Modulation of S-100 genes response to growth conditions in human epithelial tumor cells.

Many new members of the S-100 genes are known to be associated with cell differentiation, malignant transformation, and cell cycle. Of the S-100 genes examined in the present study, calcyclin, calpactin I light chain and calvasculin were expressed in most human epithelial tumor cells, and their expression levels differed according to various growth conditions. Their transcribed levels differed depending on each cell line, but their expression patterns were similarly changed under growth-modulatory conditions. Their messenger RNA levels increased parallel to the S phase population of cells, and decreased at G1/G2 phases. In contrast, this expression diminished in tumor cells under growth-inhibitory conditions, such as treatment with topoisomerase II inhibitor VP-16 or phorbol 12-myristate 13-acetate.