| Purpose:The application of bioinformatics technologies and immunohistochemistry to detect the expression of m6A modified reading protein YTHDC2 in ovarian cancer tissues and its relationship with clinicopathological characteristics and possible mechanisms of action will provide a theoretical basis for further research.Methods:The expression of YTHDC2 gene in ovarian cancer was analyzed by GEPIA and Oncomine database,and the survival analysis of YTHDC2 gene was analyzed by Kaplan Meier plotter as an online software;The RNA-seq data and corresponding clinical data of ovarian cancer samples in TCGA database were downloaded from UCSC Xena website.The 64 bit "R" software was used to run "survival ROC"package to draw time-dependent receiver operating characteristic curve(ROC curve)and evaluate the accuracy of YTHDC2 in the prognosis of ovarian cancer.Through the post-transcriptional regulation prediction website POSTAR,the downstream regulatory genes of YTHDC2 were excavated,and the m6A methylation modification database SRAMP was used to predict the information of the FLNA methylation sites of downstream target genes of YTHDC2,and the mechanism of action was analyzed.Finally,immunohistochemistry(Immunohistochemistry,IHC)was used to detect the expression of YTHDC2 and FLNA in 70 cases of epithelial ovarian cancer(EOC)and 25 cases of normal ovarian tissue.Analysis of the relationship between YTHDC2、FLNA expression and clinicopathological characteristics,To explore the clinical significance and possible mechanism of YTHDC2 gene in EOC.Results:(1)The Oncomine database screened and found 13 studies on the differential expression of YTHDC2 gene in ovarian cancer,including 3399 specimens.A statistical analysis of the results of these 13 studies showed that YTHDC2 was under-expressed in ovarian cancer,compared with normal ovarian tissue.,The difference was statistically significant(P<0.05).The GEPIA database screened 426 samples of ovarian cancer tissues and 88 normal ovarian tissues.Statistical analysis showed that the expression of YTHDC2 in ovarian cancer was significantly lower than that of normal ovarian tissues,and the difference was statistically significant(P<0.05).(2)Kaplan-Meier Plotter showed that the progression-free survival(PFS)and overall survival(OS)of patients in the YTHDC2 high expression group were significantly higher than those in the low expression group(P<0.05),the prognosis of patients with ovarian cancer in the YTHDC2 high expression group was better,and the difference was statistically significant(P<0.05).(3)The ROC curve shows that the 1-year,3-year,5-year,and 8-year survival rates AUC are 0.634,0.579,0.535 and 0.518,respectively,which are all greater than 0.5.YTHDC2 is a valuable independent prognostic factor,among which the 1-year survival rate The AUC value is the highest,and the predicted value is the best.(4)A total of about 640 downstream target genes of YTHDC2 were excavated from the POSTAR database,and FLNA was selected as the target gene of interest for in-depth mining.(5)GEPIA database analysis found that the expression of FLNA in ovarian cancer tissue was significantly lower than that in normal ovarian tissue,and the difference was statistically significant(P<0.05)(6)SRAMP as a m6A methylation modification database(sequence-based RNA adenosine methylation site predictor)predicts FLNA methylation site information.There are 151 m6A modification sites on FLNA mRNA and the base sequence of the highest scored site For GGACU.(7)IHC detects YTHDC2 and FLNA protein levels in EOC tissues and normal ovarian tissues.The positive immunohistochemical products are pale yellow to brown particles.YTHDC2 is mainly located in the nucleus,and FLNA is mainly located in the nucleus and cytoplasm.The average optical densities of YTHDC2 and FLNA in EOC tissue were 0.701 and 1.76,respectively,and in normal ovarian tissue were 1.46 and 3.01,respectively.Compared with normal ovarian tissue,the expressions of YTHDC2 and FLNA in EOC tissues were significantly reduced,and the difference was statistically significant(P<0.05).Analyzing the relationship between the expression of YTHDC2 and FLNA and the clinicopathological characteristics of EOC,it was found that the expression levels of YTHDC2 and FLNA in different histopathological types,federation international of gynecology and Obstetrics(FIGO)stage,and lymph node metastasis were different,and the difference was statistically significant(P<0.05).The positive expression rates of YTHDC2 and FLNA in the tissues of patients with serous ovarian cancer,FIGO Ⅰ-Ⅱ,and EOC without lymph node metastasis were higher than those of other types of epithelial cancers,FIGO Ⅲ-Ⅳ,and patients with lymph node metastasis.The differences are statistically significant(P<0.05).and its expression in EOC patients with different levels of tissue differentiation and age was not significantly different(P>0.05).Pearson analyzed the correlation between the expression of YTHDC2 and FLNA in EOC and found that the expression of YTHDC2 and FLNA was positively correlated(R=0.438,P=0.001).Conclusion(s):(1)The m6A reading protein YTHDC2 is low expressed in ovarian cancer and is related to the poor prognosis of patients with ovarian cancer.This gene may be a potential biomarker for ovarian cancer diagnosis,prognosis prediction and targeted therapy.(2)FLNA is one of the downstream target RNAs of YTHDC2,which is lowly expressed in ovarian cancer.YTHDC2 may be combined with FLNA to regulate the expression of FLNA with m6A modification,thereby promoting the progress of EOC,but further experiments in vivo and in vitro are needed to verify its mechanism of action. |
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