Role of human noncoding RNAs in the control of tumorigenesis

Abstract

Related studies showed that the protein PSF represses protooncogene transcription, and VL30 -1 RNA, a mouse noncoding retroelement RNA, binds and releases PSF from a proto-oncogene, activating transcription. Here we show that this mechanism regulates tumorigenesis in human cells, with human RNAs replacing VL30 -1 RNA. A library of human RNA fragments was used to isolate, by affinity chromatography, 5 noncoding RNA fragments that bind to human PSF (hPSF), releasing hPSF from a protooncogene and activating transcription. T he protein PSF (1) contains a DNA-binding domain (DBD) that binds to the regulatory region of a proto-oncogene and represses transcription, and 2 RNA-binding domains (RBDs) that bind VL30-1 RNA, releasing PSF from a repressed protooncogene and activating transcription (2-5). Mouse and human genomes encode homologous PSF proteins with Ϸ95% sequence identity, whereas the VL30-1 gene belongs to a family of mouse noncoding retroelement genes (6) that is not present in the human genome (7). To determine whether the PSF/RNA regulatory mechanism functions in human cells, a library of RNA fragments was constructed from the nuclear RNA repertoire of a human tumor cell, and the library was screened by affinity chromatography for RNAs that bind to human PSF (hPSF). The screen identified 5 hPSF-binding noncoding RNA fragments that release hPSF from a repressed proto-oncogene and activate transcription, similar to VL30-1 RNA. Each human RNA fragment maps to a matching sequence in a different human gene. The following experiments show that human hPSF-binding RNAs are involved in the control of tumorigenesis. Results Cloning and Mapping Human RNA Fragments That Bind to hPSFProtein. The finding that VL30-1 RNA, a mouse retroelement RNA that is not encoded in the human genome, binds selectively to hPSF protein and reverses repression of proto-oncogene transcription (2-5), prompted a search for human RNAs that have a similar function as VL30-1 RNA. The procedure involved synthesizing a library of RNA fragments from the nuclear RNA repertoire of a human melanoma line and selecting by affinity chromatography RNA fragments that bind to hPSF. The procedure yielded 5 such RNA fragments, 4 of which were mapped, by sequence identity, within 1 of the following genes: L1PA16, a non-LTR retroelement gene (8); MER11C, a LTR retroelement gene (9); MALAT-1, a noncoding gene (10, 11); or HN, a mitochondrial gene coding for the peptide humanin (12); a fifth fragment, not shown in the figure, maps to a region that has not been characterized ( Fig. 1 and SI Text).The sequence of the HN RNA fragment is 100% identical to a sequence in the mitochondrial 16S ribosomal RNA gene and is 85% identical to positions 21947595-21947823 on nuclear chromosome 17. Further testing showed that the HN RNA fragment is derived from the mitochondrial HN RNA and not from the nuclear RNA (SI Text). The mitochondrial HN RNA might be translocated to the nucleus or derived from a mitochondrial contamination in the nuclear preparation.Release of hPSF from ...

Overexpression of long non-coding RNA H19 is associated with unfavorable prognosis in patients with colorectal cancer and increased proliferation and migration in colon cancer cells

“…A previous study suggested that a number of lncRNAs may be involved in the development and metastasis of cancer (7). LncRNA-imprinted maternally expressed transcript (non-protein coding) (H19), initially reported in 1991 by Bartolomei et al (8), was identified to be expressed at increased levels in extraembryonic tissues, embryonic tissues and the majority of fetal tissues; however, the expression level of lncRNA H19 is markedly decreased following birth (9).…”

Long non-coding RNAs in cancer

“…This result implies that MALAT1 regulates the post-transcriptional processing or modification of RNA. MALAT1 binds to PSF (polypyrimidine tract binding protein-associated splicing factor) and prevents PSF from binding to the transcriptional regulatory region of the oncogene CAGE6, which stimulates the abundant transcription of GAGE6 and thus promotes tumorigenesis [63].…”

Binding of LINE-1 RNA to PSF transcriptionally promotes GAGE6 and regulates cell proliferation and tumor formation in vitro

“…The present study focused on the role L1 RNA may serve in lung carcinogenesis without HBV infection, which is different from HBx-LINE-1 causing hepatocarcinogenesis (16). It has previously been demonstrated that L1PA16 RNA binds to PSF protein, which is part of the LINE retrotransposons family (10). Therefore, L1 RNA, although it shares no sequence similarity with L1PA16 RNA, may bind to PSF.…”

“…The RBD and DBD function independently and their novel mechanisms for reversible gene transcription mediated by PSF protein and noncoding RNA have been investigated. It has been demonstrated that their transcription is activated by the release of PSF protein from the repressed proto-oncogene G antigen 6 (GAGE6) by five PSF-binding noncoding RNA fragments (10). This indicates that the regulatory activity of noncoding RNA in tumorigenesis occurs through its binding to the RBD of PSF and the consequent release of the transcriptionally repressed proto-oncogene from its DBD.…”