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J F Lechner

Publications and source records attributed to J F Lechner.

At least 73 records · Page 4Linked to original sources
PubMed1984

Interdependent regulation of epithelial cell replication by nutrients, hormones, growth factors, and cell density.

Considerable progress in human epithelial cell culture procedures has permitted defining nutritional growth requirements in low-serum or serum-free conditions for normal and tumorigenic prostatic and bronchial epithelial cells. Assay conditions revealed interrelationships between cell density and nutrient and factor requirements for both growth enhancement and terminal differentiation. Interactions among nutrients, growth factors, and serum have been delineated by applying the principles of Michaelis-Menton kinetics to clonal growth data: 1) epidermal growth factor (EGF) reduced the half-maximal requirement for serum and Ca2+, but neither serum nor Ca2+ altered the EGF requirement; 2) serum stimulated terminal differentiation of bronchial epithelial cells and EGF; cholera toxin and growth-arrested Swiss mouse 3T3 feeder cells inhibited serum-induced differentiation; 3) differences in the interaction of Ca2+- and Mg2+-dependent growth control of prostatic and bronchial epithelial cells were noted; and 4) a phenotypic reduction in nutritional growth requirements for bronchial epithelial cells was obtained by supplementing serum-free medium with triiodothyronine. These results indicate significant differences in both nutritional requirements and interactions for different types of human epithelial cells. Elucidation of these differences may point to plausable reasons why the malignant transformation potential of tissue types varies with specific carcinogens.

Blood↗
PubMed1983

High-frequency transfection and cytopathology of the hepatitis B virus core antigen gene in human cells.

A protoplast fusion method was developed to stably transfect human cells with pSV2-derived plasmids at frequencies greater than 10(-3). This procedure made it possible to test the biological effect of a hepatitis B virus (HBV) gene independent of the viral structures required for infection. A pSV2gpt+ plasmid constructed to carry a subgenomic fragment of HBV that contained the core antigen gene (HBc gene) was transfected into human cells. A human epithelial cell line was stably transfected with the HBc+ gene by selecting recipient cells for expression of guanine phosphoribosyl transferase expression. With this gpt+/HBc+ cell line it was shown that growth in serum-free medium or treatment with 5'-azacytidine stimulates the production of the HBV core antigen. A hepatocellular carcinoma carrying the entire HBV genome was stimulated to produce the HBc gene product in response to the same factors that stimulated HBcAg production in the gpt+/HBc+ cell line constructed by transfection. The temporal relation between the cytopathologic response and HBc gene expression was similar for both cell types, indicating a primary role for HBc gene expression in the cytopathology of HBV-infected human liver.

Azacitidine↗
PubMed1983

Formaldehyde damage to DNA and inhibition of DNA repair in human bronchial cells.

Cultured bronchial epithelial and fibroblastic cells from humans were used to study DNA damage and toxicity caused by formaldehyde. Formaldehyde caused the formation of cross-links between DNA and proteins, caused single-strand breaks in DNA, and inhibited the resealing of single-strand breaks produced by ionizing radiation. Formaldehyde also inhibited the unscheduled DNA synthesis that occurs after exposure of cells to ultraviolet irradiation or to benzo[a]pyrene diolexpoxide but at doses substantially higher than those required to inhibit the resealing of x-ray-induced single-strand breaks. Therefore, formaldehyde could exert its mutagenic and carcinogenic effects by both damaging DNA and inhibiting DNA repair.

Bronchi↗
PubMed1983

Bloom's syndrome cells have an abnormal serum growth response.

Certain growth responses of Bloom's syndrome (BS) dermal fibroblasts have been compared to those of normal human fibroblasts. By applying the principles of Michaelis-Menton kinetics to clonal dose-response data, serum and epidermal growth factor (EGF) requirements of the two cell types were found to be similar. However, the maximal clonal growth rate of BS cells was significantly lower than that of their normal counterparts. Although specific EGF binding by BS cells was marginally higher than in normal cells, EGF's growth-promoting activity was only half of that seen in normal cells. These observations indicate that the abnormally low growth rate of BS cells is not attributable to excessive requirements for serum-derived growth factors and suggest instead that the genetic defect in some way impairs the cells' ability to respond fully to growth stimulation.

Adult↗
PubMed1983

Differential control by platelet factors of squamous differentiation in normal and malignant human bronchial epithelial cells.

Recently, we developed a nutritionally optimal medium for rapid clonal growth (greater than 1 population doubling/day) of normal human bronchial epithelial (NHBE) cells. Adding fetal bovine or adult human blood-derived serum to this medium depresses the clonal growth rate of NHBE cells in a dose-dependent fashion. In contrast, 10 representative lines of human lung carcinomas either replicate poorly or fail to grow at all when inoculated at clonal density in serum-free medium, and their rates of multiplication increase in direct proportion to the amount of blood-divided serum added to the optimized medium. Thus, the growth factor requirements of these lung carcinoma cell lines are significantly different from those of their normal counterparts. Blood-divided serum reduces the clonal growth rate of NHBE cells by specifically inducing the normal cells, but not lung carcinoma cells, to undergo squamous differentiation. The differentiation-inducing activity was found in platelet lysates. In addition, a growth-inhibiting activity that did not induce squamous differentiation of NHBE cells was also identified in partially purified commercial preparations of platelet-derived growth factor. This observation was in marked contrast to results using human bronchial fibroblasts and human lung carcinoma cell lines; the growth rate of the former was significantly stimulated by commercial preparations of platelet-derived growth factor, whereas the growth rates of the tumor cell lines were unaffected. These results indicate that an aberration in the cellular differentiation as assayed in vitro is positively correlated with cancer and suggests that decreased responsiveness to inducer(s) of differentiation may be a major aspect of bronchial cell carcinogenesis.

Bronchi↗
PubMed1982

Clonal growth of normal adult human bronchial epithelial cells in a serum-free medium.

Defined culture conditions for routine clonal growth of normal human adult bronchial epithelial cells have been developed. Serum and feeder cell requirements were abrogated by: (a) optimizing the calcium concentration in nutrient medium, MCDB 151; (b) supplementing with purified factors (epidermal growth factor, 5 ng/ml; insulin, 5 micrograms/ml; transferrin, 10 microgram/ml; hydrocortisone, phosphoethanolamine and ethanolamine, each at 5 x 10(-7) M; and trace elements); and (c) coating the surface of the culture dish with a mixture of fibronectin, collagen, and bovine serum albumin. Endothelial cell growth supplement (100 micrograms/ml) and retinoic acid (3 x 10(-10) M) further enchanced growth, whereas cholera toxin was nonmitogenic and serum supplementation (greater than 2%) markedly reduced the growth rate. Using the defined system, dissociated cultures of bronchial epithelial cells, obtained from more than 15 donors, have been subcultured at clonal densities with a colony forming efficiency of 3 to 4%. In addition, high density cultures have been subcultured more than five times with four to six population doublings per passage. The features of this system permit pathobiologic investigations of bronchial epithelial cells, e.g., aging, differentiation, and carcinogenesis using conditions that isolate the results from the influence of serum, feeder cells, and other undefined factors.

Adult↗
PubMed1982

DNA repair in human bronchial epithelial cells.

The purpose of this investigation was to compare the response of human cell types (bronchial epithelial cells and fibroblasts and skin fibroblasts) to various DNA damaging agents. Repair of DNA single strand breaks (SSB) induced by 5 krads of X-ray was similar for all cell types; approximately 90% of the DNA SSB were rejoined within one hour. During excision repair of DNA damage from u.v.-radiation, the frequencies of DNA SSB as estimated by the alkaline elution technique, were similar in all cell types. Repair replication as measured by BND cellulose chromatography was also similar in epithelial and fibroblastic cells after u.v.-irradiation. Similar levels of SSB were also observed in epithelial and fibroblastic cells after exposure to chemical carcinogens: 7,12-dimethylbenz[a]anthracene; benzo[a]pyrene diol epoxide (BPDE); or N-methyl-N-nitro-N-nitrosoguanidine. Significant repair replication of BPDE-induced DNA damage was detected in both bronchial epithelial and fibroblastic cells, although the level in fibroblasts was approximately 40% of that in epithelial cells. The pulmonary carcinogen asbestos did not damage DNA. DNA-protein crosslinks induced by formaldehyde were rapidly removed in bronchial cells. Further, epithelial and fibroblastic cells, which were incubated with formaldehyde and the polymerase inhibitor combination of cytosine arabinoside and hydroxyurea, accumulated DNA SSB at approximately equal frequencies. These results should provide a useful background for further investigations of the response of human bronchial cells to various DNA damaging agents.

Asbestos↗
PubMed1982

Chromosomal instability of SV40-transformed human prostatic epithelial cell lines.

Three SV40-transformed derivatives (G1, T2, and T5) of human prostatic epithelial cells were analyzed karyotypically. For comparison, an SV40 derivative (TA) obtained from isogenic fibroblasts, was also studied. The chromosome complements of these cells, as well as a sub-clone of T2 isolated in soft agar (T2-A5), were analyzed using banding techniques. Numerical as well as structural changes were observed in all transformed cultures. Karyotypic changes in all cells at a given passage level appeared to be random. On the other hand, characteristic differences in modal chromosome number, and type and number of abnormal chromosomes were observed among the different lines. Most cells of two of the three epithelial lines (T1 and T2) were either hypo- or pseudodiploid, whereas T5 consisted of a mixed hypodiploid and hypotetraploid population. The TA subline was also predominantly hypo- and pseudodiploid. Dicentrics, telomeric associations, translocations, and loss of chromosomes were the most prominent abnormalities. The loss of chromosome 18 was characteristic for all epithelial lines. All T1 and T5 cells had lost either one or both copies of the 18. While individual cells of the original T2 line had random karyotypes, most of T2-A5 cells had a relatively uniform karyotypic pattern. They also had a similar pattern of abnormal chromosomes. These observations suggest that culture in soft agar may have selected a particular chromosomal variant. We conclude that transformation of prostatic epithelial cells by SV40 may bring about site-specific as well as random chromosomal changes. These changes could reflect either intermediate or sequential stages in progression to neoplasia.

Cell Line↗
PubMed1982

Comparison of benzo(a)pyrene metabolism in bronchus, esophagus, colon, and duodenum from the same individual.

The metabolism of benzo(a)pyrene has been investigated in cultured normal human bronchus, colon, duodenum, and esophagus obtained from the same patient. The highest total metabolism was found in bronchus and duodenum, while the highest mean binding level was observed in the bronchus followed, in order, by the esophagus, duodenum, and transverse colon. A 30-fold interindividual variation in the binding level was found in each of the four organs studied, and a positive correlation between the binding levels in bronchus, colon, and duodenum was found. In human bronchus, a positive correlation was found between level of binding of benzo(a)pyrene to DNA and the amount of both benzo(a)pyrene 7,8-diol and the combined group of 3-hydroxybenzo(a)pyrene, benzo(a)pyrene 9,10-diol, and water-soluble metabolites. A significantly higher relative amount of benzo(a)pyrene tetrols and benzo(a)pyrene 9,10-diol was formed by human bronchus compared to the gastrointestinal tissues, while a higher level of benzo(a)pyrene phenols was formed by the latter. The relative distribution of benzo(a)pyrene-DNA adducts was similar in all four organs, the major DNA adduct being formed by trans-addition of anti-7,8-dihydroxy-9,10-epoxide-7,8,9,10-tetrahydrobenzo(a)pyrene to the 2-amino group at guanine. These results indicate that the metabolism of benzo(a)pyrene by at least four different organs is qualitatively similar but that quantitative differences exist.

Adolescent↗
PubMed1981

DNA-protein cross-linking by chromium salts.

DNA-protein cross-links were detected in several types of mammalian cells in culture when they were exposed to chromate salts. The cell types included human bronchial epithelial cells--the apparent cell type of origin of the malignancies reported in chromate workers. The level of cross-linking was proportional to the concentration of chromate used. These cross-links appeared to be persistent since no removal was seen after 12 h of repair incubation. A low level of DNA single strand breaks (SSB) were also induced after exposure of the cells to chromate but were rejoined after 4 h of repair incubation. The active form of chromium appears to be the trivalent since chromic but not chromate salts induced DNA-protein cross-links in isolated nuclei. Chromic salts also produced cross-linking between DNA and protein in solution while the hexavalent form was inactive. These data imply that chromate crosses the cell membrane, is reduced to the trivalent form and induces stable linkages of DNA to protein.

Animals↗
PubMed1981

Growth control of prostatic carcinoma cells in serum-free media: interrelationship of hormone response, cell density, and nutrient media.

Two established prostatic carcinoma cell lines have been grown in long-term culture in a defined medium (PFMR-4) free of serum, hormones, or growth factors. Growth of both lines in serum-free medium was population dependent. This cell-density requirement could be replaced by mitomycin C-inactivated feeder cells, homologous conditioned medium, or fetal bovine serum, but not by hormones or growth factors. The cells responded to these factors only at high density. The nature of this hormonal response was dependent on the kind of basal nutrient medium used. Growth in PFMR-4 with added insulin was more rapid than that in DME/F12 medium with any combination of hormones or growth factors and was substantially greater than growth in DME/F12 medium with insulin alone. The results demonstrate that whereas these two prostatic carcinoma lines (PC-3 and DU 145) do not require hormones for survival or growth, they do respond to certain hormones under appropriate conditions. These conditions include both the type of basal nutrient medium used and the population density.

Animals↗
PubMed1981

Clonal growth of epithelial cells from normal adult human bronchus.

Normal primary epithelial cell cultures devoid of fibroblastic cells have been developed from tissue explants of adult human bronchi. Conditions for clonal growth of secondary cultures of bronchial epithelial cells were optimized by coculturing the human cells with mitomycin C growth-arrested Swiss 3T3 mouse feeder cells, lowering the calcium concentration of medium M199, and supplementing it with hydrocortisone, insulin, cholera toxin, epidermal growth factor, and 1.25% fetal bovine serum. The epithelial cells grew for an average of 35 population doublings and had the normal human karyotype, expressed keratin and blood group antigen epithelial cell markers, metabolized benzo(a)pyrene, and were capable of differentiating into both ciliated and squamous cells. This culture system makes it potentially possible to investigate various aspects of differentiation and carcinogenesis in human bronchial epithelial cells.

Animals↗
PubMed1980

Differential properties among clones of simian virus 40-transformed human epithelial cells.

Monolayer cultures of human prostatic epithelial cells were exposed to SV40 virus at 35th population doubling. Clones were isolated from infected plates after growth had ceased on the control plates. The nuclei of these clones were virtually all positive for viral T-antigen by immunofluorescence. When the properties of three of these lines were compared to those of normal cells, they were found to have altered morphology, ultrastructure, chromosomes, and growth behavior. All transformed lines had reduced serum dependence and were capable of growing in soft agar. However, their reduced serum dependence was not due to reduced growth factor requirements because each subline's response to growth factors was different.

Agar↗