Effects of reduced calcium on proliferation and cell viability in tumorigenic and nontumorigenic rat tracheal epithelial cell lines.

We have compared the in vitro growth and viability of tumorigenic and nontumorigenic rat tracheal epithelial cell lines over a range of calcium concentrations from 0.003 to 0.85 mM. A greater dependence on calcium for proliferation was seen in the nontumorigenic line as compared to the tumorigenic line at both the colony formation level and in mass cultures. In the latter culture condition, a marked differential effect on cell survival was also demonstrated. These differences in calcium dependence were seen in media containing fetal bovine serum or low concentrations of newborn calf serum and in a serum-free medium developed for these cells. The effect was also independent of the method used for calcium removal i.e., either by chelex treatment or the inclusion of EGTA. Therefore, loss of calcium dependence may be associated with tumorigenicity in rat tracheal epithelial cells offering a selectable marker for neoplastic cells in carcinogen-exposed preneoplastic cell populations.