Extracellular and intracellular expression pattern of nuclear isoform of dUTP pyrophosphatase in mammalian cells after chemical carcinogen exposure

AIM: To study the extracellular and intracellular expression pattern of dUTP pyrophosphatase (nuclear isoform, DUT-N) in mammalian cells after exposure to different chemical carcinogens.METHODS: Human amniotic epithelial cells (FL cells), hepatoma cells (HepG2 cells) and cervical cancer cells (HeLa cells) were treated with N-methyl-N’-nitro-N-nitrosoguanidine (MNNG, N-nitroso alkylating agent) and benzo［a］pyrene-7, 8-dihydroxy-9, 10-epoxide (BPDE, the metabolic activated form of Benzo［a］pyrene). SDS-PAGE and immunoblotting were used to examine the extracellular and intracellular protein levels of DUT-N.RESULTS: Immunoblotting showed that DUT-N appeared in the culture medium of FL cells, but not HeLa cells, after MNNG and BPDE exposure. MNNG, not BPDE induced the appearance of this protein in the culture medium of HepG2 cells. Although MNNG and BPDE treatment both induced the appearance of DUT-N, the intracellular protein level was down-regulated in the former and up-regulated in the latter.CONCLUSION: The appearance of DUT-N in the culture medium after chemical carcinogen treatment is not a phenomenon induced by specific carcinogen, but there are some common features between different carcinogens or DNA-damaging agents for given cell lines, such as FL cell. Meanwhile, the cellular mechanism of DUT-N appearance remains different from one carcinogen to another.     

外语教学中母语文化的传播

随着经济全球化时代的到来,国际交流日益增多,多元文化的相互碰撞更加明显,母语文化在外语教学中的渗透格外重要。在英语教学中,应加强母语文化输入,在中西文化的对比中弘扬中华民族的传统文化,在中西文化的差异中,认识母语文化的博大精深。