Objective To analyse the expression characteristics, prognostic value and clinical significance of phospholipase A2 group ⅡD (PLA2G2D) in patients with ovarian serous cystadenocarcinoma (OSC).

Methods Sixty-five OSC patients were selected, who were surgically treated in The People's Hospital of Danyang between January 2019 and January 2022. PLA2G2D expression characteristics and prognostic value in OSC were analysed by various public databases and immunohistochemistry (IHC). The association between PLA2G2D expression and tumour-infiltrating immune cells in OSC was analysed by TIMER2.0 database. PLA2G2D co-expressed genes were analysed by Pearson's test and functionally enriched signalling pathways were analysed. Predictive OSC patient prognostic column line plot was constructed based on the TCGA-OSC cohort. Survival curves for 65 OSC patients were constructed based on Kaplan-Meier, and associations between clinical variables and prognosis were analysed using univariate and multivariate Cox regression.

Results PLA2G2D RNAseq and protein levels were increased in OSC tissues and overall patient survival was higher (P<0.05). PLA2G2D RNAseq expression in OSC showed a significant positive correlation with macrophages (r=0.472), dendritic cells (r=0.331) and NK cells (r=0.274) and a negative correlation with B cells (r=−0.194) and neutrophils (r=−0.125), all of which were statistically significant (P<0.05). PLA2G2D was enriched in signalling pathways such as inflammatory response, leukocyte activation and positive regulation of immune response. Column line graphs constructed based on the TCGA-OSC cohort were effective in predicting 1-, 3-, and 5-year survival of OSC patients. The 5-year overall survival (OS) and recurrence-free survival (RFS) of patients in the PLA2G2D high-expression group was higher than that of the low-expression group (P<0.001). The results of multifactorial Cox risk regression showed that PLA2G2D expression was an independent influencing factor for DFShazard ratio (HR)=0.412, 95% confidence interval (CI) 0.253~0.672, P<0.001 and OS (HR=0.354, 95%CI 0.173~0.724, P=0.004) in OSC patients.

Conclusions PLA2G2D is highly expressed in OSC and is associated with a better prognosis, which may be related to its regulation of the abundance of immune cell infiltration in the tumor microenvironment, suggesting that PLA2G2D may serve as a potential prognostic biomarker and therapeutic target for OSC patients.