TRIAD1 Is a Novel Transcriptional Target of p53 and Regulates Nutlin‐3a‐Induced Cell Death

Abstract

Nutlin-3a is a non-genotoxic, p53-activating, MDM2 inhibitor being investigated as an anticancer agent. Although Nutlin-3a selectively antagonizes the ubiquitin E3 ligase activity of MDM2, its efficacy is not entirely regulated by MDM2 levels in cancer cells. Here, we report that the cytotoxic effects of Nutlin-3a are regulated by TRIAD1 via a positive feedback loop with p53. We found that Nutlin-3a enhanced TRIAD1 transcription in a p53-dependent manner. Using in silico analysis and promoter luciferase assays, we demonstrated that p53-mediated transcription of TRIAD1 is mediated by a p53 consensus sequence in the TRIAD1 promoter region. Silencing TRIAD1 expression in wild-type p53 (p53 ) cancer cells suppressed Nutlin-3a-mediated p53 activation and p53 target gene expression. These effects were enhanced in TRIAD1-overexpressing p53 cancer cells, but not in p53-deficient cancer cells. Furthermore, TRIAD1 knockdown significantly reduced the growth inhibitory and cytotoxic effects of Nutlin-3a in p53 cancer cells, as demonstrated by cell viability assays, cell cycle analysis, clonogenic growth, and soft-agar colony forming assays. Together, these data indicate that TRIAD1 regulates Nutlin-3a-mediated p53 activation and the cytotoxic activity of Nutlin-3a. J. Cell. Biochem. 118: 1733-1740, 2017. © 2016 Wiley Periodicals, Inc.

Ubiquitin ligase Triad1 promotes neurite outgrowth by inhibiting MDM2-mediated ubiquitination of the neuroprotective factor pleiotrophin

“…In this research, MDM2 was predicted as the most likely E3 ligase to regulate the PTN ubiquitination and further proved to negatively modulate PTN expression only in protein level. Although ARIH2-encoded Triad1 protein is an E3 ubiquitin ligase ( 32 ), Nutlin-3a (Mdm2 inhibitor)-induced p53 activation could be modulated by Triad1 level ( 33 ). Furthermore, the protein level of Triad1 was decreased in response to Mdm2 overexpression, which was consistent with the findings of Bae et al.…”

Targeting the Ubiquitin Signaling Cascade in Tumor Microenvironment for Cancer Therapy

“…Nutlin-3a has been reported to inhibit MDM2 to reduce angiogenesis and metastasis of neuroblastoma in mice [93]. Nutlin-3a also shows anti-tumor effects in multiple types of cancer [94], but whether Nutlin-3a can modulate HIF-1α is not clear so far. HLI98 [91] and MEL family compounds [92] can also inhibit MDM2 E3 ligases to stabilize the tumor suppressor p53.…”

ARIH2 regulates the proliferation, DNA damage and chemosensitivity of gastric cancer cells by reducing the stability of p21 via ubiquitination

“…ARIH2 belongs to the Ariadne subfamily ligase of RBR E3 ligase. At present, ARIH2 has been studied for its regulatory role in many malignant cancers [ 3 , 4 ]. Evidence has shown that ARIH2 plays an important role in the occurrence and development of acute myeloid leukemia, human non-small-cell lung cancer and other cancers [ 5 , 6 ].…”