Immunohistochemical assays for the expression of angiogenic signaling molecules and microvessel density in adenoid cystic carcinomas of human salivary glands

ABSTRACT

Adeonoid cystic carcinoma (ACC) is one of the most common malignant tumors of salivary glands. It is characterized by a relentless regrowth especially around nerve tissues and a high rate of hematogenous distant metastasis. Clinically most deaths from salivary ACC are caused by delayed lung metastases that are resistant to conventional chemotherapy. So, knowledge of cellular and molecular properties that influence the dissemination of metastatic tumor cells, is important for new treatment strategies of metastatic lesions. We determined expressions of angiogenic signaling molecules microvessel density (MVD) using surgical specimens of human salivary ACC. Protein expressions of vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-2, activated VEGFR-2, and human CD31 were assessed in 20 cases of salivary ACC by immunohistochemical staining. Most of the tumors, especially ACC with a tubulocribriform pattern, were positive for antibodies of VEGF, VEGFR-2, and activated VEGFR-2. The overall percentages of the 20 specimens expressing VEGF, VEGFR-2, activated VEGFR-2 were 90, 95, and 95%, respectively. Immunoreactivities of the biomarkers in salivary ACC were higher than those in normal salivary gland. Furthermore, immune-related cells as well as tumor cells expressed VEGF/VEGFR-2. Microvessel density of salivary ACC was higher than that of normal salivary gland (P<0.05). Taken together, angiogenic signaling molecules are actively expressed in salivary ACC. And we suggest that these molecules may have critical role in the hematogenous spread of salivay ACC, which has a propensity for delayed lung metastasis. Therefore, these biomarkers can be molecular targets for therapy of metastasis of salivary ACC.