Growth inhibition by progestins in a @entity1 @entity1204 cell line with @entity172 -independent XXXX receptors.

@entity172 @entity1 @entity1204 @entity251 @entity440 @entity1420 @entity7273 @entity53 @entity969 @entity701 @entity230 @entity18074
The presence of @entity172 -independent @entity1420 receptors ( @entity7273 ) was demonstrated in a subline of a @entity1 @entity1204 cell line, Ishikawa cells, although the original Ishikawa cells contained @entity172 -inducible @entity7273 . Scatchard plot analysis of cytoplasmic binding data in our subline (IK-90) revealed a high affinity binding site for @entity18074 (Kd, 1.0 nM) with maximum binding sites of 158 fmol/mg protein. Competition experiments showed a binding specificity similar to that of typical @entity7273 . By low-salt @entity969 gradient centrifugation, radioactive 8S and 4S peaks were found. The addition of 1 microM @entity1420 in culture medium resulted in a rapid nuclear translocation of cytoplasmic @entity7273 . In contrast to the original cells, @entity172 receptors could not be detected in IK-90 cells, and an addition of @entity53 (10 nM) to culture medium failed to increase @entity7273 . Accumulation of glycogen in cytoplasm of IK-90 cells in response to @entity18074 (0.1-1 microM) was observed by periodic acid-Schiff staining. The addition of @entity18074 to culture medium (0.1-1 microM) also caused a marked decrease in the growth of IK-90 cells, whereas the other @entity230 including @entity53 , @entity440 , @entity251 , and @entity701 had no significant effects. These results demonstrate for the first time the presence of a progestin-responsive @entity1 @entity1204 cell line that contains @entity172 -independent functional @entity7273 . IK-90 cells appear to be an ideal model for studying the mechanism of the antiproliferative effect of progestin on @entity1204 cells.
