The basement membrane-type heparan sulfate proteoglycan (perlecan) in ameloblastomas: its intercellular localization in stellate reticulum-like foci and biosynthesis by tumor cells in culture.

The localization and biosynthesis of basement membrane-type heparan sulfate proteoglycan (HSPG), known as perlecan, were studied in ameloblastomas using surgical tissue sections and cells in primary culture to demonstrate the existence of extracellular matrix (ECM) molecules in the intercellular space of epithelial tissue. HSPG was immunolocalized in the intercellular spaces of stellate reticulum-like cells and small vacuolar structures between basal cells in tumor cell nests as well as in myxofibrous stroma. By means of in-situ hybridization, mRNA signals for the HSPG core were intensely demonstrated in the cytoplasm of basal and parabasal cells of parenchyma. Furthermore, the in-vitro biosynthesis of HSPG core protein by ameloblastoma cells was confirmed using immunofluorescence, immunoprecipitation, and reverse-transcriptase polymerase chain reaction (RT-PCR). The results indicated that ameloblastoma cells synthesize HSPG and deposit it in their intercellular space. The intercellular HSPG might act as a carrier for transport of nutrients to tumor cells within ameloblastomatous foci.