BioProject

Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). More...

Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). Phorbol esters, butyrates and N-nitroso compounds are known chemical carcinogens in foodstuffs and cigarettes that have been implicated as risk factors contributing to the development of NPC. We have demonstrated previously that low dose N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.1 microg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation (Chem Biol Interact 188: 623-634). Since residents of areas with a high risk of NPC are reported to contact with these carcinogens (TPA, SB or nitrosamines) frequently, we sought to determine the consequence of repeated exposure of EBV-harboring nasopharyngeal cells to these carcinogens in a long-term, low dose, repeated manner. An NPC cell line latently infected with EBV, NA, was periodically treated with TPA/SB combined with MNNG for recurrent EBV reactivation. After 10 times of chemically-induced recurrent reactivation of EBV, the expression profile analysis indicates that many carcinogenesis-related genes were altered in recurrent reactivated NA cells when compared to the parental NA cells. The expression profile was analyzed in the recurrent EBV reactivated NA cells and the parental NA cells. Overall design: The expression profile of two NA cells, NA-P10/TS-MG and NA-P1/mock, were analyzed in this study. NA-P10/TS-MG cells were subject to 10 times of repeated chemical exposure by incubating these cells periodically with TPA/SB (10 ng/ml and 1.0 mM) in combination with MNNG (0.1 microg/ml). The NA cells at the beginning of this experiment were defined as passage 0 (P0) cells. 24 h after seeding, the cells were subjected to a 24 h period of mock or chemical treatment. After this 24 hr treatment, the cells were recovered by replacing the medium with fresh (treatment-free) medium and incubation for a further 48 h. The resulting cells were defined as passage 1 (P1) cells. Cells from P1 were trypsinized and transferred and the process repeated again to obtain the P2 cells. A total of ten treatments were applied to the cells in this study. “NA-P10/TS-MG” refers to NA cells with 10 times of combined TPA/SB and MNNG (TS-MG) treatments. NA-P1/mock is mock-treated NA cells with one time of passage that was used as reference in this study. Replicates were included for each samples. Less...