TEX19 Promotes Serous Ovarian Carcinoma Progression And Is Potential Target For Epitope Vaccine Immunotherapy

Background: Ovarian cancer(OV)is the most fatal gynecologic malignancy with the highest mortality rate worldwide due to lack of effective early diagnosis strategies as well as recurrence and drug resistance.At present,the standard treatment of advanced ovarian cancer includes primary cytoreductive(debulking)surgery followed by chemotherapy.However,the prognosis of OC patients is still poor.The most common type of OC,epithelial ovarian cancer(EOC),has a 5-year survival rate of less than 30%.Therefore,there is an urgent need to screen and develop biomarkers with high sensitivity and specificity,which has important guiding significance for understanding the pathogenesis of ovarian cancer,researching early diagnosis strategies,and developing new treatment methods.Testis Expressed 19(TEX19)is one of the cancer-testis antigen(CTA)identified in recent years and has been found to be overexpressed in a variety of tumors.However,the clinical significance and function of TEX19 in serous ovarian cancer(SOC)has been relatively few.The purpose of this study is to investigate the expression of TEX19 protein in SOC,clinical significance,and effect on the proliferation,migration and invasion of SOC cell lines,and to further screen candidate epitopes for designing anti-tumor peptide vaccines,which will provide a reference for further research on this new biomarker and treatment strategies of SOC.Materials and methods: 1.TEX19 levels were evaluated by immunohistochemistry(IHC)in 98 human ovarian tissue samples.2.ROC curves were utilized to determine the cut-off value to define the positive level of TEX19 protein.3.Based on the cut-off value,the correlation of TEX19 levels with patients' clinicopathological features was assessed.4.Kaplan-Meier plotter was used to analyze the correlation between TEX19 m RNA expression and prognosis of patients with SOC.5.Western blotting,quantitative realtime polymerase chain reaction(q RT-PCR),and immunofluorescence analysis were utilized to detect TEX19 levels in four human OC cell lines and one human ovarian epithelial cell line.6.To examine the influence of TEX19 on proliferation,migration,and invasion of SOC cells,CCK-8 assays,plate clone formation assays,wound healing assay,and transwell assay were conducted using si RNA-mediated knockdown TEX19 in OVCAR-3 and A2780.7.Four candidate epitope peptides derived from TEX19 were predicted and verified by the IEDB database and pepsite2 website.8.T2 cell binding assay verified the binding ability of the epitope peptides obtained by the above method to the HLA-A* 0201.9.MOE software was used to analyze the interaction between the potential candidate epitope and HLA-A* 0201 molecule.Results: 1.TEX19 was significantly upregulated in OC(P=0.0061).2.TEX19 expression level is significantly correlated to higher TNM stage(P=0.008),lymph node involvement(P=0.014),and invasiveness(P=0.008).3.Overall survival(OS)and progression-free survival(PFS)were shorter in patients with high TEX19 m RNA expression(P<0.05).4.TEX19 protein and m RNA levels were up-regulated in SOC cell lines,OVCAR-3,A2780 and HO-8910(P <0.05).5.Knockdown of TEX19 inhibited proliferation,migration,and invasion of SOC cells(P<0.05).6.Four peptides derived from TEX19 were screened through the IEDB database and pepsite2 website.7.TL(TLAAAPEGL)in the four candidate epitope peptides from the TEX19 amino acid sequence can bind to HLA-A* 0201 molecules,and the prediction of MOE software results show that TL and HLA-A* 0201 molecules have a relatively close interaction.Conclusion: 1.TEX19 is significantly up-regulated in ovarian cancer,may play a key role in the proliferation,invasion and metastasis of SOC and may indicate a poor prognosis for patients with SOC.2.The TL derived from the amino acid sequence of TEX19 has a strong affinity with the HLA-A* 0201 molecule and may be a candidate dominant epitope peptide for an anti-SOC therapeutic epitope peptide vaccine.