The Roles And Mechanism Of Pseudogene-derived RNA In Onset And Progression Of Liver Cancer

Liver cancer is one of the most common malignant tumors.Recently,although great improvements have been achieved in diagnosis and therapy of liver cancer,the prognosis of patients with liver cancer is still unsatisfactory.Non-coding RNAs(nc RNAs)are a class of widely spread RNA molecules.Despite nc RNAs do not code for proteins,they play key roles in various biological processes.Pseudogene-derived RNAs are a group of nc RNAs,which are transcribed from pseudogenes.Recent studies have suggested that numerous pseudogene-derived RNAs are frequently aberrantly expressed in human cancers and their dysregulation is closely linked to cancer initiation and progression.To date,a systematic study regarding the expression,function and detailed mechanism of pseudogene-derived RNA in liver cancer remains absent.To screen out potential pseudogene-derived RNAs associated with onset and progression of liver cancer,we analyzed the expression,prognostic and diagnostic values of pseudogene-derived RNAs in liver cancer by multi-dimensional analysis.Five candidate pseudogene-derived RNAs(BMS1P8,DUXAP9,UBE2SP2,GOLGA2P7,UBE2SP1)were obtained.The five candidate pseudogene-derived RNAs were significantly upregulated in liver cancer,and their upregulation indicated poor prognosis,and they possessed significant diagnostic values for liver cancer.In vitro assays demonstrated that,among the five candidate pseudogene-derived RNAs,UBE2SP1 had the strongest effects in promoting growth and metastasis of liver cancer cells in vitro.We also showed that UBE2SP1 expression was markedly increased in liver cancer cells and clinical tissue samples compared with their corresponding normal controls,and UBE2SP1 possessed significant diagnostic value in liver cancer.UBE2SP1 expression was closely correlated with progression and relapse of liver cancer.Moreover,in vivo assays also showed that UBE2SP1 facilitated growth and metastasis of liver cancer cells.We demonstrated that UBE2 S was the parental gene of UBE2SP1 by sequence alignment.UBE2SP1 enhanced expression and function of UBE2 S in liver cancer.Lnc Locator prediction and RNA nuclear/cytoplasmic separation test together indicated that UBE2SP1 was mainly located in cytoplasm.mi R-331-3p,mi R-761,mi R-3619-5p and mi R-214-3p were four common mi RNAs that could potentially bind to UBE2SP1 and UBE2 S.Subsequently,we confirmed that UBE2SP1 promoted UBE2 S by suppressing mi R-214-3p in liver cancer.Furthermore,we also explored the detailed mechanism responsible for UBE2SP1 upregulation.By combination of bioinformatic analysis and experimental validation,we found that E2F1 could bind to the promoter of UBE2SP1 and increased UBE2SP1 expression in liver cancer.We also found that dysregulation of histone deacetylation accounted for UBE2SP1 upregulation in liver cancer.Collectively,we obtained five pseudogene-derived RNAs(BMS1P8,DUXAP9,UBE2SP2,GOLGA2P7 and UBE2SP1)that might serve as independent prognostic and diagnostic biomarkers;we ascertained that UBE2SP1 significantly promoted in vitro and in vivo growth and metastasis of liver cancer cells by increasing UBE2S;we found that mi R-214-3p was involved in UBE2SP1-mediated UBE2 S upregulation in liver cancer;we confirmed that dysregulation of E2F1 and histone deacetylation accounted for UBE2SP1 overexpression in liver cancer.These findings not only provide potential therapeutic targets and promising prognostic and diagnostic biomarkers for liver cancer but also furnish route for future studies about roles and mechanisms of pseudogene-derived RNAs in human cancers.Besides,we also constructed HBV and vascular invasion-related pseudogene-derived RNA-mi RNA-m RNA networks,which lay foundation for studying the function and mechanism of pseudogene-derived RNA in HBV-related liver cancer and vascular invasion of liver cancer.