Laminin alpha-1, alpha-3, and alpha-5 chain expression in human prepubertal [correction of 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 alpha, beta, and gamma chain. Presently, five alpha (alpha1-5), three beta (beta1-3), and three gamma (gamma1-3) 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 alpha1 (Lns-1/3), alpha3 (Lns 5,6,7), and alpha5 (Lns 10/11) chains in fetal, newborn, infant, prepubertal, and adult benign and malignant prostate glands.

Results: In general, alpha1 expression was higher in normal fetal prostate glands and declined by full-term birth, whereas the alpha3 and alpha5 chains remained highly expressed in the adult normal glands. In carcinoma alpha1 (Lns 1/3) and alpha5 (Lns 5,6,7) are lost, whereas alpha5 (Lns 10/11) persists.

Conclusions: Alpha 1 (Lns 1/3) is prominent in BM, but is replaced by a laminin matrix rich in alpha3 (Lns 5,6,7) and alpha5 (Lns 10/11) in benign adult prostate glands. In carcinoma, both alpha1 (Lns-1/3) and alpha3 (Lns 5,6,7) are not expressed with persistence of a BM rich in alpha5 (Lns 10/11).