Biosynthesis and secretion of laminin and S-laminin by human prostate carcinoma cell lines.

Laminin has been previously shown to participate in tumor invasion and metastasis. Tumorigenesis by human prostate cell lines can be influenced by exogenous laminin. We have found that the human prostate tumor cell lines DU145, LNCaP, and PC-3 produce a variant form of the B1 chain of laminin, known as S-laminin. DU145 cells produce laminin containing a ratio of A:B1:B2:S of 1.8:1.0:2.5:1.0, respectively, compared to LNCaP cells, which have a ratio of A:B1:B2:S of 1.0:0:10.0:2.5. Kinetic analysis of laminin production showed that LNCaP cells retained most of their laminin production and secreted laminin forms characterized by decreased levels of n-acetyl glucosamine and sialic acid. In contrast, DU145 cells secreted most of their laminin in mature forms. LNCaP cells bound very little laminin to their surface. These features of LNCaP cells could contribute to their documented low adhesivity in vitro and its nontumorigenic phenotype.