Phenotypic, molecular and genetic-characterization of transformed human bronchial epithelial-cell strains

In order to study the phenotypic, genetic, and molecular characteristics of normal human bronchial epithelial cells (HBE) so as to establish a model of HBE cell carcinogenesis, we established six HBE cell strains by transfection with either the SV40 virus or an origin of replication defective large T plasmid. Tracheobronchial specimens were obtained from autopsy samples or heart donors from noncancer patients, cultured, and transfected using strontium chloride. Three cell strains were established by transfection with the whole SV40 virus (NL4SV, NL11SV, and NL20SV) and three cell strains were established with the origin of replication depleted T antigen (NL25, NL30-0, NL30-N). All of the cell strains senesced between passages 19-28. None of the cell strains formed colonies in 0.15% agarose. All required epidermal growth factor, whereas their requirement for fetal bovine serum was variable. None of the cell strains formed tumors in nude mice. Cytogenetic analysis revealed that none of the cell strains were diploid. They ranged from having few random changes to extreme chromosomal instability. Only one cell strain (NL30-N) had two consistent markers. About one-third of the NL30-O cells, derived from independent cultures from the same donor, had the same markers. No DNA amplification for c-myc was observed in any of the transformed HBE cell strains. No mutations were detected in K-ras codons 12, 13, and 61 using primer engineered restriction fragment-length polymorphism analysis. No mutations were detected in exons 5-9 of the p53 gene by single strand conformation polymorphism (SSCP) analysis. We conclude that despite differences in morphology, phenotype, differentiation, and karyotype between six nontumorigenic HBE cell strains, none have activation of dominant oncogenes or inactivation of tumor suppressor genes that have been described in human lung tumors. These cells should be useful as a model for molecular studies of HBE cell carcinogenesis.

Evaluation of the false-negative rate of standardized and quantitative measurement of estrogen receptor (ER) in tissue using AQUA technology

567

Background: The discovery of an astoundingly high false negative rate for estrogen receptor (ER) testing in Canada has raised questions about the accuracy and reproducibility of ER testing. One solution would be the introduction of a standardized and reproducible diagnostic test that is easily adaptable in the clinical setting. Here, we have tested the AQUA method of quantitative immunofluorescence for the standardized and reproducible quantification of ER protein expression in tissue. Methods: Quantitative Western blotting was used in conjunction with AQUA analysis to create standard curves for assessment of absolute ER protein concentration in tissue (n = 118). We used standard scoring methods and AQUA analysis to quantify ER protein expression in a large cohort of breast cancer samples (n =669). Results: Using a series of standard curves, we determined that the range of the ER AQUA assay is between 100 pg/μg and 1500 pg/μg total protein. ER protein concentration in breast cancer samples showed an expected unimodal distribution for quantitative assessment of ER. Reproducibility studies of AQUA analysis demonstrated significant instrument-to-instrument (laboratory-to-laboratory) reproducibility for 3 instruments across the range of AQUA scores (average %CV = 1.34; R2>0.99; ANOVA p = 0.67). The same cases were then read and classified by 3 pathologists using the Allred scoring system. Although their concordance is similar to that seen in the literature (Kappa = 0.81, 0.88, and 0.89), pathologist concordance rate is lower than for that observed with AQUA analysis (Kappa = 0.95, 0.96, and 0.97). Importantly, 9.0% of cases showed a change of diagnosis (positive/negative) across 3 pathologists whereas only 2.8% of cases changed classification using AQUA analysis. Additionally, misclassified cases occurred across the entire range of Allred scores, but were restricted to a narrow region defined by the cut-point for AQUA scoring. Conclusions: We have demonstrated that AQUA technology can provide for the standardized and reproducible quantification of ER with a 3 fold reduction in misclassification. This approach has the potential to decrease the problem of false negative tests for ER.

[Table: see text]

Early effects of retinoic acid on proliferation, differentiation and apoptosis in non-small cell lung cancer cell lines

BACKGROUND

Retinoids represent a potentially useful class of drugs in the chemoprevention and treatment of cancer, due to their ability to regulate cell proliferation and differentiation. However, there is controversy in the literature about the effects of all-trans retinoic acid (ATRA) in non- small cell lung cancer (NSCLC). In this study we examined the effects of ATRA on apoptotic death in NSCLC.

MATERIALS AND METHODS

Cell proliferation was determined by thymidine incorporation in cultured NSCLC cells. DNA fragmentation was measured in NSCLC cell lines as a marker of apoptosis. The expression of keratinocyte transglutaminase and cytokeratin 10 were measured as markers of squamous differentiation.

RESULTS

ATRA inhibited cell proliferation, and induced markers of both apoptosis and squamous differentiation after 24-48 hrs of treatment.

CONCLUSIONS

These results indicate the possibility of the early growth-inhibitory and apoptotic effects of ATRA in NSCLC which may result in selection of ATRA-resistant cells.

Induction of multiple programmed cell death pathways by IFN-beta in human non-small-cell lung cancer cell lines

Tissue transglutaminase (tTG) and keratinocyte transglutaminase (kTG), as well as the cross-linked envelopes (CLE) that they form, have been associated with squamous differentiation and programmed cell death in epithelial cells. When interferon-beta (IFN-beta) was used to stimulate differentiation and programmed cell death in the human lung cancer cell lines NCI-H596 and NCI-H226, the cells underwent a decrease in cellular density. In NCI-H596 IFN-beta caused an increase in kTG activity and DNA fragmentation in the lower density cells, which were significantly slower growing than control cells. However, in the higher density cells, which were only slightly slower growing than control cells, IFN-beta caused an increase in tTG activity and CLE competence. Dual-parameter flow cytometry demonstrated that IFN-beta-induced squamous differentiation preceded programmed cell death. Treatment of NCI-H596 cells with monodansylcadaverine, a transglutaminase inhibitor, prevented the increase in CLE competence, but did not inhibit DNA fragmentation. These results suggest that IFN-beta can induce NCI-H596 cells to enter multiple cell death pathways and that these pathways are not only differentiation related, but may also be growth driven.

Induction of squamous differentiation by interferon beta in a human non-small-cell lung cancer cell line

BACKGROUND

More than 95% of lung cancers occur in the bronchi, appearing as adenocarcinoma, squamous carcinoma, large-cell and small-cell carcinoma, or mixed types. Generally, the least aggressive form is squamous cell lung cancer, suggesting the possibility that promotion of squamous cell differentiation may have therapeutic potential for non-small-cell lung cancer, a disease having no effective systemic therapy. Interferons are a group of glycoproteins with known antiproliferative effects, including the ability to induce differentiation in certain cases.

PURPOSE

These studies were conducted to determine whether interferon beta induces squamous cell differentiation in non-small-cell lung cancer in vitro.

METHODS

NCI-H596 adenosquamous cells were grown to confluence to maximize their differentiation potential. Growth and parameters for squamous differentiation (cross-linked envelope competence, transglutaminase activity, and relative involucrin expression) were then measured when the cells were exposed to various concentrations of interferon beta.

RESULTS

Interferon beta inhibited growth of the NCI-H596 cell line and stimulated envelope competence, involucrin expression, and type 2 transglutaminase activity. Alterations in transglutaminase activity and involucrin expression preceded induction of envelope competence and growth suppression.

CONCLUSIONS

Interferon beta suppresses the growth and stimulates markers of squamous differentiation in NCI-H596. While the mechanism(s) for such effects are unknown, the sequence of effects suggests a causal relationship between differentiation induction and subsequent growth suppression.

IMPLICATIONS

Interferon beta may have clinical usefulness in squamous differentiation strategies for the treatment of non-small-cell lung cancer. More must be learned about the mechanisms whereby interferons and other biologic agents induce differentiation, and clinical trials will be needed to determine whether in vitro results are pertinent in vivo.