CD31 expression in human cancers: a pan-cancer immunohistochemical study

CD31 (platelet endothelial cell adhesion molecule 1) is a transmembrane glycoprotein involved in cell adhesion and signal transduction that is primarily expressed in vascular endothelial cells, platelets, neutrophils, and certain tumour cells. We investigated CD31 expression in cancer cells by conducting a pan-cancer gene expression analysis using data from cancer cell lines as well as an immunohistochemical analysis of surgically resected cancer specimens. The goal was to elucidate the frequency and distribution of CD31 expression across cancer types and its diagnostic significance.

Gene expression data from 1073 cancer cell lines were analysed to determine the frequency of CD31 expression across different cancer types. Immunohistochemical analysis was performed on 358 resected cancer specimens, focusing on adenocarcinomas and squamous cell carcinomas. The analysis compared the frequency of CD31 expression among specific cancer subtypes and between histological types.

In gene expression analyses, adenocarcinomas showed a higher frequency of CD31 expression than did squamous cell carcinomas. Immunohistochemically, CD31 expression was observed in breast apocrine carcinomas (40.0%), hepatocellular carcinomas (18.8%), uterine endometrioid adenocarcinomas (31.6%), ovarian high-grade serous carcinomas (20.0%), ovarian clear cell carcinomas (40.0%) and urothelial carcinomas (25.0%). No CD31 expression was detected in oesophageal, renal, prostate or cervical cancers.

CD31 expression is more frequent in adenocarcinomas than in squamous cell carcinomas, with variability among cancer subtypes. Recognising CD31-positive cancers is critical to avoid misdiagnosing them as endothelial-derived tumours. The mechanisms underlying CD31 expression in cancer remain unclear and warrant further investigation.