Mechanisms By Which UPF3B Promotes The Proliferation Of Hepatocellular Carcinoma Cells Through PI3K/AKT/mTOR Signaling Pathway

Object: RNA-binding proteins are a class of proteins that function by binding to each other with different types of RNA and are able to control nucleotide metabolism and gene expression.The RNA-binding protein UPF3 B has been shown to be dysfunctional in association with cancer,but its role in Hepatocellular carcinoma development remains poorly investigated.Methods: The expression pattern of UPF3 B in pan-carcinoma and HCC and its relationship with the prognosis of HCC patients were analyzed in the TCGA database.The expression level of UPF3 B was knocked down or up-regulated by si RNA or plasmid,respectively,in HCC cells.Cell proliferation ability was tested using Ed U and plate colony formation assay.Enrichment analysis of the Hallmark gene set was performed according to the expression level of UPF3 B in the TCGA-LIHC database.Western blot assay was used to detect the correlation between UPF3 B and PI3K/AKT/m TOR signaling pathway-related protein expression.HCC cells were treated with PI3K/AKT/m TOR signaling to detect their effects on the expression of UPF3 B and cell proliferation.Results:(1)The expression profile of UPF3 B in various cancers was evaluated based on RNA sequencing data in the database TCGA,and UPF3 B was found to be highly expressed in various cancers(P < 0.05).(2)Analysis of the sequencing data of UPF3 B transcripts in the TCGA-LIHC database showed that UPF3 B was significantly highly expressed in HCC tissues compared with normal liver tissues(P < 0.001).(3)Univariate and multivariate Cox analysis of the association between UPF3 B and clinical characteristics(HR:2.168,95% CI:1.260 – 3.700,P < 0.01;HR:1.105,95% CI:1.043 – 1.170,P < 0.001)showed that high UPF3 B expression was associated with poor prognosis in HCC patients.(4)KEGG analysis showed enrichment in the cell cycle gene set in the highly expressed UPF3 B group.Knockdown of UPF3 B by si RNA inhibited the proliferation of Hep G2 and MHCC97 H cells(P < 0.01),and transfection of plasmid vectors containing UPF3 B into HCC cell lines Hep3 B,SNU-387,and Hu H7 up-regulated UPF3 B showed the opposite effect(P < 0.001).(5)Enrichment analysis of the Hallmark gene set showed that the UPF3 B high expression group was significantly enriched in the m TORC1 signaling pathway and the PI3K/AKT/m TOR signaling pathway.Western blot analysis showed that knockdown of UPF3 B significantly decreased the expression of PI3K/AKT/m TOR signaling pathway-related proteins(phosphorylated AKT and phosphorylated S6),and overexpression of UPF3 B showed the opposite effect.Addition of PI3K/AKT/m TOR signaling pathway inhibitors,namely rapamycin(m TORC1 inhibitor)and MK2206(AKT inhibitor),significantly reduced the proliferation ability of HCC cells.Conclusion: UPF3 B is highly expressed in HCC and is associated with poor prognosis,which can promote the proliferation of HCC cells by regulating PI3K/AKT/m TOR signaling pathway.UPF3 B may be a novel biomarker and therapeutic target for HCC.