Dataset Information

The miR-106a~363^Xpcl1 miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27^Kip1 cell cycle inhibitor.

ABSTRACT: The miR-106a~363 cluster encodes 6 miRNAs on the X-chromosome which are abundant in blood cells and overexpressed in a variety of malignancies. The constituent miRNA of miR-106a~363 have functional activities in vitro that are predicted to be both oncogenic and tumor suppressive, yet little is known about their physiological functions in vivo. Mature miR-106a~363 (Mirc2) miRNAs are processed from an intragenic, non-protein encoding gene referred to as Xpcl1 (or Kis2), situated at an X-chromosomal locus frequently targeted by retroviruses in murine lymphomas. The oncogenic potential of miR-106a~363 ^Xpcl1 has not been proven, nor its potential role in T cell development. We show that miR106a~363 levels normally drop at the CD4+/CD8+ double positive (DP) stage of thymocyte development. Forced expression of Xpcl1 at this stage impairs thymocyte maturation and induces T-cell lymphomas. Surprisingly, miR-106a~363 ^Xpcl1 also induces p27 transcription via Foxo3/4 transcription factors. As a haploinsufficient tumor suppressor, elevated p27 is expected to inhibit lymphomagenesis. Consistent with this, concurrent p27 ^Kip1 deletion dramatically accelerated lymphomagenesis, indicating that p27 is rate limiting for tumor development by Xpcl1. Whereas down-regulation of miR-106a~363 is important for normal T cell differentiation and for the prevention of lymphomas, eliminating p27 reveals Xpcl1's full oncogenic potential.

SUBMITTER: Kuppers DA

PROVIDER: S-EPMC5584189 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature

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The miR-106a~363Xpcl1 miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27Kip1 cell cycle inhibitor.

Kuppers Daniel A DA Schmitt Thomas M TM Hwang Harry C HC Samraj Lavanya L Clurman Bruce E BE Fero Matthew L ML

Oncotarget 20170407 31

The miR-106a~363 cluster encodes 6 miRNAs on the X-chromosome which are abundant in blood cells and overexpressed in a variety of malignancies. The constituent miRNA of miR-106a~363 have functional activities in vitro that are predicted to be both oncogenic and tumor suppressive, yet little is known about their physiological functions in vivo. Mature miR-106a~363 (Mirc2) miRNAs are processed from an intragenic, non-protein encoding gene referred to as Xpcl1 (or Kis2), ...[more]

PMID: 28881594

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Project description:MicroRNAs (miRs) have been identified as potent regulators of both normal development and the hallmarks of cancer. Targeting of microRNAs has been shown to have preclinical promise, and select miR-based therapies are now in clinical trials. Ewing Sarcoma is a biologically aggressive pediatric cancer with little change in clinical outcomes despite improved chemotherapeutic regimens. There is a substantial need for new therapies to improve Ewing Sarcoma outcomes and to prevent chemotherapy-related secondary sequelae. Most Ewing Sarcoma tumors are driven by the EWS/Fli-1 fusion oncoprotein, acting as a gain-of-function transcription factor causing dysregulation of a variety of targets, including microRNAs. Our previous studies, and those of others, have identified upregulation of miRs belonging to the related miR-17~92a, miR-106b~25, and miR-106a~363 clusters in Ewing Sarcoma. However, the functional consequences of this have not been characterized, nor has miR blockade been explored as an anti-cancer strategy in Ewing Sarcoma. To simulate a potential therapeutic approach, we examined the effects of blockade of these clusters, and their component miRs. Using colony formation as a read-out, we find that blockade of selected individual cluster component miRs, using specific inhibitors, has little or no effect. Combinatorial inhibition using miR "sponge" methodology, on the other hand, is inhibitory to colony formation, with blockade of whole clusters generally more effective than blockade of miR families. We show that a miR-blocking sponge directed against the poorly characterized miR-106a~363 cluster is a particularly potent inhibitor of clonogenic growth in a subset of Ewing Sarcoma cell lines. We further identify upregulation of miR-15a as a downstream mechanism contributing to the miR-106a~363 sponge growth-inhibitory effect. Taken together, our studies provide support for a pro-oncogenic role of the miR-106a~363 cluster in Ewing Sarcoma, and identify miR-106a~363 blockade, as well as miR-15a replacement, as possible strategies for inhibition of Ewing Sarcoma growth.

Project description:BackgroundPoly C Binding Protein 1 (PCBP1) is an RNA-binding protein that binds and regulates translational activity of subsets of cellular mRNAs. Depletion of PCBP1 is implicated in various carcinomas, but the underlying mechanism in tumorigenesis remains elusive.MethodsWe performed a transcriptome-wide screen to identify novel bounding mRNA of PCBP1. The bind regions between PCBP1 with target mRNA were investigated by using point mutation and luciferase assay. Cell proliferation, cell cycle, tumorigenesis and cell apoptosis were also evaluated in ovary and colon cancer cell lines. The mechanism that PCBP1 affects p27 was analyzed by mRNA stability and ribosome profiling assays. We analyzed PCBP1 and p27 expression in ovary, colon and renal tumor samples and adjacent non-tumor tissues using RT-PCR, Western Blotting and immunohistochemistry. The prognostic significance of PCBP1 and p27 also analyzed using online databases.ResultsWe identified cell cycle inhibitor p27Kip1 (p27) as a novel PCBP1-bound transcript. We then demonstrated that binding of PCBP1 to p27 3'UTR via its KH1 domain mainly stabilizes p27 mRNA, while enhances its translation to fuel p27 expression, prior to p27 protein degradation. The upregulated p27 consequently inhibits cell proliferation, cell cycle progression and tumorigenesis, whereas promotes cell apoptosis under paclitaxel treatment. Conversely, knockdown of PCBP1 in turn compromises p27 mRNA stability, leading to lower p27 level and tumorigenesis in vivo. Moreover, forced depletion of p27 counteracts the tumor suppressive ability of PCBP1 in the same PCBP1 over-expressing cells. Physiologically, we showed that decreases of both p27 mRNA and its protein expressions are well correlated to PCBP1 depletion in ovary, colon and renal tumor samples, independent of the p27 ubiquitin ligase Skp2 level. Correlation of PCBP1 with p27 is also found in the tamoxifen, doxorubincin and lapatinib resistant breast cancer cells of GEO database.ConclusionOur results thereby indicate that loss of PCBP1 expression firstly attenuates p27 expression at post-transcriptional level, and subsequently promotes carcinogenesis. PCBP1 could be used as a diagnostic marker to cancer patients.

Dataset Information

The miR-106a~363^Xpcl1 miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27^Kip1 cell cycle inhibitor.

Publications

The miR-106a~363<sup>Xpcl1</sup> miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27<sup>Kip1</sup> cell cycle inhibitor.

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Dataset Information

The miR-106a~363Xpcl1 miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27Kip1 cell cycle inhibitor.

Publications

The miR-106a~363&lt;sup&gt;Xpcl1&lt;/sup&gt; miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27&lt;sup&gt;Kip1&lt;/sup&gt; cell cycle inhibitor.

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OmicsDI is part of the ELIXIR infrastructure

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The miR-106a~363^Xpcl1 miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27^Kip1 cell cycle inhibitor.

The miR-106a~363<sup>Xpcl1</sup> miRNA cluster induces murine T cell lymphoma despite transcriptional activation of the p27<sup>Kip1</sup> cell cycle inhibitor.