Estrogen induces cytokeratin aggregation in primary cultures of Armenian hamster hepatocytes

The effect of estrogen administration to cultured Armenian hamster was stud ied. Isolated Armenian hamster hepatocytes were cultured in RPMI medium sup plemented with beta-estradiol (E-2) beta-estradiol treatment for 24-48 hr i nduced cytoplasmic inclusion bodies which by immunocytochemistry were posit ive for cytokeratin (CK) 8, CK 18, and ubiquitin but negative for CK 7 and CK 19. These inclusion bodies appeared as filamentous tangles or amorphous aggregates when observed by electron microscopy. F-actin, tubulin, and desm osomes were not influenced by the presence of the inclusion bodies. Additio n of ethanol to culture medium increased the incidence of the inclusion for mation. In combination with 0.5% ethanol 1 mu M of E-2 induced five to six times more inclusion bodies, while the number of inclusion bodies decreased when epidermal growth factor (EGF) was added to the medium in combination with E-2. This reduction effect was nullified by treatment with anti-EGF re ceptor antibody. These findings suggest that E-2 treatment to Armenian hams ter hepatocytes in vitro induces Mallory body-like inclusions whose inciden ce can be influenced by addition of ethanol or EGF to the culture medium. C ell Motil. Cytoskeleton 43:35-42, 1999. (C) 1999 Wiley-Liss, Inc.