Differential Expression of Type IV Collagen alpha 1 to alpha 6 Chains in Basement Membrane of Human Tooth Germ and Odontogenic Tumors

Type IV collagen, the major component of basement membrane (BM), demonstrates a stage- and position-specific distribution of its isoforms during tooth development. To determine its localization in BM of benign odontogenic neoplasms, immunohistochemistry using six anti-alpha(IV) chain-specific monoclonal antibodies was performed. Results disclosed that BM demonstrated an irregular alpha(IV) chain profile in tooth germ as compared to benign odontogenic neoplasms. No alpha3(IV) chains were detected. Expression of alpha1(IV)/alpha2(IV) and alpha5(IV)/alpha6(IV) chains was stronger in desmoplastic than in ordinary ameloblastomas. The adenomatoid odontogenic tumor distinctly expressed these chains in BM of cribriform areas and hyaline materials (which was also alpha4(IV)-positive), but weakly around epithelial whorls/rosettes/nests and mineralized foci. These five chains also stained BM and tumor cells of ameloblastic fibroma and odontoma but not the inductive hard tissues. The present results suggest that modification and remodeling of BM collagen IV alpha chains occur during odontogenic neoplasms progression.