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

INTRODUCTION: 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).

MATERIAL AND METHODS: 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.

RESULTS: 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).

CONCLUSIONS: 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.