Expression Of POLD1 Gene In TNBC And Its Correlation With Prognoses Of The Patients By Bioinformatic Analysis

Objective:Triple-negative breast cancer(TNBC)is a subtype with a poor prognosis among all breast cancers.The purpose of this study was to detect the expression and prognosis of the DNA poly merase chain catalytic subunit gene(POLD1)in the human triple-negative breast cancer tissue and the corresponding adjacent tissue.Methods:The gene expression profiles of GSE38959 and GSE45287 were downloaded from Gene Expression Omnibus database.Differentially expressed genes(DEGs)were screened performing with GEO2 R.After Gene ontology terms,Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway enrichment analyzing and Protein-protein-interaction(PPI).POLD1 was selected as hub gene.Moreover,The expression levels of POLD1 protein in 110 TNBC tissue specimens and their corresponding para-cancerous tissues were detected by immunohistochemistry.To analyze the relationship between the expression of POLD1 protein and the clinicopathological features and prognosis of the patients.Results:In 110 cancer tissues,81(73.6%)were positive for POLD1 expression,and 29(26.4%)were negative.In adjacent tissues,POLD1 expression was positive in 24 cases(21.8%)and negative in 86 cases(78.2%).POLD1 expression is inconsistent in cancer tissues and adjacent tissues,and it is significantly higher in cancer tissues than in adjacent tissues(?2=59.195,P=0.000)?.The expression of POLD1 was related to histological grade,TNM stage,and lymph node metastasis(P=0.002,0.010,and 0.018),and was not related to age,tumor size,Ki-67 marker index,p53,and EGFR expression.The Kaplan-Meier method was used to analyze the overallsurvival and disease-free survival.The disease-free survival of patients with high expression of POLD1 was significantly shorter than that of patients with low expression of POLD1(P=0.038),but it had no significant effect on overall survival.In addition,Coxproportional hazards model showed that POLD1 expression,lymph node metastasis and TNM staging were independent risk factors of DFS in patients(Risk ratio=0.380,95% confidence interval: 1.447-0.985;hazard ratio=2.810,95% confidence interval:1.435-5.506;hazard ratio=4.816,95% confidence interval: 1.856-12.496,all P< 0.05).Conclusion:The high expression of POLD1 is may associated with the poor clinical outcome of TNBC.