Abstract
The oncogene MDMX is overexpressed in many cancers, leading to suppression of the tumor suppressor p53. Inhibitors of the oncogene product MDMX therefore might help reactivate p53 and enhance the efficacy of DNA-damaging drugs. However, we currently lack a quantitative understanding of how MDMX inhibition affects the p53 signaling pathway and cell sensitivity to DNA damage. Live cell imaging showed that MDMX depletion triggered two distinct phases of p53 accumulation in single cells: an initial postmitotic pulse, followed by low-amplitude oscillations. The response to DNA damage was sharply different in these two phases; in the first phase, MDMX depletion was synergistic with DNA damage in causing cell death, whereas in the second phase, depletion of MDMX inhibited cell death. Thus a quantitative understanding of signal dynamics and cellular states is important for designing an optimal schedule of dual-drug administration.
🔬 Techniques
✨ Fluorophores
🧪 Sample Preparation
🔬 Cell Lines
🏭 Microscope Brands
🏛️ Research Organizations (ROR)
Affiliated research institutions:
📊 Figures
Figure 1
Single cells show two phases of p53 dynamics after MDMX depletion
(A) Abundance of MDMX, p53 and actin in western blots of extracts from MCF7 cells were transfected with either scrambled siRNA (sc, 5nM) or siRNA targeting MDMXu2019s mRNA (0.5, 5, 50 nM) for the indi...
Figure 2
MDMX suppresses p53 oscillations in non-stressed conditions and after DNA damage
(A) Schematic of the p53 and MDMX reporter constructs. (B) Abundance of mKate2-MDMX in p53-MDMX reporter cells treated with doxycycline analyzed by western blot. (C and D) Time-lapse microscopy images...
Figure 3
p53 oscillations during phase II are required to maintain p21 accumulation and cell cycle arrest
(A) Expression of p53 target genes measured by qPCR after MDMX knockdown. Genes are grouped according to their function (n = 3; error bars represent SD). (B) Schematic of suppressing p53 oscillations ...
Figure 4
Synergistic or antagonistic effects of MDMX depletion on DNA damage depending on the time interval between treatments
(A) Experimental design for applying DNA damage (UV radiation, 16 J/m 2 ) during phase I and phase II of p53 dynamics post MDMX knockdown. (Bu2013C) Survival curve of cells with DNA damage applied dur...
Figure images are served from the NIH/NLM PubMed Central Open Access Subset or Europe PMC; copyright remains with the publishers and authors.
💬 Discussion
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