Decreased efficiency of γ-ray-induced DNA double-strand break rejoining in malignant transformants of human bronchial epithelial cells generated by alpha-particle exposure

Author: Sun J.-F.   Sui J.-L.   Zhou P.-K.   Geng Y.   Hu Y.-C.   Cao Z.-S.   Ge S.-L.   Lou T.-Z.   Wu D.-C.  

Publisher: Informa Healthcare

ISSN: 1362-3095

Source: International Journal of Radiation Biology, Vol.78, Iss.9, 2002-09, pp. : 773-780

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Abstract

Purpose: To investigate the cytogenetic changes and DNA double-strand break (DSB) rejoining of transformed cell lines generated from human bronchial epithelial cells by α-particle exposure.Materials and methods: Transformed cell lines were derived from the HPV 18-immortalized human bronchial epithelial cell line BEP2D generated by 1.5 Gy of α-particles emitted by a 238Pu source. Two cell lines, BERP35T1 and BERP35T4, were investigated. Karyotypes were analyzed by trypsin/Giemsa banding. Cell survival was estimated by colony assay. PFGE was used to detect the DNA DSB. mRNA expression was analyzed by RT-PCR.Results: Abnormal chromosomes 2 and 12 with elongated long arm and deletions of chromosomes 2, 12, 13 and 17 were observed in the transformed cell lines. BERP35T4 showed a much higher proportion of polyploid cells (40.5%) compared with parental BEP2D cells and the BERP35T1 cell line (5%). BERP35T1 and BERP35T4 showed a markedly lower capacity for rejoining of γ-ray-induced DNA DSB and increased radio-sensitivity compared with parental BEP2D cells. The analysis of mRNA levels revealed a 2.5- to 6.5-fold down-regulated expression of the DNA repair genes XRCC-2, XRCC-3 and Ku80 in BERP35T1 and BERP35T4 cells.Conclusion: The karyotypic changes of chromosomes 2, 12, 13 and 17 and the deficiency of DSB rejoining could be related to the malignant transformation processing of BEP2D cells initiated by α-particle exposure.

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