Alkaline phosphatase from two HeLa S3 subclones: one producing Regan and the other, Kasahara isozyme.

HeLa S3 cells have been found to possess heat-stable alkaline phosphatase. However, the present electrophoretic study indicated that this cell line also contained a heat-labile isozyme as a minor component with the major heat-stable (Regan) isozyme. Histochemical demonstration of these two isozymes was also made through heat treatment and inhibition tests. By the single cell cloning of HeLa S3 cells, two subclones, HeLa S3-5 with heat-labile Kasahara isozyme and HeLa S3-10 with Regan isozyme, were established. All 18 subclones from this HeLa S3-5 possessed the same type of heat-labile alkaline phosphatase. These two isozymes were expressed in two cell lines, respectively, during long term culture. The present study suggests that certain cell populations of HeLa S3 have changed their phenotype to Kasahara isozyme due to alteration of a regulatory gene during long term cell culture.