RESUMEN
BACKGROUND: Oral squamous cell carcinoma (OSCC) is the most common malignancy in this region, and thus, further elucidation of its tumoral mechanisms is important. One of the main roles of the acute-phase protein orosomucoid-1 (ORM1) is the promotion of angiogenesis, which is key for tumor nutrition and growth. AIM: Our aim was to evaluate the immunohistochemical expression of ORM1 and the angiogenic activity indicated by microvascular density (MVD) in OSCC samples according to histological grade. MATERIALS AND METHODS: Formalin-fixed, paraffin-embedded sections from 45 OSCC cases were submitted to immunohistochemistry: 25 were well-differentiated OSCC, 18 were moderately differentiated OSCC and 2 were poorly differentiated OSCC. ORM1 staining was evaluated by a semiquantitative method, and CD34-positive blood vessels were quantified to calculate the MVD. The results were statically analyzed. RESULTS: All cases exhibited immunoexpression of ORM1 and CD34. However, no significant differences were found between the expression of both markers among the histological grades. In addition, the presence of ORM1 in inflammatory cells and in the extracellular matrix was detected in most cases. CONCLUSION: These results suggest that the induction of angiogenesis is not the main role of ORM1 in OSCC and may be associated with the regulation of the immune/inflammatory response or the transport of protumoral molecules, such as sialyl-Lewis X or phorbol esters, which requires confirmation in future studies.