Effect Of EBV On The Expression Of MAP9 In EBV-associated Gastric Carcinoma

Objective: The aim of this study is to explore the expression of MAP9(Microtube-associated protein 9)in EBV-associated gastric carcinoma(EBVa GC)and the effect of EBV encoding latent genes on MAP9,and to further study the roles of MAP9 in the occurrence of EBVa GCMethods: The m RNA expression of MAP9,PLK1(Polo-like kinase 1),and AURKA(mitotic kinases Aurora A,AURKA)genes were detected by real time-q PCR.Bisulfite genome sequencing(BGS)in combination with TA clone were used to detected methylation of MAP9 in 6 gastric cancer cell lines.The expression of MAP9 protein in cell lines and tissues was detected by western blotting and immunohistochemistry.Latent membrane protein 2A(LMP2A)and EBER1(EBV-encoded RNA)overexpression gastric cancer cell line models were established by plasmid transfection.Results:(1)The transcript level and protein level of MAP9 gene in EBV-associated gastric cancer cell line was higher than that of EBV negative gastric carcinoma cell line(0.66±0.39、0.00±0.00,t=5.831,P<0.0001;0.54±0.38、0.18±0.19,t=3.430,P=0.0265).No significant difference in transcriptional levels of PLK1 and AURKA were observed in EBV-negative and EBV-associated gastric cancer cell lines(0.54±0.50 、0.18±0.13,t=1.219,P=0.2897;6.26±4.26、1.83±0.85,t=1.766,P=0.1522).(2)The methylation rate of EBV-negative gastric cancer cell lines was higher than that of EBV-associated gastric cancer cell lines(0.40%±0.46% 、 80.00%±15.39%,t=8.957,P=0.0009).(3)There was no significant difference in the positive rate of MAP9 protein between EBVn GC tissues and EBVa GC tissues,(P=0.746).(4)Overexpression of LMP2 A and EBER1 has no obvious effect on the expression of MAP9.Conclusion:(1)The transcript level and protein level of MAP9 gene in EBV-positive gastric cancer cell lines were significantly higher than those in EBV-negative gastric cancer cell lines,suggesting that EBV infection can regulate the expression of MAP9 gene and further affect the proliferation of cancer cells.(2)The methylation status of MPA9 gene promoter region was different in EBV-positive gastric cancer and EBV-negative gastric cancer cell lines,suggesting that EBV infection can cause the methylation status of MAP9 gene promoter region to change.Hypermethylation of the promoter region of the MAP9 gene is one of the reasons for inhibiting the decrease of the gene transcription level.(3)There was no significant difference in the positive rate of MAP9 protein between EBVa GC tissues and EBVn GC tissues,suggesting that there may be other more complicated regulatory pathways for MAP9 expression in gastric cancer tissues.(4)The two coding latent genes of EBV,LMP2 A and EBER1,had no significant effect on the expression of MAP9.