Apoptosis-induced and -suppressed cells in salivary gland adenoid cystic carcinoma: correlation with histological growth patterns.

Abstract

It is well known that adenoid cystic carcinoma (ACC) arising from salivary glands shows a correlation between prognosis and histological growth patterns. The aim of the study was to evaluate whether three growth patterns of ACC are related to the distributions of apoptosis-induced and -suppressed tumor cells. We examined 77 cases of ACC including tubular (18 cases), glandular (50) and solid (9) patterns. In order to visualize the apoptotic cells, terminal deoxynucleotidyl transferase (TdT)- mediated dUTP-biotin nick end labeling (TUNEL) and avidin-biotin complex staining using Lewis Y (LeY) antibody were applied to paraffin sections. For detection of the apoptosis-suppressed cells, immunohistochemistry employing bcl-2 antibody was utilized. Apoptosis index (AI) based on the TUNEL-stained specimens were tubular, 7.0; glandular 2.4; solid, 5.1. In tubular type, apoptotic cells were frequently located in the inner tubular layer rather than the outer layer. Solid type had scattered apoptotic cells in the nests. Bcl-2 expression was found in 61% of tubular, 20% of glandular and 22% of solid cases. The localization of bcl-2 protein was noticed in outer tubular cells, and peripheral cells or undifferentiated cells in solid pattern. The peculiar distribution of apoptotic cells may result from the various proportions and distinctive arrangement of neoplastic ductal cells and neoplastic myoepithelial cells in ACC. Apoptotic cells and bcl-2 positive apoptosis-suppressed cells may participate in the construction of characteristic histological appearances of ACC.