Temporal effects of ethanol on growth, thymidine uptake, protein and collagen production in human foetal lung fibroblasts

Abstract

Foetal Alcohol Syndrome is observed in 2/1000 live births worldwide and is characterized by decreased pre-natal and postnatal growth, physical anomalies and mental retardation. To determine the effects of ethanol (Et) on foetal cells cultured in the absence of hormones or growth factors, human foetal lung (HFL1) fibroblasts were exposed to Et-supplemented media (0.1–2% Et) for 6 hr to 7 days. Growth rates, thymidine incorporation into DNA, protein synthesis and degradation, and collagen production were assessed. For growth experiments, cells were seeded at 1 3 confluent density and incubated in Et-supplemented medium 24 hr later. Metabolic labelling was performed on confluent monolayers using [ 3H]thymidine (TdR), [ 3H]leucine or [ 3H]proline. Exposure to Et for 3 or 7 days decreased cell numbers but normal proliferation resumed when cells were re-plated in control medium. Exposure to 0.5% Et for 7 days resulted in a 3.5-fold increase in [ 3H]TdR uptake. Et suppressed protein production and enhanced degradation. The most significant decrease was seen at 6 hr, but was influenced by the amino acid used for labelling. Agarose-gel chromatography suggests that Et preferentially alters the lower-molecular-weight species. The percentage of the total protein secreted into the medium was not changed. Collagen production, as a percentage of total protein, decreased after a 48-hr label and a 7-day incubation with Et. The percentage of total collagen that was secreted into the medium was also not influenced by Et. The results indicate that, in the absence of endocrine or nutritional manipulation, acute exposure to Et in vitro inhibits cell growth and protein production; protein secretion, however, remains intact.