The Molecular Mechanisms And Roles Of MiR-363-3p/SPAG5/CEP55 Axis In Promotion The Invasion And Metastasis Of Hepatocellular Carcinoma

Background: Primary liver cancer represents a mostly frequent malignant diseases all over the world and in China.Histopathologically,there is 70%-90% of primary liver cancer belongs to hepatocellular carcinoma(HCC) that is a highly invasive tumors.Some literatures had indicated that deregulation the cell cycle genes contributes to the carcinogenesis of hepatocellular carcinoma.Sperm-associated antigen 5(SPAG5),that is a microtubule-associated protein associated with spindles is essential in the cell growth.Overexpression of SPAG5 has been reported in several cancers and found its correlation with poor clinical outcome and adverse clinicopathological features.The upregulation of SPAG5 affected the response of cancer cells to chemotherapy.However,the clinical significance of SPAG5 and its role in HCC.It is still unclear that the exact roles of SPAG5 in hepatocellular carcinoma.Deregulation of microtubules and centrosome integrity is response for the initiation and progression of human cancers.Sperm-associated antigen 5(SPAG5)is essential for the spindle apparatus organization and chromosome segregation,but its role in hepatocellular carcinoma(HCC) remains undefined.Methods: Patients:Twenty-seven fresh HCC specimens were collected for determination of mRNA and protein levels of SPAG5 from The first Affiliated Hospital of Nanchang University and Sun Yat-sen University Cancer Center.A cohort of 298 paraffin-embedded HCC cases and another 93 HCC cases with venous metastases diagnosed between January 2010 to December 2014 was recruited either.None of the patients had received radiotherapy or chemotherapy before surgery.All samples were anonymous.This project was approved by Institute Research Ethics Committee of The first Affiliated Hospital of Nanchang University and Sun Yat-sen University Cancer Center.Clinical parameters and Statistical analysis:The Student's t-test was used for comparisons between groups.Kaplan–Meier analyses were used for survival analysis.Differences were considered significant for P-values less than 0.05.All data from three separate experiments are presented as mean ± SEM.models in vitro and in vivo: The expression of SPAG5 in HCC were examined in a large cohort of patients by RT-PCR,western blot and IHC.The clinical significance of SPAG5 was next determined by statistical analyses.The biological function of SPAG5 in HCC and the underlying mechanisms were investigated,using in vitro and in vivo models.Results: SPAG5 expression was increased in HCC and correlated with poor outcomes.High SPAG5 expression was associated with poor tumor differentiation,larger tumor size,advanced TNM stage,tumor vascular invasion and lymph node metastasis.In vitro and in vivo data showed that SPAG5 overexpression promoted tumor growth and metastasis,whereas SPAG5 knockdown led to the opposite phenotypes.SPAG5 interacted with centrosomal protein CEP55 to trigger the phosphorylation of AKT at Ser473.Inhibition of PI3K/AKT signaling markedly attenuated SPAG5-mediated cell growth.Furthermore,SPAG5 expression was suppressed by miR-363-3p which inhibited the activity of SPAG5 mRNA 3'UTR.Ectopic expression of SPAG5 partly abolished the miR-363-3p-caused cell cycle arrest and suppression of cell proliferation and migration.Conclusions: Collectively,these findings indicate that SPAG5 serves a promising prognostic factor in HCC and functions as an oncogene via CEP55-mediated PI3K/AKT pathway.The newly identified miR-363-3p/ SPAG5/CEP55 axis may represent a potential therapeutic target for the clinical intervention of HCC.