title: Sequential cytogenetic and molecular cytogenetic characterization of an SV40T-immortalized nasopharyngeal cell line transformed by Epstein-Barr virus latent membrane protein-1 gene.
abstract: Cytogenetic and molecular cytogenetic analyses were performed on four sublines derived from a newly established, SV40T-immortalized nasopharyngeal (NP) cell line, NP69, with two of the sublines expressing LMP1, an Epstein-Barr virus-encoded gene. A total of seven cytogenetically related subclones were identified, all having highly complex karyotypes with massive numerical and structural rearrangements. Centromeric rearrangements in the form of isochromosomes and whole-arm translocations were prevalent. A cytogenetic sign of gene amplification [i.e., homogeneously staining region (HSR)] was detected at 1q25 in all metaphase cells analyzed. Multicolor combined binary ratio labeling fluorescence in situ hybridization (COBRA-FISH) was used to confirm the karyotypic interpretations. Furthermore, multicolor COBRA-FISH also showed that part of the HSR contained chromosome 20 material. Extensive clonal evolution could be observed by the assessment of karyotypic variation among different subclones and individual metaphase cells. The evaluation of clonal evolution enabled the identification of the temporal order of chromosome aberrations during cell immortalization and malignant transformation. A striking karyotypic similarity was found between sublines expressing LMP1 and an NP carcinoma cell line, with loss of genetic material from chromosome arm 3p being an important recurrent observation. More interestingly, the karyotypic features of NP69 were also similar to those of many epithelial malignancies. Our observations suggest that serial transformation of NP cell lines might provide a useful in vitro model for the study of the multistep neoplastic transformation of NP cells.
authors.affiliation: Department of Anatomy, Faculty of Medicine, University of Hong Kong, 21, Sassoon Road, Hong Kong, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.forename: Sai Wah
authors.initials: SW
authors.lastname: Tsao
authors.forename: Charlotte
authors.initials: C
authors.lastname: Jin
authors.forename: Bodil
authors.initials: B
authors.lastname: Strömbeck
authors.forename: Po Wing
authors.initials: PW
authors.lastname: Yuen
authors.forename: Yok-Lam
authors.initials: YL
authors.lastname: Kwong
authors.forename: Yuesheng
authors.initials: Y
authors.lastname: Jin
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods; D002472:Cell Transformation, Viral / Q000235:genetics*; D002874:Chromosome Mapping; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D009305:Nasopharynx; D013539:Simian virus 40 / Q000235:genetics*; D014162:Transfection; D014763:Viral Matrix Proteins / Q000235:genetics*
chemical_list: C037662:EBV-associated membrane antigen, Epstein-Barr virus; D014763:Viral Matrix Proteins