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Mouse models of Mdm2 and Mdm4 and their clinical implications
1Department of Genetics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. sxiong@mdanderson.org
Abstract:
Mdm2 and Mdm4 are two key negative regulators of the tumor suppressor p53. Deletion of either Mdm2 or Mdm4 induces p53-dependent early embryonic lethality in knockout mouse models. The tissue-specific deletion of Mdm2 induces p53-dependent apoptosis, whereas the deletion of Mdm4 induces both p53-dependent apoptosis and cell cycle arrest. Compared to Mdm4 deletion, Mdm2 deletion causes more severe phenotypic defects. Disrupting the Mdm2 and Mdm4 interaction using knockin mice models causes embryonic lethality that can be completely rescued by the concomitant loss of p53, suggesting that Mdm2 and Mdm4 heterodimerization is critical to inhibit p53 activity during embryogenesis. Overexpression of Mdm2 and Mdm4 in mice induces spontaneous tumorigenesis, which clearly indicates that Mdm2 and Mdm4 are bona fide oncogenes. Studies from these mouse models strongly suggest that blocking Mdm2- and Mdm4-mediated p53 inhibition is an appealing therapeutic strategy for cancer patients with wild-type p53 alleles.
Insights
Mdm2 and Mdm4 proteins regulate the tumor suppressor p53. Inhibiting their interaction is crucial for embryogenesis and blocking p53. This suggests targeting Mdm2/Mdm4 is a promising cancer therapy strategy.
Area of Science:
- Molecular Biology
- Oncology
- Genetics
Background:
- Mdm2 and Mdm4 are critical negative regulators of the tumor suppressor p53.
- Their functions are essential for embryonic development, as evidenced by embryonic lethality in knockout models.
Purpose of the Study:
- To investigate the roles of Mdm2 and Mdm4 in p53 regulation and embryonic development.
- To explore the therapeutic potential of targeting the Mdm2-Mdm4 interaction in cancer.
Main Methods:
- Utilized knockout and knockin mouse models to study Mdm2 and Mdm4 function.
- Analyzed p53-dependent apoptosis and cell cycle arrest phenotypes.
- Assessed the impact of Mdm2/Mdm4 disruption on embryonic lethality and tumorigenesis.
Main Results:
- Deletion of Mdm2 or Mdm4 leads to p53-dependent embryonic lethality.
- Mdm2 deletion causes more severe defects than Mdm4 deletion.
- Disrupting the Mdm2-Mdm4 interaction is lethal but rescued by p53 loss, highlighting its importance in inhibiting p53 during embryogenesis.
- Overexpression of Mdm2/Mdm4 induces tumors, confirming their oncogenic potential.
Conclusions:
- Mdm2 and Mdm4 are essential oncogenes that inhibit p53.
- Their heterodimerization is critical for suppressing p53 activity during embryogenesis.
- Targeting Mdm2/Mdm4-mediated p53 inhibition represents a potential therapeutic strategy for cancers with wild-type p53.
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