Abstract:

Objective To discuss the expression level of gasdermin E （GSDME） in the epithelial ovarian cancer （EOC） tissue， and to clarify the effect of GSDME on the occurrence and development of EOC. Methods The expressions of GSDME mRNA in normal tissue and EOC tissue was detected by R language based on the Cancer Genome Atlas （TCGA） and Genotype-Tissue Expression （GTEx） Databases；the correlation between the expression level of GSDME and the occurrence of EOC was analyzed. The difference analysis， Gene Ontology （GO） analysis，Kyoto Encyclopedia of Genes and Genomes （KEGG） pathway richment analysis， Gene Set Enrichment analysis （GSEA）， protein-protein interaction （PPI） network， HUB gene interaction network，and immune infiltration analysis were used to discuss the genes and signaling pathways associated with GSDME and their effects on the occurrence and development of EOC. The pathological tissue sections of 40 EOC patients were collected and divided into low-grade group （well-differentiated and moderately-differentiated，n=24） and high-grade group （poorly differentiated，n=16） based on the pathological grades； according to the sensitivity to cisplatin （DDP）， the pathological tissue sections were divided into DDP resistant group and DDP sensitive group. In addition， 5 tissue sections of normal ovary， benign ovarian tumor， and 5 tissue sections of borderline ovarian carcinoma were collected as controls. The expression intensities of GSDME in all the tissue sections were detected by immunohistochemistry （IHC） method. Besides， 10 pairs of fresh ovarian cancer and paracancerous tissues were selected， and the expression levels of GSDME protein in the samples in two groups were detected by Western blotting method. The ovarian cancer Skov3 cells and Skov3/DDP cells were cultured in vitro， and the expression levels of GSDME protein in the cells were detected by Western blotting method and the relationship between the expression level and DDP-resistance of ovarian cancer was analyzed. Results The analysis results of unpaired samples in the TCGA and GTEx Databases showed that compared with normal ovarian tissue， the expression level of GSDME mRNA in EOC tissue was significantly decreased （P<0.05）， and the expression of GSDME mRNA in EOC tissue in high-grade group was higher than that in low-grade group（P<0.05）.The GSDME single gene difference analysis results showed that there were 460 up-regulated and 329 down-regulated genes |（Log₂ fold charge（FC）|>1，P<0.05）.The functional enrichment and immune infiltration analysis results showed that high expression of GSDME could upregulate the activities of humoral immunie response pathways，leukocyte migration pathway and immunoglobulin complex pathway mediated by circulating immunoglobulin and promote the infiltration of immune cells in tumor microenvironment. The IHC staining results showed that GSDME was related to the pathological grade and drug resistance of EOC； the expression intensity of GSDME in EOC tisssue in DDP sensitive group was higher than that in DDP resistant group（P<0.05）.The Western blotting results showed that compared with paracancerous tissue， the expression level of GSDME protein in EOC tissue was significantly decreased （P<0.05）； compared with Skov3 cells， the expression level of GSDME protein in the Skov3/DDP cells was significantly decreased （P<0.05）. Conclusion GSDME is closely related to the malignancy and cisplatin resistance of EOC. The low expression of GSDME is a key factor leading to the decreasing of tumor immune infiltration， EOC deterioration and resistance.GSDME may be a potential molecular target for the treatment of EOC.

Key words: Gasdermin E, Epithelial ovarian neoplasm, Gene expression, Bioinformatic