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.