Publications (5)7.9 Total impact
-
Article: Novel human bronchial epithelial cell lines for cystic fibrosis research.
[show abstract] [hide abstract]
ABSTRACT: Immortalization of human bronchial epithelial (hBE) cells often entails loss of differentiation. Bmi-1 is a protooncogene that maintains stem cells, and its expression creates cell lines that recapitulate normal cell structure and function. We introduced Bmi-1 and the catalytic subunit of telomerase (hTERT) into three non-cystic fibrosis (CF) and three DeltaF508 homozygous CF primary bronchial cell preparations. This treatment extended cell life span, although not as profoundly as viral oncogenes, and at passages 14 and 15, the new cell lines had a diploid karyotype. Ussing chamber analysis revealed variable transepithelial resistances, ranging from 200 to 1,200 Omega.cm(2). In the non-CF cell lines, short-circuit currents were stimulated by forskolin and inhibited by CFTR(inh)-172 at levels mostly comparable to early passage primary cells. CF cell lines exhibited no forskolin-stimulated current and minimal CFTR(inh)-172 response. Amiloride-inhibitable and UTP-stimulated currents were present, but at lower and higher amplitudes than in primary cells, respectively. The cells exhibited a pseudostratified morphology, with prominent apical membrane polarization, few apoptotic bodies, numerous mucous secretory cells, and occasional ciliated cells. CF and non-CF cell lines produced similar levels of IL-8 at baseline and equally increased IL-8 secretion in response to IL-1beta, TNF-alpha, and the Toll-like receptor 2 agonist Pam3Cys. Although they have lower growth potential and more fastidious growth requirements than viral oncogene transformed cells, Bmi-1/hTERT airway epithelial cell lines will be useful for several avenues of investigation and will help fill gaps currently hindering CF research and therapeutic development.AJP Lung Cellular and Molecular Physiology 11/2008; 296(1):L82-91. · 3.66 Impact Factor -
Article: Comparison of flow cytometry- and microscopy-based methods for measuring micronucleated reticulocyte frequencies in rodents treated with nongenotoxic and genotoxic chemicals.
[show abstract] [hide abstract]
ABSTRACT: The development of automated flow cytometric (FCM) methods for evaluating micronucleus (MN) frequencies in erythrocytes has great potential for improving the sensitivity, reproducibility, and throughput of the traditional in vivo rodent MN assay that uses microscopy-based methods for data collection. Although some validation studies of the FCM evaluation methods have been performed, a comprehensive comparison of these two data collection methods under routine testing conditions with a variety of compounds in multiple species has not been conducted. Therefore, to determine if FCM evaluation of MN frequencies in rodents was an acceptable alternative to traditional manual scoring methods in our laboratory, we conducted a comparative evaluation of MN-reticulocyte (MN-RET) frequencies determined by FCM- and microscopy-based scoring of peripheral blood and bone marrow samples from B6C3F1 mice and Fisher 344 rats. Four known inducers of MN (cyclophosphamide, ethyl methanesulfonate, vincristine sulfate, acrylamide) were assayed in bone marrow and peripheral blood of both mice and rats. In addition, MN-RET frequencies were measured in bone marrow (microscopy) and peripheral blood (FCM) of mice treated with five nongenotoxic chemicals (S-adenosylmethionine chloride, cefuroxime, diphenolic acid, 3-amino-6-methylphenol, pentabromodiphenyl oxide). No significant differences were observed between results obtained by the two methods in either species. These results support the use of FCM for determining MN-RET frequency in rodents after chemical exposure.Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 02/2008; 649(1-2):101-13. · 2.85 Impact Factor -
Article: Telomerase expression is sufficient for chromosomal integrity in cells lacking p53 dependent G1 checkpoint function.
[show abstract] [hide abstract]
ABSTRACT: Secondary cultures of human fibroblasts display a finite lifespan ending at senescence. Loss of p53 function by mutation or viral oncogene expression bypasses senescence, allowing cell division to continue for an additional 10-20 doublings. During this time chromosomal aberrations seen in mitotic cells increase while DNA damage and decatenation checkpoint functions in G2 cells decrease. To explore this complex interplay between chromosomal instability and checkpoint dysfunction, human fibroblast lines were derived that expressed HPV16E6 oncoprotein or dominant-negative alleles of p53 (A143V and H179Q) with or without the catalytic subunit of telomerase. Cells with normal p53 function displayed 86-93% G1 arrest after exposure to 1.5 Gy ionizing radiation (IR). Expression of HPV16E6 or p53-H179Q severely attenuated G1 checkpoint function (3-20% arrest) while p53-A143V expression induced intermediate attenuation (55-57% arrest) irrespective of telomerase expression. All cell lines, regardless of telomerase expression or p53 status, exhibited a normal DNA damage G2 checkpoint response following exposure to 1.5 Gy IR prior to the senescence checkpoint. As telomerase-negative cells bypassed senescence, the frequencies of chromosomal aberrations increased generally congruent with attenuation of G2 checkpoint function. Telomerase expression allowed cells with defective p53 function to grow >175 doublings without chromosomal aberrations or attenuation of G2 checkpoint function. Thus, chromosomal instability in cells with defective p53 function appears to depend upon telomere erosion not loss of the DNA damage induced G1 checkpoint.Journal of Carcinogenesis 10/2005; 4:18. -
Article: Chromosomal abnormalities in bronchial epithelium from smokers, nonsmokers, and lung cancer patients.
[show abstract] [hide abstract]
ABSTRACT: The identification of individuals who are at greatest risk of developing lung cancer would greatly improve diagnosis and possibly lead to early treatment. To study the use of karyotypes for this purpose, we used short-term human bronchial epithelial (hBE) cell cultures from nonsmokers, smokers, and lung cancer patients. Twenty-five metaphases were scored for hBE cell cultures obtained from 32 patients: 8 were nonsmokers, and 24 had a history of smoking (of whom 11 had had lung cancer surgery). The number of abnormal metaphases ranged from 0 to 4 per cell culture. No overall differences in the number of abnormal metaphases were observed between nonsmokers and smokers or between lung cancer patients and non-lung cancer patients. The most commonly observed abnormalities were structural changes in chromosome 1 (six cultures), loss of chromosome 17 (six cultures), and trisomy of chromosome 20 (three cultures). These specific alterations were found almost exclusively in patients with a history of tobacco smoking. The results did not indicate that general chromosomal abnormalities are a useful marker for tobacco smoke exposure or cancer risk.Cancer Genetics and Cytogenetics 07/2005; 159(2):137-42. · 1.39 Impact Factor -
Article: Telomerase expression is sufficient for chromosomal integrity in cells lacking p53 dependent G<sub>1 </sub>checkpoint function
[show abstract] [hide abstract]
ABSTRACT: Abstract Background Secondary cultures of human fibroblasts display a finite lifespan ending at senescence. Loss of p53 function by mutation or viral oncogene expression bypasses senescence, allowing cell division to continue for an additional 10 – 20 doublings. During this time chromosomal aberrations seen in mitotic cells increase while DNA damage and decatenation checkpoint functions in G<sub>2 </sub>cells decrease. Methods To explore this complex interplay between chromosomal instability and checkpoint dysfunction, human fibroblast lines were derived that expressed HPV16E6 oncoprotein or dominant-negative alleles of p53 (A143V and H179Q) with or without the catalytic subunit of telomerase. Results Cells with normal p53 function displayed 86 – 93% G<sub>1 </sub>arrest after exposure to 1.5 Gy ionizing radiation (IR). Expression of HPV16E6 or p53-H179Q severely attenuated G<sub>1 </sub>checkpoint function (3 – 20% arrest) while p53-A143V expression induced intermediate attenuation (55 – 57% arrest) irrespective of telomerase expression. All cell lines, regardless of telomerase expression or p53 status, exhibited a normal DNA damage G<sub>2 </sub>checkpoint response following exposure to 1.5 Gy IR prior to the senescence checkpoint. As telomerase-negative cells bypassed senescence, the frequencies of chromosomal aberrations increased generally congruent with attenuation of G<sub>2 </sub>checkpoint function. Telomerase expression allowed cells with defective p53 function to grow >175 doublings without chromosomal aberrations or attenuation of G<sub>2 </sub>checkpoint function. Conclusion Thus, chromosomal instability in cells with defective p53 function appears to depend upon telomere erosion not loss of the DNA damage induced G<sub>1 </sub>checkpoint.Journal of Carcinogenesis. 01/2005;
