Biosynthesis and secretory pathway of basement membrane molecules by salivary gland carcinoma cells.

点击翻译按钮获取中文摘要

Biosynthesis of basement membrane molecules (BMMs) and fibronectin was determined in vitro in the two different human cell systems, ACC2 and ACC3, established from adenoid cystic carcinomas of the salivary gland by using immunofluorescence and confocal microscopy. When the cells were attached and spread on dishes, fine granular immunofluorescence for type IV collagen, laminin, heparan sulfate proteoglycan, entactin, and fibronectin first appeared diffusely in the cytoplasm, and then they changed into 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 monolayr, extracellular signals started to decrease in the reverse proportion of reappearance of intracellular ones. Heparanase and other enzymes were immunolocalized in the nuclei when BMMs were started to be synthesized. Their signals migrated to the cytoplasm and were later condensed in the perinuclear area. Finally, they were co-localized with BMMs in the intercellular spaces. When cultured in collagen gel, the cells formed spherical colonies with vacuolar structures containing BMMs, that was shown by light and electron microscopic immunohistochemistry. The results indicated that the parenchymal cells of adenoid cystic carcinoma synthesize these five extracellular matrix molecules, secrete them into the extracellular milieu, and remodel the extracellular deposits. It is hence suggested that the characteristic stromal architecture of adenoid cystic carcinoma, represented by stromal pseudocysts, is resulted from their own secretion and enzymatic degradation of the basement membrane molecules and fibronectin by the tumor cells.