Rapid aggregation and tight junction formation in single cell suspensions of tumor cells after very low dose trypsin treatment.

The possible participation of tight junction formation in intercellular adhesion of tumor cells was studied in single cell suspensions of HT29 adenocarcinoma cells. Very low dose trypsin treatment (0.15 micrograms/ml, 30 min, 37 degrees C) induced rapid intercellular adhesion of suspended HT29 colon carcinoma cells. Intercellular adhesion was independent of the presence of divalent cations. Electron microscopy of freeze-fractured membrane fragments of trypsin-treated HT29 cells revealed a dramatic increase of typical tight junction structures during aggregation.