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Angiogenic factor AGGF1 acts as a tumor suppressor by modulating p53 post-transcriptional modifications and stability via MDM2.

ABSTRACT: Angiogenesis factors are widely known to promote tumor growth by increasing tumor angiogenesis in the tumor microenvironment, however, little is known whether their intracellular function is involved in tumorigenesis. Here we show that AGGF1 acts as a tumor suppressor by regulating p53 when acting inside tumor cells. AGGF1 antagonizes MDM2 function to inhibit p53 ubiquitination, increases the acetylation, phosphorylation, stability and expression levels of p53, activates transcription of p53 target genes, and regulates cell proliferation, cell cycle, and apoptosis. AGGF1 also interacts with p53 through the FHA domain. Somatic AGGF1 variants in the FHA domain in human tumors, including p.Q467H, p.Y469 N, and p.N483T, inhibit AGGF1 activity on tumor suppression. These results identify a key role for AGGF1 in an AGGF1-MDM2-p53 signaling axis with important functions in tumor suppression, and uncover a novel trans-tumor-suppression mechanism dependent on p53. This study has potential implications in diagnosis and therapies of cancer.

SUBMITTER: Si W

PROVIDER: S-EPMC8457774 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Mdm2 and Mdm4 are homologous RING domain-containing proteins that negatively regulate the tumor suppressor p53 under physiological and stress conditions. The RING domain of Mdm2 encodes an E3-ubiquitin ligase that promotes p53 degradation. In addition, Mdm2 and Mdm4 interact through their respective RING domains. The in vivo significance of Mdm2-Mdm4 heterodimerization in regulation of p53 function is unknown. In this study, we generated an Mdm4 conditional allele lacking the RING domain to investigate its role in Mdm2 and p53 regulation. Our results demonstrate that homozygous deletion of the Mdm4 RING domain results in prenatal lethality. Mechanistically, Mdm2-Mdm4 heterodimerization is critical for inhibiting lethal p53 activation during early embryogenesis. However, Mdm2-Mdm4 interaction is dispensable for regulating p53 activity as well as the stability of Mdm2 and p53 at later stages of development. We propose that Mdm4 is a key cofactor of Mdm2 that inhibits p53 activity primarily during early embryogenesis but is dispensable for regulating p53 and Mdm2 stability in the adult mouse.

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