Differential expression profiles between alpha-dystroglycan and integrin beta 1 in ameloblastoma: two possible perlecan signalling pathways for cellular growth and differentiation

Aims: Intercellular deposition of perlecan, an extracellular matrix molecule, results in characteristic stellate reticulum-like structures in ameloblastomas. The aims of this study were to elucidate which types of perlecan receptors function within any particular type of tissue architecture of ameloblastoma. Methods and results: Protein and gene expression profiles for alpha-dystroglycan and integrin beta 1 were examined comparatively with those of their ligands in ameloblastoma using surgical specimens and cells in primary culture. In the follicular-type tumour cell foci, alpha-dystroglycan was localized uniformly over the stellate reticulum-like cells, while integrin beta 1 was restricted mainly to peripheral cells facing the stroma with the interface of the basement membrane, which was also rich in perlecan. In the plexiform-type, mRNA and protein signals for alpha-dystroglycan were enhanced in the periphery of tumour cell foci, especially in their invading fronts. Integrin beta 1 was also immunolocalized in the basal cell zone, which was considered to be the proliferation centre of ameloblastoma cells. Furthermore, biosynthesis of alpha-dystroglycan and integrin beta 1 by ameloblastoma cells was confirmed in vitro using immunofluorescence and reverse transcriptase-polymerase chain reaction. Conclusions: Ameloblastoma cells proliferate and are differentiated by capturing perlecan differentially with alpha-dystroglycan and integrin beta 1, respectively.