Abstract
The effects of the major human serum bile acid, glycochenodeoxycholic acid (GCDC), as well as unconjugated chenodeoxycholic acid (CDC), on the MCF-7 human breast cancer cell line have been studied in vitro under oestrogen and bile acid deprived culture conditions. GCDC increased the growth of the breast cancer cells over the range 10-300 microM. At concentrations in excess of the bile acid binding capacity of the medium cell growth was prevented. In contrast 10 microM CDC tended to reduce cell growth. Oestrogen (ER) and progesterone (PgR) receptors, pS2 and total cathepsin D were quantified by monoclonal antibody based immunoassays. Ten to 100 microM GCDC and 10 microM CDC down-regulated ER protein and this was accompanied by induction of the oestrogen-regulated proteins PgR, pS2 and possibly cathepsin D, including increased secretion of the latter two proteins into the culture medium. All these changes were quantitatively similar to those observed with 10 nM oestradiol. The bile acid effects on ER and PgR were not due to interference with the assay procedures. Cells incubated with 50 microM GCDC or 10 microM CDC had higher pmolar concentrations of the bile acids than controls. This study suggests that naturally occurring bile acids influence the growth and steroid receptor function of human breast cancer cells.
Highlights
1992 © Macmillan Press Ltd., Bile acids influence the growth, oestrogen receptor and oestrogen-regulated proteins of MCF-7 human breast cancer cells
Since bile acid binding to serum albumin is a characteristic of the degree of hydroxylation of the steroid nucleus rather than glycine conjugation (Lawrence et al, 1980), these data suggest that medium containing 5% dextran-coated charcoal (DCC)-FCS would have a glycochenodeoxycholic acid (GCDC) protein binding capacity of approximately 500 JIM
These latter results have been confirmed in separate experiments in which whole cells, harvested every 2 days and processed as described above, had increasingly higher levels of GCDC or chenodeoxycholic acid (CDC) compared with controls; this indicates that the cell-associated bile acid is not due to simple cell adherence or residual medium
Summary
Cells were grown at 37°C with 5% CO2 in air and were maintained prior to experimentation in DME:Ham's F-10 (1:1) or DME media, both with phenol red, and containing 10% or 5% FCS and supplemented with glutamine (2mM), penicillin (50 IU ml1), streptomycin (50 fig ml-') and usually 1% non-essential amino acids (NEAA) and insulin (1ltg ml'). For growth experiments cells were usually plated out in triplicate into 35 mm petri dishes, while for the study of receptors and proteins 75 or 80 cm flasks were used in order to obtain sufficient numbers of cells. In these experiments triplicate cultures were not set up for practical reasons, but independent experiments were run on several separate occasions. Oestradiol and antioestrogens were added to experimental medium in ethanol (0.1 % final concentration or less); controls received the same amount of ethanol alone These agents were added in fresh medium when cells were plated out or 24 h later, and every 2-3 days when medium was changed. Cells were harvested with trypsin/EDTA (Flow Laboratories) and washed with medium and phosphate buffered saline (PBS) prior to counting or homogenisation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
