Construction Of A Prognostic LncRNA Signature Associated With Vascular Invasion In Hepatocellular Carcinoma And Study On The Function Of The Hub Gene BBOX1-AS1

Part Ⅰ:Construction of a ceRNA Network and a Prognostic lncRNA Signature associated with Vascular Invasion in HepatocellularCarcinoma based on Weighted Gene Co-Expression Network Analysis Objective:Understanding risk factors for vascular invasion(Ⅵ)is crucial for assessing the risk of recurrence and overall prognosis of hepatocellular carcinoma(HCC).This study aimed to construct a prognostic long non-coding RNA(lncRNA)a ceRNA Network and signature associated with vascular invasion in HCC.Methods:Differentially expressed genes(DEGs)of HCC patients associated with VI were identified by analyzing data from TCGA.Weighted gene co-expression network analysis(WGCNA)was used to identify associations between gene expression modules and clinical features.A Ⅵ-related prognostic lncRNA signature was then stablished using univariate,LASSO and multivariate Cox proportional hazards regression analyses.Based on the hub modules identified by the WGCNA,we constructed a Ⅵ-related lncRNA-miRNA-mRNA ceRNA network and screened hub lncRNAs for further research.Results:The key module related to VI and OS was identified using WGCNA,after which a prognostic model consisting of nine lncRNAs was established,and verified using timedependent receiver operating characteristic(ROC)curve analysis.The results showed that the lncRNA prognostic signature could predict the prognosis of HCC patients in all these data sets,accurately.Conclusions:The Ⅵ-related lncRNA signature established in this study can be used to predict the clinical outcomes of HCC patients.In addition,we constructed a Ⅵ-related lncRNA-miRNA-mRNA ceRNA network which probably reflect all the interactions between these genes.Part Ⅱ:Relationship between expression of BBOX1-AS1 and clinical features and prognosis of HCC patientsObjective:To screen the most hub gene BBOX1-AS1 from the above vascular invasionrelated lncRNA prognostic model.The expression level of BBOX1-AS 1 was detected in the samples of 83 patients with HCC,and the correlation between the expression level of BBOX1-AS1 and the clinical characteristics of HCC patients and the prognosis of patients was analyzed based on the clinical characteristics and follow-up data of patients.Methods:83 tumor and paracancer tissue specimens of HCC patients who underwent tumor resection were collected in the Liver Surgery Center of Tongji Hospital,Wuhan.All the specimens were confirmed by the pathology department of Tongji Hospital.RNA was extracted from frozen tissues and the expression levels of 9 genes in the vascular invasionrelated lncRNA prognostic model were analyzed by qRT PCR.The relationship between BBOX1-AS1 expression and important clinical features and prognosis of hepatocellular carcinoma patients was investigated by analyzing the data of TCGA and 83 HCC patients in tongji cohort.Results:1.The hub gene BBOX1-AS1 was screened from the vascular invasion-related lncRNA prognostic model;2.BBOX1-AS1 is highly expressed in liver cancer tissues,and the high expression of BBOX1-AS1 suggests poor prognosis of HCC patients;3.The expression level of BBOX1-AS1 was positively correlated with tumor stage and grade,and BBOX1-AS1 was a robust independent prognostic factor.Conclusions:Vascular invasion-related lncRNA BBOX1-AS 1 is highly expressed in liver cancer tissues,and the high expression of BBOX1-AS1 suggests higher stage and grade of tumor and worse prognosis.Part Ⅲ:Oncogenic lncRNA BBOX1-AS1 promotes PHF8-mediated autophagy and elicits sorafenib resistance in hepatocellular carcinoma Objective:Some long non-coding RNAs(lncRNAs)have been documented to be involved in cancer progression and anticancer drug resistance in hepatocellular carcinoma(HCC).Thus,approaches designed to target these genes may facilitate the development of promising strategies for treating HCC.Previously,we showed that lncRNA BBOX1-AS1 was highly expressed and might play an oncogenic role in HCC.However,the potential functions and mechanisms through which BBOX1-AS1 regulates HCC progression and drug resistance remain unclear.Methods:Firstly,the function of BBOX1-AS 1 on the progression,autophagy and drug resistance of HCC was demonstrated HCC cell lines.Then,the mechanism was explored by a series of experiment including FISH,RIP and dual-luciferase reporter assays.Results:In this study,we for the first time revealed that BBOX1-AS 1 could promote tumor progression,autophagy and drug resistance by upregulating PHF8 in HCC cells.Mechanistically,BBOX1-AS1 enhanced the stability of PHF8 mRNA by targeting the PHF 8 inhibitor miR-361-3p to regulate tumor progression and autophagy in HCC.The functional rescue experiments showed that PHF8 acted as a key factor in regulating the biological effects induced by BBOX1-AS1 and miR-361-3p in HCC,indicating that BBOX1-AS1 promotes tumor progression and sorafenib resistance by regulating miR-361-3p/PHF8.Finally,mouse tumor models and patient-derived organoid models were established to further confirm these findings.Conclusions:Taken together,the results demonstrate that BBOX1-AS1 promotes HCC progression and sorafenib resistance via the miR-361-3p/PHF8 axis.