PubMed Health⌕ Search

Biomedical subjects

J F Lechner

Publications and source records attributed to J F Lechner.

At least 55 records · Page 3Linked to original sources
PubMed1988

Human bronchial epithelial cells with integrated SV40 virus T antigen genes retain the ability to undergo squamous differentiation.

Human bronchial epithelial cells transformed by either DNA virus infection (SV40 or Adenovirus 12-SV40 hybrid virus) or transfection with the SV40 large T antigen gene were studied for their ability to undergo squamous differentiation when exposed to 12-O-tetradecanoylphorbol-13 acetate (TPA), transforming growth factor-beta 1 (TGF-beta 1), or fetal bovine serum (FBS), agents that induce the squamous differentiation of normal human bronchial epithelial cells. Squamous differentiation occurred in all ten T-antigen-positive cell cultures when they were exposed to either FBS or TGF-beta 1, but none differentiated when exposed to TPA. From one cell line, designated BEAS-2B, two subclones were isolated, one of which was induced to undergo squamous differentiation by FBS, and a second that failed to undergo squamous differentiation and was mitogenically stimulated when exposed to serum. These phenotypically different subclones provide a new in vitro cellular system for delineating the mechanism(s) of human bronchial epithelial cell squamous differentiation in response to FBS or TGF-beta 1.

Antigens, Viral↗
PubMed1988

Human bronchial epithelial cells neoplastically transformed by v-Ki-ras: altered response to inducers of terminal squamous differentiation.

Many human bronchial adenocarcinomas have been shown to contain an activated Ki-ras oncogene (Rodenhuis et al., N. Engl. J. Med. 317 929-935, 1987). To test the hypothesis that activated Ki-ras may be causally related to human bronchial carcinogenesis, v-Ki-ras oncogene was transferred into an established human bronchial epithelial cell line, BEAS-2B, by infection with Kirsten murine sarcoma virus (Ki-MSV) or by transfection with a plasmid containing the transforming region of Ki-MSV. These cells formed poorly differentiated adenocarcinomas in athymic nude mice. Cell lines established from these tumors expressed v-Ki-ras p21 protein and were highly tumorigenic. Whereas serum or transforming growth factor beta 1 induced the BEAS-2B cells at clonal density to undergo growth arrest and squamous differentiation, BEAS-2B cells containing activated ras genes were unaffected by transforming growth factor beta 1 and were mitogenically stimulated by serum.

Animals↗
PubMed1987

Comparison of production of transforming growth factor-beta and platelet-derived growth factor by normal human mesothelial cells and mesothelioma cell lines.

Steady state mRNA levels for transforming growth factor beta, platelet-derived growth factor (PDGF) A-chain, and PDGF B-chain were measured in normal human mesothelial cells, SV40 large T-antigen expressing human mesothelial cells, and human mesothelioma cell lines. The mRNA expression level for transforming growth factor beta was similar in all three types of culture while normal human mesothelial cells secrete more transforming growth factor beta than do mesothelioma cell lines or T-antigen expressing mesothelial cells. In contrast, both PDGF A- and B-chain mRNAs are expressed at higher levels in mesothelioma cell lines than in normal human mesothelial cells. PDGF-like mitogenic activity was readily detectable in medium conditioned by a mesothelioma cell line and was undetectable in conditioned medium from normal cells. These results suggest the hypothesis that PDGF may be an autocrine growth factor in mesothelioma.

Cell Line↗
PubMed1986

Type beta transforming growth factor is the primary differentiation-inducing serum factor for normal human bronchial epithelial cells.

Type beta transforming growth factor (TGF-beta) was shown to be the serum factor responsible for inducing normal human bronchial epithelial (NHBE) cells to undergo squamous differentiation. NHBE cells were shown to have high-affinity receptors for TGF-beta. TGF-beta induced the following markers of terminal squamous differentiation in NHBE cells: (i) increase in Ca ionophore-induced formation of crosslinked envelopes; (ii) increase in extracellular activity of plasminogen activator; (iii) irreversible inhibition of DNA synthesis; (iv) decrease in clonal growth rate; and (v) increase in cell surface area. The IgG fraction of anti-TGF-beta antiserum prevented both the inhibition of DNA synthesis and the induction of differentiation by either TGF-beta or whole blood-derived serum. Therefore, TGF-beta is the primary differentiation-inducing factor in serum for NHBE cells. In contrast, TGF-beta did not inhibit DNA synthesis of human lung carcinoma cells even though the cells possess comparable numbers of TGF-beta receptors with similar affinities for the factor. Epinephrine antagonized the TGF-beta-induced inhibition of DNA synthesis and squamous differentiation of NHBE cells. Although epinephrine increased the cyclic AMP levels in NHBE cells, TGF-beta did not alter the intracellular level in NHBE cells in either the presence or absence of epinephrine. Therefore, epinephrine and TGF-beta appear to affect different intracellular pathways that control growth and differentiation processes of NHBE cells.

Bronchi↗
PubMed1985

Transformation of human bronchial epithelial cells transfected by Harvey ras oncogene.

Transfection of normal human bronchial epithelial (NHBE) cells with a plasmid carrying the ras oncogene of Harvey murine sarcoma virus (v-Ha ras) changed the growth requirements, terminal differentiation, and tumorigenicity of the recipient cells. One of the cell lines isolated after transfection (TBE-1) was studied extensively and shown to contain v-Ha ras DNA. Total cellular RNA from TBE-1 cells hybridized to v-Ha ras structural gene fragment probes five to eight times more than RNA from parental NHBE cells. The TBE-1 cells expressed phosphorylated v-Ha ras polypeptide p21, showed a reduced requirement for growth-factor supplements, and became aneuploid as an early cellular response to v-Ha ras expression. As the transfectants acquire an indefinite life-span and anchorage independence they became transplantable tumor cells and showed many phenotypic changes suggesting a pleiotropic mechanism for the role of Ha ras in human carcinogenesis.

Animals↗
PubMed1985

Relationship of ornithine decarboxylase activity and cAMP metabolism to proliferation of normal human bronchial epithelial cells.

The mechanisms of action of extracellular mitogens for normal human bronchial epithelial cells (NHBE) were investigated by observing their effects on selected biochemical pathways when the cells were incubated in serum-free media. We find that (a) epidermal growth factor (EGF) stimulates ornithine decarboxylase (ODC) activity and the rate of cell division without stimulating cAMP; (b) alone, pituitary extract (PEX) does not stimulate ODC activity, cAMP levels, or cell division; (c) when PEX is added to medium containing EGF there is a further increase in both ODC activity and the rate of cell division, again with no increase in cAMP levels; (d) in contrast, alone, L-epinephrine (EPI) stimulates an increase in both ODC and cAMP but does not stimulate cell division; (e) when EPI is added to medium containing both EGF and PEX a further increase in the rate of cell division is noted; (f) the specific inhibitor of ODC, alpha-(difluoromethyl)-ornithine (DMFO), also inhibits NHBE cell proliferation; and (g) the beta-adrenergic receptor antagonist propranolol inhibits the mitogenic action and ODC induction by EPI observed under condition e. We conclude that an increase in ODC activity is necessary but not sufficient for an increase in proliferation of NHBE cells. In contrast, cAMP stimulation is not necessary for an increase in NHBE cell division. However, in the presence of undefined factors in PEX, increases in cAMP levels result in a synergistic increase in the rate of EGF-stimulated clonal growth. By correlating the biochemical pathways invoked by EGF, PEX, EPI, and combinations thereof with their mitogenic actions, we have better defined the role each of these different mitogens plays in stimulating epithelial cell division.

Bronchi↗
PubMed1985

Asbestos-associated chromosomal changes in human mesothelial cells.

Replicative cultures of human pleural mesothelial cells were established from noncancerous adult donors. The cells exhibited normal mesothelial cell characteristics including keratin, hyaluronic acid mucin, and long branched microvilli, and they retained the normal human karyotype until senescence. The mesothelial cells were 10 and 100 times more sensitive to the cytotoxic effects of asbestos fibers than normal human bronchial epithelial or fibroblastic cells, respectively. In addition, cultures of mesothelial cells that survived two cytotoxic exposures of amosite fibers were aneuploid with consistent specific chromosomal losses indicative of clonal origin. These aneuploid cells exhibit both altered growth control properties and a population doubling potential of greater than 50 divisions beyond the culture life span (30 doublings) of the control cells.

Asbestos↗
PubMed1985

In vitro studies of human lung carcinogenesis.

Advances in the methodology to culture normal human lung cells have provided opportunities to investigate fundamental problems in biomedical research, including the mechanism(s) of carcinogenesis. Using the strategy schematically shown in Figure 1, we have initiated studies of the effects of carcinogens on the normal progenitor cells of the human cancers caused by these carcinogens. Extended lifespans and aneuploidy were found after exposure of mesothelial cells to asbestos and bronchial epithelial cells to nickel sulfate. These abnormal cells may be considered to be preneoplastic and at an intermediate position in the multistage process of carcinogenesis. Human bronchial epithelial cells can also be employed to investigate the role of specific oncogenes in carcinogenesis and tumor progression. Using the protoplast fusion method for high frequency gene transfection, vHa-ras oncogene initiates a cascade of events in the normal human bronchial cells leading to their apparent immortality, aneuploidy, and tumorigenicity in athymic nude mice. These results suggest that oncogenes may play an important role in human carcinogenesis.

Animals↗
PubMed1985

Effects of formaldehyde, acetaldehyde, benzoyl peroxide, and hydrogen peroxide on cultured normal human bronchial epithelial cells.

The effects of several aldehydes and peroxides on growth and differentiation of normal human bronchial epithelial cells were studied. Cells were exposed to formaldehyde, acetaldehyde, benzoyl peroxide (BPO), or hydrogen peroxide (HPO). The effect of each agent on the following parameters was measured: (a) clonal growth rate; (b) squamous differentiation; (c) DNA damage; (d) ornithine decarboxylase activity; (e) nucleic acid synthesis; (f) aryl hydrocarbon hydroxylase activity; and (g) arachidonic acid and choline release. None of the agents were mitogenic, and their effects were assessed at concentrations which reduced growth rate (population doublings per day) to 50% of control. The 50% of control concentrations for the 6-h exposure were found to be 0.065 mM BPO, 0.21 mM formaldehyde, 1.2 mM HPO, and 30 mM acetaldehyde. BPO-exposed cells were smaller than controls (median cell planar area, 620 sq microns versus 1150 sq microns), and acetaldehyde-exposed cells were larger than controls (median cell planar area, 3200 sq microns). All agents increased the formation of cross-linked envelopes and depressed RNA synthesis more than DNA synthesis. HPO caused DNA single-strand breaks, while formaldehyde and BPO caused detectable amounts of both single-strand breaks and DNA-protein cross-links. Other effects included increased arachidonic acid and choline release due to HPO. The similarities and differences of the effects of these aldehydes and peroxides to those caused by tumor promoters are discussed.

Acetaldehyde↗
PubMed1984

Bombesin and the C-terminal tetradecapeptide of gastrin-releasing peptide are growth factors for normal human bronchial epithelial cells.

Bombesin and the C-terminal portion of gastrin-releasing peptide (GRP14-27) each increase clonal growth rate and colony-forming efficiency of normal human bronchial epithelial cells. These effects occur in the presence or absence of an optimal concentration (5 ng/ml) of epidermal growth factor (EGF). In contrast to EGF bombesin and GRP14-27 do not stimulate cell migration. Thus, bombesin and the C-terminal fragment of gastrin-releasing peptide represent a new class of peptides mitogenic for normal human epithelial cells.

Adult↗
PubMed1984

Effects of nickel sulfate on growth and differentiation of normal human bronchial epithelial cells.

Epidemiological studies have shown that inhalation of nickel compounds enhances the risk of human respiratory cancer. Cultures of normal human bronchial epithelial cells were continuously exposed to a dose (5-20 micrograms/ml) of NiSO4 that reduced their colony forming efficiency by 30-80%. After 40 days of incubation, the cultures consisted of large, squamous cells; mitotic cells were not observed. The cells were then maintained in medium without NiSO4. After 40-75 total days of incubation, colonies of mitotic cells appeared at a rate of 1 colony per 100 000 cells originally at risk; no colonies appeared in control cultures or in cultures exposed to less than 5 micrograms NiSO4/ml for 90 days. Twelve NiSO4-altered cell cultures isolated from five experiments have been expanded into mass cultures. Most of the cell lines have an increased population doubling potential (greater than 50 divisions). Some exhibit aberrations in the squamous (terminal) differentiation process whereas others have lost the requirement for epidermal growth factor for clonal growth. Aneuploidy and marker chromosomes have also been noted. However, none of these NiSO4-altered cell cultures are anchorage independent nor do they produce tumors upon injection into athymic nude mice.

Bronchi↗
PubMed1984

Acute effects of 12-O-tetradecanoylphorbol-13-acetate, teleocidin B, or 2,3,7,8-tetrachlorodibenzo-p-dioxin on cultured normal human bronchial epithelial cells.

Effects of teleocidin B, 12-O-tetradecanoylphorbol-13-acetate (TPA), phorbol, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 2,7-dichlorodibenzo-p-dioxin (DCDD) on normal human bronchial epithelial cell cultures were assessed by quantitation of cellular morphology, clonal growth (population doublings per day), cross-linked envelope (CLE) formation and the enzymatic activities of aryl hydrocarbon hydroxylase (AHH), ornithine decarboxylase (ODC) and plasminogen activator (PA). Toxicity was assessed by clonal growth assays. Teleocidin B and TPA had similar effects on growth, morphology and enzyme activities. When the cells were incubated with TPA or teleocidin B at concentrations of 1-100 nM for 6 h, RNA synthesis was unaffected, but DNA synthesis decreased and squamous differentiation, marked by an increase in cell surface area and cross-linked envelope formation, was increased. TPA and teleocidin B also increased ODC activity in LHC-0 medium (a maintenance medium without epidermal growth factor) but caused a decrease of ODC activity in LHC-4 (a growth medium containing epidermal growth factor). Finally, TPA and teleocidin B each caused an increase of PA and a decrease of AHH activities in both media. Phorbol, a non-promoting analogue of TPA, had no effect on growth, morphology or biochemical assays. TCDD (100 nM) caused a 15% decrease in cell growth when cells were incubated in LHC-4, and this was accompanied by an increase in cell surface area, PA activity, and CLE formation. TCDD caused an increase in AHH and ODC activities when the cells were incubated in either LHC-0 or LHC-4 medium. DCDD did not alter cell growth, and its morphological and biochemical effects were similar to those of TCDD although less marked. In conclusion, results reported here are consistent with the hypothesis that an important property of some tumor promoters is their ability to induce terminal differentiation in normal, non-initiated epithelial cells.

Alkaloids↗
PubMed1984

Induction of squamous differentiation of normal human bronchial epithelial cells by small amounts of serum.

Recently we reported a low calcium (110 microM) serum-free medium (LHC-1) for clonal growth of normal human bronchial epithelial (NHBE) cells. NHBE cells within colonies are small (mean surface area = 1,250 mu2) rarely migratory, have few tonofilaments, and multiply with an average population doubling time of 28 h. We have also noted that adding small amounts of blood-derived serum to LHC-1 medium (as little as 2%) significantly decreased the clonal growth rate. We have now found that the growth inhibiting effect of serum is due to the induction of squamous (terminal) differentiation. Serum quickly increases the size of the cells (mean surface area = 4,900 mu2). In addition, the cells acquire numerous desmosomal junctions and an extensive network of keratin bundles. In contrast, human lung carcinoma cells multiply rapidly at clonal density in LHC-1 medium containing as much as 8% serum. Although high concentrations of calcium ions in the medium are known to induce squamous differentiation of epidermal keratinocytes in the absence of serum, high levels of Ca2+ (up to 1,000 microM) increased the number of desmosomal junctions, but did not significantly affect the clonal growth rate or size of the NHBE cells. However, high concentrations of calcium (above 450 microM) were found to potentiate serum differentiation-inducing activity. On the other hand, cholera toxin (10 ng/ml) inhibited the differentiation-inducing activity of serum. These results show that squamous differentiation of NHBE cells can be induced by serum and the potency of these serum factors can be modulated. In addition, the data show that lung carcinoma cells differ from their normal counterparts by not undergoing differentiation in the presence of serum.

Blood Physiological Phenomena↗
PubMed1984

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.

Cell Division↗