Differential expression of extracellular matrix molecules and the α₆-integrins in the normal and neoplastic prostate

The epithelial basal lamina composition and integrin expression profile of normal and neoplastic human prostate was characterized using immunohistochemical analysis of frozen samples. The major components of the basal lamina surrounding normal acini were laminin, type IV collagen, entactin, and type VII collagen with variable amounts of tenascin. The basal lamina of neoplastic acini had a similar composition, except for the loss of type VII collagen, which was observed in all grades of carcinoma. The basal cells of the normal prostate express the α₆-, β₁-, and β₄-integrin subunits, suggesting that both the α₆β₁- and α₆β₄-integrin complexes are formed. In prostate carcinoma there is a complete loss of β₄ expression and the α₆- and β₁-integrin subunits, which are restricted to the basal and basal lateral surfaces of basal cells, are distributed diffusely throughout the cytoplasmic membrane. The differential expression of type VII collagen and β₄ are discussed in relationship to their possible role in tumor progression.