Ethanol enhances the stimulatory effects of lysophosphatidic acid on DNA synthesis but not cell proliferation in human and mouse fibroblasts.

Lysophosphatidic acid (LPA), a constituent of serum, is a positive regulator of cell growth, while ethanol (EtOH) has been shown to exert both inhibitory and stimulatory effects on mitogenesis. In this work, we examined possible interactions between the effects of EtOH and LPA on DNA synthesis, cell proliferation, activating phosphorylation of p44/p42 mitogen-activated protein kinases (MAPK), and p70 S6 kinase (p70 S6K) activity. In fibroblasts derived from human or mouse embryo or the skin of healthy human subjects, LPA (1-20 microM) and EtOH (40-80 mM) synergistically stimulated DNA synthesis in a zinc-dependent manner.

Ethanol has multiple effects on DNA synthesis in fibroblasts depending on the presence of secreted growth regulators and zinc as well as the level of protein kinase C activation.

Earlier we showed that in serum-starved (27 h), washed mouse fibroblasts and other cell lines 40-80 mM concentrations of ethanol (EtOH) potentiate, in a zinc (Zn2+)-dependent manner, the combined stimulatory effects of calcium (Ca2+) and insulin (Ins) on DNA synthesis. We now report that the promitogenic EtOH effects require removal of the used medium at least 6 h prior to treatments with EtOH, Zn2+, and Ins. If serum-starved (27 h) cells were continuously incubated for another 18-h period without replacing the medium, a secreted cellular factor moderately enhanced the mitogenic effect of Ins and simultaneously blocked the potentiating effect of EtOH on DNA synthesis measured during the last hour of treatments.

Promitogenic effects of ethanol, methanol, and ethanolamine in insulin-treated fibroblasts.

The zinc-dependent potentiating effect of ethanol (EtOH) on insulin-stimulated DNA synthesis was studied with a focus on the possible site of EtOH action and the ability of other alcohols to elicit similar promitogenic effects. In serum-starved (27 hr) NIH 3T3 fibroblasts, 200-300 mM methanol (MeOH) and 0.1-1.

Expression of human choline kinase in NIH 3T3 fibroblasts increases the mitogenic potential of insulin and insulin-like growth factor I.

In mammalian cells, growth factors, oncogenes, and carcinogens stimulate phosphocholine (PCho) synthesis by choline kinase (CK), suggesting that PCho may regulate cell growth. To validate the role of PCho in mitogenesis, we determined the effects of insulin, insulin-like growth factor I (IGF-I), and other growth factors on DNA synthesis in NIH 3T3 fibroblast sublines highly expressing human choline kinase (CK) without increasing phosphatidylcholine synthesis. In serum-starved CK expressor cells, insulin and IGF-I stimulated DNA synthesis, p70 S6 kinase (p70 S6K) activity, phosphatidylinositol 3-kinase (PI3K) activity, and activating phosphorylation of p42/p44 mitogen-activated protein kinases (MAPK) to greater extents than in the corresponding vector control cells.

alpha(1)-antitrypsin can increase insulin-induced mitogenesis in various fibroblast and epithelial cell lines.

alpha(1)-Antitrypsin (AT), the archetypal member of the superfamily of serine proteinase inhibitors, inhibits leukocyte elastase activity and thereby can prevent lung damage. Here we show that in fibroblasts from human fetal lung and mouse embryo as well as in certain epithelial cells AT can also enhance the stimulatory effects of insulin on DNA synthesis and cell proliferation. Warming of AT at a moderate (41 degrees C) temperature for a longer time (21 h) or at a higher (65 degrees C) temperature for 30 min before treatment increased its stimulatory effects on both DNA synthesis and activating phosphorylation of p42/p44 mitogen-activated protein kinases.