IMMUNOHISTOCHEMICAL LOCALIZATION OF A NOVEL BETA(1) INTEGRIN IN NORMAL AND PATHOLOGICAL SQUAMOUS EPITHELIA

The 10.1.2 MoAb reacts with a novel alpha chain that associates with the beta(1) integrin chain and is widely distributed among epithelial and endothelial cells of human adult and fetal tissues. In the epidermis and in other squamous epithelia, alpha(10.1.2) chains are expressed exclusively in the basal cell layer. Here we describe the immunohistochemical localization of alpha(10.1.2) in human epidermis, in other squamous epithelia, as well as in cultured keratinocytes. alpha(10.1.2) chain localization has also been investigated in a variety of non-neoplastic and neoplastic lesions of the skin, the uterine cervix, and the lung. We show that alpha(10.1.2) chains retain their basal keratinocyte localization in hyperplastic skin diseases and in benign tumors of the epidermis and that they are strongly expressed in basal cell carcinomas. In contrast, alpha(10.1.2) expression is decreased in keratinocytes that differentiate in vitro and is lost in epidermal dysplastic conditions, in the invading front of squamous cell carcinomas of the epidermis, in microinvasive cervical cancers, and in well-differentiated squamous lung tumors. These findings indicate that alpha(10.1.2) beta(1) integrin is downregulated during keratinocyte differentiation in vitro and in vivo. Moreover, lack of alpha(10.1.2) expression in basal cells of squamous epithelia is associated with early dysplastic changes and with the acquisition of invasive capacity.