Dataset Information

A Nucleolar Stress-Specific p53-miR-101 Molecular Circuit Functions as an Intrinsic Tumor-Suppressor Network.

ABSTRACT: BACKGROUND:Activation of intrinsic p53 tumor-suppressor (TS) pathways is an important principle underlying cancer chemotherapy. It is necessary to elucidate the precise regulatory mechanisms of these networks to create new treatment strategies. METHODS:Comprehensive analyses were carried out by microarray. Expression of miR-101 was analyzed by clinical samples of lung adenocarcinomas. FINDINGS:We discovered a functional link between p53 and miR-101, which form a molecular circuit in response to nucleolar stress. Inhibition of RNA polymerase I (Pol I) transcription resulted in the post-transcriptional activation of miR-101 in a p53-dependent manner. miR-101 induced G2 phase-specific feedback regulation of p53 through direct repression of its target, EG5, resulting in elevated phosphorylation of ATM. In lung cancer patients, low expression of miR-101 was associated with significantly poorer prognosis exclusively in p53 WT cases. miR-101 sensitized cancer cells to Pol I transcription inhibitors and strongly repressed xenograft growth in mice. Interestingly, the most downstream targets of this circuit included the inhibitor of apoptosis proteins (IAPs). Repression of cIAP1 by a selective inhibitor, birinapant, promoted activation of the apoptosis induced by Pol I transcription inhibitor in p53 WT cancer cells. INTERPRETATION:Our findings indicate that the p53-miR-101 circuit is a component of an intrinsic TS network formed by nucleolar stress, and that mimicking activation of this circuit represents a promising strategy for cancer therapy. FUND: National Institute of Biomedical Innovation, Ministry of Education, Culture, Sports & Technology of Japan, Japan Agency for Medical Research and Development.

SUBMITTER: Fujiwara Y

PROVIDER: S-EPMC6085539 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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A Nucleolar Stress-Specific p53-miR-101 Molecular Circuit Functions as an Intrinsic Tumor-Suppressor Network.

Fujiwara Yuko Y Saito Motonobu M Robles Ana I AI Nishida Momoyo M Takeshita Fumitaka F Watanabe Masatoshi M Ochiya Takahiro T Yokota Jun J Kohno Takashi T Harris Curtis C CC Tsuchiya Naoto N

EBioMedicine 20180707

<h4>Background</h4>Activation of intrinsic p53 tumor-suppressor (TS) pathways is an important principle underlying cancer chemotherapy. It is necessary to elucidate the precise regulatory mechanisms of these networks to create new treatment strategies.<h4>Methods</h4>Comprehensive analyses were carried out by microarray. Expression of miR-101 was analyzed by clinical samples of lung adenocarcinomas.<h4>Findings</h4>We discovered a functional link between p53 and miR-101, which form a molecular c ...[more]

PMID: 30049386

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Project description:p53 protects us from cancer by transcriptionally regulating tumor suppressive programs designed to either prevent the development or clonal expansion of malignant cells. How p53 selects target genes in the genome in a context- and tissue-specific manner remains largely obscure. There is growing evidence that the ability of p53 to bind DNA in a cooperative manner prominently influences target gene selection with activation of the apoptosis program being completely dependent on DNA binding cooperativity. Here, we used ChIP-seq to comprehensively profile the cistrome of p53 mutants with reduced or increased cooperativity. The analysis highlighted a particular relevance of cooperativity for extending the p53 cistrome to non-canonical binding sequences characterized by deletions, spacer insertions and base mismatches. Furthermore, it revealed a striking functional separation of the cistrome on the basis of cooperativity; with low cooperativity genes being significantly enriched for cell cycle and high cooperativity genes for apoptotic functions. Importantly, expression of high but not low cooperativity genes was correlated with superior survival in breast cancer patients. Interestingly, in contrast to most p53-activated genes, p53-repressed genes did not commonly contain p53 binding elements. Nevertheless, both the degree of gene activation and repression were cooperativity-dependent, suggesting that p53-mediated gene repression is largely indirect and mediated by cooperativity-dependently transactivated gene products such as CDKN1A, E2F7 and non-coding RNAs. Since both activation of apoptosis genes with non-canonical response elements and repression of pro-survival genes are crucial for p53's apoptotic activity, the cistrome analysis comprehensively explains why p53-induced apoptosis, but not cell cycle arrest, strongly depends on the intermolecular cooperation of p53 molecules as a possible safeguard mechanism protecting from accidental cell killing.

Project description:BackgroundMicroRNAs have an important role in diverse biological processes including tumorigenesis. MiR-223 has been reported to be deregulated in several human cancer types. However, its biological role has not been functionally characterized in lung squamous cell carcinoma (LSCC). The following study investigates the role of miR-223-3p in LSCC growth and metastasis and its underlying mechanism.MethodsMicroRNA profiling analyses were conducted to determine differential miRNAs expression levels in LSCC tumor tissues that successfully formed xenografts in immunocompromised mice (XG) and failed tumor tissues (no-XG). RT-PCR and in situ hybridization (ISH) was performed to evaluate the expression of miR-223-3p in 12 paired adjacent normal tissues and LSCC specimens. Cell proliferation and migration were assessed by CCK-8, colony formation and Transwell assay, respectively. The role of miR-223-3p in LSCC tumorigenesis was examined using xenograft nude models. Bioinformatics analysis, Dual-luciferase reporter assays, Chromatin immunoprecipitation (ChIP) assay and Western blot analysis were used to identify the direct target of miR-223-3p and its interactions.ResultsMiR-223-3p was downregulated in LSCC tissues that successfully formed xenografts (XG) compared with tumor tissues that failed (no-XG), which was also significantly reduced in LSCC tissues compared with the adjacent normal tissues. Gain- and loss-of function experiments showed that miR-223-3p inhibited proliferation and migration in vitro. More importantly, miR-223-3p overexpression greatly suppressed tumor growth in vivo. Mechanistically, we found that mutant p53 bound to the promoter region of miR-223 and reduced its transcription. Meanwhile, p53 is a direct target of miR-223-3p. Thus, miR-223-3p regulated mutant p53 expression in a feedback loop that inhibited cell proliferation and migration.ConclusionsOur study identified miR-223-3p, as a tumor suppressor gene, markedly inhibited cell proliferation and migration via miR-223-3p-mutant p53 feedback loop, which suggested miR-223-3p might be a new therapeutic target in LSCC bearing p53 mutations.

Dataset Information

A Nucleolar Stress-Specific p53-miR-101 Molecular Circuit Functions as an Intrinsic Tumor-Suppressor Network.

Publications

A Nucleolar Stress-Specific p53-miR-101 Molecular Circuit Functions as an Intrinsic Tumor-Suppressor Network.

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