Laminin‐1 and α6β1 integrin regulate acinar morphogenesis of normal and malignant human prostate epithelial cells

Background Cell–matrix interactions via integrin receptors are critical for acinar morphogenesis. The non‐tumorigenic, human prostate epithelial cell line RWPE‐1 was used in a three‐dimensional (3D) cell culture model to identify the matrix protein and its integrin receptor required for acinar morphogenesis. Methods 3D cultures, immunostaining, confocal microscopy, and Western blot analysis were used to examine acinar formation on matrix proteins and to determine integrin receptor expression. Results RWPE‐1 cells differentiate into acini of polarized cells with a distinct lumen in 3D Matrigel culture. In contrast, the malignant WPE1‐NB26 prostate epithelial cells form solid cell masses. In 3D gels of laminin‐1, type IV collagen, or fibronectin, RWPE‐1 cells form acini only in laminin‐1. Anti‐laminin‐1 antibody reduces acinar formation in a dose‐dependent manner. Polarized RWPE‐1 cells showed basal expression of α6 and β1 integrin subunits. Blocking antibodies to α6 or β1 reduced acinar formation to 9 and 6? of control, respectively. The β1 integrin colocalized with focal adhesion kinase (FAK). Inhibition of extracellular signal‐regulated kinase kinase activity significantly reduced acinar formation to 38? of control, suggesting that β1 integrin‐mediated signal transduction may be regulated through a FAK pathway. Conclusions While basal expression of α6β1 integrin in RWPE‐1 cells correlates with their ability to polarize and form acini, a decrease or loss of α6, and diffused β1 expression in WPE1‐NB26 cells correlates with loss of acinar‐forming ability. Results show that laminin‐1 and a functional α6β1 integrin receptor are required for 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. © 2001 Wiley‐Liss, Inc.