EFFECTS OF EXOGENOUS TRANSGLUTAMINASE ON SPREADING OF HUMAN COLORECTAL-CARCINOMA CELLS

Using pre-confluent cultures of a human colon tumor cell line deficien t in transglutaminase (LS174T cells), we have investigated the effect of adding exogenous transglutaminase (TGA) on cell spreading. The cell s were plated at either 4.5 x 10(5) cells per well (low-seeded culture s) or 9 x 10(5) cells per well (high-seeded cultures) in 24-well dishe s and treated for either 1 or 4 days (low- and high-seeded cultures re spectively) under following conditions: Chee's Essential Medium (CEM) + 10% fetal calf serum (FCS); CEM + 10% FCS + TGA; CEM + 10% FCS + dit hiothreitol (DTT) + CaCl2; CEM + 10% FCS + DTT + CaCl2 + TGA. Photomic rography of the cells after these treatments revealed that in both low - and high-seeded cultures, TGA inhibited the spreading of the cells b oth in the presence and absence of DTT and calcium. Individual colony sizes were significantly smaller in the presence of TGA. This phenomen on may be related to the ability of TGA to promote cell interactions w ith the underlying tissue matrices and metastasis.