EGFR Promote Perineural Invasion In Salivary Adenoid Cystic Carcinoma Cells Via Activation Of PI3K/AKT And MEK/ERK Signaling Pathways

Backgroud:Salivary adenoid cystic carcinoma(SACC)is a common adcnocarcinoma that originates from the salivary glands,which accounts for 24%of salivary gland malignancies.Epidermal growth factor receptor(EGFR)plays one of key role in tumor progression,whose downstreams-PI3K/AKT and MEK/Erk pathways are associated with salivary adenoid cystic carcinoma(SACC)metastasis,progression and perineural invasion(PNI).However,study on the molecular mechanism of SACC is incomplete.Objective:To verify whether the PNI of SACC was through EGFR,PI3K/AKT,MEK/Erk pathways,whether EGFR inhibitors act on targets of PI3K/AKT and MEK/Erk,and whether the targets of PI3K/AKT and MEK/Erk superimposed on pathways can inhibit the invasion of SACC.Methods:We investigated the expression of NGF,EGF,Vimentin,MMP2,E-cadherin,EGFR,Akt,p-Akt,ERK and p-ERK by immunohistochemistry and immunofluorescence in salivary gland adenoid cystic tissues and SACC-S3 cell lines.Targeted on EGFR,AKT and MEK in tumor pathway were interfered by adding inhibitors.Cytological experiments were carried out to verify that the target proteins were closely related to PNI.Superimposition of inhibitors of AKT and MEK proteins were carried out,which were closely related to PNI on downstream of EGFR in SACC.AKT and MEK were inhibited by EGFR intervention.Western blot were carried out to verify the inhibition of relevant signal pathways.Finally,SACC-83 cells were injected into Balb/c-nu nude mice,the inhibition effect of PD153035(EGFR inhibitor),LY294002(PI3K inhibitor)and PD98059(MEK inhibitor)was evaluated in vivo,then observing tumor volume,hanging wrist,claudication due to PNI.Results:Our results showed that EGFR are improving in viability,migration,and invasion of SACC.The PNI was affected via the PI3K/AKT and MEK/Erk pathways,which were both launched by EGFR.The epithelial-mesenchymal transition(EMT)and PNI were regulated by the EGFR,PI3K/AKT and MEK/Erk pathways.Our findings demonstrated the importance of suppressed EGFR、PI3K/AKT and MEK/Erk signaling pathways in PNI of SACC by co-culture and neural-tumor in vitro.Our results demonstrated the inhibitors of EGFR,PI3K/AKT,and MEK/Erk suppressed the proliferation,migration and PNI of SACC-83 cells though the PI3K/AKT or MEK/Erk pathway,which found that inhibition of EGFR was reduced EMT in SACC by inhibiting PI3K/AKT and MEK/Erk signaling pathways.Our results suggested the therapeutic targets inhibited PNI of SACC by PI3K/AKT inhibition and MEK/Erk inhibition.In animal model,we injected PD153035(EGFR inhibitor),LY294002(PI3K inhibitor)or PD98059(MEK inhibitor),and found them decrease the PNI and growth of SACC transplanted tumors,suggesting intervention of EGFR,PI3K or MEK can inhibit the occurrence and development of SACC in vivo.Conclusion:We confirmed that SACC PNI affected through EGFR,PI3K/AKT,MEK/Erk pathway by immunohistochemistry.And confirmed EGFR inhibitor acted on both PI3K/AKT and MEK/Erk targets by cytological studies.We also found the inhibitory effect of PNI and EMT via EGFR induced by AKT or MEK in SACC.The study also confirmed superimposed inhibition on EGFR and its downstream AKT and MEK to clarify the related pathway expression in PNI of SACC.Finally,animal experiments showed that targeted interventions with EGFR,PI3K or MEK can significantly inhibit the growth of SACC transplanted tumors and PNI in vivo.In summary,these results indicate that targeted intervention of EGFR,PI3K or MEK can be explored as a potential clinical treatment against SACC,which provided novel idea for the clinical treatment to SACC by using EGFR-targeted drugs such as cetuximab and nimotuzumab.