Differential Distribution of Type IV Collagen α1 to α6 Chains Suggests Distinct Molecular Interaction between the Epithelial and Mesenchymal Components of Benign Odontogenic Tumors

Abstract

Type IV collagen is the principal constituent component of the basement membrane(BM). It have been reported that the alpha chains of type IV collagen [α(IV)] showed temporal and spatial localization pattern in different stages of the developing tooth germ except α3(IV) chain. In this study, we investigated the localization of α(IV) chains in benign odontogenic tumor in comparison with their localization in the cap stage human tooth germ by immunohistochemistry. All the tumor samples studied as well as the tooth germ were negative to α3(IV). In ameloblastoma that resembles the enamel organ of the tooth germ, all types of tumor (follicular, plexiform and desmoplastic) were not reactive to α4(IV) chains similar to the α(IV) chains composition in the BM of outer enamel epithelium and dental lamina. All α(IV) chains except α3(IV) were localized in the tumors in which the odontogenic epithelium is accompanied by odontogenic ectomesenchyme like adenomatoid odontogenic tumor (pseudoglandular spaces), odontoma and ameloblastic fibroma and this is similar to the α(IV) chains composition in the BM of inner enamel epithelium of the tooth germ. From the results, the presence of α4(IV) chains is thought to be important for the differentiation and induction of the dental papilla like tissue formation in odontogenic tumors.