BS I-B4 isolectin as a probe for an investigation of membrane alterations and transformation phenotypes of mouse L cells.

BS I-B4, an alpha-D-galactopyranosyl-binding isolectin from Bandeiraea simplicifolia seeds, was found to interact differently with transformed mouse L cells and non-transformed mouse 3T3 cells. The lectin induces detachment of 3T3 cells but increases adhesiveness and clustering of L cells. However, the induced cell aggregation does not lead to cell fusion. A variant clone of L cells, resistant to BS I-B4, which had lost the capacity for agglutination in the presence of the lectin, was isolated. Fluorescence binding studies of this variant suggest a lesion involving alpha and beta-D-galactopyranosyl units on its cell-surface structures. Although the variant cells form colonies in a methylcellulose medium, they do not produce tumours, as do the parental cells, when transplanted in athymic nude mice. The results demonstrate that alterations in cell membrane glyco-conjugates play an important role in tumourigenesis of animal cells, but anchorage-independent growth in vitro, as one of the transformation phenotypes, cannot be correlated absolutely with tumourigenicity in vivo.