Comparative Proteomics Study On Cervical Lymph Nodes Of Radioiodine-refractory Thyroid Cancer And Well Differentiated Thyroid Cancer And Preliminary Screening Of Interest Protein

Introduction: To search for the differential proteins between well differentiated thyroid cancer and radioiodine-refractory differentiated thyroid cancer and study the pathogenesis of radioiodine-refractory differentiated thyroid cancer,which might provide potential molecular target for radionuclide therapy.Methods: The study collected 3 metastatic lymph nodes from patients with differentiated thyroid cancer and 3 metastatic lymph nodes from patients with radioiodine-refractory differentiated thyroid cancer from nuclear medicine department,the first affiliated hospital of Chongqing Medical University.Differentiated proteins were detected by iTRAQ technology coupled with Mass Spectrometry.GO function annotation and KEGG signal pathway analysis of differential proteins were performed by bioinformatics methods.Besides,parts of the differential proteins were verified with the use of TCGA and TCPA database.On top of that,TMpredwas used to predict the tertiary structure of proteins in order to select structurally appropriate proteins.Immunohistochemical was performed to detect the location of interest protein.Furthermore,up-regulating the interest protein by lentiviral transfection and measure the expression of sodium iodine symporter by western blotting.Results: The study obtained 665 differential proteins in total(327proteins were significantly up-regulated and 338 proteins were significantly down-regulated in radioiodine-refractory differentiated thyroid cancer).Differential proteins function as regulating the activity of transporters and enzymes,and involve in many biological processes,including cellular metabolism.Differential proteins were rich in metabolism process,focal adhesion,and other signal pathways.TMpred suggested that there were several transmembrane domains in tertiary structure of CHI3L1.CHI3L1 was confirmed to locate on the cytomembrane and cytoplasm by immunohistochemical and it was significantly up-regulated in radioiodine-refractory differentiated thyroid cancer comparing to differentiated thyroid cancer.According to western blotting,the expression of sodium iodine symporter was significantly inhibited in CHI3L1over-expression stable transfectant compared with differentiated thyroid cancer.In addition,MEK/ERK/1/2 signal pathway was activated in CHI3L1 over-expression stable transfectant.Discussion: Differential proteins,including ECM1,CHI3L1,LAMA5,14-3-3 eta,CDC42,RAC2,MYL9 and so on,involve in tumor angiogenesis,invasion,metastasis,and cell dedifferentiation processions generally.CHI3L1,ECM1,and CDC42 could promote tumor progression by interacting with some proteins in MAPK signal pathway.Transmembrane protein CHI3L1 might be the potential molecular target of radionuclide therapy for radioiodine-refractory differentiated thyroid cancer.