Biosynthesis of basement membrane molecules by salivary adenoid cystic carcinoma cells: an immunofluorescence and confocal microscopic study.

The biosynthesis of basement membrane molecules and fibronectin was studied in vitro in the two different human cell systems (ACC2 and ACC3) established from adenoid cystic carcinomas (ACC) of the salivary gland using immunofluorescence and confocal microscopy. When cells were attached and spread on dishes, fine granular immunofluorescence for type IV collagen, laminin, heparan sulphate proteoglycan, entactin, and fibronectin first appeared diffusely in the cytoplasm, and then changed in aggregation of coarse granules in the perinuclear area. With formation of colonies, these signals were present in the extracellular space, initially in the basal aspect of attached cells and consequently in the lateral intercellular space. After the cells formed a confluent monolayer, extracellular signals started to decrease in inverse proportion to the reappearance of intracellular ones. The results indicate that the parenchymal cells of ACC synthesize these five extracellular matrix molecules, secrete them into the extracellular milieu and remodel the extracellular deposits. It is suggested that the characteristic stromal architecture of ACC, represented by stromal pseudocysts, results from their own secretion of the basement membrane molecules and fibronectin.