Laminin-induced retinoblastoma cell differentiation: possible involvement of a 100-kDa cell-surface laminin-binding protein.

Gene and protein expression of Y-79 retinoblastoma cells growing on poly(D-lysine) is switched from a photoreceptor-like to a conventional neuron-like pathway by the basement membrane glycoprotein laminin. Unlike other cell systems where laminin influences differentiation, Y-79 cells can neither attach to nor chemotactically respond to laminin. However, laminin increases attachment to poly(D-lysine). The laminin effects therefore seem to occur via an adhesion- and chemotaxis-independent mechanism. Moreover, these tumor cells do not exhibit high-affinity laminin binding, having only a single binding site of intermediate affinity. Laminin-Sepharose affinity chromatography of Y-79 cell surface proteins labeled with 125I revealed a single major radiolabeled 100-kDa protein eluted by 20 mM EDTA, with an electrophoretic behavior different from that of integrins. No other proteins were eluted under more stringent conditions. This material, which we call LBM-100 (100-kDa laminin-binding molecule), may be a "differentiative" laminin-binding protein through which laminin influences gene expression and development independently of attachment.

[Use of reconstituted basal membranes for the study of invasion of human tumor cells: current status and future prospects]. / Uso di membrane basali ricostituite per lo studio dell'invasione di cellule tumorali umane: stato attuale e prospettive future.

Tumor metastasis is the major cause of death of oncology patients. One of the characteristic properties acquired by the metastatic cell is the ability to cross basement membranes. These are compartments of extracellular matrix composed largely by collagen type IV, laminin and a heparan sulphate proteoglycan. Here we review the use of a reconstituted basement membrane (Matrigel) in the Boyden chamber assay (Chemoinvasion Assay) for the assessment of the invasiveness of tumor cells of human origin. The possibility of using this test for the rapid evaluation of human tumor specimens from operated patients is discussed.

Effect of vitamin A on chemotactic and chemoinvasive behaviour of an osteosarcoma cell line.

Vitamin A is known to be able to modulate cell growth and differentiation and to act as an inhibitor of the process of carcinogenesis in some experimental models. Here we have studied the effect of different concentrations of vitamin A on chemotactic and chemoinvasive behaviour of a metastatic osteosarcoma cell line. The cell proliferation was partially inhibited in the presence of 10(-5) M retinol after 4 days of incubation. Retinol effect on chemotactic and chemoinvasive activity of osteosarcoma cells seemed to be dose-dependent. The highest retinol concentration used (10(-5) M) had an inhibitory effect on migratory and invasive cell response. Lower retinol concentrations seemed to be able to enhance (10(-8) M) both chemotactic and chemoinvasive activity of osteosarcoma cells. Chemotaxis and chemoinvasion assays provide rapid and quantitative tools to study the "in vitro" behaviour of metastatic cells. Furthermore, they represent a mean to screen for drugs, hormones and other substances able to alter the metastatic phenotype.

Growth of cells from esophageal squamous cell carcinoma biopsies in a reconstituted basement membrane.

Cells from esophageal carcinoma biopsies were cultured on or inside a three-dimensional basement membrane matrix (matrigel). Their growth was compared to cells derived from control esophageal biopsies. Cells from both normal and neoplastic tissue attached poorly to tissue culture plastic. Matrigel coating improved adhesion and growth. When cells were grown inside a matrigel matrix, a striking difference was noticed between carcinoma cells and controls. Carcinoma cells grew invasively in the three-dimensional substrate and digested the matrix after a few weeks; control cells did not grow and only a few necrotic cells were visible with time. Matrigel provided a better growth substrate than plastic for esophageal derived cells and discriminated between carcinoma-derived and control cells when used as a three-dimensional growth substrate. Our studies suggest a possible use of matrigel for the selective growth of tumor cells derived directly from tissue biopsies.