Laminin Alpha-1, Alpha-3, and Alpha-5 chain expression in human prepubetal benign prostate glands and adult benign and malignant prostate glands

BACKGROUND. Laminins (Lns) are a family of extracellular matrix glycoproteins located in the basement membrane (BM) of epithelial cells. They exist as heterotrimers composed of an α, β, and γ chain. Presently, five α (α1-5), three β (β1-3), and three γ (γ1-3) chains have been identified with different combinations of these chains resulting in 14 laminin heterotrimers thus far identified (1, 3-5). METHODS. In this study, using immunohistochemistry with chain-specific antibodies, we characterized the expression of the α1 (Lns-1/3), α3 (Lns 5,6,7), and α5 (Lns 10/11) chains in fetal, newborn, infant, prepubertal, and adult benign and malignant prostate glands. RESULTS. In general, α1 expression was higher in normal fetal prostate glands and declined by full-term birth, whereas the α3 and α5 chains remained highly expressed in the adult normal glands. In carcinoma α1 (Lns 1/3) and α5 (Lns 5,6,7) are lost, whereas α5 (Lns 10/11) persists. CONCLUSIONS. Alpha 1 (Lns 1/3) is prominent in BM, but is replaced by a laminin matrix rich in α3 (Lns 5,6,7) and α5 (Lns 10/11) in benign adult prostate glands. In carcinoma, both α1 (Lns-1/3) and α3 (Lns 5,6,7) are not expressed with persistence of a BM rich in α5 (Lns 10/11).