Immortalization of primary human airway epithelial cells by ectopic expression of telomerase and their transformation by heavy ions

Full text: Human tumor cells are often immortalized with about 90% of them express telomerase. Ectopic expression of telomerase can contribute to in vitro malignant transformation . Lung cancer is the most frequent cause of cancer death throughout the world, and high-LET radiation is a well established contributing factor. In this studies, normal human small airway epithelial cells (SAEC) were transfected with the construct pBabest2 containing cDNA encoding hTERT by retrovirus-mediated gene transfer. Cells resistant to G418 were continuously cultured for more than 150 PDs. The hTERT-transfected cells (hTERT-SAE) expressed high telomerase activity, had a normal karyotype, without p16 and p53 alterations, and were non-tumorigenic in nude mice. The results indicated that the hTERT-SAE cell line was immortal and expressed normal phenotypes. The hTERT-SAEC cells were exposed to 60 cGy of 56Fe ions at passage 5 after selection with G418. The irradiated hTERT-SAE (hTERT-SAE-Fe) cells have also been cultured for over 150 PDs. They lost contact inhibition of growth and acquired anchorage independent phenotype. Tumorigenic potential of hTERT-SAE-Fe cells is currently being evaluated. The hTERT-immortalized SAEC cell line (hTERT-SAE) may be a better human bronchial epithelial cell model than their viral-immortalized counterparts in ascertaining the cellular and molecular pathways leading to radiation induced bronchial carcinogenesis