[Establishment of an estrogen receptor positive 3'-methyl-4-dimethylaminoazobenzene induced hepatoma cell line of rat and investigation of hormonal therapy].

An estrogen receptor (ER) positive cell line was newly established from a Wistar King Aptekman (WKA) rat, 3'-methyl-4-dimethylaminoazobenzene (DAB) induced hepatoma cell lines. The impact of hormonal therapy on cell growth was investigated. This cell line produced alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA) and ferritin in the conditioned medium. Progesterone receptors (PgR) were positive but androgen receptors (AR) were not detected. This cell line's doubling time was about 10.5 hours in a routine medium and 12.2 hours in the endogenous estrogen removed medium (exponential phase). The morphological features of the cell were of a hepatocellular type as observed by light microscopy. The modal chromosome number was 56 and the DNA ploidy pattern was aneuploid as observed by flow cytometry. The addition of 17 beta-estradiol (E2) did not increase cell growth but tamoxifen (TAM) in vitro inhibited cell growth in the lag phase. Surgical castration or oral administration of E2 or TAM in vivo inhibited tumor growth in the early phase. There were no additional effects between surgical castration and the administration of E2. Surgical castration plus the administration of TAM were not effective when combined. The administration of TAM caused the physiological effect of castration eg., diminished blood testosterone level same as E2 administration. TAM also decreased the maximal binding capacity (Bmax) of ER. A morphological change to the cholangiocell carcinoma type was noticed. These results that this cell line was ER dependent in the early phase of tumor growth.