LINE-1 ORF-1p functions as a novel androgen receptor co-activator and promotes the growth of human prostatic carcinoma cells

BackgroundMyeloid ecotropic viral integration site 1 (MEIS1) protein plays a synergistic causative role in acute myeloid leukemia (AML). However, MEIS1 has also shown to be a potential tumor suppressor in some other cancers, such as non-small-cell lung cancer (NSCLC) and prostate cancer. Although multiple roles of MEIS1 in cancer development and progression have been identified, there is an urgent demand to discover more functions of this molecule for further therapeutic design.MethodsMEIS1 was overexpressed via adenovirus vector in clear cell renal cell carcinoma (ccRCC) cells. Western blot and real-time qPCR (quantitative Polymerase Chain Reaction) was performed to examine the protein and mRNA levels of MEIS1. Cell proliferation, survival, in vitro migration and invasion were tested by MTT, colony formation, soft-agar, transwell (in vitro invasion/migration) assays, and tumor in vivo growthwas measured on nude mice model. In addition, flow-cytometry analysis was used to detect cell cycle arrest or non-apoptotic cell death of ccRCC cells induced by MEIS1.ResultsMEIS1 exhibits a decreased expression in ccRCC cell lines than that in non-tumor cell lines. MEIS1 overexpression inhibits ccRCC cells proliferation and induces G1/S arrest concomitant with marked reduction of G1/S transition regulators, Cyclin D1 and Cyclin A. Moreover, MEIS1-1 overexpression also induces non-apoptotic cell death of ccRCC cells via decreasing the levels of pro-survival regulators Survivin and BCL-2. Transwell migration assay (TMA) shows that MEIS1 attenuates in vitro invasion and migration of ccRCC cells with down-regulated epithelial-mesenchymal transition (EMT) process. Further, in nude mice model, MEIS1 inhibits the in vivo growth of Caki-1 cells.ConclusionsBy investigating the role of MEIS1 in ccRCC cells’ survival, proliferation, anchorage-independent growth, cell cycle progress, apoptosis and metastasis, in the present work, we propose that MEIS1 may play an important role in clear cell renal cell carcinoma (ccRCC) development.

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“…Colony number was manifested as the mean ± SD of three independent experiments scored after 3-4 weeks of growth [26]. …”

Section: Methodsmentioning

confidence: 99%

MEIS1 inhibits clear cell renal cell carcinoma cells proliferation and in vitro invasion or migration

Zhu

Cui

et al. 2017

BMC Cancer

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“…In somatic cells retrotransposons are tightly repressed; however, in conditions of misregulated cellular controls such as cancer, some classes of retrotransposons have been shown to evade suppression (27)(28)(29)(30)39). To show a functional relevance of the KAP1-URI-PP2A complex, we analyzed the effect of URI depletion on the expression of retroelements in prostate cancer cells.…”

Section: Uri Depletion Induces Reactivation Of Mobile Retroelements Imentioning

confidence: 99%

“…LINE-1 transcription is driven by its 5Ј-UTR promoter, which mediates sense and antisense transcription (23,24). Reactivation of retroelements has also been demonstrated in several types of cancers including prostate cancer, and it has been postulated to fuel genomic rearrangements (25)(26)(27)(28)(29)(30).…”

mentioning

confidence: 99%

URI Regulates KAP1 Phosphorylation and Transcriptional Repression via PP2A Phosphatase in Prostate Cancer Cells

Mita

Savas

Briggs

et al. 2016

Journal of Biological Chemistry

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Edited by Xiao-Fan WangURI (unconventional prefoldin RPB5 interactor protein) is an unconventional prefoldin, RNA polymerase II interactor that functions as a transcriptional repressor and is part of a larger nuclear protein complex. The components of this complex and the mechanism of transcriptional repression have not been characterized. Here we show that KAP1 (KRAB-associated protein 1) and the protein phosphatase PP2A interact with URI. Mechanistically, we show that KAP1 phosphorylation is decreased following recruitment of PP2A by URI. We functionally characterize the novel URI-KAP1-PP2A complex, demonstrating a role of URI in retrotransposon repression, a key function previously demonstrated for the KAP1-SETDB1 complex. Microarray analysis of annotated transposons revealed a selective increase in the transcription of LINE-1 and L1PA2 retroelements upon knockdown of URI. These data unveil a new nuclear function of URI and identify a novel post-transcriptional regulation of KAP1 protein that may have important implications in reactivation of transposable elements in prostate cancer cells.The URI (unconventional prefoldin RPB5 interactor protein) has structural homology to members of the prefoldin family of molecular chaperones. URI protein is distributed throughout the cell to coordinate cellular processes involving metabolism, proliferation, and gene expression. In the mitochondria, URI binds and represses PP1␥ phosphatase, thus sustaining survival signaling through the mToR pathway (1, 2). Cytoplasmic URI is part of the Hsp90 and R2TP/prefoldin-like complex that assembles RNA polymerase II before nuclear translocation (3, 4). In the nucleus, URI functions as a transcriptional repressor that binds RPB5, the shared subunit of the RNA polymerases (5). Despite several reports demonstrating that URI binds assembling (3) and transcribing (6) RNA polymerase II, and key regulators of RNA polymerase II transcription (7, 8) and in conjunction with prefoldin-like protein ART-27, represses androgen receptor-dependent gene expression (9) in prostate cells, little is known about the mechanism of URI transcriptional repression. In Saccharomyces cerevisiae, URI binds the phosphorylated C-terminal domain (CTD) 2 of RNA polymerase II and affects the recruitment of the chromatin remodeling complex RSC (10).Here we show that in the nucleus URI interacts with KAP1 and the protein phosphatase PP2A. KAP1 is recruited on the DNA by zinc finger transcription factors containing a KRAB domain (KRAB-ZFP) (11,12). KAP1 functions as a scaffold for the recruitment of a repression complex that includes histone deacetylases (13), HP1 (heterochromatin protein 1) (14), and the histone methyltransferase SETDB1 (15). The assembly of the KAP1 repression complex is tightly controlled. SUMOylation of KAP1 is necessary for recruitment of the repression machinery. ATM phosphorylation of KAP1 on Ser 824 interferes with KAP1 SUMOylation and consequently, relieves the KAP1-mediated transcription repression through displacement of the repression compl...

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“…siRNA targeting sequences for L1ORF1 were designed by RNAi designer (Ambion), and two candidates (5¢-GTGTTAAGGG CAGCC AGAGA-3¢ and 5¢-GAGAACGCCACAAAGATAC-3¢) were selected and prepared as previously described Lu et al, 2013). To construct recombinant plasmid, the hairpin construct was designed for each sequence and shown as follows.…”

Section: Recombinant Plasmids Constructionmentioning

confidence: 99%

L1-ORF1p, a Smad4 Interaction Protein, Promotes Proliferation of HepG2 Cells and Tumorigenesis in Mice

Zhu

Feng²,

Yu³

et al. 2013

DNA and Cell Biology

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Long interspersed nucleotide element (LINE-1; L1) as an autonomous retrotransposon is localized usually in AT-rich, low-recombined, and gene-poor regions of genome. It is transiently activated in embryonic development and continuously activated in all tumor cells tested so far. Full-length L1 gene contains 5' untranslated region, two open reading frames (ORFs) encoded L1ORF1p and L1ORF2p, and a 3' terminal polyadenylation site. Compared with L1ORF2p, a protein encompassing reverse transcriptase and endonuclease activities, L1ORF1p remains to be elucidated. With liver cancer cells and tissues, the expression and sub-localization of L1ORF1p were investigated and shown that L1-ORF1p expresses just in liver cancer cells and tissues but not in normal liver cells and almost not in adjacent tissues. To characterize L1ORF1p, the strategies for over-expression and down-regulation of L1ORF1p in transfected cells were implemented. The phenomenon of promoting cell proliferation and colony formation was observed in transfected cells with L1ORF1p over-expression and vice versa. Down-regulation of L1ORF1p suppresses tumorigenesis in vitro and in vivo. Smad4 as an interaction protein of L1ORF1p is identified for the first time, while L1ORF1p is responsible for Smad4 sequestration in the cytoplasm. Thus, L1ORF1p contributed to tumorigenesis and may attribute to, at least partly, its participation in Smad4-signaling regulation.

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LINE-1 ORF-1p functions as a novel androgen receptor co-activator and promotes the growth of human prostatic carcinoma cells

Cited by 45 publications

References 33 publications

MEIS1 inhibits clear cell renal cell carcinoma cells proliferation and in vitro invasion or migration

MEIS1 inhibits clear cell renal cell carcinoma cells proliferation and in vitro invasion or migration

URI Regulates KAP1 Phosphorylation and Transcriptional Repression via PP2A Phosphatase in Prostate Cancer Cells

L1-ORF1p, a Smad4 Interaction Protein, Promotes Proliferation of HepG2 Cells and Tumorigenesis in Mice

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