connection with breast cell differentiation and stem cell regulation, we showed that a major effect of p63 is regulation of cell adhesion, a process important in metastasis and invasion of tumour cells. That this effect is not seen in mesenchymal-type TNBC cells suggests lineage-dependent functions, mirroring the expression of Delta Np63 alpha in primary human breast cancers.
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