LAMININ-5. A POTENTIAL TOOL IN DIAGNOSIS OF HEAD AND NECK SQUAMOUS CELL CARCINOMA

Abstract

The heterotrimeric extracellular matrix protein laminin-5 (ln-5) is a regular constituent of the basement membrane in oral and pharyngeal mucosa consisting of the α 3, β 3 and γ 2 chain. On the one hand, it is an integral part of the epithelial adhesion complex which connects the hemidesmosomes of the basal cells with the basement membrane. In this position, ln-5 strictly acts against migration and invasion and may fundamentally contribute to the distinction between intraepithelial neoplasia vs. invasive carcinoma. On the other hand, single chains of ln-5, in particular the γ 2 chain, are able to promote migration. The immunohistochemical ln-5 demonstration outside the basement membrane in the keratinocyte cytoplasm or in the stroma of the invasive front, as well as ln-5 synthesis, indicate epithelial cells potentially able to migrate and to invade. The extent of the ln-5 demonstration outside the basement membrane, as well the loss of ln-5 from the basement membrane, is therefore of prognostic value.A diagnostic interpretation of ln-5 immunostainings has to consider the contrary functions of ln-5 or ln-5 fragments: within the basement membrane it acts as anchoring protein and outside the basement membrane it represents a migration/ invasion factor.

Keywords

• basement membrane
• hemidesmosome
• anchoring protein
• invasion
• prognosis