Localization of Collagen Type IV Alpha Chains at the Basement Membrane of Oral Squamous Cell Carcinoma

Destruction of basement membrane is an important element in invasion of cancer cells. Type IV collagen, the major component of basement membrane has six distinct a chains. In this study, we investigated the localization of six a chains and matrix metalloproteinases (MMPs) in oral squamous cell carcinoma immunohistochemically. In well differentiated squamous cell carcinoma, the localization of a chains showed various patterns.α1 (IV), α2 (IV),α5 (IV) αnd α6 (IV) chains were stained in almost all basement membranes in the central of cancer. Unique staining with only α5 (IV) and α6 (IV) chains was also observed. In the invasive point of cancer, all a chains mainly became negative, but MMP-2 and MMP-9 were stained strongly. In poorly differentiated squamous cell carcinoma, both a chains and MMPs were not stained. Furthermore, we examined the correlation between distribution of a1 chain and invasive pattern of cancer. We found that the disappearance of a chains correlated closely with invasive activity of cancer.