Immunohistochemical study on neuropilin 1 (NRP1) immunoexpression in oral squamous cell carcinoma

Neuropilins (NRPs) are multifunctional glycoproteins that play an important role in angiogenesis and cancer progression. The aim of the study was to examine the immunoexpression of neuropilin 1 (NRP1), the number of NRP1+ infiltrating cells and CD163+ macrophages, and density of microvessels (MVD) in oral squamous cell carcinoma (OSCC).

The study was performed on 45 OSCC patients with metastases (OSCCM+), 51 patients without metastases (OSCCM-) and 17 control cases. The microvessels were identified by the presence of CD31 and the expression of the studied proteins was assessed by immunohistochemistry.

The immunoexpression of NRP1, the mean numbers of NRP1+, CD163+ infiltrating cells, and MVD were significantly increased in OSCCM+ patients in comparison to OSCCM-, and control groups. Moreover, in OSCCM- patients all these parameters were also significantly increased in comparison to controls. In OSCCM+ and OSCCM- groups, there were positive correlations between the immunoexpression of NRP1 and MVD (r = 0.41, p < 0.006; r = 0.51, p < 0.001, respectively), and between the number of NRP1+ infiltrating cells and CD163+ macrophages (r = 0.56, p < 0.001, r = 0.49, p < 0.001, respectively).

The present study revealed overexpression of NRP1 in OSCC, especially in OSCC patients with metasta-sis, suggesting that NRP1 could potentially contribute to metastasis of oral cancer. The correlation between the number of NRP1+ infiltrating cells and CD163+ macrophages suggests that NRP1+ infiltrating macrophages are present in tumor microenvironment and may play a role in the progressions of oral cancer.