IDDF2018-ABS-0126 The pseudogene DUXAP8 promotes pancreatic cancer cell proliferation and inhibites cell apoptosis by epigenetically silencing CDKN1A and KLF2

Abstract

Background Pseudogene has been shown to involve in human cancer biology, but their mechanisms of action are mainly undocumented. Current evidence suggested that pseudogene play a critical role in the regulation of pancreatic cancer cellular processes, such as proliferation, apoptosis, and metastasis. However, only a small proportion of these pseudogene has been functionally characterised. Methods By utilising publicly available pseudogene expression profiling data and other publicly available pseudogene expression profiling data, we screened out DUXAP8, whose expression is significantly increased in pancreatic cancer (PC) tissues. The quantitative reverse transcriptase PCR (qRT-PCR) was used to analyse the expression of DUXAP8 in 50 PC tissues and correspond adjacent normal tissues and three PC cell lines. Loss of function approaches was used to investigate the biological role of DUXAP8 both in vitro and in vivo. Bioinformatics analysis followed by qRT-PCR was performed to identify the putative targets of DUXAP8, which were further verified by RNA immunoprecipitation (RIP), Chromatin immunoprecipitation (ChIP), rescue experiments and western blotting assays. Results In this study, we analysed of GEO RNA sequencing data and other publicly available microarray data. We found that a pseudogene, DUXAP8, which expression was significantly up-regulated in PC tissues compared to adjacent normal tissues. Furthermore, qRT-PCR results verified that DUXAP8 is over-expressed in PC tissues. In vitro and in vivo assays of DUXAP8 alterations revealed a complexly integrated phenotype affecting cell growth and apoptosis. Mechanistically, DUXAP8 repressed underlying target gene CDKN1A and KLF2 transcription through binding to histone methyltransferase EZH2 and histone demethylase LSD1. Conclusions DUXAP8 is significantly up-regulated in PC tissues compared with adjacent normal tissues, suggesting that the ectopic expression of DUXAP8 was related to the tumorigenesis of PC. Mechanistic investigations showed that DUXAP8 could repress the tumour suppressors CDKN1A and KLF2 by recruiting EZH2 and LSD1, thereby affecting cell proliferation and apoptosis in PC. Taken together, our findings indicated that the pseudogene DUXAP8 might act as an oncogene in PC by silencing CDKN1A and KLF2 transcription by binding with EZH2 and LSD1, which may serve as a new therapeutic target in pancreatic cancer.