Monensin and tunicamycin-induced inhibition of HT29 cell spreading and growth.

HT29 cells originating from a human colon adenocarcinoma, spread very rapidly after seeding on their own extracellular matrix (ECM). Preincubation of cells with the inhibitor of protein glycosylation tunicamycin (TM) or with the ionophore monensin substantially suppressed cell spreading in serum-free medium without affecting cell adhesion to ECM. Addition of the drugs after cell attachment and spreading inhibited cell growth.

Characterization of the vasoactive intestinal peptide (VIP) binding sites: a biochemical and an immunological approach.

The initial event of VIP action is its interaction with a specific receptor at the surface of a target cell. The understanding of the fine mechanism of action of VIP requires the characterization and of course the purification of the receptor. The understanding of the mechanism which regulates the number of receptor sites at the cell surface, if it occurs, is also a way to characterize the properties of VIP receptor.

Covalent cross-linking of vasoactive intestinal peptide (VIP) to its receptor in intact colonic adenocarcinoma cells in culture (HT 29).

[125I]Monoiodinated vasoactive intestinal peptide (125I-VIP) was cross-linked with human colonic adenocarcinoma cells (HT29 cells) grown as a monolayer using dithiobis(succinimidylpropionate) as cross-linking reagent. The cross-linked polypeptides were separated by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. A major polypeptide of Mr = 67 000 was characterized and it behaved like a high-affinity binding site for VIP according to the following data.