| Objectives:To determine the expression of m~6A methyltransferase METTL14 in thyroid cancer,to analyze the relationship between the expression of METTL14 and the clinicopathological characteristics of thyroid cancer patients,to study the effect of METTL14 on the biological function of thyroid cancer cells in vitro,and to explore the downstream regulation mechanism of METTL14 in thyroid cancer.Methods:40 pairs of blood samples from patients with thyroid cancer and normal controls were collected to detect,the expression of METTL14 by qPCR.In addition,the expression of METTL14 in thyroid cancer tissues of 56 patients with thyroid cancer and non-thyroid cancer tissues of 36 patients without thyroid cancer was detected by immunohistochemical method,and the relationship between METTL14 expression and clinicopathological features was analyzed.Combined with the clinical information of TCGA database,the relationship between the expression of METTL14 and the prognosis of patients was analyzed.The METTL14 knock-down thyroid cancer cell lines were constructed,and the changes of m~6A expression in the cell lines were detected by m~6A methylation quantitative detection kit.CCK8,Transwell and scratch test were used to detect and observe the changes of cell biological function.The downstream target genes related to METTL14 were screened by bioinformatics analysis,and the expression changes of downstream target genes were verified by qPCR experiment after knocking down METTL14 in thyroid cancer cells.Results:The results of qPCR detection showed that the expression level of METTL14 m RNA in blood samples of cancer patients was higher than that of normal blood samples(P<0 01).The results of immunohistochemistry showed that among the 56 cases of thyroid cancer tissues,45 cases were positive for METTL14,with a positive rate of 80.4%(45/56),and 20 cases of non-cancerous tissues were positive for METTL14,with a positive rate of 52.6%(20/38).The difference of positive rate between thyroid cancer tissues and non-cancerous tissues was statistically significant(P<0.01).Combined with the analysis of clinical data,there was no significant correlation between the expression of METTL14 and age,sex,pathological classification,or TNM stage(P>0.05).Combined with clinical information analysis of TCGA database,it was found that the high expression of METTL14 was associated with poor prognosis of thyroid cancer patients.(2)After knocking-down＿METTL14 in thyroid cancer cells TPC-1 and SW-579,it was found that the level of m6A modification and the ability of cell proliferation,invasion and migration decreased significantly(P<0.05).(3)Three signaling pathways related to proliferation and migration were screened out by GSEA analysis,cancer-related pathway,m TOR pathway and MAPK pathway.According to the genes related to KEGG signaling pathway,the downstream genes related to METTL14 were screened out,VCAN,ENOPH1,SLC3A2 and FN1.Correlation analysis showed that there was a significant positive correlation between METTL14 expression and VCAN,ENOPH1(both P<0.001).There was no significant correlation between SLC3A2,FN1 and METTL14(both P>0.05).Furthermore,the expression of VCAN,ENOPH1,SLC3A2 and FN1 decreased significantly after knocking-down METTL4 in thyroid cancer cells.Conclusions:(1)METTL14 is highly expressed in thyroid cancer,and the high expression of METTL14 is related to the poor prognosis of thyroid cancer patients.(2)METTL14 can promote the proliferation,migration and invasion of thyroid cancer cells.(3)VCAN,ENOPH1,SLC3A2 and FN1 are downstream target genes of METTL14 in thyroid cancer. |
