2010-2006
首页  科学研究  发表论文  2010-2006

Role of human noncoding RNAs in the control of tumorigenesis(Proc Natl Acad Sci USA, 2009, 106(31): 12956-12961)

Abstract

Related studies showed that the protein PSF represses proto-oncogene 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 proto-oncogene and activating transcription. Each of the 5 RNA fragments maps to a different human gene. The tumorigenic function of the hPSF-binding RNAs was tested in a human melanoma line and mouse fibroblast line, by determining the effect of the RNAs on formation of colonies in agar and tumors in mice. (i) Expressing in human melanoma cells the RNA fragments individually promoted tumorigenicity. (ii) Expressing in human melanoma cells a shRNA, which causes degradation of the endogenous RNA from which an RNA fragment was derived, suppressed tumorigenicity. (iii) Expressing in mouse NIH/3T3 cells the RNA fragments individually resulted in transformation to tumorigenic cells. (iv) A screen of 9 human tumor lines showed that each line expresses high levels of several hPSF-binding RNAs, relative to the levels in human fibroblast cells. We conclude that human hPSF-binding RNAs drive transformation and tumorigenesis by reversing PSF-mediated repression of proto-oncogene transcription and that dysfunctional regulation of human hPSF-binding RNA expression has a central role in the etiology of human cancer.

The 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 proto-oncogene and activating transcription (25). Mouse and human genomes encode homologous PSF proteins with ≈95% sequence identity, whereas theVL30–1gene 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.