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Expression of laminin and its receptor LBP‐32 in human and rat hepatoma cells
Author(s) -
Rescan PierreYves,
Clement Bruno,
Yamada Yoshihiko,
Glaise Denise,
SeguiReal Bartolome,
GuguenGuillouzo Christiane,
Guillouzo André
Publication year - 1991
Publication title -
hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.488
H-Index - 361
eISSN - 1527-3350
pISSN - 0270-9139
DOI - 10.1002/hep.1840130214
Subject(s) - laminin , receptor , microbiology and biotechnology , cancer research , chemistry , medicine , biology , extracellular matrix
Dramatic cellular changes that occur during hepatocarcinogenesis are associated with major alterations in extracellular matrix formation and in the relationships between cells and their microenvironment. We have studied the expression of laminin, the major noncollagenous glycoprotein of basement membrane, and the laminin receptor 32 kD laminin‐binding protein in two rat (Faza 967 and HTC) and two human (HepG 2 and HBGC 2 ) hepatoma cell lines that express a variety of liver‐specific functions. Laminin was found in the rough endoplasmic reticulum of these cells when the indirect immunoperoxidase method and electron microscopic examination were used. Radiolabeled laminin, immunoprecipitated from both media and cell extracts, was resolved by electrophoresis on sodium dodecyl sulfate gel in two major polypeptides that comigrated with the A and B subunits from Engelbreth‐Holm‐Swarm tumor laminin. Immunoblot analysis showed that the Mr = 400,000 polypeptide did not correspond to the A subunit of laminin. Northern blot analyses demonstrated large amounts of B 1 and B 2 mRNAs but no A chain mRNA. We conclude that the tumor cells produce the laminin B chains only. In contrast, normal adult hepatocytes from either man or rat lacked laminin mRNAs, whereas in 1‐day primary culture, B chain mRNAs became detectable. The steady‐state level of 32 kD laminin‐binding protein mRNA was 10‐fold and threefold higher in rat hepatoma cells than in freshly isolated and 1‐day cultured normal rat hepatocytes, respectively. In human hepatocytes, the steady‐state levels of 32 kD laminin‐binding protein mRNAs varied depending on the donor and never reached the level of the human hepatoma cells. Subsequently, Faza, HTC and HepG 2 cells, which were selected for their ability to grow on soft agar, were injected into the flank of nude mice and formed solid tumors with no formation of secondary tumors. The tumors contained laminin in sparse deposits between adjacent cells and accumulated around vessels. None of the hepatoma cell lines studied was found to penetrate a reconstituted basement membrane using a chemoinvasion assay with a Boyden chamber. Our data show that hepatoma cells produce the B chains of laminin and express a high level of receptor 32 kD laminin‐binding protein mRNA. However these properties appear to be insufficient for these cells to form metastases in vivo . (H EPATOLOGY 1991;13:289–296).