Neuropilin-1 expression in the tumour microenvironment of oral squamous cell carcinoma

Background: Neuropilin-1 (Nrp-1) is a transmembrane glycoprotein involved in multiple biologic and pathologic processes including carcinogenesis. It is widely expressed in cancers where it has been correlated with poorer prognosis. Nevertheless its expression profiles and significance in oral squamous cell carcinoma (OSCC) remain elusive. Objective: To investigate the expression of Nrp-1 in OSCC and oral epithelial dysplasia (OED) using immunohistochemistry (IHC), and to examine its co-localisation with markers for angiogenesis and T regulatory cell (Tregs), namely vascular endothelial growth factors 2 (VEGFR2) and forkhead box P3 (FoxP3) respectively, using double-labelling immunofluorescence (DLIF). Method: Formalin-fixed paraffin-embedded (FFPE) blocks were obtained from the archives of the Oral Pathology Centre, University of Otago. These specimens were divided into three groups namely OSCC, OED and non-specifically inflamed mucosa (NIM). The samples from these groups comprised well-differentiated OSCC (n=21) and moderately-differentiated OSCC (n=2), low-risk OED (n=8) and high-risk OED (n= 9), and NIM (n= 14). Immunohistochemistry was performed with an antibody against Nrp-1. Hotspot locations in the epithelium and connective tissue (n=3 each) from each specimen were photographed and analysed semi-quantitatively. Kruskal-Wallis tests were performed with p