Background & objective: The authors have selected three different biological character sublines, including 5-8F (the highest tumorigenic and metastatic ability), 6-10B(the lowest tumorigenicity and lack of metastatic ability), and 13-9B(lack of tumorigenic ability), from colony lines of nasopharyngeal carcinoma cell line(SUNE-1). The aim of this study was to determine the molecular mechanisms of different biological character of SUNE-1 and its three sublines from two aspects of genetic and virology.
Method: 1. Amplifying Epstein-Barr virus(EBV) BamHI W fragment by PCR. 2. Determining the expression of latent membrane protein1(LMP1) of EBV in the sublines using in situ hybrization. 3. Molecular cytogenetic analysis of the cell line and sublines by comparative genomic hybridization (CGH).
Results: 1. There was EBV BamHI W fragment in SUNE-1 and its three sublines. 2. Expression of LMP1 was observed in the SUNE-1 and its three sublines, and their expression intensity was identical. 3. There were DNA copy number gains on chromosomes 1, 2p, 3, 4, 5p, 6, 7, 9, 10q, 11, 12q, 13q, and 18q as well as loss on 22q in the SUNE-1 cell line; DNA copy number gains on chromosomes 3p, 7q, 8q, 9q, and 10q were observed in 5-8F subline; DNA copy number loss on few chromosomes, but no DNA copy number gain was observed in the 6-10B and 13-9B sublines.
Conclusion: There were expression of EBV and different genetic changes in the SUNE-1 and its three sublines. It is suggesting that the different biological character tumorgenesis and metastasis of nasopharyngeal carcinoma cell sublines may be due to genetic changes; and EBV infection may play an important role in keeping the malignant phenotypic of nasopharyngeal carcinoma.