Expression And Significance Of MFN1 And MFN2 In ESCC Carcinogenesis

Background and purposeEsophageal cancer is a malignant tumor with the seventh highest incidence rate and the sixth highest mortality rate in the world.There are obvious differences in regional distribution and histological types.More than 90%of esophageal cancer in my country is ESCC,and Chaoshan area is one of the areas with high incidence of ESCC in my country.As an organelle with a double-layer membrane structure,mitochondria are important places for energy production and material metabolism in cells.One of the important characteristics of tumors is metabolic reprogramming,which is the key to tumor development.At the same time,the morphology of mitochondria also changes dynamically during tumor development.The previous research of the research group also found that in esophageal squamous cell carcinoma,the energy metabolism and morphology of mitochondria are often dysregulated.The morphology of mitochondria is regulated by the two opposite processes of division and fusion.Through division,a sufficient number of mitochondria can be produced,and fusion can promote the complementarity between damaged mitochondria and reshape mitochondria.Studies have shown that mitochondrial fusion protein 1/2(MFN1/2)in the process of promoting mitochondrial fusion will produce a more complete mitochondrial network,and can dilute the mitochondrial matrix to eliminate reactive oxygen species(ROS).And other damaged proteins,lipids,mitochondrial DNA(mt DNA)mutations,etc.Therefore,mitochondria with a larger and more complete structure can repair mitochondrial damage and maintain the normal biological function of mitochondria.In the past,studies on mitochondria in tumors often focused on the metabolism of various enzymes in mitochondria.There were few studies on mitochondrial fusion proteins.Therefore,we aimed to explore the role of mitochondrial fusion protein(MFN1/2)in the process of esophageal squamous cell carcinoma.It is expected to provide new evidence for discovering the molecular mechanism in the evolution of esophageal squamous cell carcinoma.Materials and methods(1)Database source:Download ESCC genome-wide expression profile chip data from GEO database,and download ESCC RNA-seq data from TCGA database.(2)Human tissue samples:Collected in the Cancer Hospital of Shantou University Medical College,a total of 105 surgical resection specimens of esophageal cancer patients(without radiotherapy/chemotherapy before surgery)were included.Samples of cancer,adjacent tissues and normal tissues were screened according to the results of HE staining.Finally,70 matched samples of three stages of ESCC were obtained.At the same time,collect fresh postoperative specimens of 13 patients with ESCC,take their ESCC tissues and matched normal mucosal tissues,and extract RNA.(3)Cell source:Human ESCC cell lines CSEC216,KYSE520,KYSE150 and human esophageal immortalized epithelial cell lines NE2 were selected.(4)Animal samples:Use the samples of the esophageal squamous cell carcinoma mouse model induced by 4NQO in our laboratory,and take samples with feeding weeks of 0,8,12,16,20,24,and 28 weeks.(5)HE staining:used to determine the pathological type,tumor invasion and differentiation of normal esophagus,adjacent tissues and esophageal cancer tissues.(6)Immunohistochemical staining:to detect the expression of MFN1 and MFN2 proteins in human esophageal squamous cell carcinoma tissues and normal esophageal mucosa;to detect the expression of MFN1 and MFN2 proteins in a mouse model of esophageal cancer.(7)RT-PCR:To detect the expression of MFN1 and MFN2 m RNA in human esophageal cancer tissues and cell lines.(8)Western blotting:used to detect the expression of MFN1 and MFN2 proteins in cell lines.(9)Immunofluorescence and confocal:used to observe the location,morphology and structure of MFN1 and MFN2 in esophageal cancer tissues and cell lines.Experimental result(1)MFN1 and MFN2 are highly expressed in the transcriptome database of ESCC.(P<0.01).(2)The expression of MFN1 and MFN2 m RNA in esophageal squamous cell carcinoma tissue increased,and the m RNA expression of the two had a significant correlation(r_s=0.692,P<0.001).(3)The expression of MFN1 and MFN2 protein gradually increased with the progress of the carcinogenesis of esophageal squamous cell carcinoma(P<0.001),and it also showed a high expression state in esophageal squamous cell carcinoma cell lines.(4)There is a high degree of positive correlation between the expression levels of MFN1and MFN2 proteins in the process of esophageal carcinogenesis(r_s=0.547,P<0.001).(5)In a mouse model of esophageal squamous cell carcinoma induced by 4NQO,the expression of MFN1 and MFN2 proteins increased during the carcinogenesis of mouse esophageal squamous cell carcinoma.ConclusionIn the process of carcinogenesis of esophageal squamous cell carcinoma,the expression of MFN1 and MFN2 gradually increase,and the expression levels of the two have a significant positive correlation,suggesting that the mitochondrial fusion process is overactivated in ESCC,and the two maybe synergistically promote the occurrence and development of tumors.