Laminin-1 and alpha 6 beta 1 integrin regulate acinar morphogenesis of normal and malignant human prostate epithelial cells

BACKGROUND. Cell-matrix interactions via integrin receptors are critical fo r acinar morphogenesis. The non-tumorigenic, human prostate epithelial cell line RWPE-1 was used in a three-dimensional (3D) cell culture model to ide ntify the matrix protein and its integrin receptor required for acinar morp hogenesis. METHODS. 3D cultures, immunostaining, confocal microscopy, and Western blot analysis were used to examine acinar formation on matrix proteins and to d etermine integrin receptor expression. RESULTS. RWPE-1 cells differentiate into acini of polarized cells with a di stinct lumen in 3D Matrigel culture. In contrast, the malignant WPE1-NB26 p rostate epithelial cells form solid cell masses. In 3D gels of laminin-1, t ype IV collagen, or fibronectin, RWPE-1 cells form acini only in laminin-1. Anti-laminin-1 antibody reduces acinar formation in a dose-dependent manne r. Polarized RWPE-1 cells showed basal expression of alpha6 and beta1 integ rin subunits. Blocking antibodies to alpha6 or beta1 reduced acinar formati on to 9 and 6% of control, respectively. The beta1 integrin colocalized bet a1 with focal adhesion kinase (FAK). Inhibition of extracellular signal-reg ulated kinase kinase activity significantly reduced acinar formation to 38% of control, suggesting that beta1 integrin-mediated signal transduction ma y be regulated through a FAK pathway. CONCLUSIONS. While basal expression of alpha6 beta1 integrin in RWPE-1 cell s correlates with their ability to polarize and form acini, a decrease or l oss of alpha6, and diffused beta1 expression in WPE1-NB26 cells correlates with loss of acinar-forming ability. Results show that laminin-1 and a func tional alpha6 beta1 integrin receptor are required fur acinar morphogenesis . This novel 3D cell culture model is useful for elucidating regulation of acinar morphogenesis and its loss during prostate carcinogenesis. Prostate 46:142-153, 2001. (C) 2001 Wiley-Liss, Inc.