Role of human noncoding RNAs in the control of tumorigenesis

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.