B7-H3 Regulates Epithelial Mesenchymal Transformation And Metastasis Of Lung Adenocarcinoma Cells Through AKT/SIRT1 Signaling Pathway

Background Lung adenocarcinoma accounts for more than 50% of non-small cell lung cancer,most patients with lung adenocarcinoma have distant metastasis at the time of diagnosis,and the prognosis is very poor,so elucidating the metastatic mechanism of lung adenocarcinoma has a very important clinical value.Epithelial-mesenchymal transition(Epithelial-mesenchymal transition,EMT))is the key mechanism that mediates tumor metastasis.B7-H3 is abnormally expressed in a variety of tumor tissues,including lung adenocarcinoma,and plays a key role in promoting EMT,migration and invasion of lung adenocarcinoma,but the specific signal mechanism is not clear.SIRT1(Sirtuin 1)is an evolutionarily conserved class III histone deacetylase((HDAC),)dependent on nicotinamide adenine dinucleotide(NAD+),which can directly regulate the EMT process through deacetylation.Our previous studies have shown that B7-H3 can regulate the expression of SIRT1,but whether the latter is involved in the B7-H3-mediated EMT process has not been reported.Objective To investigate the molecular mechanism of B7-H3 regulating EMT,migration and invasion of lung adenocarcinoma cells.Methods Using lung adenocarcinoma cell line A549 as the research object,we used CRISPR/Cas9 technology to target B7-H3 knockout in A549 cells,the knockout efficiency of B7-H3 was detected by western blots and RT-q PCR.The levels of SIRT1,T-Akt,p-Akt,ZEB1,E-cadherin,N-cadherin and vimentin in B7-H3 knockout cells and control cells were detected by western blots,and using transwell assay to analysis the effect of B7-H3 on the migration and invasion of knockout cells.SIRT1 of A549 cells was silenced with si RNA,and SIRT1,ZEB1,E-cadherin,N-cadherin and vimentin in SIRT1 silences cells were detected by western blot.The effect of SIRT1 on cell migration and invasion was detected by Transwell assay.Western blot was used to detect SIRT1 expression in A549 cells treated with PI3K/Akt inhibitor.Results Compared with control cells,E-cadherin protein was increased and p-Akt,SIRT1,ZEB1,N-cadherin,and Vimentin protein was decreased in A549 cells with B7-H3 knockout.and the results of transwell show that migration and invasion capabilities are weakened.In A549 cells interfered with SIRT1,the proteins of ZEB1,N-cadherin,and Vimentin decreased,while the proteins of E-cadherin increased,and the ability of migration and invasion decreased,which was consistent with the effect of knocking out B7-H3.The expression of SIRT1 in A549 cells was down-regulated after PI3K/Akt inhibitor treatment.Conclusions In lung adenocarcinoma cells,B7-H3 regulates EMT by activating the Akt/SIRT1 pathway,and further promotes its migration and invasion.Inhibition of B7-H3 can down-regulate EMT,suggesting that B7-H3 can be an effective target for the treatment of lung adenocarcinoma.