Comparative studies of Calretinin expression by WiDr cell line in vivo in xenografts in nude mice and in vitro

WiDr cells from a human colon adenocarcinoma cultivated in vitro express th e calcium binding protein calretinin. The immunoreactivity is present in so me interphasic cells and decreases after seven days in culture together wit h the augmentation of the cell number. Calretinin expression is maintained in the undifferentiated cells of the tumoral mass developed in nude mice an d in recultivated isolated tumour cells from the xenograft. From the experi ments here described, the protein expression is quantitatively influenced i n vitro by the addition of drugs, such as colchicine and taxol, which inter vene in cytoskeleton organisation. The percentage of the calretinin immunor eactive cells increases after the addition of colchicine to the medium whil e the immunoblot analysis shows a higher calretinin content in the cells tr eated with taxol.