LMP1 Induced By Nicotine Suppressed NESG1 To Stimulate NPC Migration And Invasion

Background and purposeNasopharyngeal carcinoma(NPC)is one of the most common malignant tumors in China and Southeast Asian countries.The main causes of NPC are considered to be related to diet,EB virus exposure and gene factors.LMP1 is a coding protein related to EB virus.It is often reported to have carcinogenic effects on EB virus-related cancers,including nasopharyngeal carcinoma.LMP1 can promote invasion and metastasis of nasopharyngeal carcinoma cells by regulating various signaling pathways.The above studies indicate that LMP1 plays an important role in the pathogenesis of nasopharyngeal carcinoma.In a recent study,smoking was considered to be a non-viral risk factor for the development of nasopharyngeal carcinoma.Nicotine,the main component of tobacco,has been proved to cause cancer proliferation,apoptosis,metastasis and chemotherapy.Alpha 7 nAChR is one of the 16 different subunits of nicotinic acetylcholine receptor.It is mainly expressed in the airway and plays an important role in regulating nicotine.However,the molecular mechanism of nicotine-induced metastasis of nasopharyngeal carcinoma remains unclear.NESG1 is a tumor suppressor gene specifically expressed in nasopharyngeal epithelium.It is obviously low expressed in nasopharyngeal carcinoma tissue and can be used as a predictor of adverse prognosis of nasopharyngeal cancer patients.However,the molecular mechanism in nasopharyngeal cancer is still unclear.MiR-1254 has been reported as an anti-cancer molecule in many tumors,but its molecular mechanism in nasopharyngeal carcinoma are still unclear.This study aims to provide a new molecular mechanism for the pathogenesis of invasion and metastasis of nasopharyngeal carcinoma.Research MethodThe expression levels of microRNA-1254,HDGF and NESG1 in nasopharyngeal mucosa and nasopharyngeal carcinoma tissues were detected by RT-q PCR and in situ hybridization.The correlation between the expression of microRNA-1254 in nasopharyngeal carcinoma tissues and the pathological parameters and prognosis of nasopharyngeal carcinoma patients was analyzed by statistical method.The stable overexpressing microRNA-1254 and its negative control nasopharyngeal carcinoma cell lines were constructed.Transwell,Boyden and scratch tests were carried out to detect the invasion and metastasis ability of the cells,and liver envelope experiments were carried out to verify the changes of the invasion and metastasis of the over-expression of microRNA-1254 cells in vivo.The regulation signaling of microRNA-1254,HDGF/DX5 complex,NESG1,nicotine and LMP1 was analyzed by Western blotting.The target genes of microRNA and microRNA-1254 mediated by NESG1 were detected by microRNA chip and luciferase reporter gene assay,respectively.We respectively used ChIP,EMSA and CO-IP experiments to validate DNA-protein binding complexes and protein-protein binding complexes.Research ResultWe observed that microRNA-1254,as a tumor metastasis suppressor,inhibited the metastasis of nasopharyngeal carcinoma by down-regulating the feedback loop of HDGF/DDX5/beta-catenin/TCF4/ZEB 1 and inhibiting the signal of epithelial mesenchymal transformation(EMT).In addition,we observed that microRNA-1254 inactivated HDGF/DDX5/beta-catenin/c-Myc-mediated transcriptional inhibition and formed a feedback loop to induce its self-expression.In addition,NESG1 induces the expression of microRNA-1254 by inhibiting PI3K/Akt/c-Myc pathway,and stimulates its expression by down-regulating the transcription inhibition of NESG1 promoter mediated by NESGl/c-JUN complex,which further reduces the EMT signal and inhibits the migration and invasion of nasopharyngeal carcinoma.Finally,we observed that nicotine induced LMP1 by regulating alpha 7nAchR/NF-?b signal reversed the NESG1-mediated complex signal network of miR-1254/HDGF/DDX5/beta-catenin/TCF4/ZEB1/c-Myc/c-JUN,and promoted the metastasis of nasopharyngeal carcinoma.In clinical samples,the expression of HDGF was negatively correlated with the expression of miR-1254,which was a negative prognostic factor,and positively correlated with NESG1.ConclusionThis study provides a new mechanism for nicotine-induced LMP1 to regulate the complex signaling network between NESG1/miR-1254/HDGF/DDX5/?-catenin/TCF4/ZEB1/c-Myc/c-JUN.