ABSTRACT
Objective: To investigate the expression and significance of protease activated receptor 2 (PAR2) in ovarian epithelial carcinoma. Methods: PAR2 mRNA expression levels in 410 cases of epithelial ovarian carcinoma and 88 cases of human normal ovary were analyzed from cancer Genome Atlas (TCGA) database and tissue genotypic expression database (GTEx). Immunohistochemical (IHC) staining of PAR2 protein was performed in 149 patients with ovarian cancer who underwent primary surgical treatment at Cancer Hospital of Chinese Academy of Medical Sciences. Then the relationship between mRNA/protein expression of PAR2 and clinicopathological features and prognosis was analyzed. Gene functions and related signaling pathways involved in PAR2 were studied by enrichment analysis. Results: The mRNA expression of PAR2 in epithelial ovarian carcinoma was significantly higher than that in normal ovarian tissue (3.05±0.72 vs. 0.33±0.16, P=0.004). There were 77 cases showing positive and 19 showing strong positive of PAR2 IHC staining among the 149 patients, accounting for 64.4% in total. PAR2 mRNA/protein expression was closely correlated with tumor reduction effect and initial therapeutic effect (P<0.05). Survival analysis showed that the progression free survival time (P=0.033) and overall survival time (P=0.011) in the group with high PAR2 mRNA expression was significantly lower than that in the low PAR2 mRNA group. Multivariate analysis showed tumor reduction effect, initial therapeutic effect were independent prognostic factors on both progression-free survival and overall survival (P<0.05). The progression-free survival (P=0.016) and overall survival (P=0.038) of the PAR2 protein high expression group was significantly lower than that of the low group. Multivariate analysis showed PAR2 expression, initial treatment effect and chemotherapy resistance were independent prognostic factors on both progression-free survival and overall survival (P<0.05). Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), PAR2 target genes were mainly enriched in function related to intercellular connection, accounting for 40%. Gene enrichment analysis (GSEA) showed that the Wnt/β-catenin signaling pathway (P=0.023), the MAPK signaling pathway (P=0.029) and glycolysis related pathway (P=0.018) were enriched in ovarian cancer patients with high PAR2 mRNA expression. Conclusions: PAR2 expression is closely related to tumor reduction effect, initial treatment effect and survival of ovarian cancer patients. PAR2 may be involved in Wnt/β-catenin signaling pathway and intercellular connection promoting ovarian cancer invasion and metastasis.