Biochemical and morphological effects of cigarette smoke condensate and its fractions on normal human bronchial epithelial cells in vitro.

We investigated the effect of cigarette smoke condensate (CSC), two basic fractions (BIa and BIb) of CSC, the ethanol-extracted weakly acidic fraction (WAe), and the methanol-extracted neutral fraction (Nmeoh) on the clonal growth rate, plasminogen activator (PA) activity, cross-linked envelope (CLE) formation, and ornithine decarboxylase activity, epidermal growth factor (EGF) binding, thiol levels, and DNA single strand breaks in cultured human bronchial cells. Neither CSC nor any of the fractions were mitogenic over the range 0.01-100 micrograms/ml. All were growth inhibitory at higher concentrations. The 40% growth inhibitory concentrations for CSC, BIa, BIb, WAe, and Nmeoh were 10, 10, 10, 3, and 1 micrograms/ml, respectively. Effects on CLE formation, morphology, PA, and ornithine decarboxylase activities, EGF binding, and thiol levels were evaluated using 40% growth inhibitory concentrations. We found that CSC and all fractions caused an increased formation of CLEs, from a baseline of 0.5% in the untreated cells to a maximum increase of 25% induced by Nmeoh. A squamous morphological change was observed within 1 h after exposure to Nmeoh, WAe, and CSC. The BIa and BIb fractions had little effect. Only Nmeoh increased PA significantly, from 2.5 +/- 0.4 to 5.1 +/- 0.3 units/mg cellular protein. CSC and the WAe and Nmeoh (Nmeoh greater than WAe greater than CSC) fractions caused a decrease in EGF binding, in each case reaching a maximum effect after a 10-12-h incubation. This effect on EGF binding was further characterized in the case of Nmeoh. In untreated normal human bronchial epithelial cells, by Scatchard analysis the kd was 2.0 nM and there were 1.2 X 10(5) receptors/cell. In cells incubated in medium containing Nmeoh (3 micrograms/ml) the kd was 3.2 nM and there were 1.1 X 10(5) receptors/cell. Thus, inhibition of EGF binding by Nmeoh was due primarily to a decrease in the affinity. At the 40% growth inhibitory concentrations neither CSC nor any of the fractions significantly affected intracellular thiol levels. While a 3-h incubation in medium containing CSC caused significant DNA single strand breaks only at a concentration of 100 micrograms/ml, Nmeoh caused a marked effect at 5 micrograms/ml. Neither CSC nor any of the fractions had an effect on ornithine decarboxylase activity. Due to the effects of the Nmeoh fraction on growth, morphology, EGF binding, PA activity, and formation of single strand breaks we consider it to be the most likely portion of CSC to contain compounds with actions similar to those of the phorbol ester, indole alkaloid, and polyacetate tumor promoters.

Differential effects of 12-O-tetradecanoylphorbol-13-acetate on cultured normal and neoplastic human bronchial epithelial cells.

The effects of the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) on 10 human lung carcinoma cell lines were compared to those seen on normal human bronchial epithelial (NHBE) cells. TPA (0.1 to 100 nM) did not enhance the clonal growth rate for any of the cell lines. As little as 3 nM TPA induced the NHBE cells to undergo terminal squamous differentiation and thus completely inhibited their proliferation; in contrast, none of the carcinoma cell lines was significantly inhibited at this concentration, and they all continued to proliferate in as much as 100 nM TPA. To determine if this lack of TPA inhibition of clonal growth reflected resistance to TPA induction of terminal squamous differentiation, we measured the ability of TPA to induce cross-linked envelope formation and to increase plasminogen activator activity in four carcinoma cell lines. Cross-linked envelopes were not induced in two lines, and only a small number were induced in the other two lines relative to NHBE cells; plasminogen activator activity was induced in NHBE cells but not in any of the cell lines.

Effects of aplysiatoxin and debromoaplysiatoxin on growth and differentiation of normal human bronchial epithelial cells.

The effects of aplysiatoxin and debromoaplysiatoxin on the clonal growth rate, cross-linked envelope formation and plasminogen activator secretion of normal human bronchial epithelial cells were studied. Neither compound was mitogenic over a wide range of concentrations (10(-13) to 10(-7)M). Both aplysiatoxin and debromoaplysiatoxin inhibited clonal growth rate with 50% inhibitory concentrations of 3 x 10(-11)M and 10(-10)M, respectively. Both compounds induced the formation of cross-linked envelopes and increased plasminogen activator secretion with equal potency. These data are similar to those previously obtained with 12-O-tetradecanoylphorbol-13-acetate and teleocidin B and suggest that aplysiatoxin and debromoaplysiatoxin induce terminal squamous differentiation in normal human bronchial epithelial cells.